Polymers - Amazon S3Tech+Briefs+-+Polymers.pdf · 2018-03-20 · Polymers In Packaging | 4 ETBs of COMMON PACKAGING MATERIALS: POLYMERS Polymers In Packaging OvERvIEw The use of polymers

COMMON PACKAGING MATERIALS

Environmental Technical Briefs of

Polymers

Prepared by

We graciously thank all our dedicated resident experts in the Sustainable Packaging Coalition and packag-ing industry who volunteered to review several iterations of each material brief and gave us sound guidance to make this report possible.

© 2009 Green Blue Institute®. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means-electronic, mechanical, photocopying, recording or otherwise without the permission of the Green Blue Institute.

Environmental Technical Briefs of Common Packaging Materials, prepared by the Sustainable Packaging Coalition®, summarize the environmental, human health and other relevant issues associated with the production, use and end–of–life of common packaging materials.

Project Lead: Minal Mistry Advisor: Anne Johnson Contributors: Benson Gabler, Anne Johnson, Martha Stevenson, Cal Trepegnier, Alex Tsuji and Metafore Designer: Peter Massarelli

The Sustainable Packaging Coalition (www.sustainablepackaging.org) is a project of GreenBlue,® a nonprofit institute that works with the private sector to enable the positive redesign of industrial systems.

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E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Contents

INTROduCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

About The Sustainable Packaging Coalition 1Background 1

POLyMERS IN PACKAGING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Overview 4Ethylene & Propylene Monomer Production Process 5

POLyPROPyLENE (PP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Assumptions and Limitations 6Overview 6Production Methods 6Emissions 8Material Health 8End-of-Life 8Sustainability Potential 9

HIGH-dENSITy POLyETHyLENE (HdPE) . . . . . . . . . . . . . . . . . . . 11


LOw-dENSITy POLyETHyLENE (LdPE) . . . . . . . . . . . . . . . . . . 16


POLyETHyLENE TEREPHTHALATE (PET) . . . . . . . . . . . . . . . . . 21

Assumptions and Limitations 21


Overview 21Production Methods 21Emissions 23Material Health 24End-of-Life 24Sustainability Potential 25

POLySTyRENE (PS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


POLyvINyL CHLORIdE (PvC) . . . . . . . . . . . . . . . . . . . . . . . . . . 33


POLyLACTIdE (PLA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40


REfERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45


List of figuresFigure 1: Life Cycle Phases of Packaging. . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2: Generalized Life Cycle Data Boundary . . . . . . . . . . . . . . . . . . 2

Figure 3: U.S. Packaging Market (FPA 2008) . . . . . . . . . . . . . . . . . . . . . 2

Figure 4: Container and Packaging MSW Data for 2007—Total: 78.4 million tons (U.S. EPA 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure 5: 2007 Packaging Material Discards and Recovery in U.S. (U.S. EPA 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 6: 2007 Percent Recovery Discard for Packaging Material (U.S. EPA 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 7: 2007 Plastics Packaging Disposal and Recovery Data—Total: 13.6 million tons (U.S. EPA 2008) . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 8: Simplified Flow Diagram of Virgin Monomer and Polymer Production (modified from APME 2005) . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 9: Flow Diagram of Virgin Polypropylene Production (McKetta 1992) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 10: Flow Diagram of Recycled Polypropylene Processing . . . . . . . 7

Figure 11: Life Cycle Inventory Data Boundary for Polypropylene . . . . . 7

Figure 12: Flow Diagram of Virgin HDPE Production (modified from Brown and Cole 1993) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 13: Flow Diagram of Recycled HDPE Processing . . . . . . . . . . . 12

Figure 14: HDPE Life Cycle Inventory Data Boundary . . . . . . . . . . . . 12

Figure 15: End Use of Recycled HDPE Bottles (APC 2007). . . . . . . . . 14

List of TablesTable 1: U.S. Polymers in Municipal Solid Waste (MSW) Data(U.S. EPA 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4


Figure 16: Flow Diagram of Virgin LDPE Production (modified from Brown and Cole 1993) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 17: Flow Diagram of Recycled LDPE Production . . . . . . . . . . . 17

Figure 18: LDPE Life Cycle Inventory Data Boundary. . . . . . . . . . . . . 17

Figure 19: Flow Diagram of Virgin PET Production (NAPCOR 2006) 21

Figure 20: Flow Diagram of Recycled PET (rPET) Production . . . . . . 22

Figure 21: Chemical Recycling of PET via Glycolysis (modified from Verma 2004) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 22: PET Life Cycle Inventory Data Boundary . . . . . . . . . . . . . . 23

Figure 23: Flow Diagram of Virgin Monomer Production (modified from APME 2005a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 24: Flow Diagram of Virgin Polystyrene Production (modified from APME 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 25: Flow Diagram of Batch Polystyrene Process (U.S. EPA 2008a). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 26: Flow Diagram of Continuous Polystyrene Process (U.S. EPA 2008a). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 27: PS Life Cycle Inventory Data Boundary . . . . . . . . . . . . . . . 29

Figure 28: Flow Diagram of PVC Production (modified from University of Bristol, 2008) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 29: Flow Diagram of Virgin PVC Production (modified from APME 2006, Tukker et al 1995, Baitz et al 2004,Postle et al 2000). . . . . 35

Figure 30: PVC Life Cycle Inventory Data Boundary. . . . . . . . . . . . . . 36

Figure 31: Simplified Flow Diagram of Virgin PLA Production (adapted from Vink et al 2007) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 32: Life Cycle Data Boundary for PLA Production . . . . . . . . . . 42

Introduction | 1E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Introduction

ABOuT THE SuSTAINABLE PACKAGING COALITION

The Sustainable Packaging Coalition (SPC) is an in-dustry working group composed of over 200 compa-nies within the packaging value chain. The Coalition is internationally recognized as a resource for credible information about packaging and sustainability (www.sustainablepackaging.org).

The SPC works to develop educational resources and tools to support the design and development of environ-mentally improved packaging. Members contribute indi-vidual technical expertise to help create shared, publicly available resources.

BACKGROuNd

Scope Of Environmental Technical Briefs

The purpose of packaging materials briefs is to assist pack-aging designers and engineers in understanding the gross environmental and human health impacts of the material used for packaging purposes. The information contained in this report is for the most part confined to the United States.

The information in these briefs is by necessity simplified and is intended to provide general information only. It is not intended to replace life cycle analysis used to compare material specific applications. We encourage readers to use the resources at the end of this document for further information.

Figure 1 is a conceptualized graphic of the packaging life cycle. The life cycle inventory data used in this report come from various publicly available sources, and includes life cycle phases from raw material extraction to primary (vir-gin) and secondary (recycled) material manufacture. Life cycle data for conversion, distribution, use and end-of-life stages are not included.

Contents

Packaging serves many purposes. They include physical protection of the product, marketing and branding, theft protection, convenience, and portion control. Depending on the intended use, one or many of these may be deci-sion factors in packaging design. Many materials are used

individually or in combination to meet the performance requirements of modern packaging.

This report presents production and environmental infor-mation for polymers commonly used to make packaging. Materials included in this report include: polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terepthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), and polylactic acid (PLA).

Material briefs were compiled by GreenBlue staff and ex-ternally reviewed by industry experts from within the SPC membership.

Life Cycle Perspective

Each brief presents an overview of the production meth-ods; resource intensity; material health, end-of-life implica-tions, sustainability concerns, and innovations related to each material. Details of each brief vary depending on the availability of information and data.

The material briefs included in this report address issues across the lifecycle of a material with a particular focus on packaging. Where data are available, attempts have been made to offer comparison of environmental loads of pro-cessing both virgin and recycled materials.

figure 1: Life Cycle Phases of Packaging

©GreenBlue

http://www.sustainablepackaging.org

http://www.sustainablepackaging.org


Boundary Assumptions

Figure 2 depicts the boundary of the life cycle data covered. The energy, water, and waste information in these briefs is limited to the extraction of raw material through the pro-cessing steps just prior to container fabrication as depicted in Figure 2.

Packaging Materials Recovery And discard data

Figures 3 through 6 illustrate the U.S. market for various types of packaging, their proportion in the waste stream, and their recovery and discard rates (U.S. EPA 2008). Full municipal solid waste (MSW) data are available from the U.S. Environmental Protection Agency’s website.

Recovery Initiatives

The European Union has a Packaging and Packaging Waste Directive setting a 2008 target of recycling 60% of packag-ing waste, which includes incineration. There is a specific material goal of 22.5% for plastics, counting exclusively material that is recycled back into plastics (OJEC 2004). The European Parliament voted for the goal of recycling or re-using half of the main types of EU household waste by 2020 and 70% of all waste from building and demolition (Harisson 2008).

One of the key drivers for recycling in Japan is the Law for Promotion of Sorted Collection and Recycling of Contain-ers and Packaging. This legislation mandates manufacturers to recycle a percentage of waste packaging sorted and col-lected by local governments (JEPSRA 2008).

Processes analyzed inthe document

Raw MaterialExtraction

ContainerFabrication

ConsumerUse

End-of-Life

Recycled MaterialData

Recycling

MaterialProcessing

figure 2: Generalized Life Cycle Data Boundary

Other(15%)Glass (3%)

flexible plastics(18%)

Rigid Plastics(17%)

Paperboard(11%)

Corrugated(24%)

Metal Cans(12%)

figure 3: U.S. Packaging Market (FPA 2008)

wood(11%)

Plastics(17%)

Aluminum(2%)

Steel(3%)

Glass(15%)

Paper & Paperboard(52%)

figure 4: Container and Packaging MSW Data for 2007—Total: 78.4 million tons (U.S. EPA 2008)


0

5

10

15

20

25

30

35

40

discardedRecovered

Paper &Paperboard

PlasticsGlasswoodSteelAluminum

Mill

ions

of

Tons

figure 5: 2007 Packaging Material Discards and Recovery in U.S. (U.S. EPA 2008)

0%

20%

40%

60%

80%

100%

% discard% Recovery

Paper&

Paperboard

PlasticsGlasswoodSteelAluminum

figure 6: 2007 Percent Recovery Discard for Packaging Material (U.S. EPA 2008)

Polymers In Packaging | 4E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polymers In Packaging

OvERvIEw

The use of polymers and biopolymers in packaging is grow-ing. This section contains environmental technical briefs for some of the most common polymers used in packaging applications: polyethylene terephthalate (PET, SPI resin code 1); high-density polyethylene (HDPE, SPI resin code 2); polyvinyl chloride (PVC, SPI resin code 3); low-density polyethylene (LDPE, SPI resin code 4); polypropylene (PP, SPI resin code 5); polystyrene (PS, SPI resin code 6), and polylactic acid (PLA, currently SPI resin code 7 or Other) (see Table 1). Of these materials, PLA is the only bio-based polymer.

Plastics are estimated to account for 21% of all packaging materials in volume (Plastemart 2008). In 2007, plastics made up 12% (31 million tons) of the U.S. municipal solid waste (MSW). About fourteen million tons of this plastic was in the form of containers and packaging (see Figure 7). Twelve percent of plastic packaging was recovered (U.S. EPA 2008).

Recovery and discard data from 2007 MSW for the seven commercial resin codes for containers and packaging are displayed in Table 1 and Figure 7.

Factors influencing the economic viability of commercial re-covery of plastics include contamination problems, volumes generated, variability of polymer formulations, inability to separate composite polymeric materials, and the availability of infrastructure and appropriate end-of-life technology. As a result, the recovery rates for individual polymer types re-main relatively low compared to more established materials such as steel and paper-based packaging. However, the ex-perience of Europe and other countries over the past decade shows that there are significant opportunities for increasing collection and recycling to divert materials with high value away from traditional disposal in landfills.

u .S . MuNICIPAL SOLId wASTE

Polymer SPICode

2007Recovery

Polyethylene Terephthalate (PET) 1 23%

High-Density Polyethylene (HDPE) 2 14%

Polyvinyl Chloride (PVC) 3 0%

Low- Density Polyethylene (LDPE) 4 10%

Polypropylene (PP) 5 0.5%

Polystyrene (PS) 6 6.7%

Other (includes PLA) 7 -

Table 1: U.S. Polymers in Municipal Solid Waste (MSW) Data (U.S. EPA 2008)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

discardedRecovered

Other(7)

PS(6)

PP(5)

LdPE/LLdPE

(4)

PvC (3)

HdPE(2)

PET(1)

Note: The number in the parentheses below the material label represents the Society of the Plastics Industry’s (SPI) resin identifi-cation code for that material.

Thou

sand

s of

Ton

s

figure 7: 2007 Plastics Packaging Disposal and Recovery Data—Total: 13.6 million tons (U.S. EPA 2008)

Polymers In Packaging | 5E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

ETHyLENE & PROPyLENE MONOMER PROduCTION PROCESS

All the fossil fuel-based polymers in this report start with monomers, basic building blocks derived from petroleum or natural gas via the process of steam cracking. Ethylene (CAS # 87701-65-3) and propylene (CAS# 76-63-1) are hydrocarbon fractions derived from the steam cracking of crude oil or natural gas as depicted in Figure 8. Ethylene in particular is the basis for many polymer synthesis pro-cesses.

Both natural gas and petroleum are extracted from the earth. After being transported to a gas processing plant or oil refinery, the gas or oil is mixed with naphtha prior to the steam cracking process (APME 2005). The extreme heat used in the process reduces or ‘cracks’ the molecule size of the natural gas or oil, forming lighter and more reactive hydrocarbons like ethylene and other monomers such as propylene (APME 2005). To produce ethylene, the cracking process reduces the naphtha molecules from a length of six or ten carbons to two carbons.

Natural Gas Extraction

Cracking

Polymerization Polymerization

ETHyLENE

LDPE,LLDPE,HDPE

PVCPSPET

PROPyLENE

Natural Gas Processing

Oil Refining

Crude Oil Extraction

Crude Oil

intermediate steps

PP EpoxyResins

Poly-carbonate

intermediate steps

Natural Gas (raw)

Naptha Natural Gas (pure)

figure 8: Simplified Flow Diagram of Virgin Monomer and Polymer Production (modified from APME 2005)

Polypropylene | 6E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polypropylene (PP)

ASSuMPTIONS ANd LIMITATIONS

• The information in this brief is focused on North America but European and Asian data and infor-mation are included where possible.

• The life cycle inventory data used for this brief include raw material extraction through pellet production.

OvERvIEw

Polypropylene (PP), SPI resin code #5, is a member of the polyolefin family of plastics which includes high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE).

Polypropylene is commonly used to make ketchup bottles, yogurt containers, medicine bottles, margarine tubs, lids and caps, snack food packaging and labels. It is strong with excellent hinge strength, has a high melting point and high chemical resistance (APC 2006). Polypropylene and polyethylene (PE), especially high-density polyeth-ylene (HDPE), have similar properties and compete for many of the same packaging applications. An advantage of polypropylene is that it is stiffer than PE and has higher temperature resistance. A common practice is to thin-wall PP containers to save material and cost. Polypropylene film can be coated with an extremely thin layer of aluminum as a barrier to light, moisture, and oxygen.

