Plastics“I just want to say one word to you... just one word...

-the graduate

”

What are Polymers?

greek for many parts

long chains of repeating molecules (monomers)

natural polymers: proteins, starch, cellulose

synthetic polymers...

synthetically polymerized material... typically from hydrocarbons

from crude

6-10 percent of U.S. oil consumption - approximately 2 million barrels a day *

What is Plastic?

* lawrence livermore, 2004; metabolix 2007

green plastic oil can

Thermoplastics vs Thermosets

THERMO (heat) PLASTIC (deform)

THERMO (heat) SET (permanent)

ThermosetsPermanent, Chemical Reaction! Polymer Chains are cross-linked.

Usually two-part exothermic, or heat treated

Used in for high temp, high tolerance, or joining

not recyclable.

melamine

phenolics

vulcanized rubber

Acrylonitrile-Butadiene-Styrene (ABS)

PolyVinyl Chloride (PVC)

PolyPropylene (PP)

PolyEthylene (PE)

PolyStyrene (PS)

PolyMethylMethArylate (Acrylic)

PolyCarbonate (PC)

PolyEsters (PET, PETE)

PolyAmide (Nylon, PA)

Thermoplasticsmost common with toys

easy to (re)shape with different processes. chains relax

mostly recyclable

9 common thermoplastics

Plastic Shaping Processes

Compression Molding (thermosets)

Injection Molding

Thermoforming

Blow Molding

Rotational Molding

pdes 3706 designing for manufacture (fall)

Compression Molding

for complex parts with various thickness

thermosets

Injection Moldingfor thin constant thickness parts

gate, parting lines, ejector pins

mass production, molds are expensive

Thermoforming

glass transition, relaxing the chains

for thin sheets, simple one sided forms

Blow Molding

for open thin walled hollow parts

milk jugs, most bottles

Rotational Molding

for simple closed hollow shapes

good for inexpensive large parts

Crazing

network of small voids or cracks

strain whitening

Acrylonitrile-Butadiene-Styrene (ABS)

PolyVinyl Chloride (PVC)

PolyPropylene (PP)

PolyEthylene (PE)

PolyStyrene (PS)

PolyMethylMethArylate (Acrylic)

PolyCarbonate (PC)

PolyEsters (PET, PETE)

PolyAmide (Nylon, PA)

Thermoplastics

ABS PVC PP PE

popular toy plastics

PS PETPMMA PC

popular clear plastics

Physical Properties: feel, look, smell, density, stiffness, opacity, surface finish

Manufacturing Properties: What are the processes used with this plastic? thickness, detail, size?

Design Considerations: Which types of products use this plastic? What is the cost of these products?

Thermoplastics Game

ABS PVC PP PE

popular toy plastics

PS PETPMMA PC

popular clear plastics

ABSHard with high impact resistance

Takes color well with excellent surface finish

Consumer product cases

Most expensive out of PVC, PP, PE

PolyVinylChloride (PVC)cheap, heavy, rigid, durable but not tough without plasticizers

vinyl designer toys - not constant thickness

outdoor/water products

characteristic smell

environment concerns

PolyEthylene (PE)most common plastic

HDPE, LDPE

cheap, very flexible, easy to (blow) mold, less dense than water

waxy feel, milky, crazes

highly resistant to food, water, salt, chemicals

PolyPropylene (PP)VERY similar to PE but...

a bit more rigid

doesn’t fatigue: hinges, snaps

shinier surface with better color acceptance

harder to scratch and craze

Compare ABS, PVC, PP, PE

ABS PVC PP PEHard

ColorfulStrong

Durable/GummyFlexible*

Unique shapes

No FatigueTough

Shiny Surface

FlexibleFood/Chemical Safe

Waxy

Stiff Flexible

High $ Low $

Nicest Finish Worst Finish

Polystyrene (PS)

clear, hard, cheap, brittle, tinny sound

typically foamed to Styrofoam

good for lightweight insulation

if it cracks or crazes easily

PolyMethylMethAcrylatePMMA, Acrylic, Plexiglass

transparent like glass, hard, brittle, but stronger than PS

great for laser cutting

can weld with superglue

PMMA particles suspended in water

Polycarbonate (PC)

the “engineering” plastic

expensive, extremely tough and rigid...

and clear

Polyesters (PET, PETE)cheap, transparent, easy to blow mold

food products, barrier to moisture

tough, able to withstand high pressures

easy to recycle, require less energy than glass bottles

Compare PS, PMMA, PC, PET

PETAcrylic PCPStin sound

brittlelight weight

glass likeless brittle

toughhard

water prooftough

blow mold

Brittle StrongLow $ High $

Quiz1. Identify the plastic that makes up the majority of each toy piece.

2. What makes you think it is that plastic? / Why was that plastic used?

Plastic Recycling

* 2001 Environment Agency report

not everything gets recycled (even if it’s recyclable)

collecting “air”, sorting, shredding, cleaning processing

80% is sent to landfill 8% is incinerated 7% is recycled *

Paper vs. Plastic2 plastic bags use 13% less energy to make than one paper bag

and produce 72% less pollutants than one paper bag

but do not degrade and come from a non renewable resource

* institute for lifecycle environmental assessment

Logistics

ONLY 3 Weeks left!

PLAYsentations are Wednesday May 3rd, 6pm, Coffman Theatre

Rehearsal is Monday May 1st, 2-930 pm, Coffman Theatre (30 min slots)

Presentation Consultations: April 24 and 26 in Rapson 37 (Bring 3 ideas) (Kate Maple and Chris Schlichting)

Keynote

PLAYsentations guidelines Monday lecture

Questions