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UNIVERSITY OF PORT HARCOURT
COLLEGE OF ENGINEERING
FACULTY OF PRODUCTION, POWER SYSTEMS
AND
COMMUNICATION ENGINEERING
DEPARTMENT OF MECHANICAL ENGINERRING
A
PROJECT REPORT
ON
DESIGN AND FABRICATION
OF
A POLYTHENE RECYCLING MACHINE
(WITH AN EXTRUDER)
SUBMITTED
BY
OLORI OVIE (U2008/3025307)
UCHENDU STANLEY (U2008/3025347)
IN
PARTIAL FULFILLMENT FOR THE AWARD
OF THE DEGREE OF BACHELOR OF ENGINEERING (B.ENG)
IN
MECHANICAL ENGINEERING
JUNE 2014
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CERTIFICATION
We certify that this project on the design and fabrication of
a
polythene recycling machine was carried out by OLORI OVIE
(U2008/3025307) of the Department of mechanical engineering,
faculty of engineering, university of Port Harcourt. We have
examined it and found it acceptable for the award of the
bachelor
of engineering (B.Eng) in Mechanical Engineering
Engr. Dr. T. A Briggs .............................
................................
(Project supervisor) Signature Date
Dr. H. U Nwosu .............................
................................
Head of Department Signature Date
Prof. Ndubuisi S. N ..............................
................................
(Dean of Faculty) Signature Date
............................... ...............................
..............................
Project Coordinator Signature Date
............................... .............................
................................
External Examiner Signature Date
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DEDICATION
This work is dedicated to the almighty god for his grace,
protection strength and ability given to me during my research
to
successful completion of this work.
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ACKNOWLEDGEMENT
My profound gratitude goes to Almighty God for his
protection,
guidance, wisdom and blessings.
My gratitude also goes to my supervisor Eng. Dr. T. A Briggs
who
made remarkable contributions on my final year project. I
want
to thank him for his positive response, explanation, guidance
and
advice in completing this project. I owe many thanks to my
Head
of Department Dr. H.U Nwosu
I would also like to acknowledge and appreciate the efforts
and
knowledge imparted to me by the lecturers of mechanical
engineering department. My profound gratitude goes to Mr
Ihejirika in providing the necessary information needed for
this
project and his full commitment in guiding me through this
project.
Special mention must be made of my beloved parents Mr and
Mrs
Obi and my wonderful siblings, my friends Harry Iyomahan,
Omotoke Okeyemi.
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ABSTRACT
This research involves the design and fabrication of a
polythene
recycling machine that minimizes the limitations of the
already
existing. The machine employs the principle of conveying and
heating to effect shredding and melting of the materials fed
through the hopper through a screw conveyor chamber. The
screw conveyor was driven by a 1.5HP single phase electric
motor
that rotates at a predetermined speed. The hot zone was
heated
with a resistance heating element and the heat being
regulated
by a thermocouple. The barrel was insulated with rock mat
and
aluminium surface jacketing to prevent heat loss. The results
of
experimental analysis show that for every plastic fed into
the
hopper, a temperature of about 200C, Khanna O. P (2005) is
required to melt it. The performance test analysis carried
out
defines the characteristics of the machine and shows that at
a
speed of 53rpm, the machine functions effectively in
performing
its task with a high finishing recycling efficiency of 95.6%
which
translates to a significant time. The resulting soft material
was
extruded through the die at the end of the chamber.
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TABLE OF CONTENT
Title
page.....................................................................................i
Certification................................................................................ii
Dedication.................................................................................iii
Acknowledgement......................................................................iv
Abstract......................................................................................v
Table of
content.........................................................................vi
List of
figures............................................................................vii
List of
tables............................................................................viii
CHAPTER ONE: INTRODUCTION
1.1
Background..........................................................................1
1.2 Statement of the
problem......................................................2
1.3 Aims and
objectives..............................................................3
1.4 Scope of the
project..............................................................3
1.5 Significance of
study............................................................