In 2007, polypropylene represented 15% (4.6 million tons) of all plastics in U.S. municipal solid waste, 0.2% of which was recovered. Of the 2,040 million tons of PP packaging waste generated in 2007, recovery of polypropylene pack-aging was 0.5% (U.S. EPA 2008). Detailed recovery rates of all packaging materials from the municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section of the introduction.

PROduCTION METHOdS

Primary Production

The monomer production process is described in the introductory section for plastics, Ethylene & Propylene Monomer Production Process.

Virgin Source Materials

• Monomer – Propylene

• Catalyst – Ziegler-Natta catalyst

• Solvent – Hexane, heptane or liquid propylene

• Hydrogen

Polymer Production Process

Polypropylene is typically formed in either liquid or gas phase propylene reactors (see Figure 9). Liquid propylene polymerization is carried out at a pressure of about 365 - 510 psi (2.5 – 3.5 MPa) and a temperature of 140 – 175 °F (60 – 80°C). Gas phase polymerization (see figure below), is carried out at a pressure of about 300 – 510 psi (2.1 – 3.5 MPa) and a temperature of 160 - 195 °F (70 - 90 °C) (APME 2005d). The process requires a reactor for the propylene monomer (CAS # 115-07-1), hydrogen, and catalyst (Ziegler-Natta catalyst based on titanium tetrachloride—CAS # 7550-45-0) (Rodriguez et al 2003) – on a magnesium dichloride support) (McKetta 1997). An ethylene co-monomer is sometimes incorporated to help increase the versatility of the polypropylene (Tall et al 2001). As the propylene monomer flows through the reactor, about 50% of it reacts and becomes polypropylene polymer. The unreacted propylene is recycled back to the reactor. The polypropylene polymer is fed into a pelletizer to form pellets (McKetta 1997).

Additives

The most common additives in polypropylene used for packaging are heat and light stabilizers, slip, anti-block and anti-static agents, and pigments. Polypropylene does not require plasticizers when used in packaging. Fillers such as calcium carbonate or talc can be added to up to 30% by weight to improve stiffness, lower mold shrinkage and lower cost (Strong 2000).

TitaniumTetrachloride

Propylene(monomer)

PPPellets

PP ParticlesReactor Pelletizer

Hydrogen

figure 9: Flow Diagram of Virgin Polypropylene Production (McKetta 1992)


Secondary Production (Recycled)

Recycled Material

• Pre-consumer and post consumer PP

Secondary Production Process

Polypropylene is typically collected at curbside or recycling centers where it is transported to a Material Recovery Facil-ity (MRF) (see Figure 10). At the MRF, the PP is washed and separated from other types of plastic through hand sorting or optical sorting and baled for sale to process-ing plants. Once at the processing plant, the plastic goes through a washing and grinding process with further sepa-ration that results in clean PP flakes (Brown 1993).

Resource Intensity of Raw Material Production

Boundary Assumption

• The energy, water, and waste information in this brief are limited to data from the extraction of the raw material (i.e. oil or natural gas) through the production of polypropylene pellets (see Figure 11). The impacts from the specific package fabrication

(e.g. bottles or food containers) as well as impacts from consumer use are not included.

• LCI data for recycled polypropylene are not in-cluded.

Energy Consumption

Virgin

About 27.6 million Btus per 1,000 pounds of virgin poly-propylene resin or 64.2 GJ per 1,000 kilograms of resin are needed (Franklin 2007). Oil and natural gas are the primary sources of energy used in virgin PP production. While 12% of the energy is consumed in the production process, much of the energy (45.2 million Btus) is em-bedded within the resin itself and can be reclaimed in the future (Franklin 2007).

Recycled

Currently there are no available data for recycled polypro-pylene packaging.

Processing Plant

Post-Consumer

PP

RecyclingCenter

Collection

Pre-Washing

Sorting PPflakesGrinding DryingTechnical

Separation

MRF

figure 10: Flow Diagram of Recycled Polypropylene Processing




ConsumerUse

End-of-Life

Recycled PPData

Recycling

MaterialProcessing

PPPellets

figure 11: Life Cycle Inventory Data Boundary for Polypropylene


EMISSIONS

Greenhouse Gas

Virgin

About 1,343 lbs of greenhouse gases as CO2 equivalents are generated for every 1,000 pounds of virgin polypropylene produced (1,343 kg per 1,000 kilograms of virgin poly-propylene produced) (Franklin 2007). Carbon dioxide, methane and nitrous oxide are the major greenhouse gases emitted. Seventy-six percent of the GHG emissions are due to fuel use (Franklin 2007).

Recycled


Air Emissions

Virgin

The main air emissions from virgin polypropylene produc-tion include CO2, sulfur dioxide and methane. Carbon dioxide is mainly from the combustion of fuel, while sulfur dioxide and methane are mainly attributable to the pro-duction process (Franklin 2007).

Recycled


water discharges

Virgin

The primary pollutants found in wastewater from primary polypropylene production include dissolved solids, chlo-rides, and sodium. These stem mainly from processing of the PP (Franklin 2007).

Recycled


Solid waste

Virgin

Approximately 83.4 lbs of solid waste are generated per 1,000 pounds of polypropylene produced (83.4 kg per 1,000 kilograms of PP produced). Solid wastes associated with virgin PP production result from the combustion of fuels for process and transportation energy as well as from

the processes used to produce the resin itself. About 40% of the solid waste are landfilled (Franklin 2007).

Recycled


MATERIAL HEALTH

Manufacture

There are no known human or ecological health issues spe-cific to polypropylene production beyond those typically related to polymer production.

use

There are no known health issues related to the use of un-additivated polypropylene.

End-of-Life

There may be health consequences associated with the open burning of PP. Please see “End-of-Life” section below.

ENd-Of-LIfE

Typical End-of-Life Scenarios

Probable end-of-life scenarios for polypropylene packaging include landfilling, waste-to-energy incineration, recycling, litter and open burning.

United States

In 2006, the primary application of polypropylene in packaging was in coatings, films, closures, caps, trays and shapes. At 2,040 million tons, polypropylene is the fourth largest fraction of plastic packaging in the municipal solid waste stream; only 0.5% of it is recovered. Overall, 4.6 million tons (4.2 million tonnes) of polypropylene MSW were discarded in the U.S. in 2007, which is about 99.8% of all polypropylene waste generated (U.S. EPA 2008).

When recycled, polypropylene can be made into auto-mobile battery cases, signal lights, battery cables, brooms, brushes, ice scrapers, oil funnels, bicycle racks, rakes, bins, pallets, sheeting and trays (APC 2006).

Impact in End-of-Life Scenarios

• Recycling: Used polypropylene is highly recyclable and suitable for a variety of recycled applications. Along with reuse, recycling is the preferred end-of-


life scenario for polypropylene. For more details, refer to the Sustainability Potential section.

• Incineration/Waste to Energy: PP has an energy value of approximately 45.2 million Btus per ton (52.6 GJ per metric tons) (EPIC 2004). However, incineration must be done at well designed facilities that use the best available control technologies to minimize air pollution.

• Landfilling: PP does not readily biodegrade and represents the loss of a highly recyclable, non-renewable, fossil-fuel based material resource if landfilled. According to the U.S. EPA (2008), over 99% of polypropylene containers and packaging was landfilled in 2007.

• Littering: PP does not readily biodegrade and is physically persistent if released to the environment.

• Open Burning: PP is not suitable for open burn-ing. It evolves into CO2 and carbon monoxide (Boettner et al, 1973).

SuSTAINABILITy POTENTIAL

Polypropylene is a lightweight polymer appropriate for many packaging applications. As a technical material made from non-renewable fossil-fuel-based resources, recycling and reuse are key to the sustainable use of polypropylene in packaging. Like many plastics, the low recovery rate is related to lack of collection and reprocessing infrastruc-ture, poor consumer participation in recycling, and a lack of domestic markets for the material. At present these are all deterrents to the inclusion of recycled PP in consumer products. The infrastructure for polymer collection and automated sorting of polymers needs to be developed. Al-though resin codes #3 through #7 are recyclable, and occa-sionally are recycled, the actual level of recycling is limited by the continuing challenge of reaching a critical mass of readily recognizable bottles for economical collection and processing (APPR 2006).

To purify plastic material, recyclers separate plastics by density. Consequently, plastics with a similar density or with fillers that change the density cause contamination problems. The main contaminant of PP is high-density polyethylene (HDPE). Polypropylene and HDPE have similar densities and are difficult to separate from each oth-er. Since the end market tolerates an HDPE contamination of 5%, the amount of HDPE in PP packaging should not exceed 5% of the total packaging weight (Recoup 2006).

A variety of material and design attributes affect the re-cyclability of polypropylene. Barrier materials, pigments,

and other additives used in some packaging applications may adversely affect the recyclability of PP, and care should be taken in their use and specification. When designing packaging based on PP, the following information should be taken into account to maximize the recycling value of the polypropylene:

• Unpigmented recycled PP has the highest value and widest variety of end-use applications.

• End-use applications for recycled PP can tolerate HDPE contamination up to 5%.

• Closure systems with no residuals (e.g. rings or lin-ers) are the easiest to recycle.

• Modest amounts of adhesives, water soluble at 140-180 °F (60-80 °C), are the easiest to process during recycling.

• Shrink sleeves are preferred to adhered labels, and shrink sleeves made from PE or PP are preferred. The use of PVC sleeves should be avoided. (APPR 2007)

• PP, oriented PP, HDPE, LDPE, LLDPE or PS label stock is preferred to other label materials, including paper (APPR 2007).

• Lightweight plastic laminates (thickness <100 microns) are generally not recycled.

• Metallized PP film is not recycled.

Main Sustainability Concerns

The main environmental issues associated with PP packag-ing are:

• Low recovery rate in the U.S. of a highly recyclable, non-renewable resource

• The energy intensity of virgin production

• Persistence of the material, if released into the environment

Innovations

The addition of nucleating agents allows polypropylene to develop a highly crystalline structure for improved clar-ity, stiffness, and heat resistance. These innovations have expanded the use range of PP. Polypropylene has the lowest density of any polymer, allowing it to replace heavier pack-aging materials and plastics for reduced material usage, lower transportation energy, and less waste.

Improvements in polypropylene catalyst and processing technology are producing PP and PP copolymers with im-


proved stiffness, impact resistance, low temperature tough-ness, transparency, and heat resistance. Once reinforcement materials are added, they complicate PP recycling, making it impractical (Professional Engineering 2005).

To confront this challenge, researchers at Queen Mary, University of London have created a new material called “PURE” (Veazy 2003). PURE is made of very stiff PP tapes coated with a thin layer of PP. The tapes are woven into fabrics and made into sturdy sheets by sealing several layers together. PURE has the strength of fiberglass-reinforced PP, but is lighter and can be recycled (Harvey 2002). Emerging research can help to further the use of PP while taking environmental impacts into account.

High-Density Polyethylene | 11E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

High-density Polyethylene (HdPE)


• The information in this brief is focused on North America but European and Asian information is included where possible.

• The life cycle inventory data used for this brief includes raw material extraction through HDPE pellet production.

OvERvIEw

High density polyethylene (HDPE), SPI resin code #2, is a member of the polyolefin family of plastics, which in-cludes low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polypropylene (PP) (APME 2006). Polyethylenes are a class of thermoplastics based primarily on the monomer ethylene. The different types of polyethylenes are distinguished from each other by the degree of molecular linearity or branching and crystallinity within the polymer, which affects their density. HDPE is typically produced in low pressure reactors and has a linear molecular structure with little branching (5-10 branches per 1,000 carbon atom backbone), 50-85% crystallinity, and a density of about 0.94 – 0.96 g/cm3 (APME 2005a and Carraher 1996). HDPE has a higher chemical resis-tance, is stiffer, stronger, and more abrasion-resistant than LDPE (Strong 2000).

These attributes have led to HDPE being used in a variety of packaging applications such as juice bottles, milk and water jugs, bleach, detergent and shampoo bottles, mo-tor oil containers, and plastic grocery bags (Miller 2005). The material is commonly used for the construction of reusable pallets, crates, trash carts, and chemical storage tanks (Strong 2000). About 40% of all HDPE products are containers, and about 90% of all rigid HDPE containers are bottles (Miller 2005). The single largest use of HDPE is milk bottles, which made up 6% of the municipal solid waste (MSW) in 2007. Twenty-eight percent of the HDPE milk containers were recycled in 2007 (U.S. EPA 2008).

In 2007, HDPE represented 18% of all plastics in the MSW, 10% of which was recovered. Recovery of HDPE packaging was 14% in 2007 (U.S. EPA 2008). Detailed re-covery rates of all packaging materials from the municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section in the introduction.

PROduCTION METHOdS

Primary Production

The primary component of HDPE is the monomer eth-ylene (CAS# 74-85-1), which is polymerized to form polyethylene. Small amounts of co-monomers such as butene (CAS# 106-98-9), hexene (CAS# 592-41-6) or octene (CAS# 111-66-0) are sometimes added to influ-ence polymer properties like the percent crystallinity. The monomer production process for ethylene is described in the introductory section for plastics, Ethylene & Propylene Monomer Production Process.


• Ethylene

• Aluminum trialkyltitanium tetrachloride and chro-mium oxide are the most common catalysts (Brown and Cole,1993)


The polymerization of ethylene and co-monomers into HDPE occurs in a reactor in the presence of hydrogen at a temperature of up to 230 °F (110 °C) and at a pressure range of 500 - 600 psi (3.4 – 4.1MPa) (see Figure 12). The most common catalysts are aluminum trialkyltitanium tetrachloride or chromium oxide on a silica/aluminum support (APME 2005a). The resulting HDPE powder is then fed into a pelletizer to make HDPE pellets (Brown and Cole 1993).

Additives

For packaging, the most common additives are heat and light stabilizers, slip, anti-block and anti-static agents, and pigments (Brown and Cole 1993). HDPE does not require plasticizers when used in packaging (Platt et al 2005).

Titanium-basedcatalyst

Ethylene(monomer)

HdPEPellets

HDPEPowderReactor Pelletizer

Hydrogen

figure 12: Flow Diagram of Virgin HDPE Production (modi-fied from Brown and Cole 1993)



Recycled Source Materials

• Pre-consumer and post-consumer HDPE bottles are the dominant form of HDPE recovered in the U.S.

Post-consumer Recycled Production Process

HDPE is typically reclaimed through a mechanical recy-cling process. Post consumer HDPE is collected at curbside or drop off recycling centers and transported to a Material Recovery Facility (MRF) (See Figure 13). At the MRF, the HDPE is washed and separated from other types of plastic through hand sorting or optical sorting and baled for sale to processing plants. Once at the processing plant, the plastic goes through a grinding process that results in HDPE flakes. These flakes are washed to remove further contaminants and dried (Brown and Cole 1993).


Boundary Assumption

The energy, water, and waste information in this brief is limited to data from the extraction of the raw material (oil

or natural gas) through production of the HDPE pellet (see Figure 14). The impacts from the specific package fabrica-tion (e.g. bottle or food container) and from consumer use and disposal are not included.

The majority of the HDPE recycling life cycle inventory data are from Brown and Cole (1993), which includes HDPE bale breaking through HDPE flake production. It also includes the impacts of transporting the recovered material to a remanufacturing facility and any other trans-portation needed up to the production of HDPE flake. Brown and Cole (1993) do not include the impacts associ-ated with the collection and separation of the recyclable materials. Water pollutants included are those present after wastewater treatment and discharge. Air emissions and wa-ter discharges are those that are regulated and reported to regulatory agencies.

Energy Consumption

• Virgin: Approximately 59.2 million Btus per ton (68.9 GJ per metric ton) is used to manufacture HDPE (Franklin 2007). The primary source of energy for virgin HDPE production is either oil or natural gas. While some of the energy is consumed

Processing Plant

Post-Consumer

HdPE

RecyclingCenter

Collection

Pre-Washing

Sorting HdPEflakesGrinding DryingTechnical

Separation

MRF

figure 13: Flow Diagram of Recycled HDPE Processing




ConsumerUse

End-of-Life

Recycled HDPEData

Recycling

MaterialProcessing

HDPEPellets

figure 14: HDPE Life Cycle Inventory Data Boundary


during production, a significant amount (approxi-mately 46.7 million Btus per tons) is embedded in the HDPE resin itself and can be reclaimed in the future (Franklin 2007).

• Recycled: Approximately 12 million Btus per ton (14 GJ per metric ton) is consumed to manufacture recycled HDPE (Tellus 1992, Tellus 1994 and Franklin 1992).

EMISSIONS

Greenhouse Gas

Virgin

About 1,478 lbs carbon dioxide equivalents per 1,000 lbs HDPE or 1,478 kg carbon dioxide equivalents per 1,000 kg HDPE are generated during virgin HDPE production (Franklin 2007). Seventy-nine percent of the greenhouse gas emissions are fuel related and 21% of the greenhouse gas emissions are process related (Franklin 2007). The primary greenhouse gases from the fuel used to produce and manufacture PVC are carbon dioxide, methane, and nitrous oxide (Franklin 2007).

Recycled

About 160 lbs of greenhouse gases as CO2 equivalents are generated per 1,000 lbs of recycled HDPE produced (160 kg per 1,000 kg recycled HDPE) (Brown and Cole 1993). For recycled HDPE production, the majority of the carbon dioxide is from electrical energy production (Brown and Cole 1993).

Air Emissions

Virgin

The main air emissions from virgin HDPE production include CO2, methane, and sulfur oxides. Carbon dioxide stems mainly from the combustion of fuels in processing and transportation while methane and sulfur oxides stem largely from the processes used to produce HDPE (Frank-lin 2007).

Recycled

Air emissions associated with recycling are largely CO2 due to electricity use (Brown and Cole 1993).

water discharges

Virgin

The primary pollutants found in wastewater from virgin HDPE production include dissolved solids, chlorides, and

sodium which result from the processes used to produce HDPE (Franklin 2007). HDPE plants capture and treat waste water before discharging it.

Recycled

The primary pollutant associated with wastewater from re-cycled HDPE production is the chemical oxygen demand from washing and processing the HDPE (Brown and Cole 1993). The water is treated before being discharged.

Solid waste

Virgin

About 78.1 lbs per 1,000 pounds (78.1 kg per 1,000 ki-lograms) of solid waste is generated during virgin HDPE production. Solid wastes associated with virgin HDPE production result from the combustion of fuels for pro-cessing and transportation as well as from manufacturing processes. Most of the solid wastes from processing are landfilled (Franklin 2007).

Recycled

Currently no data are available for recycled HDPE.

MATERIAL HEALTH

Manufacture

There are no known human or ecological health issues spe-cific to HDPE production beyond those typically related to polymer production.

use

There are no known health issues related to the use of HDPE plastic.

End-of-Life

There may be health consequences associated with the open burning of HDPE. Please see “End-of-Life” section below.

ENd-Of-LIfE


Probable end-of-life scenarios for HDPE packaging include recycling, landfilling, waste-to-energy incineration, litter, and open burning.


United States

The U.S. generated around 5.7 million tons (5.2 million tonnes) of HDPE waste in 2007. Seventy-four percent or 4.2 million tons (3.8 million tonnes) were in the form of containers and packaging (U.S. EPA 2008). Most recycled HDPE comes from milk bottles. Over 40% of recycled HDPE bottles become new non-food bottles, and more than 20% is reclaimed in the plastic pipe industry. Other markets for recycled HDPE are shown in Figure 15.


• Recycling: Used HDPE is highly recyclable and suitable for a variety of recycled applications. Along with reuse, recycling is the preferred end-of-life scenario for HDPE. For more details, refer to the Sustainability Potential section.

• Incineration/Waste to Energy: HDPE has an energy value of approximately 46.7 million Btus per ton (54.3 GJ per metric tons) (APME 2005a). However, incineration must be done at properly designed facilities to avoid uncontrolled release of air pollutants.

• Landfilling: HDPE represents the loss of a highly recyclable, non-renewable, fossil-fuel based material resource if landfilled. According to the 2007 MSW data (U.S. EPA 2008), about 86% of HDPE con-tainers and packaging are landfilled or incinerated.

• Littering: HDPE does not readily biodegrade and is physically persistent if released to the environ-ment.

• Open Burning: Open burning of mixed plastic waste including HDPE can produce carbon dioxide and carbon monoxide. Combustion of HDPE powder in lab conditions also detected methane, ethylene, ethane, propylene, propane, 1-butene, and butane (Boettner and Ball 1973).


HDPE is a lightweight polymer appropriate for many packaging applications.

Recycling is key to the sustainability of HDPE, as it is de-rived from a non-renewable fossil fuel. The low collection rate of post-consumer HDPE in North America is a deter-rent to its cost-effective use in consumer products.

A variety of material and design attributes affect the re-cyclability and utility of recovered HDPE. Plastics in the MSW are sorted based on material density. Consequently, plastics with a similar density or whose density is altered by fillers end up as contaminants in certain recycling streams. The presence of barrier materials, pigments, and other additives used in some packaging applications may also adversely impact the recyclability of HDPE, so care should be taken in their use and specification. When designing packaging applications using HDPE the following should be taken into account to maximize the recycling value of the HDPE:

• Non-pigmented recycled HDPE (as used for milk and other beverage bottles) has the highest value and widest variety of end-use applications (Recoup 2006).

• Direct printing onto colorless HDPE can poten-tially decrease the value of the recycled HDPE (Recoup 2006).

• Current polyethylene (PE) recycling systems can tolerate small amounts of EVOH (Ethylene Vinyl Alcohol) barrier layers (Recoup 2006).

• End use applications for recycled HDPE can toler-ate up to 5-10 % polypropylene (PP).

• Closure systems that leave no residuals (e.g. rings or liners) are the easiest to recycle.

• Modest amounts of adhesives, water soluble at 140-180 °F (60-82 °C), are the easiest to process during recycling (Recoup 2006).

Buckets/Crates(1%)

Pallets (2%)

Non-foodBottles (43%)

Pipe(22%)

Lawn & Garden(12%)

PlasticLumber

(9%)

film/Sheet(7%)

Automotive (4%)

figure 15: End Use of Recycled HDPE Bottles (APC 2007)


• Shrink sleeves made from PP or PE are preferred to adhered labels. The use of PVC sleeves should be avoided (APPR 2007).

• PP, oriented PP, HDPE, LDPE, LLDPE or PS label stock is preferred to other label materials such as paper (APPR 2007).


The main environmental issues associated with HDPE packaging are:

• Low recovery rate in the US of a highly recyclable, non-renewable resource

• High energy intensity of virgin production

• Persistence of the material if released into the environment

Innovations

Innovations in HDPE catalyst and processing technology continue to improve HDPE stiffness, toughness, and sol-vent and crack resistance, which allows lighter weight bot-tles and thinner bags with equal or improved performance. There has been significant progress in using bio-based feedstocks such as sugarcane to produce monomers like ethylene that are the starting blocks for many traditional polymers. Polymers produced from monomers derived from renewable feedstocks will match traditional polymers of the same type (i.e. PE) in terms of performance and end-of-life recovery. The use of renewable feedstock reduces the carbon footprint of the polymer but does not necessarily imply that the polymer will be compostable.

Low-Density Polyethylene | 16E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Low-density Polyethylene (LdPE)


• The life cycle inventory data used for this brief includes raw material extraction through LDPE pellet production.

OvERvIEw

Low-density polyethylene (LDPE), SPI resin code #4, is a member of the polyolefin family of plastics which includes high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polypropylene (PP) (APME 2006). Polyethylenes are a class of thermoplastics based primarily on the monomer ethylene. The different types of plastics are distinguished from each other by their density, which is affected by the degree of molecular linearity or branching and crystallinity within the polymer. LDPE has a density of about 0.92-0.94 g/cm3, a linear molecular structure with branching (2-50 branches per 1,000 carbon atom backbone), and 35-75% crystallinity (APME 2005, APME 2005a and Carraher 1996). LDPE is flexible, tough, and resistant to stress cracking. Of all polyethylenes (PE), LDPE is the easiest to process.

Due to its physical attributes, LDPE is use in applications such as films and bags, flexible tubing, toys, and squeeze bottles. LDPE is polymerized under high temperature and high pressure. Its density is low because polymerization conditions cause long polymer branches to form which prevent molecules from packing closely together (Strong 2000).

In 2007, LDPE represented 21% of all plastics in MSW, 5% of which was recovered. Of the 3 million tons of LDPE/LLDPE packaging waste generated in 2007, 10.3% was recovered (U.S. EPA 2008). Detailed recovery rates of all packaging materials from municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section of the introduction.

PROduCTION METHOdS

Primary Production

LDPE is made from the monomer ethylene (CAS# 74-85-1), which is polymerized to form polyethylene. The monomer production process is described in the introduc-

tory section for plastics, Ethylene & Propylene Monomer Production Process.


• Ethylene monomer


Oxygen peroxide is thermally decomposed into a free radi-cal and reacted with ethylene (see Figure 16). The ethylene’s double bond is opened to form reactive radicals that attach to each other producing a long chain LDPE polymer. This reaction is done at a high temperature (up to 570 °F or 300 °C) and high pressure (up to 44,000 psi or 300 MPa) in either an autoclave or tubular reactor. The autoclave reac-tor is a thick-walled cylindrical reactor stirred by paddles. About 20% of the ethylene is converted into LDPE in an autoclave reactor, while up to 35% of the ethylene can be converted into LDPE using a tubular reactor. In both cases, any unreacted ethylene is circulated for reuse. Molten LDPE is then extruded through a pelletizer forming LDPE pellets (APME 2005a, Brown and Cole 1993).

Co-polymerization

Copolymers of LDPE with co-monomers such as vinyl esters, acrylate esters, and carboxylic acids may be created during polymerization to modify the LDPE properties. For example, to increase the toughness, clarity, and gloss of LDPE films, 1-7% of vinyl acetate is added (Ebewele 1996).

Additives

For packaging, the most common additives are heat and light stabilizers, slip, anti-block and anti-static agents, and pigments (Brown and Cole 1993). This polymer does not typically require plasticizers when used in packaging (Platt et al 2005).

Ethylene

Oxygen

LdPEPellets

MoltenLDPEPolymerization Pelletizer

figure 16: Flow Diagram of Virgin LDPE Production (modi-fied from Brown and Cole 1993)




• Pre-consumer and post-consumer LDPE

Recycled Production Process

LDPE is typically collected at curbside or recycling cen-ters where it is transported to a Material Recovery Facility (MRF) (See Figure 17). At the MRF, the LDPE is washed and separated from other types of plastic using hand sort-ing and/or optical sorting, and baled for sale to processing plants. At the processing plant the plastic is mechanically ground into LDPE flakes. The flakes undergo technical separation and are washed to remove contaminants, fol-lowed by drying (Brown and Cole 1993).


Boundary Assumption

• The energy, water, and waste information in this brief is limited to data from the extraction of the raw material (i.e. oil or natural gas) through production of LDPE pellet (see Figure 18). The impacts of specific package fabrication (e.g. bottle

or food container) and impacts from consumer use are not included.

• The data for LDPE recycling include LDPE bale breaking through LDPE flake production.

Energy Consumption

Virgin

About 29.5 million Btus per 1,000 pounds (68.5 GJ per 1,000 kilograms) of energy is needed to manufacture LDPE (Franklin 2007). The energy source for virgin LDPE production is primarily fossil fuel (oil or natural gas). While about 18% of the energy is consumed in the production of LDPE, approximately 40 million Btus per ton (47 MJ per metric ton) of the energy is embedded in the resin itself and can be reclaimed in the future (EPIC 2004 and Franklin 2007).

Recycled

The energy needed to manufacture recycled LDPE is about 17 million Btus per ton (20 GJ per metric tonne) (Tellus 1992, Tellus 1994, Franklin 1992).

Processing Plant

Post-Consumer

LdPE

RecyclingCenter

Collection

Pre-Washing

Sorting LdPEflakesGrinding DryingTechnical

Separation

MRF

figure 17: Flow Diagram of Recycled LDPE Production




ConsumerUse

End-of-Life

Recycled LDPEData

Recycling

MaterialProcessing

LDPEPellets

figure 18: LDPE Life Cycle Inventory Data Boundary


EMISSIONS

Greenhouse Gas

Virgin

About 1,479 lbs of greenhouse gases as CO2 equivalents are generated per 1,000 pounds of virgin LDPE produced (1,479 kg per 1,000 kilograms of virgin LDPE produced) (Franklin 2007). Carbon dioxide, methane, and nitrous oxide are the main contributors. Seventy-five percent of GHG emissions are fuel-related (Franklin 2007).

Recycled

About 0.15 tons of greenhouse gases as CO2 equivalents are generated for every ton of recycled LDPE produced (0.15 metric ton per metric ton of recycled LDPE produced) (Brown and Cole 1993). For recycled LDPE production, most of the carbon dioxide is from electrical energy use (Brown and Cole 1993).

Air Emissions

Virgin

The main air emissions from virgin LDPE production in-clude: CO2, methane, and sulfur oxides. Carbon dioxide comes mainly from the combustion of fuels for process-ing and transportation while methane and sulfur oxides stem largely from the processes used to produce LDPE. (Franklin 2007).

Recycled

Air emissions from recycling include CO2 emitted from electricity use (Brown and Cole 1993).

water discharges

Virgin

The primary pollutants associated with wastewater from virgin LDPE production are dissolved solids, chlorides, and sodium resulting from production processes (Franklin 2007). LDPE plants typically capture and treat wastewater before discharging it (APME 2005a).

Recycled

There are no available data for recycled LDPE.

Solid waste

Virgin

Solid wastes associated with virgin LDPE production result from the combustion of fuels for processing and

transportation as well as from the production of LDPE. Processing-related solid wastes are typically landfilled (Franklin 2007).

Recycled

The predominate source of solid waste in recycled LDPE production is unspecified waste from manufacturing and fuel use (Brown and Cole 1993).

MATERIAL HEALTH

Manufacture

There are no known human or ecological health issues spe-cific to LDPE production beyond those typically related to polymer production.

use

There are no known health issues related to the use of LDPE plastic. There are no known health issues related to the use of vinyl acetate (VA) copolymers of LDPE with less than ten percent copolymer.

End-of-Life

There may be health consequences associated with the open burning of LDPE. Please see “End-of-Life” section below.

ENd-Of-LIfE


Probable end-of-life scenarios for LDPE packaging include landfilling, recycling, waste-to-energy, litter and open burning.