4
1.6
Limitations...........................................................................5
1.7 Project
outline......................................................................5
CHAPTER TWO: LITERATURE REVIEW
2.1 Early
development................................................................6
2.2 Recent
development..............................................................8
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2.3 Limitations of previous
works..............................................9
2.4 Knowledge
contribution......................................................10
2.5 Terminologies associated with
recycling..............................12
2.6
Fundamentals....................................................................14
2.6.1 What is
polyethylene?......................................................14
2.6.2 What is recycling & plastic
recycling?...............................15
2.6.3 The three R's of
recycling.................................................15
2.6.4 Why the need to recycle
polythene?..................................16
2.6.5 Plastics identification
code...............................................17
2.6.6 Classification of
polyethylene...........................................18
2.6.7 Selected properties of
polythene.......................................20
CHAPTER THREE: MATERIALS AND METHODS
3.1 Description of the polythene recycling
machine...................21
3.2 Design consideration and material
selection........................21
3.3 Principles of operation of the
machine.................................27
3.4 Design
Analysis(Calculation)...............................................22
3.4.1 Design calculation for
hopper...........................................29
3.4.2 Length of
belt...................................................................30
3.4.3 Maximum torque transmitted by
shaft.............................31
3.4.4 Velocity ratio of belt
drive.................................................32
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3.4.5 Angle of
warp...................................................................32
3.4.6 Angle of
contact...............................................................33
3.4.7 Power transmitted by belt
drive........................................33
3.4.8 Analysis of
shaft..............................................................35
3.4.9 Diameter of
shaft.............................................................37
3.4.10 Heat
source...................................................................38
3.5 Assembly
procedure...........................................................39
3.6 Project design
specification.................................................41
3.7 Component
specification.....................................................42
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Sources of
waste.................................................................43
4.2 Fabrication testing and
result.............................................43
4.3 Performance
analysis..........................................................45
4.4 Discussion of
result............................................................47
4.5
Maintenance.......................................................................48
4.5 Cost analysis of materials and production of
machine........49
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION
5.1
Conclusion.........................................................................50
5.2
Recommendations..............................................................51
REFERENCES
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APPENDIX
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LIST OF FIGURES
Figure 2.1: Plastic identification
codes.....................................14
Figure 3.1: Frustum of a cone for the
hopper............................23
Figure 3.2: Belt and
pulley........................................................27
Figure 3.3: Shaft support in bearing and carrying
pulley...........29
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LIST OF TABLES
Table 2.1: Properties of HDPE and
LDPE...................................15
Table 3.1: Mechanical properties of steels used for
shafts.........20
Table 3.2: Coefficient of friction between belt and
pulley...........21
Table 3.3: Design
specification.................................................34
Table 3.4 Components
specification.........................................35
Table 4.1: Performance test for
machine..................................38
Table 4.2: Bill of engineering measurement and
estimation.......41
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CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
Recycling is an aspect of environmental engineering that
deals with the development of technically reasonable solutions
to
environmental problems by designing, building and
maintaining
systems to control wastes produced by municipalities and
private
industries. Plastics are one of the most commonly used
materials
in the world today and their inert nature renders them
resistant
to bio-degradation which leads them to an increase in the
amount of plastic wastes in dump sites. The manufacturing of
pure plastic raw material consumes large quantities of
energy
and plastics are not degradable materials, therefore its
accumulation after use generates an environmental problem.
In a bid to conserve limited resources and alleviate
environmental pollution, Anaekwe Everistus et al, (2010)
said
nylon and plastic waste recycling will complement the
international concern for environment and our governments
campaign against deforestation and Ozone layer depletion
which
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leads to climate change therefore plastic recycling is where
our
hope lies for the future in terms of waste management.
Consequently, action should be taken to promote recycling
of plastic materials. Plastic recycling is bound to realize a
lot of
saving in production costs, conserve limited resources and
alleviate environmental pollution. Evans & Williams
(2003)
suggested that the menace of plastic pollutions can be
controlled
by the new technological breakthrough called recycling.
1.2 STATEMENT OF THE PROBLEM
In recent times, polythene packaging has increased in
the area of table water, beverages, medicine and soft drinks
and
has replaced the bio degradable leaves traditionally used in
wrapping consumer goods in Nigeria. Onibokun & Kumuyi
(1981)
believed that because of the extensive use of the polythene
materials in almost every facet of Nigerian life and economy,
the
sachets, wrappers, containers etc are littered in almost
every
nook and cranny of our roads, markets, streets and non
designated places. Owing to the fast rate at which
consumptions
of the products packaged with polythene are going, a high
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demand is being placed on the collection and processing of
the
virgin materials from which polythene products are made.
1.3 AIMS AND OBJECTIVES
The aims and objectives of this project are as follows:
1. To design and fabricate an economically-viable polythene
recycling machine from locally sourced materials.
2. To design a machine capable of converting the
polythene-nylon
wastes into strips that can be used in the manufacture of
strip
woven bags through a process known as extrusion.
3. To reduce the environmental impacts associated with the
dumping of waste polythene materials.
4. To reduce energy input and time waste with a high
finishing
recycling efficiency.
5. To enable individuals and small businesses to recycle
polythene wastes and generate profit.