United States

Recycling data for LDPE is combined with linear low-density polyethylene (LLDPE), another polyethylene variation with similar applications. In 2007, the U.S. gen-erated around 6.4 million tons of LDPE/LLDPE waste. Approximately 3 million tons (2.7 million tonnes) of that was packaging waste. Out of that, 310,000 tons (281,000 tonnes) of LDPE/LLDPE from packaging waste was re-covered, for a recovery rate of about 10%. Overall, about 6.1 million tons (5.5 million tonnes) of LDPE/LLDPE (including packaging) was discarded in 2007 (U.S. EPA 2008).

Recovery rates of all packaging materials from the munici-pal waste stream can be found in the U.S. Packaging Ma-terials Recovery and Discard section earlier in this report.



• Recycling: LDPE is a highly recyclable material and suitable for a variety of recycled applications, yet currently nearly 90% is discarded (U.S. EPA 2008). Along with reuse, recycling is the preferred end-of-life scenario for LDPE. For more details, refer to the Sustainability Potential section.

• Incineration/Waste to Energy: LDPE has an energy value of approximately 40 million Btus per ton (47 MJ per metric ton) (EPIC 2004). However, incineration should be limited to properly designed facilities with the best available control technologies to avoid the uncontrolled release of air pollutants and to appropriately manage bottom ash. The combustion of any fossil-fuel-based resource emits greenhouse gases that contribute to the carbon budget of the atmosphere.

• Landfill: LDPE does not readily biodegrade and represents the loss of a highly recyclable, fossil-fuel based material resource if landfilled.

• Litter: LDPE does not readily biodegrade and is physically persistent if released into the environ-ment.

• Open Burning: Open burning of LDPE produces carbon dioxide and carbon monoxide (Boettner and Ball 1973).


LDPE is a polymer material appropriate for many packag-ing applications and readily recyclable. As a technical mate-rial made from non-renewable fossil resources, recycling is crucial to the sustainable use of LDPE packaging. LDPE and LLDPE represent 22% of all plastics used for con-tainer and packaging applications, and only 10% of that material is recovered. Like many plastics, the low recovery rate is related to the lack of a collection and reprocessing infrastructure, poor consumer participation in recycling, and a lack of domestic markets for the material. At present these are all deterrents to the inclusion of recycled LDPE in consumer products.

A variety of material and design attributes affect the recy-clability and utility of LDPE within the recycling stream. The presence of barrier materials, pigments, and other ad-ditives used in some packaging applications may adversely affect the recyclability of LDPE. End-of-life considerations should be taken into consideration when selecting and using additives. When designing packaging applications based on LDPE the following information should be taken

into account to maximize the value of the recycled LDPE (Recoup 2006):

• Unpigmented recycled LDPE has the highest value and widest variety of end-use applications.

• Direct printing onto colorless LDPE can potential-ly decrease the value of the recycled LDPE stream.

• Current PE recycling systems can tolerate EVOH barrier layers.

• Modest amounts of adhesives, water soluble at 140-180 °F (60-80 °C), are the easiest to process during recycling.

• PE or PP shrink sleeves are preferred to adhered labels. The use of PVC sleeves should be avoided. (APPR 2007).

• PP, oriented PP, HDPE, LDPE, LLDPE or PS label stock are preferred to other label materials such as paper (APPR 2007).

• Lightweight plastic laminates (thickness <100 microns) are generally not recycled.


The main environmental issues associated with LDPE packaging are:

• Low recovery rate in the U.S. of a highly recyclable, non-renewable resource

• The energy intensity of virgin production


Innovations

LDPE is used in substantial quantities as agricultural film and some U.S. companies are confronting the economic hurdle of recycling it. Farmers use agricultural film because it keeps winter crops safe and clean. However, plastic film is a nuisance for landfill managers because it can wrap around landfill equipment and trap pockets of methane gas. Every year in Ventura County, California, farmers dispose of 3,500 to 6,000 tons (3,200 to 5,400 metric tons) of plastic film into landfills (Richard 2006). This makes up about 2-3% of the waste in rural parts of the county. Eno Plastics will open the first washing line for agricultural plastics on the West Coast, a $1.6 million recycling facility (Toloken 2005 and Plastic News 2006). The company targets agri-cultural film because of their pre-existing collection system for this LDPE material (Toloken 2005). One of the main hurdles is contamination. The film will be acceptable for


recycling only if the plastic is handled correctly and has little residue (Richard 2006).

LDPE is used in combination with other plastics such as HDPE and LLDPE to produce tough packaging con-structions for improved product protection yet clear for see-though convenience. LDPE with improved toughness and elasticity has been developed for clear secondary and tertiary packaging to bundle items (shrink wrap) and to wrap pallets of goods (stretch hoods) for ease of handling. LDPE over wraps have the advantage of being lightweight for lower transportation cost, and reduced waste. Innova-tions in LDPE copolymers have taken the form of new comonomers with improved thermal stability, lower heat sealing temperatures, and stronger seals.

Polyethylene Terephthalate | 21E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polyethylene Terephthalate (PET)


• The life cycle inventory data used for this brief include raw material extraction through PET pellet production.

OvERvIEw

Polyethylene terephthalate (PET), SPI resin code #1, was originally produced for textiles, until the mid 1960’s when it was first used for packaging films. Due to its clarity and relative strength, PET is now used to make containers for soft drinks, water, juices, alcoholic beverages, cleaning products, fruits, vegetables, toys, electronics and many other packaging applications. PET has become a market leader for soft drink bottles due to physical properties suit-able for maintaining taste and carbonation.

In 2007, PET represented 12% of plastics in the U.S. municipal solid waste stream, with an 18% recovery rate which was dominated by bottles. Detailed recovery rates of all packaging materials from the municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section of the introduction.

PROduCTION METHOdS

Primary Production


• Monomers, typically TPA (terephthalic acid) and EG (ethylene glycol) (U.S.)

• Catalyst typically antimony trioxide (U.S.)


The first step in virgin PET production is the preparation of the reactant monomers and catalyst (see Figure 19). PET is made from two monomers, TPA (terephthalic acid) and EG (ethylene glycol). These monomers are derived from a petroleum derivative (paraxylene) and a natural gas-based derivative (ethylene). TPA self-catalyzes to initiate the es-terification reaction that forms the intermediate (BHET – Bishydroxyethyl terephthalate) which is followed by melt-phase polymerization of PET. Antimony trioxide (United States), germanium dioxide (Japan) or titanium-based catalysts are used to catalyze the polymerization of BHET to a polymer. A small amount (<200 ppm) of the antimony catalyst is incorporated into the resulting poly-mer (NAPCOR 2006).

In continuous production facilities, during the melt phase polymerization step, BHET is polymerized to a moder-ate molecular weight PET. The molecular weight of the polymer is increased by condensing BHET molecules to remove excess ethylene glycol, which is recycled for reuse. The polymer is fed in molten form into a pelletizer, which forms continuous strands of polymer (2-4 mm diameter) which are cooled and chopped into pellets. These pellets are heated in a process called solid stating or solid state po-lymerization, which increases the degree of polymer align-ment (crystallinity) and increases the molecular weight, or intrinsic viscosity (IV) of the PET.

Depending on the packaging application for PET, the intrinsic viscosity (IV) needs to be between 0.72 – 1.0 (0.72 – 0.78 for thermoformed applications, 0.78 – 0.82 for bottles, 0.95 – 1.0 for strapping and crystallized trays) (NAPCOR 2006). Amorphous PET (APET) is in the low-er IV range and is transparent in the final package, while nucleated and crystallized PET (CPET) are in the higher IV range and are opaque in the final package.

Copolymers of PET (e.g. PETG) may be created during the polymerization process to enhance PET processing and

Unreacted monomer (EG)

Monomers(EG & TPA)

ReactantPreparation Esterification BHET

Catalyst(Antimony Trioxide)

Melt phasepolymerization Pelletizer

PETPellets

PackagingGrade PET

Solid statingPET

figure 19: Flow Diagram of Virgin PET Production (NAPCOR 2006)


the economic performance of the material, expanding the possible use of the resin to applications for which regular PET is not suited.

Additives

Additives and coatings are added during container fabrica-tion (i.e. when the bottle is formed). The most common additives are colorants or dyes. Barrier coatings, layers, or dispersions such as nylon and ethylene vinyl alcohol copolymers (EVOH) may be used to enhance the proper-ties of PET. Other additives may provide ultraviolet light protection (to protect liquid products such as orange juice) (NAPCOR 2006).



• Pre-consumer and post-consumer PET bottles are the dominant form of PET recovered in the U.S.

Recycled Production Process

Figure 20 depicts the typical flow of recycled PET (rPET) production. PET is most commonly reclaimed through mechanical recycling. PET bottles represent most of the PET that is collected, baled and transported to recycling facilities. The first step in the mechanical recycling of PET bottles is separating the PET from possible contaminants. This may include grinding, washing, and technical separa-tion (sink-float separation and air separation (elutriation)). The resulting clean flakes undergo drying and heating, and are extruded and pelletized. If necessary, the pellets may undergo a solid stating process to raise the IV (intrinsic viscosity) of the PET. When PET is melted, its molecular weight or IV decreases. However, the intrinsic viscosity can be renewed through solid stating, making PET somewhat unique compared to other polymers (NAPCOR 2006).

The primary factor that determines the quality of rPET is the technical recycling process and the rigor of the process-ing. If the recycling process is not robust, residual contami-nation from additives and coatings may affect the quality of rPET. Coatings in particular need to be designed to be released during the recycling process (NAPCOR 2006).

Chemical recycling may also be used to recover PET. Methanolysis and glycolysis are two technologies that have been used commercially to recover PET. Glycolysis is de-scribed in Figure 21.


Boundary Assumption

• The energy, water, and waste information in this brief is limited to raw material extraction through pellet production (see Figure 22). The impact of the specific packaging fabrication (e.g. bottle or food container) as well as impacts from consumer use is not included. Transportation impacts during raw material extraction and material production are included.

• The data for PET recycling includes baling through recycled PET manufacturing via mechanical repro-cessing.

Energy Consumption

Virgin

About 29.7 million Btus per 1,000 pounds (69.1 GJ per 1,000 kilograms) of energy is needed to manufacture PET (Franklin 2007). The energy source for virgin PET pro-duction is primarily fossil fuel (oil or natural gas). While about 43% of the energy is consumed in the production of PET, approximately 18.6 million Btus per ton (21.6 GJ per metric ton) of the energy is embedded in the resin

PET Containers

Bailing Grinding Washing AirSeparation

PackagingGradePET

PelletizerDrying &Heating

Solidstating

PET Flakes

figure 20: Flow Diagram of Recycled PET (rPET) Production


itself and can be reclaimed in the future (EPIC 2004 and Franklin 2007).

Recycled

Approximately 11 million Btus are consumed per ton of recycled PET manufactured (12.8 GJ per metric ton) (Tel-lus 1992, Tellus 1994, Franklin 1992). Transportation fuels have the highest impact in rPET manufacture. A smaller portion of energy is consumed to heat boiler water for the recycling process (NAPCOR 2006).

EMISSIONS

Greenhouse Gas

Virgin

About 2,538 lbs of carbon dioxide equivalents per 1,000 lbs PET (2,538 kg carbon dioxide equivalents per 1,000 kg PET) are generated during virgin PET production (Franklin 2007). Eighty-five percent of the greenhouse gas

emissions are fuel related and 15% of the greenhouse gas emissions are process related (Franklin 2007). The primary greenhouse gases resulting from fuel for the production and manufacturing of PET are carbon dioxide, methane, and nitrous oxide (APME 2006, Franklin 2007).

Recycled

Approximately 0.2 tons of greenhouse gases (CO2 equiva-lents) are generated for every ton of recycled PET produced (0.2 metric ton per metric ton) (Brown 1993). Transporta-tion and energy generation account for most greenhouse gases emitted during rPET production (NAPCOR 2006).

Air Emissions

Virgin

Carbon dioxide and combustion gases such as sulfur oxides are the main air emissions from virgin PET production (APME 2005, NAPCOR 2006). These emissions are mainly from fuel production and fuel use (APME 2005).

Catalyst (antimony oxide)Filters

Ethylene Glycol

Reactor(high T & P)

Post-Consumer

PET

PETPelletsCooling

Excess Glycol

Reactor(under

vacuum)

PolymerStrands Pelletizer

GlycolizedOligomers Oligomers

figure 21: Chemical Recycling of PET via Glycolysis (modified from Verma 2004)




ConsumerUse

End-of-Life

Recycled PETData

Recycling

MaterialProcessing

PETPellets

figure 22: PET Life Cycle Inventory Data Boundary


Recycled

Air emissions from recycling are mainly from transporta-tion and energy generation (NAPCOR 2006).

water discharges

Virgin

BOD (biological oxygen demand) and COD (chemical oxygen demand) are the main water pollutants from virgin PET production (APME 2005, Brown and Cole 1993). PET plants typically capture and treat all water before dis-charging it (NAPCOR 2006).

Recycled

Recycled PET production uses less water than virgin and the main contaminants are BOD (APME 2005) from residual product (e.g. juice). This water is also typically treated before being discharged (NAPCOR 2006).

Solid waste

Virgin

About 141 pounds of solid waste are generated for every 1,000 lbs of virgin PET produced (141 kilograms of solid waste per 1,000 kg) (Franklin 2007). Mining waste and energy generation waste (e.g. coal ash) are the main solid wastes associated with primary PET production (APME 2005).

Recycled

The dominant source of solid waste in recycled PET pro-duction is from paper labels, product residue and binding wires (NAPCOR 2006).

MATERIAL HEALTH

Manufacture

Antimony trioxide, the most common catalyst in PET pro-duction, is a suspected human carcinogen (OEHHA 2009 and ACGIH 2008). Some production waste residues are contaminated with antimony trioxide and require proper disposal.

use

Residual antimony is present in PET at approximately 200 ppm or less (NAPCOR 2006) and this issue has received attention. Long-term testing (ILSI 1994) of extraction from PET containers shows less than 5 ppb, which is close to the detection limits. Currently, research is ongoing.

End-of-Life

In combustion scenarios, antimony trioxide forms an in-soluble oxide that contributes to the defined heavy metal content of the resulting ash. Antimony trioxide does not readily vaporize and is not likely to contribute to air emis-sions (NAPCOR 2006).

ENd-Of-LIfE


Probable end-of-life scenarios for PET packaging include recycling, landfilling, waste-to-energy incineration, litter and open burning.

United States

In 2007, the U.S. generated around 3 million tons (2.7 million metric tons) of containers and packaging PET waste, and recycled about 23% of the generated amount (U.S. EPA 2008). To address this loss of resources, many communities have made considerable efforts to increase PET recycling rates. California enforces its Rigid Plas-tics Packaging Container Law requiring the use of 25% post consumer recycled (PCR) content in all rigid plastic packaging of non-food products (NAPCOR 2004). About 48% of the PET bottles collected in the U.S. are exported (NAPCOR 2006a). After bottles, PET strapping is the most commonly collected form of PET packaging. Other forms such as clamshells and blister packaging are rarely collected (NAPCOR 2006).

The majority (over 50%) of the recycled PET is used to make fiber products (e.g. polyester carpeting, sleeping bag filler, and clothing). Around 14% of the recycled PET is used for food and beverage bottles and another 13% for industrial strapping applications. The remainder is used for non-food bottles (7%), sheets & films (7%), other uses (3%), and engineering resins (2%) (NAPCOR 2004).

Europe and Japan

In 2002, Europe collected over 2.8 million tons (2.5 mil-lion metric tons) of plastic packaging materials, with an average recycling rate of 25% (ASSURRE 2002). Look-ing specifically at PET, in 2004 Europe collected over 720,000 tons (650,000 metric tons). Japan has a PET bottle recycling rate of 46%, collecting around 240,000 tons (220,000 metric tons) of the 514,000 tons generated (470,000 metric tons) (Japan’s Council for PET Bottle Recycling 2005).



• Recycling: Used PET is a valuable material, highly recyclable and suitable for a variety of high-value recycled applications. PET is based on non-renew-able petroleum resources. Recycling is the preferred material management option. For more details, please refer to the Sustainability Potential section.

• Incinerating/Waste to Energy: PET has an energy value of approximately 18.6 million Btus per ton (21.6 GJ per metric ton) (EPIC 2004). However, incineration should be limited to properly designed facilities with the best possible control technologies to avoid uncontrolled release of air pollutants and appropriately manage bottom ash. The combustion of any fossil-fuel-based resource emits greenhouse gases that contribute to climate change.

• Landfilling: PET does not readily biodegrade and represents a loss of a highly recoverable fossil-fuel based material resource if landfilled. About 82% of all PET in the MSW stream and 77% of PET in the form of containers and packaging is landfilled (U.S. EPA 2008).

• Littering: PET is physically persistent as it does not readily biodegrade in the environment.

• Open Burning: PET is not suitable for open burn-ing. It evolves carbon dioxide, carbon monoxide and acetaldehyde in the oxygen-limited conditions, common in uncontrolled combustion. Ash residues contain non-volatile, insoluble antimony oxides (NAPCOR 2006).


Recycling PET back into packaging or other high-value products is critical to the sustainability profile of PET packaging. PET is a technical material that can be brought back to near virgin properties through solid stating. As a re-sult, products can be made with high percentages of rPET with no reduction in performance. However, the limited collection and consequently limited supply of recycled PET in North America continues to limit the amount of recycled content in many applications. Barrier material and other additives used in some packaging applications may ad-versely impact the recyclability of the PET and care should be taken in their use and specification (NAPCOR 2006).


The main environmental issues associated with PET pack-aging are:

• Low recovery rate in the U.S. of a highly recyclable and non-renewable resource

• The energy intensity of virgin production com-pared to rPET is very high


• Concern about antimony trioxide in some end-of-life scenarios like incineration or open combustion

Innovations

New technologies are being commercialized to reduce the energy consumption associated with virgin PET produc-tion. Eastman’s patented IntegRex™ technology used to make ParaStar™ PET resin is substantially more energy-ef-ficient than conventional PET manufacturing processes. A Franklin Associates life cycle assessment shows that energy used by the IntegRex™ technology process to convert raw materials to PET is 51% lower than the energy consumed in conventional processes. When combined with the ener-gy associated with the raw materials, the overall reduction in total energy is around 10%—a substantial reduction, considering that well over three-fourths of the total energy is tied to the raw materials themselves. These innovations could have a positive impact on the environmental profile of PET, not only reducing its energy requirements but also reducing the emissions associated with energy use (NAP-COR 2006). Additionally, the increasing demand for rPET from brand owners and retailers is a positive development that is likely to drive innovative PET recovery and recy-cling.

Polystyrene | 26E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polystyrene (PS)


• The life cycle inventory data used for this brief include virgin polystyrene (PS) production (raw material extraction through pellet production).

OvERvIEw

Polystyrene (PS), resin code #6, is a thermoplastic used in the following major markets (listed in order of consump-tion): packaging, consumer and institutional goods, electri-cal and electronic goods, building and construction, furni-ture, industrial and machinery, and transportation (U.S. EPA 2008a). Polystyrene packaging comes in many shapes and forms, from foamed egg cartons and meat trays to soup bowls and salad boxes, from coffee cups and utensils to CD “jewel boxes,” and from produce trays to “peanuts” used in packing and the lightweight foam pieces that cushion new appliances and electronics (ACC 2007 and PSPC 2006). The main forms of PS are listed below.

• General purpose polystyrene (GPPS) is made without large amounts of additives. GPPS is clear, very brittle, and easily reacts with solvents (APME 2006, Strong 2000). It is used for CD jewel boxes, salad clamshells, and plastic cutlery (CIWMB 2004).

• High impact polystyrene (HIPS) is opaque due to the incorporation of rubber compound addi-tives (up to 30%, but more commonly 3-10%) which help reduce the brittleness (APME 2006, Strong 2000). HIPS is up to 7 times more impact resistant than GPPS (Strong 2000) and is used in TV casings, horticultural trays, drink cups, yogurt containers and office supplies (rulers, file trays, etc.) (CIWMB 2004).

• Expanded polystyrene (EPS) is made by adding a blowing (or expanding) agent to the polystyrene and is also sometimes called foamed polystyrene or Styrofoam™. Common applications of EPS include take-out deli cartons, egg cartons, meat trays, and beverage cups. Foamed polystyrene is made from GPPS. EPS is approximately 95% air and only 5% PS (ACC 2008).

General purpose polystyrene and EPS make up more than half of all types of PS manufactured. About 53% of all PS

manufactured in the U.S. goes toward packaging and single use applications (e.g., food serviceware) (ACC 2007).

In 2007, polystyrene represented 8.5% of all plastic in U.S. municipal solid waste, 0.8% of which was recovered. Recovery of PS packaging for 2007 was 6.7% (U.S. EPA 2008). EPS achieved a 19.3% recycling rate in 2006, with 32 million pounds of post-consumer EPS recycled (AFPR 2007). Detailed recovery rates of all packaging materials from the municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section of the introduction.

PROduCTION METHOdS

Primary Production

Source Material For Virgin Polymer Production (EPA 1997)

• Monomer – Styrene

• Catalyst – Heat and organic peroxides

Monomer Production Process

Polystyrene (PS) is made from styrene (CAS# 100-42-5), a colorless liquid that evaporates easily. Styrene is created using the monomer ethylene which is derived from the steam cracking of crude oil or natural gas (see Figure 23, and Ethylene & Propylene Monomer Production Process.). Further processing using naphtha in the presence of hy-drogen and platinum catalyst produces benzene and other aromatics (APME 2005a).

Natural GasExtraction

Cracking

Propylene

Natural GasProcessing

AromaticPlant

Natural Gas (raw)

Natural Gas (pure)

PlatinumCatalyst

Ethylene

Oil Refining

Crude OilExtraction

Crude Oil

Naptha

Benzene

figure 23: Flow Diagram of Virgin Monomer Production (modified from APME 2005a)


The resulting benzene is combined with ethylene and an aluminum chloride catalyst to produce ethylbenzene (see Figure 24) (APME 2005 and APME 2005b). The ethyl-benzene is then used to produce styrene in one of two ways (APME 2005c):

• Reacting ethylbenzene with a catalyst (an oxide of zinc, chromium, magnesium, or iron) at a high temperature (1170° F or 630° C).

• Oxidizing ethylbenzene and reacting it with pro-pylene to produce an alcohol. This alcohol is then dehydrated to produce styrene.

The energy needed for the reaction is supplied by super-heated steam (at 1330° F or 720° C) injected into a verti-cally mounted fixed bed catalytic reactor with vaporized ethylbenzene. The catalyst is iron oxide-based and also con-tains chromium oxide (Cr2O3) and a potassium compound (KOH or K2CO3) as reaction promoters. Typically, 2.5-3 kg of steam is required for each kilogram of ethylbenzene present to ensure sufficiently high temperatures through-out the reactor. The superheated steam supplies the neces-sary reaction temperature of 1020-1130° F (550-6200 C) throughout the reactor. Ethylbenzene conversion is typi-cally 60-65% and the remaining ethylbenzene is trapped and recycled through the styrene conversion process.

The three significant byproducts from this process are tolu-ene, benzene, and hydrogen. The product stream (contain-ing styrene, toluene, benzene, and unreacted ethylbenzene) is fractionally condensed after the hydrogen is flashed from the stream. The hydrogen from the reaction is used as fuel to heat the steam (boiler fuel). After adding a polymeriza-tion inhibitor (usually a phenol), the styrene is vacuum distilled in a series of four columns (often packed columns) to reach the required 99.8% purity (Faessler et al 2005).


Two main processes are used to produce polystyrene from the styrene monomer: bulk (mass) polymerization or suspension polymerization. The bulk (mass) process

is the most widely used today. In bulk polymerization, the reaction takes place as the monomer is dissolved in a small amount of solvent, such as ethylbenzene. The most common solvent used for the polymerization reaction of styrene is 1, 2-dichloroethane (EDC). Other suitable solvents include carbon tetrachloride, ethyl chloride, meth-ylene dichloride, benzene, toluene, ethylbenzene, or chlo-robenzene. The preferred initiator is a mixture of boron trifluoride and water (Faessler et al 2005). The suspension process is also common, especially for the production of expandable beads. Suspension polymerization takes place with the monomer suspended in a water phase.

Reactors

Polymer production can be achieved using batch reactors or continuous reactors. Various grades of polystyrene can be produced by a variety of batch processes. Batch process-es generally have high conversion efficiency, leaving only small amounts of unreacted styrene to be emitted should the reactor be purged or opened between batches. A typical plant will have multiple process trains, each usually capable of producing a variety of grades of polystyrene (U.S. EPA 2008a). See Figure 25.

As with the batch process, various continuous steps are used to make a variety of grades of polystyrene or copo-lymers of styrene. In continuous processes, the chemical reaction does not approach completion as efficiently as in batch processes. As a result, a lower percentage of styrene is converted to polystyrene, and larger amounts of unreacted styrene may be emitted from continuous process sources. A typical plant may contain more than one process line, producing either the same or different grades of polymer or copolymer (U.S. EPA 2008a). See Figure 26.

Additives

Styrene is combined with additives, mineral oil (lubricant and plasticizer), small amounts of recycled polystyrene, antioxidants, and other additives in proportions that vary according to the grade of resin to be produced (U.S. EPA

High ImpactPolystyrene (HIPS)

Crystal or General PurposePolystyrene (GPPS)

ExpandablePolystyrene (EPS)

Polybutadiene

Pentane

EthylbenzeneProduction

Catalyst

Ethylene

Benzene

StyreneProduction

StyrenePolymerization

figure 24: Flow Diagram of Virgin Polystyrene Production (modified from APME 2008)


2008a). Expanded polystyrene foam and expandable poly-styrene beads may use pentane or carbon dioxide (CO2) as a blowing agent (APME 2008). Colorants are sometimes added prior to extrusion (EPIC 2007, EPS Recycling In-ternational 2008).


Recycled Material

• Pre-consumer and post consumer polystyrene


Recycling schemes for rigid polystyrene include collection and sorting of the material from the waste stream, compac-tion of the material for size reduction, and transportation to a recycling facility. The polystyrene is then fed into a granu-lator that chops the material into smaller pieces, which are then blended with other recycled or virgin PS granules. The blended material is fed into an extruder where it is melted.

Color can be added and the extruded material can then be molded into new products. Some typical recycled products include EPS packaging for the transport of delicate fruit such as grapes, office accessories, construction materials, and industrial reels and spools (EPIC 2007, EPS Recycling International 2008). Only virgin polystyrene is used in food contact applications (Franklin 2006).


Boundary Assumption

• The energy, water, and waste information in this brief is limited to the extraction of raw material through the production of PS pellet (see Figure 27). The impacts from the specific package fabrica-tion (e.g. food container) including manufacturing processes such as blowing, and impacts from consumer use are not included. The data include transportation impacts.

FeedMaterialStorage

IsothermalFeed

DissolverAgitator Vacuum

DevolatilizerProductStorage

Mass (bulk)PolymerizationBath Reactors

CondenserVent Drum

VacuumSystem

Extruder &Pelletizer

ByproductRecovery

Unit

DevolatilizerCondenser

Tank

figure 25: Flow Diagram of Batch Polystyrene Process (U.S. EPA 2008a)

FeedMaterialStorage

IsothermalFeed

Dissolver

VacuumDevolatilizer

ProductStorage

Mass (bulk)PolymerizationBath Reactors

Condenser

StyreneRecoveryColumn

StyreneCondenser

VacuumSystem

Extruder &Pelletizer

VacuumSystem

figure 26: Flow Diagram of Continuous Polystyrene Process (U.S. EPA 2008a)


Energy Consumption

Virgin

General Purpose Polystyrene: The average gross energy re-quired to produce GPPS resin is 36.4 million Btus per 1,000 pounds of resin (84.7 GJ per 1,000 kilograms of resin) (Franklin 2007). Fossil fuels like oil and natural gas are the primary energy sources for virgin PS production. While 32% of the energy is consumed during the produc-tion process, much of it is embedded within the resin itself and can be reclaimed in the future (APME 2006 Franklin 2007).

High Impact Polystyrene: The average gross energy required to produce HIPS resin is 36.9 million Btus per 1,000 pounds of resin (85.8 GJ per 1,000 kilograms of resin) (Franklin 2007).

Recycled

Currently no life cycle inventory data are available for re-cycled polystyrene packaging.

EMISSIONS

Greenhouse Gas

Virgin

About 2,763 lbs of carbon dioxide equivalents are generated per 1,000 lbs of virgin GPPS or HIPS produced (Franklin 2007). Eighty-two percent of the greenhouse gases are fuel-related. The main emissions are CO2, methane and nitrous oxide (APME 2006, Franklin 2007).

Recycled

Currently no data are available for recycled polystyrene packaging.

Air Emissions

Virgin

About 2.41 tons of air emissions are generated for every ton of virgin GPPS or HIPS produced (Franklin 2007). The main air emissions from virgin GPPS or HIPS production include CO2 from fuel production, use, and processing; SO2 and NOx, mainly from fuel production and use; and methane mainly from fuel production and PS processing (Franklin 2007, APME 2006).

Recycled

Currently, no data are available for recycled polystyrene packaging.

water discharges

Virgin

About 0.84 tons of waterborne emissions are generated for every ton of virgin GPPS or HIPS (0.84 tonnes for every tonne) (Franklin 2007). The primary pollutants in wastewater from PS production include sulfate, chemical oxygen demand, and chlorine. These emissions are all from processing the PS (APME 2006). Styrene released to water rapidly evaporates and is degraded by microbes. It does not bind well to soils and may leach into groundwater, but it is rapidly biodegraded. It does not tend to accumulate in aquatic life (EPA 2008).




ConsumerUse

End-of-Life

Recycled PSData

Recycling

MaterialProcessing

PSPellets

figure 27: PS Life Cycle Inventory Data Boundary


Recycled


Solid waste

Virgin

General Purpose Polystyrene: About 109 pounds of solid waste is generated for every 1,000 pounds of virgin GPPS produced (109 kilograms per 1,000 kilograms) (Franklin 2007). The main solid wastes associated with primary PS production include mining waste, incineration waste, slag and ash, and tailings (APME 2006).

High Impact Polystyrene: About 113 lbs of solid waste are generated for every 1,000 pounds of virgin HIPS produced (113 kilograms per 1,000 kilograms) (Franklin 2007). The main solid wastes associated with primary HIPS produc-tion include mining waste, incineration waste, slag and ash, and tailings (APME 2006).