1.4 SCOPE OF PROJECT
This research work tends to look at the used water sachets
as blessing by converting them to a more useful product. The
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effective management of the polythene waste through
conversion
into further usable products turns the littered surrounding to
an
environmentally friendly one by preventing outspread of
disease
and simultaneously creating employment for both skilled and
unskilled labour. Conclusively, used pure water sachet can
be
converted into strip woven bags, this is certainly a technology
for
reducing a growing waste system problem by converting the
waste to an environmental beneficial and useful product.
1.5 SIGNIFICANCE OF STUDY
Recycling of used products rather than disposing them of
as waste is a desirable approach for several reasons (Callister
&
Rethwisch, 2012). The economic importance of waste
management will increase dramatically in coming years. Waste
disposal and recycling are now major concerns of government
environmental bodies, local authorities and industry and there
is
a pressing urgency for society to reduce its waste and for
experts
to find solutions for managing the growing environmental
problems. This project directly contributes to sustainable
development by helping to reduce our impact on the planet,
which is a step forward towards the implementation of
effective
waste management strategy.
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1.6 LIMITATIONS
As a result of pressure from other activities, the problems
encountered during the period of developing and writing this
project include:
1. Difficulty of sourcing for needed materials
2. financial constrain
3. Struggling to meet supervisors demand on proper write up
1.7 PROJECT OUTLINE
The full project is divided into five progressively linked
chapters in the order: (1) Introduction, (2) Literature Review,
(3)
Materials and Methods, (4) Results and Discussion, (5)
Conclusion. In writing this report, each of the chapters is
developed with proper research and supported with strong
references from published literature. Detailed diagrams and
CAD
models were also used to better understanding and aid
visualization. All published literature used in support of
this
project were properly referenced and strict measures were
taken
to ensure that there is no error of omission, misspelling or
typography.
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CHAPTER TWO
LITERATURE REVIEW
2.1 EARLY DEVELOPMENT
Polythene Recycling came to fruition during the
environmental
revolution of the late 1960's as plastic is one of the most
popular
building materials of modern human culture, but its
widespread
use brought us many problems and caused environmental
danger of unprecedented scale. Since its mass adoption in
the
1950's, discarded plastic products have filled landfills and
contained seas and earth with materials that will not break
down
for centuries and centuries. To combat this problem,
governments of many countries around the world formed rules
for recycling plastic, established industrial processes for
transforming discarded plastic into useful materials and
educated communities to the benefit of recycling all around
the
world.
In 1972, the first plastic recycling plant for waste techniques
was
built in Conshohocken, Pennsylvania, marking the beginning
for
all future recycling plants, it took several years and a
concerted
effort for the average Joe to embrace the recycling habit,
but
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embrace he did and continues to do so in increasing numbers.
Plastic recycling is unlike glass or metal processes due to
the
greater number of steps involved and the use of dyes fillers
and
other additives used in ''virgin'' plastics.
Mr. Phillipe Julien (1976) developed the Jet recycling
technology
to provide a solution to the worlds ever increasing issue of
plastic
waste disposal. Mr. Juliens original machine had the capacity
to
process 50kg of mixed plastic waste per hour and represented
ground-breaking technology at the time.
The first decade after World War II saw the development of
polypropylene and high density polythene was introduced in
1978 and this introduction made it possible to produce
polyethylenes with densities ranging from 0.90 to 0.96. The
raw
materials (polyethylenes) began to compete with the older
plastics
and even with the more traditional materials such as wood,
paper, metal, glass and leather. The machine used was
generally
designed to accommodate re-processing by injection moulding
method, blow moulding method, extrusion method to
manufacture plastic products similar to those of the
original
parts.
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2.2 RECENT DEVELOPMENT
Today, recycling machines has advanced to the point where
machines have the capacity to process up to 800kg of mixed
waste per hour. Today's machines are fully automatic (or
semi-
automatic), as opposed to the earlier manual versions. All
JET
recycling machines are built according to strict design and
quality control guidelines.
Bamisaiye (2010) designed and developed a low density
polyethylene using simple standard engineering principles,
the
machine was tested to recycled used pure water sheets
following
a series of agglomeration which consists of heating at a
temperature of about 115C to melt the material with the
cooling
of the melted material aided by a water coolant, the machine
has
an input capacity of 5kg, an output capacity of 3.6kg and a
power requirement of 2kW. The machine has a cutting speed
(shaft speed) of 1450rpm with a melting efficiency of 81%.