Recycled


MATERIAL HEALTH

The most commonly raised health concern related to PS is the potential migration of residual monomer (styrene) from rigid PS food containers into food and drinks. This is an increased concern for packaging from non-North American manufacturers since the manufacturing processes do not always follow best quality practices. Lickly (1995) found that trace levels of styrene (0.003 ppm) can leach into food directly in contact with PS packaging.

From 1999 to 2002, a comprehensive review of the po-tential health risks associated with exposure to styrene was conducted by a 12-member international expert panel selected by the Harvard Center for Risk Analysis. The Harvard study reported that styrene is naturally present in foods such as strawberries, beef and some spices, and is naturally produced in the processing of foods such as wine and cheese. The study also reviewed all the published data on the quantity of styrene contributed to the diet due to migration from food packaging and disposable contain-ers. The conclusion was that there is no cause for concern for the general public from exposure to styrene (Cohen 2002).

Styrene exposure levels in the general population and among most workers are for the most part very low (CI-WMB 2004, U.S. EPA 2006). The California Office of En-

vironmental Health Hazard Assessment does not include styrene on the list of chemicals known to cause cancer or reproductive toxicity (OEHHA 2008). However, styrene is listed by the International Agency for Research on Cancer as a possible human carcinogen (IARC 2007).

Manufacturing

Some concerns have been raised over residual styrene monomer present in polystyrene manufactured in Asia.

use

Recent studies have concluded that the human health risk associated with polystyrene is extremely low.

End-of-Life

There may be health consequences associated with the open burning of PS. Please see “End-of-Life” section below.

ENd-Of-LIfE


Probable end-of-life scenarios for PS packaging include landfilling, incineration, recycling, litter, and open burn-ing.

United States

A small fraction of polystyrene packaging waste generated in the United States is recycled. Like many materials, certain forms of PS have higher post-consumer recovery rates than others. Expanded polystyrene (EPS) had a 19% recycling rate in 2006, with 32 million pounds of post-consumer EPS recycled (AFPR 2007). Approximately 280,000 tons of polystyrene packaging, accounting for about 2.3% of all plastic packaging, was disposed of in the U.S. in 2007 (U.S. EPA 2008).

Recycled polystyrene can be made into automobile battery cases, signal lights, brooms, brushes, ice scrapers, oil fun-nels, bicycle racks, rakes, bins, pallets, sheeting, trays, and packing ‘peanuts’ (APC 2006, AFPR 2001). Polystyrene used in food service applications is difficult to recycle due to food contamination and high transportation costs since EPS is bulky and not easily compacted (Franklin 2006). However, in the U.S. the Evergreen Partnering Group (East Coast) and Packaging Development Resources (West Coast) have focused on recycling EPS food service packag-ing from schools and institutions. In addition, the City of Los Angeles recently instituted a PS food service recycling program. The collected material is being recycled into a building product sold at Home Depot.


Canada

In 1989, the Canadian Polystyrene Recycling Association (CPRA) set up a pilot plant to demonstrate the feasibil-ity of recycling post-consumer PS. CPRA processes 20-25 tons of material per day, 5-6 days a week (CIWMB 2004), and is the largest horticulture polystyrene recycling facility in North America (Roulston 2003). Sixty-five to 75% of their feedstock material is from commercial packaging and graphic industry signs, 20-25% is from the horticulture industry (trays and flats), and 5-10% is from curbside collection programs. CPRA manufactures 100% post-consumer black HIPS, half of which is used by the horti-culture industry. The remainder is formed into non-critical applications such as office products (CIWMB 2004). The Canadian Polystyrene Recycling Alliance currently man-ages the plant (Mississauga News 2008).


• Recycling: Rigid polystyrene (GPPS) is one of the least recovered plastic resins. Recycling is the preferred material management option. Expanded polystyrene has a higher recycling rate, but it incurs high transport costs due to being simultaneously bulky and light weight. In addition, single use food application of EPS has food contamination that presents barriers to achieving economies of scale for recycling.

• Incineration/Waste to Energy: PS has an energy value of approximately 38.5 million Btus per ton (41.6 GJ per metric tonne), similar to that of #2 fuel oil (48.5 GJ per metric tonne) (APME 2006, APME 2006a, EPIC 2004). Polystyrene is rarely collected by curbside programs. However, conver-sion of PS into fuel may be a potential alternative to recycling (CIWMB 2004).

• Landfilling: PS does not readily degrade and represents the loss of a moderately recyclable fossil-fuel-based material resource if landfilled. The bulk of GPPS is landfilled, and about 80% of EPS packaging is landfilled (CIWMB 2004, U.S. EPA 2008).

• Littering: If released to the environment, poly-styrene does not readily degrade and is physically persistent. EPS is a significant component in coastal litter collection programs and monitoring studies. EPS is of particular concern because it is light, it floats, and it is highly visible. In addition, EPS foam breaks into minute pieces, increasing the chance of ingestion by wildlife, and increasing the

difficulty and cost of collection. (CIWMB 2004). It is unknown how much of the EPS in marine litter is coming from packaging waste.

• Open Burning: PS is not suitable for open burning as it evolves styrene, benzene, toluene, ethylben-zene, benzaldehyde, phenol, methylstyrene, n-pro-pyl benzene, indene, acetophenone, methyl indene, naphathalene, cinnamyl alcohol, methylnaphtha-lene, biphenyl, acenaphthene, methylbiphenyl, and diphenylehtane (Boettener et al 1973, EPIC 2004).


Polystyrene is a lightweight material appropriate for many packaging applications. As a technical material made from non-renewable, fossil-fuel-based resources, recycling and reuse are keys to the sustainable use of polystyrene in packaging. Like many plastics, the low recovery rate is related to lack of collection and reprocessing infrastruc-ture, poor consumer participation in recycling, and a lack of domestic markets for the material. At present these are all deterrents to the inclusion of recycled PS in consumer products. Working to increase recycling rates is important to improving the sustainability profile of PS. Polystyrene is one of the least-recovered plastics with one exception – the EPS recycling rate of 19.3% is higher than the rate of some other materials. To enhance the materials’ sustain-ability potential, polystyrene packaging used in the food and beverage industry needs to be incorporated into the wider materials collection, sorting, and processing schemes (PSPC 2006a).

Some forms of expanded polystyrene packaging are ex-cellent candidates for reuse. Recycling the product for the same use has many environmental benefits since it eliminates the need for new material – a substantial energy savings. The Plastic Loose Fill Council directs consumers to local packaging businesses willing to accept used EPS loose fill “peanuts” for their own packaging needs. Over 30% of all EPS loose fill is reused (The Plastic Loose Fill Council 2008).

Post-consumer packaging can be processed as a partial or direct substitute for virgin polymer into raw material for the production of loose-fill packing or even for new EPS moldings. It can be re-used in non-foam applications such as plastic stationery products, video and CD cases, coat hangers, plant pots, etc. Other reuse applications include hardwood replacement in the form of garden furniture, window and picture frames, and even in lightweight con-crete and building products (ground EPS is mixed with cement to make a lightweight concrete material for insulat-


ing swimming pools, flat roofs, floors, etc.) (EPS Recycling International 2008).


The main environmental issues associated with PS packag-ing are:

• Low recovery rate in the U.S. of a recyclable and non-renewable resource.

• The energy intensity of virgin production.

• Health concerns associated with the monomer styrene and the potential of styrene leaching from packaging into food.

• Persistence in the environment and the environ-mental hazard to marine wildlife that inadvertently ingest the debris.

Innovations

Various commercial compaction technologies are being de-veloped to effectively reduce the bulk of EPS for efficient transport to processing facilities. For example, Purex Inter-national has developed a system called Styromelt® that uses thermal compaction of EPS waste into a form that can be recycled into new products or used as fuel. Packaging De-velopment Resources (PDR), a California-based company actively engaged in collecting and recycling polystyrene packaging from the food service industry, remanufactures the recycled material back into packaging (PDR 2007).

There has been some work on using a special strain of the soil bacterium Pseudomonas putida and styrene oil obtained via pyrolysis of polystyrene. The bacterium can feed on styrene and convert the oil into PHA (polyhydroxyalkano-ates). The process might also be used to convert other types of discarded plastics into PHA, which readily breaks down in soil, water, septic systems and backyard composts (Ward et al 2006, Steinbuchel and Valentin 1995).

In Japan, the Sony Research Center (Center for Envi-ronmental Technologies) has developed an EPS recycling system using limonene extracted from orange peels. When applied to EPS packaging, limonene liquefies the EPS, reducing the volume to 5% of the original volume. Sony has developed a mobile unit to collect the EPS packaging waste from its retail stores. The foam is dissolved while it is being transported to the recycling facility. Using a se-ries of heat treatments, the limonene and polystyrene are separated and each is reused, the limonene as the solvent and the polystyrene processed into pellets for reuse. The limonene method has carbon dioxide emissions of about 0.6 kg of CO2 per kg of PS recovered, about one third

of the emissions associated with new polystyrene synthesis (Sony Corporation 1997).

Polyvinyl Chloride | 33E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polyvinyl Chloride (PvC)


• The life cycle inventory data used for this brief include virgin PVC production (raw material extraction through pellet production).

OvERvIEw

Polyvinyl chloride (PVC), SPI resin code #3, was first produced in 1930. Mass production and use of PVC took off in the 1950s and 1960s. PVC packaging has increased from 945 million pounds (428 million kilograms) in 2001 to 971 million pounds (440 million kilograms) in 2006 (ACC 2007).

Two types of polyvinyl chloride (PVC) are produced: rigid resins which have considerable strength and hardness, good clarity, excellent processing performance and resistance to grease, oil and chemicals; and flexible resins, containing a large proportion of plasticizers to make them soft and flex-ible (ICIS 2008). Examples of rigid PVC packaging include bottles, clamshells and blister packs used as pharmaceutical and medical packaging. Flexible applications include films, bags, and pouches used for food, housewares and medical applications (e.g. blood bags) (AGPU 2004). Additives are used to tailor the polymer for various applications. Rigid PVC contains 2-15% additives, while flexible PVC has 35-65% additives (Tukker et al 1995, Postle et al 2000).

In 2007, PVC represented 5.4% of all plastics in the U.S. municipal solid waste stream. Negligible amounts of PVC are recovered from the U.S. waste stream (U.S. EPA 2008). Detailed recovery rates of all packaging materials from the municipal waste stream can be found in the U.S. Packaging Materials Recovery and Discard section in the introduc-tion.

PROduCTION METHOdS

Primary Production

Monomer Production Process

PVC is made from the monomer vinyl chloride (CAS # 75-01-4). Petroleum or natural gas and rock salt are the primary raw materials used to produce the ethylene and chlorine feedstocks for the production of vinyl chloride (Baitz et al 2004). The ethylene monomer production pro-

cess is described in the introductory section for plastics, Ethylene & Propylene Monomer Production Process.

Chlorine Production

Chlorine is obtained through the electrolytic refining of a purified sodium or potassium brine solution at a chlor-alkali facility (Baitz et al 2004). Salt (sodium chloride) is dissolved in water to form the brine solution. This solution is placed in a cell and electrical current is passed through it to produce chlorine, sodium hydroxide and hydrogen (see Figure 28).

Three technologies are used for the electrolytic separation of chlorine and other co-products from the brine: the diaphragm, mercury and membrane cell processes. Each technology differs in cell, process design and production efficiency. Use of these technologies varies significantly from region to region around the world. Mercury cells were the most widely used technology in North America until the 1990s and have been a common technology in Europe (Lindley 1997). Significant concerns associated with the use and emission of mercury from these facilities led to a technology conversion in most parts of the world.

The World Chlorine Council estimates there are 135 mercury-cell plants operating worldwide. In Japan, all mercury-based production was phased out by 1987. In the U.S. currently about 9% of production is based on mercury cells, while mercury cells accounted for 48% of European capacity in 2005. Western European producers have committed to close or convert all mercury cell plants by 2020 (World Chlorine Council 2007).

There are more than 500 chlor-alkali producers at over 650 sites around the world, with a total annual production capacity of over 58 million metric tons of chlorine (ACC 2007). The Dow Chemical Company is the world’s larg-est producer of chlorine, producing more than 13 billion pounds (5.9 million metric tons) (Dow Chemicals 2008). Thirty percent of the chlorine produced industrially is used in the manufacture of PVC.

Virgin Vinyl Chloride Production

Ethylene and chlorine are reacted together over an iron chloride catalyst at temperatures between 50°C and 120°C to form ethylene dichloride (EDC). After cooling, wash-ing and distillation, the ethylene dichloride is heated in a high temperature furnace and converted to vinyl chloride (IPPC 2003). This process generates hydrogen chloride as a byproduct, which is reacted with ethylene and oxygen over copper chloride catalyst in a process called oxychlorination to form further ethylene dichloride (raw) (IPPC 2003).


At room temperature vinyl chloride is a gas and is pres-surized to form a liquid. Vinyl chloride gas and liquid are highly flammable. The vapor forms an explosive mix-ture with air (explosive limits 4-22%) (Matheson Trigas 2008).

Virgin Source Material (EPA 1997)

• Monomer – vinyl chloride and ethylene

• Catalysts – iron chloride and copper chloride

• Initiator – organic peroxides

• Solvent – water

• Suspending agent or emulsifier


There are essentially four polymerization techniques used for the manufacture of PVC polymer: suspension, emul-sion1, bulk, and mass2. Suspension is by far the most com-mon polymerization process and accounts for about 90%

1 In emulsion polymerization, surfactants are used to disperse vinyl chloride monomer in water (APME 2006). Polymerization generally takes place in micelles or in emulsion particles using water soluble initiators. The process can either be continuous or batch; both lead to a polymer latex, a very fine suspension of polymer particles (~0.1 um diameter) in water. Excess monomer is recovered, recycled, and the particle polymers are dried (APME 2006).

2 Bulk or mass polymerization occurs in the complete absence of water, protec-tive colloids or emulsifying agents. The vinyl chloride is mechanically agitated in a vertical autoclave with the appropriate initiators until conversion of 7-10%. Heat is removed by continually condensing the vapor above the liquid reaction mixture. The pre-polymer is transferred to a horizontal autoclave equipped with a slow paddle. The particles already formed grow by formation of further polymer until 70-90% of the monomer has been converted (APME 2006).

of the global production of 30 million tons (Plastemart 2008).

Suspension Polymerization

In the suspension polymerization process vinyl chloride monomer (VCM), water, organic peroxides (initiator), and suspending agents are mixed in a stirred-tank pres-surized reactor (See Figure 29) (APME 2006, Tukker et al 1995). The mixture in the reactor is heated to 50-70°C and agitated (Tukker et al 1995). Suspending agents and agi-tation stabilize the monomer droplets and newly-formed polymer particles and keep them from clumping together until approximately 20% conversion is achieved (APME 2006). The reaction is continued to about 90% conversion of VCM to PVC.

The unreacted vinyl chloride monomer is removed from the vessel, purified in a vinyl chloride recovery unit and recycled into the reactor. The PVC polymer slurry is steam-stripped to reduce the residual monomer to about 50 ppm. Any water recovered from the process is separated and sent to the process water treatment facility. The wet polymer is dried.

During compounding, additives (stabilizers, plasticizers, fillers, pigments) are added and heated to create a PVC compound dry mix. This dry mix can be fed directly to an extruder or injection molder to produce products or can be pelletized.

PvC Pellets

ElectrolysisCell

Cracker

Salt

Electricity

Natural GasVinyl Chloride

Monomer (VCM)Plant

PVC PlantVCM GasEthyleneGas

Chlorine Gas

HydrogenGas

CausticSoda

Chlor-alkali

Process

Hydrochloric AcidHydrocarbonsand Oil

Oxygen

figure 28: Flow Diagram of PVC Production (modified from University of Bristol, 2008)


Additives

To make PVC products and packaging, various additives are combined with the resin in different combinations depending on the desired end products. This produces PVC formulations suitable for many different processing technologies and results in a wide range of performance characteristics (rigid, flexible, semi-liquid, clear, colorful, thick, thin, etc.). Common additives include stabilizers, plasticizers, fillers and pigments. For example, thermal stabilizers preserve polymer color and stability during pro-cessing.

Plasticizers are added to induce flexibility. Some commonly used plasticizers in plastic wrap applications include di-2-ethylhexyl adipate (DEHA) and dioctyl adipate (DOA). Adipates are typically used in packaging applications such as cling film and high temperature cables (Plasticisers Infor-mation Centre 2008). Another class of plasticizers includes di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DINP), di-isodecyl phthalate (DIDP), di-butyl phthalate (DBP) and butylbenzyl phthalate (BBP). Other additives can include bio-sourced products such as soy bean oil and citrus oil. Flexible PVC can contain up to 60% plasticizer when used as a coating and in very soft products. On aver-age, flexible PVC contains about 30% plasticizer.

Pigments are added to achieve different colors. The most common pigments include titanium dioxide (white) and carbon black (Potting and Block 1995). Approximately 1-8 % may be added to the PVC formulation depending on other components and the final application (Euro-pean Commission 2000). Inert materials such as calcium

carbonate (chalk), talc, and kaolin, are used as fillers to improve some mechanical properties of PVC as well as to reduce production costs (European Commission 2004, Baitz et al 2004).


Recycled Material

• Post-consumer PVC.


There is essentially no post-consumer collection or recovery of PVC packaging in the U.S. In Europe, there is limited infrastructure for the post-consumer collection and re-covery of PVC packaging, resulting in some recycling of non-packaging PVC.


Boundary Assumption

The energy, water, and waste information in this brief is limited to the extraction of raw material through the pro-duction of the PVC pellet (see Figure 30).

Energy Consumption

Virgin

The energy needed is about 22.5 million Btus per 1,000 pounds of virgin PVC manufactured (52.4 GJ per 1,000 kilograms) (Franklin 2007). Fifty-one percent of the en-ergy is consumed during the manufacturing processes. Pe-

BlowdownVessel

PressurizedReactor

Dryer Compounding Pelletizer PvCPelletsFusion

PVC PolymerDroplets

Vinyl Chloride Monomer &Byproducts (chlorinated andnon-chlorinated)

Suspending Agent

Organic Peroxides

Water

Vinyl ChlorideMonomer

figure 29: Flow Diagram of Virgin PVC Production (modified from APME 2006, Tukker et al 1995, Baitz et al 2004, Postle et al 2000)


troleum, natural gas, and coal represent 97% of the energy associated with virgin PVC production (Franklin 2007).

Recycled

A minimal amount of post-consumer PVC packaging is commercially recycled. Life cycle inventory data for re-cycled PVC are currently not available.

EMISSIONS

Greenhouse Gas

Virgin

About 2,029 lbs CO2 equivalents per 1,000 lbs PVC (2,029 kg CO2 equivalents per 1,000 kg) are generated during virgin PVC production. Ninety-one percent of the greenhouse gas emissions are fuel-related and 9% of the greenhouse gas emissions are process-related (Franklin 2007). The primary greenhouse gases from the fuel for the production and manufacturing of PVC are carbon diox-ide, methane, and nitrous oxide (APME 2006, Franklin 2007).

Recycled

Currently, minimal amounts of post-consumer PVC pack-aging are commercially recycled. Life cycle inventory data for recycled PVC are currently not available.

Air Emissions

Virgin

About 1,764 lbs per 1,000 pounds of PVC (1,764 kg per 1,000 kilograms) of air emissions are released during the

production of virgin PVC (Franklin 2007). The primary air emissions from virgin PVC production include carbon dioxide, sulfur dioxide, methane, other sulfur oxides, and carbon monoxide (APME 2006, Franklin 2007).

Recycled

Life cycle inventory data for recycled PVC are currently not available.

water discharges

Virgin

About 499 lbs per 1,000 pounds of PVC (499 kg per 1,000 kilograms) of various water pollutants are discharged dur-ing the production of virgin PVC (Franklin 2007). For virgin PVC production, the primary pollutants in waste-water include chlorine, sulfate, sodium, calcium, lithium, and magnesium (APME 2006, Franklin 2007).

Recycled

Minimal amounts of post-consumer PVC packaging are commercially recycled. Life cycle inventory data for re-cycled PVC are currently not available.

Solid waste

Virgin

About 131 pounds of solid waste are generated for every 1,000 pounds of virgin PVC produced (131 kilograms of solid waste per 1,000 kilograms) (Franklin 2007). Solid waste associated with primary PVC production includes carbon from process filters, calcium chloride from the dry-ing of process flows, and sewage sludge. Solid waste and




ConsumerUse

End-of-Life

Recycled PVCData

Recycling

MaterialProcessing

PVCPellets

figure 30: PVC Life Cycle Inventory Data Boundary


sludge can contain organohalogens including dioxins (EC 2004).

Recycled

Minimal amounts of post-consumer PVC packaging are commercially recycled. Life cycle data for recycled PVC are currently not available.

MATERIAL HEALTH

Manufacture

PVC is made from the monomer vinyl chloride, a known human carcinogen (U.S. EPA 2008, OEHHA 2008, IARC 2007). Plants that manufacture PVC emit vinyl chloride, and potentially residual solvents used as carriers for initia-tors. One such residual solvent is odorless mineral spirits, a very highly purified form of mineral spirits that has been refined to remove the more toxic aromatic compounds.

At high vapor concentrations vinyl chloride depresses the function of the central nervous system and brain, causing dizziness, light-headedness and unconsciousness. Dermal (skin) exposure to liquid vinyl chloride is possible and burns may result due to rapid evaporation of liquid vinyl chloride and consequent freezing of the skin (Dow Chemi-cals 2008, Work Cover 1991).

use

A 2007 study by the Northeast Recycling Council exam-ined heavy metals in packaging. Flexible PVC packages failed the screening test where one or more of the restricted heavy metals (cadmium, lead, chromium, and mercury) were detected at a concentration greater than 100 ppm (the regulated total amount allowable in packaging for heavy metals). Historically, these metals were used in colorants and inks, and as stabilizers in PVC to retard the degrada-tion of plastics exposed to heat and ultraviolet light. In the U.S., these metals have been largely phased out. The study found that packages of imported products continue to use raw materials containing heavy metals. A high per-centage of the samples with elevated lead and cadmium levels were flexible PVC packages for imported products (TPCH 2007).

Plasticizers: Phthalates are given off freely by PVC (called “off-gassing”) because they are not chemically bonded to PVC molecules. Off-gassing increases with mechanical stress (i.e. bending, pressure, and chewing) and exposure to solvents such as fats, oils, saliva, and temperatures over 85° Fahrenheit. However, a recent study has shown that DEHP inhibits the deterioration of the red blood cell

membrane resulting from the refrigerated storage of whole blood (Estep et al 2008). The ecological and health effects of phthalates and some chlorinated paraffins are begin-ning to become a concern. Some EU Member States have banned the use of phthalates in certain toys and child care articles (Plinke et al 2000).

Five phthalates—DEHP, BBP, DBP, DIDP, and DnHP—are listed on the California Proposition 65 list of chemicals known to cause cancer or reproductive toxicity. In 2006, San Francisco enacted a prohibition on the use of DEHP, DBP, and BBP in all toys and child care articles and pro-hibition on the use of DINP, DIDP, and DNOP in toys and child care articles for children under three years of age that can be put in the mouth. In October 2007, California became the first state in the country to pass the same ban at the state level (Environment California 2008).

End-of-Life

Currently, post-consumer PVC packaging is not collected for recycling. The broad array of performance characteris-tics that are valued for PVC products work against its re-cyclability. Since PVC is highly variable in its composition it is difficult to get a consistent and economically viable recycling stream. As a result, essentially all PVC packaging is either landfilled or incinerated in the U.S. Like other fossil-fuel-based polymers, PVC does not degrade in land-fills and it may release vinyl chloride. Compared to other polymers, PVC has a low calorific value since it is about 50% chlorine.

ENd-Of-LIfE


Probable end-of-life scenarios for PVC packaging include landfilling, recycling, waste-to-energy incineration and lit-ter.

United States

Negligible amounts of PVC were recycled in the U.S. in 2007. The U.S. disposed of about 410,000 tons (372,000 metric tons) of PVC packaging, which accounted for about 3% of all plastic packaging in 2007(U.S. EPA 2008). When recycled, PVC can be made into packaging, deck-ing, paneling, gutters, mud flaps, film and sheet, flooring, cables and garden hoses (APC 2006).

The majority of the disposed PCV packaging in 2006 consisted of coatings, closures, caps, trays, clamshells and other rigid packaging. PVC makes up only 1% of the bottle market (R.W. Beck Inc. 2004) and appears only


in small amounts in the recycling stream. With such a small volume, PVC is not economical to recycle (Baitz et al 2004). Various groups including the Association of Post-consumer Plastic Recyclers (APR) have labeled PVC products as contaminants to recycling streams for other plastics (APR 2006, Toloken 1998, Recoup 2006, World Wastes 1998).

Europe

Like the U.S., very little post-consumer PVC waste is re-cycled in Europe mainly due to high costs of collection, separation, and processing. The recycled material mainly consists of cables and packaging. These are typically pro-cessed as mixed plastic, which produces low value recyclate. High quality recycling of post-consumer waste exists for single product groups (bottles, pipes, window frames) but only in very low quantities (Plinke et al 2000).


• Recycling: Less than 1% of PVC is recycled in the U.S. About 3% of post-consumer PVC waste is recycled in Europe (European Commission 2004).

• Incinerating/Waste to Energy: PVC has an energy value of approximately 16.3 million Btus per ton (19 MJ per metric tonne) (EPIC 2004). As with combustion of all polymers, incineration must be done at facilities with well designed and appropri-ate control technologies to avoid release of dioxin and other air pollutants, including heavy metals. PVC has a direct effect on the quantity of chlorine in the combustion gases and requires the use of control technology (Jacquinot et al 2000). Recent studies have shown that the presence of PVC in materials incinerated has no significant effect on the amount of dioxins in air emissions (PE Europe 2003, TNO 1999). Incineration is preferable to landfilling since solid waste and sludge containing organohalogens can be avoided (EC 2004).

• Landfilling: PVC represents a substantial loss of a fossil-fuel-based material resource.

• Littering: If released to the environment, PVC does not biodegrade and is physically persistent.

• Open Burning: PVC is not suitable for open burning. It emits a number of toxic compounds including carbon monoxide, heavy metals, dioxin, PAH (polycyclic aromatic hydrocarbons) and HCl (hydrogen chloride) (Moller et al 1999, Baitz et al 2004).


Recycling PVC is critical to the sustainability profile of the material, yet the large variety of PVC formulations is a sig-nificant limitation to its recoverability. Lack of a collection infrastructure and reprocessing facilities is a barrier to the amount of recycled PVC available for any use.


The main environmental issues associated with PVC pack-aging are:

• Low recovery rate in the U.S. of a moderately recy-clable and non-renewable resource.

• The use of problematic additives to obtain physi-cal properties in PVC packaging applications is a source of human and ecological concerns, particu-larly if sourced from China.

• The use of a carcinogenic monomer required for material manufacture and its potential for release.

• Potential for release of toxic substances in various end-of-life scenarios, including landfilling, incin-eration and open burning.

Due to its legacy of poor environmental performance, qual-ity concerns related to overseas production, and increasing concerns about the use of additives, PVC is subject to significant negative attention from the NGO community and campaigns that advocate its discontinuation. Many retailers over the past several years have committed to limit or ban the use of PVC in packaging.

Innovations

The European Council of Vinyl Manufacturers created a voluntary industry program called Vinyl 2010 to reduce the environmental impact of PVC waste. This program has helped to double the current amount of PVC recycled since 2004 to over 42,800 tons (38,800 metric tonnes). How-ever, the quantity of PVC waste available for recycling has decreased, mainly due to the increasing lifespan of some PVC products and market conditions that make it cheaper to export or landfill waste rather than to recycle it. A sig-nificant amount of the recycled PVC is from construction waste where financial incentives were given to accredited recovery firms and recyclers (Higgs 2006).

Though PVC package recycling information could not be found, there have been breakthroughs in the recycling of other PVC products. These recent developments could cre-ate opportunities for increased PVC package recycling.


Two subsidiaries of Kobe Steel started Japan’s first polyvinyl chloride waste recycling plant (Platts Commodity News 2006 and Japan Chemical Week 2006). It is the first plant in Japan to extract PVC from used PVC-based goods rath-er than transforming it into industrial material like carpet lining (Japan Energy Scan 2006). The plant will be able to process up to 28,700 tones (26,000 metric tons) per year of PVC waste and produce 19,400 tons (17,600 metric tons) per year of recycled PVC (Japan Chemical Week 2006, Platts Commodity News 2006).

Solvay, a Belgium based firm, developed a PVC solvent separation recycling process. It begins by cleaning and fragmenting PVC waste. Then ketone solvents selectively dissolve the PVC, separating it from other materials. The solvents are vaporized using steam, leaving PVC in granu-lar form containing the plasticizer and stabilizer (Japan Chemical Week 2006). The quality of the resulting PVC is equivalent to the original product (Japan Chemical Week 2006). Currently, the recycling facility will focus mainly on PVC from agricultural sheeting, wallpaper, and wire coating materials (Japan Energy Scan 2006, Platts Com-modity News 2006). The facility expects to accept PVC piping later (Platts Commodity News 2006).

Polylactide | 40E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

Polylactide (PLA)


• The life cycle inventory data used for this brief include all agricultural practices from corn plant-ing, harvesting, and processing through PLA pellet production.

OvERvIEw

Polylactide (PLA) is a bio-based polymer derived from sugar or starch feedstocks. The current production rate of bio-based polymers—plastics made from biological resources—has been stimulated by mounting economic and environmental concerns about the global increase in petroleum use, climate change, and European and Japa-nese legislative incentives (ICIS 2006a). The demand for bio-based polymers is currently growing more than 25% a year and forecasted to grow at a rate around 20% for the next several years (ICIS 2006, Chemical Engineering Progress 2006). The recent push by several large retailers to move into bio-based packaging (including Wal-Mart in the U.S and Carrefour in Europe) has significantly increased worldwide interest in PLA (ICIS 2006a).

In the U.S., corn has been the primary feedstock used for the first generation of PLA-based polymers. Corn is rich in starch and has historically been abundant and cheap (Vink et al 2003). However, due to recent federal subsidies for biofuels and the resulting expansion of the ethanol market, corn prices have risen from increased competition for avail-able corn stocks. In 2007, according to the USDA, U.S. corn production was the largest on record as producers harvested the most corn acres for grain since 1933.

With principal manufacturing operations located in Blair, Nebraska, NatureWorks LLC is currently the world’s larg-est producer of PLA with an annual nameplate production capacity of 300 million pounds (140,000 metric tons) (NatureWorks 2008). After reorganization in 2007, Na-tureWorks LLC is now a 50/50 joint venture with Cargill, a multi-national agribusiness and provider of corn wet milling and starch technologies, and Teijin, a Japanese multi-national technology firm with expertise in polymer and fiber applications (NatureWorks 2008). At this time, there are several other smaller producers of PLA in Japan, China and Europe.

Like other biopolymers, PLA represents innovation in the front end manufacture of a polymer through the use of bio-based and renewable carbon feedstocks. While currently not

a significant benefit due to the lack of composting facilities, PLA also represents innovation in expanding the potential end-of-life management options for polymers because it is certified by the Biodegradable Products Institute to be compostable in managed composting systems. Managed or industrial composting systems provide higher temperature, moisture and microbial conditions than possible in typical backyard composting settings.

The most common packaging applications of PLA include films, coatings, thermoformed food and beverage contain-ers, food service ware, and wrappers. PLA biopolymer can be clear, opaque, flexible or rigid. It provides gloss and clar-ity similar to polystyrene, and exhibits tensile strength and modulus comparable to hydrocarbon-based thermoplastics (Natureworks LLC 2007, NatureWorks LLC 2008).

PROduCTION METHOdS

Primary Production


• Any starch/sugar feedstock such as corn, rice, sugar beets, sugarcane, wheat, and sweet potatoes (Vink et al 2003).3

• About 2.7 tons of corn (2.5 metric tons) is needed to produce one ton of PLA (NatureWorks LLC 2006).

Field Corn Production Process

NatureWorks LLC uses No. 2 yellow dent field corn, which is an animal feed corn that is often genetically modified (GMO) (Glasbrenner 2006). However, when requested, non-GMO modified can be used for PLA production. A 2008 estimate from USDA cites that approximately 80% of all corn planted for food, feed and industrial purpose was genetically modified. This is a significant increase from an estimate of 60% in 2006 (USDA 2009).

In the U.S. Corn Belt (Iowa, Indiana, Illinois, Ohio, and parts of South Dakota, Minnesota, Wisconsin, Michigan, Missouri, Kentucky, Kansas and Nebraska) corn plant-ing extends from late March to mid-May (Hickman and Shroyer 1994). It takes about 120 days for corn to mature for harvest (Vanderlip and Fjell 1994). Corn is a water-intensive crop and requires more nutrients than any other crop grown in the U.S. (Rogers 1994). High corn yields require additional nutrients from chemical fertilizers, ma-

3 At full capacity NatureWorks will use 0.11% of the No 2 yel-low field dent corn grain production in the U.S. (NatureWorks 2008).


nures or legume rotations, with nitrogen, phosphorous, po-tassium and lime being the most common nutrients added (Lamond 1994). Weeds, insects, and disease pose a threat to the yield and quality of the crop (Regehr 1994) and typical management practices include the use of herbicide-resistant and other genetically modified corn hybrids, crop rotations, as well as herbicides and pesticides (Ransom et al 2004, Jardine 1994).

Corn Wet Milling and Lactic Acid Production

As shown in the Figure 31, harvested field corn is taken to a corn wet mill where it undergoes a series of processing steps to separate the starch from other parts of the corn kernel (proteins, fats and fibers) (Vink et al 2007). Various products are produced from corn wet milling processes in-cluding corn gluten meal, corn gluten feed, corn oil, corn oil meal and starch. The resulting starch can be used in a number of finishing processes to produce ethanol, corn syrup, modified and unmodified corn starches, dextrin and dextrose (U.S. EPA 2009).

In the U.S., the current PLA production practice is to con-vert dextrose into lactic acid through a fermentation step. The fermentation process uses energy in the form of steam and electricity, with sulfuric acid and calcium hydroxide as chemical inputs (IFEU 2006). A final purification step removes any remaining impurities, producing pure lactic acid ready for polymerization (Vink et al 2007).

Polymerization, Devolving, Crystallizing, and Drying

The polymerization of PLA from lactic acid occurs in two steps. The first step is the conversion of lactic acid into a ring form made up of two lactide molecules, with subse-quent purification by distillation. In the second step, the polymerization of lactide to polylactide takes place in the presence of a tin catalyst via ring-opening polymerization (IFEU 2006). After polymerization is complete, any re-maining unreacted lactide is removed and recycled back into the process (Vink et al 2007). The PLA polymer goes through final processing in a crystallizer and dryer to make PLA pellet (Vink et al 2007).

Additives

A variety of additives, fillers and coatings can be used with PLA depending on the intended application. The use of additives is an active area of research and innovation. Like all polymers, additives should be selected with care, but this is especially true if the intended disposition for the packaging is composting.


While PLA is readily recyclable through both mechanical and chemical processes (hydrolysis), currently PLA is not currently recovered in sufficient quantities to make recy-cling and secondary production economically feasible. The Association of Post-Consumer Plastics Recyclers estimates that it requires around 50 million pounds of resin to be collected (around 400 millions pounds of material in the marketplace) to make polymer recycling economically vi-able. This assumes there is material of sufficiently uniform composition to be collected, an efficient recycling infra-structure in place and economically viable end uses.


Boundary Assumption

• The information in this brief on energy, water, and waste is limited to data on steps from corn produc-tion through PLA pellet production as part of the NatureWorks LLC process for manufacturing PLA resin (see Figure 32). For corn production, the in-puts include the production of corn seed, fertilizers, herbicides, insecticides, limestone, electricity and fuel, and irrigation water used on the farm (Vink et al 2007). Transportation impacts from taking the corn from the fields to the mill are also included. The mill and the PLA plant are at the same loca-tion, so no additional transportation is needed. The impacts of specific package fabrication (bottles or food containers) and from consumer use are not included. (Vink et al 2003).

• Most of the data are from Vink et al 2003, 2007, and IFEU 2006 and are specific to NatureWorks LLC PLA production methods.

Corn Production,Harvesting, Drying

and Transport

DextroseProduction

Lactic AcidProduction

LactideProduction PLA PelletsPolyactide

Production

figure 31: Simplified Flow Diagram of Virgin PLA Production (adapted from Vink et al 2007)


• The three reports produced by NatureWorks LLC (Vink et al 2003, 2007, and IFEU 2006) use the same methodology, software and core databases as the APME for the plastic eco-profiles.

Energy use

Virgin

About 50 million Btus per ton (58 GJ per metric ton) of energy is used during the manufacture of NatureWorks PLA resin (Vink et al 2007). Current production of PLA uses 54 MJ of fossil resources per kg of PLA pellet (Na-tureworks FAQ 2008). The fermentation process requires energy in the form of steam and electricity, and contributes substantially to the fossil energy demand of PLA (IFEU 2006). The total energy input comes from feedstock energy (corn), wind energy, and energy from delivered fossil fuel. In addition, fuel is used in delivery and transport (Vink et al 2007).

Recycled

Currently, there are no available data for recycled PLA packaging.

EMISSIONS

Greenhouse Gases

Virgin

About 3.8 tons of greenhouse gases as CO2 equivalents are generated for every ton of virgin NatureWorks PLA pro-duced (Vink et al 2007). During the growing phase of corn production, CO2 is taken up from the environment and incorporated into the corn plant itself through the process of photosynthesis. This CO2 sink is about 1.94 kg CO2/kg PLA.

NatureWorks LLC purchases renewable energy credits (RECs) which offset CO2 equivalent emissions to 0.27 tons of greenhouse gases per ton of virgin PLA produced (0.25 metric ton per metric ton). The primary Greenhouse gases

emitted from PLA production include carbon dioxide, nitrogen oxide, and methane (Vink et al 2007).

Recycled


Air Emissions

Virgin

Air emissions from the production of PLA include carbon dioxide, nitrogen dioxide, dinitrogen oxide and methane sulfur oxide (Vink et al 2007, Ecoinvent 2008).

Recycled


water discharges

Virgin

About 32 pounds of water pollutants are generated for ev-ery ton of NatureWorks PLA produced (14.5 kilograms per metric tonne) (Vink et al 2007). The main water pollutants released are chemical oxygen demand4 and suspended solids from the manufacturing process (Vink et al 2007). Fertiliz-ers used for corn cultivation are known to degrade ground and surface water quality due to high concentrations of nitrogen and phosphorus in storm water runoff (Ransom et al 2004). Other water pollutants include nitrate, sulfate, and chloride (EcoInvent 2008).

Recycled


4 Chemical oxygen demand measures the amount of organic pollutants found in surface water.


CornProduction


ConsumerUse

End-of-LifeCorn Wet

Milling & LactideProduction

Polymerization

figure 32: Life Cycle Data Boundary for PLA Production


Solid waste

Virgin

About 102 pounds of solid waste are generated for every ton of virgin NatureWorks PLA produced (46.3 kilograms per metric tonne) (Vink et al 2007). The main solid wastes include plastics, mineral waste, slag and ash, mixed regulat-ed, unregulated, and inert industrial chemicals, construc-tion waste, waste to recycling, waste returned to the mine, and unspecified refuse (Vink et al 2007).

Recycled


MATERIAL HEALTH

Manufacturing

There are no known human or ecological health concerns specific to the production of PLA.

use

There are no known human or ecological health concerns associated with PLA.

End-of-Life

There are no known human or ecological health concerns associated with the end-of-life management of PLA. It is important to note that when PLA is composted, all the components and additives in PLA are potentially released into the environment. PLA additives must be carefully se-lected to avoid environmental risks to wildlife or humans after composting.5

ENd-Of-LIfE


Probable end-of-life scenarios for PLA packaging include landfill, recycling, industrial composting, incineration/waste to energy, open burning and litter.


• Recycling: Along with industrial composting and reuse, recycling is a preferred end-of-life option for

5 Neat PLA has passed all eco-toxicity tests—Material Characteristics, Biodegrada-tion, Disintegration, and Ecotoxicity. Description of the requirements of these tests can be found by geographical area: DIN V 54900-1 (Germany), EN 13432 (EU), ASTM D 6400 (USA), GreenPla (Japan).

PLA. For more details, please refer to the Sustain-ability Potential section.

• Incineration/Waste to Energy: Incineration of PLA should occur at a properly designed facility with the best available control technology and will release CO2 and carbon monoxide, similar to traditional polymers. Improper incineration will result in uncontrolled release of air pollutants and/or bottom ash.

• Landfilling: PLA does not readily biodegrade under landfill conditions and represents the loss of a highly recyclable, bio-based material resource if landfilled.

• Industrial Composting: PLA will degrade into carbon dioxide, water, and humus when com-posted in an industrial composting system. The Biodegradable Products Institute certified PLA as compostable according to ASTM 6400-99 (Nature-Works LLC 2005). There are over 100 industrial composting facilities in the US, but only a quarter of these accept residential food scraps (Royte 2006), the most likely recycling stream for PLA.

• Backyard Composting: PLA will not biodegrade in a backyard composting environment.

• Open Burning: PLA will readily burn and evolve CO2 and other greenhouse gases.

• Littering: Like any polymer, PLA will persist if released into the environment.


Feedstock

There are significant environmental impacts associated with grain production, including corn. The size and extent of the oxygen poor area (Dead Zone) in the Gulf of Mexico is strongly correlated to nutrient-rich runoff from fertilizers used for crop production in the Midwest. The Dead Zone is caused by excessive algal growth due to the presence of nutrient-rich water followed by algal death and decay, which consumes the available oxygen in the water column. This process, referred to as eutrophication, can lead to an-oxic conditions that threaten aquatic organisms. The use of genetically modified corn, herbicides and pesticides also pose concerns.

Mechanical Recycling Production Process

PLA is a thermoplastic and can be mechanically ground and re-extruded. However, due to the low volume of PLA in the marketplace, it is not recycled at a commercial scale


at this time. It is important to note that PLA has a similar density to PET (1.24 g/cc for PLA and 1.34 g/cc for PET). The two materials are not easily separated from each other in a float sink separation system and PLA can contaminate the PET recycling stream (Truini 2006). However, PLA is readily separable from other plastics, including PET, using optical scanning equipment (Verespej 2006).

PLA acts similar to PET in downstream post-consumer reclamation processes. A PLA reclamation stream can be handled by the current infrastructure in place at typical Materials Recovery Facilities (MRFs) and recycling facili-ties designed to handle mixed bales. Nature Works LLC has a buyback program to create market-driven demand for post-consumer PLA bottles and encourage their separation in the plastics recycling stream at recycling facilities (Solid Waste Report 2006).

Chemical Recycling Production Process

PLA can be chemically recycled through hydrolysis. The process turns PLA back into lactic acid, its original building block. Chemical recycling involves boiling the PLA plastic mixed with water at about 212 – 480° F (100 – 250° C). A strong acid such as nitric or sulfuric acid is used as a cata-lyst. The hydrolysis reaction forms lactic acid. The resulting lactic acid is purified to remove any contaminants and fed back into the manufacturing process to create a new PLA pellet. This is not currently done on a commercial scale.


The main environmental issues associated with PLA pack-aging are:

• PLA production in the U.S. currently depends on corn, and corn cultivation has a number of known environmental concerns.

• Consumer confusion over the compostability and appropriate post-use disposition of PLA is a prime concern since the material needs to enter an indus-trial composting facility to fully decompose.

• The low volume of material in the marketplace and the current lack of infrastructure for industrial composting or mechanical recycling is a barrier to beneficial recovery of PLA packaging.

• The fate of additives in compostable materials needs further research. The establishment of an approval process for these materials will facilitate acceptance of compostable materials by commercial composting facilities.

Innovations

The popularity of PLA has caused NatureWorks LLC to maximize production at their main plant in Blair, Nebras-ka. In less than three years, NatureWorks LLC has doubled their customer base and has an annual growth rate of over 45% (Renstrom 2006). They have experience triple-digit growth since 2005 in rigid plastic packaging (ICIS 2006a). In the next ten years, bio-based plastics could capture about 1.5-4.8% of the total plastics market (ICIS 2006a).

NatureWorks LLC created a next-generation PLA produc-tion system, implemented in early 2006, which offers two significant improvements:

• A new process technology reducing energy use, raw materials and co-product (gypsum and landfill waste) generation.

• Implementation of renewable electricity generation.

The introduction of PLA to the marketplace has encour-aged the introduction of a number of other bio-based polymer innovations.

References | 45E T B s of CO M M O N PAC K A G I N G M AT E R I A L S : P O LY M E R S

References

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HdPE

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LdPE

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PET

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Additional Resources:

• The Association of Plastics Manufacturing in Eu-rope (APME)—www.plasticseurope.org

• The Association of Post consumer Plastic Recyclers (APR)—www.plasticsrecycling.org

• National Association for PET Container Resources (NAPCOR) – www.napcor.com

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PS

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PvC

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APC (American Plastics Council). 2006. “Resin identifi-cation codes – Plastic recycling codes.” Organization


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