Ugoamadi et al (2011) optimized the development of a plastic
recycling machine that minimizes the limitation of the
already
existing (imported) ones to a great extent and at the same
time
ensuring effective waste management. the results showed that
for
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every used plastic fed into the hopper, about temperature of
200C is required to melt it. The machine employs the principle
of
conveying and heating to effect shredding and melting of the
materials fed through the hopper, and requires only two
persons
to operate. But the use of chain drive from the electric motor
is a
disadvantage as a direct coupling system adopted in this
design
gives effective power and significant mechanical advantage.
Odior et al (2012) developed a polythene recycling machine
from
locally sourced materials from Nigeria which uses design
fixed
and rotary blades for slicing the loaded wastes. The rotary
blades
are rotated by a single phase, high speed electric motor and
the
friction generated provides the heat required to soften the
waste
charges. The recycling machine produces an average of 35kg
of
small flakes of recycled waste per hour at a machine speed
of
2880rpm. But the friction effects generated in the system is
considered inappropriate as this would cause frequent changes
of
the friction parts involved.
2.3 LIMITATIONS OF PREVIOUS WORKS
Developing a polythene recycling machine from locally
sourced materials isn't a perfect product, it does have its
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limitations. It was not possible to include all the desired
functionality to make it commercially marketable. However
saying this, it does contain the most important and user
friendly
features. Areas in which the product fails to meet expectations
on
a commercial scale is performance.
2.4 KNOWLEDGE CONTRIBUTION
The objective of the present project is to contribute in the
improvement of the technology used in designing and
manufacturing of the recycling machine to enhance its
performance. The technological improvement employed in the
project includes:
1) Modification of the feeding system by designing a hopper
to
aid the feeding process and to ensure operators safety and
prevent injury from the rotating screw.
2) Modification of the end part of the heating system to
improve the extrusion process by adding a heater to the die
set.
3) Change from chain drive to belt drive for easier fix,
cheap
cost of replacement, steady operation and low noise.
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4) Each alloy has its benefits and each its drawbacks,
Stainless steel was used for the extruder barrel instead of
mild steel because of its corrosion resistance properties.
5) The extruder barrel was insulated with aluminium to
prevent heat loss.
6) A loader was incorporated at the hopper to prevent the
polythene from falling out due to action of the rotating
screw.
The machine with new design modifications, reasonable
configuration in size, steady operation, low noise, low
energy
consumption and high output offers many basic design
advantages that enable it to be used for minimizing energy
and
process costs like: versatility, high productivity, low cost,
ability
to produce shapes (strip like form), high product quality.
Other
advantages include:
1) It is environmentally friendly.
2) It consumes less energy.
3) It removes the impurities that will mix with the output.
4) Cheaper and easy to maintain.
5) Single screw extruder with specifically designed screw
and
barrel ensure good quality final products.
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6) Little or no technical knowledge.
2.5 TERMINOLOGIES ASSOCIATED WITH RECYCLING
EXTRUSION: A plastic shaping process in which resin is
melted
and then pushed out of the machine. As it exits the machine,
a
die shapes the resin.
MOULDING: The process of manufacturing by shaping liquid or
pliable raw material using a rigid frame called a mould.
INJECTION MOULDING: Involves heating plastic granules to
their melting point and then injecting them at high pressure
through a nozzle into a mould.
BLOW MOULDING: This is the process used to make bottles and
containers. The mould closes and seals a thin plastic tube
called
a parison. It also cuts it to the required length.
BARREL: The holding chamber of an extrusion or injection
moulding machine. The barrel holds the resin as the screw
melts
and mixes it.
DIE: A tool containing a recess which provides space for the
shaping of plastic.
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EXTRUDER SCREW: along screw that turns inside the barrel of
the extruder. The extruder screw mixes the resin
FEED THROAT: The entry way for the resin into the extrusion
barrel. The feed throat connects the hopper and the barrel.
HOPPER: A large funnel shaped device located on top of the
barrel on extrusion molding machines. The hopper serves as
entry way for resin into the barrel.
PULTRUSION: A moulding process in which heated resin cures
as it is pulled through a die. Pultrusion is a variation of
the
extrusion process, during which resin is pushed through a
die.
RESIN: A raw polymer, usually in the form of beads or
pellets,
that is not yet formed into its final or moulded shape.
SHAPING: The process of shaping of a piece of plastic.
Extrusion
is an example of shaping processes.
THERMOFORMING: A plastic shaping process that shapes
heated plastic sheets around a mould.
THERMOPLASTIC: A polymer that is solid at room temperature
and can be melted at high temperatures. Thermoplastics can
be
shaped by heating and then applying pressure.
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THERMOSET: A polymer that can either be a liquid or a solid.
It
can be moulded by heating and placing into a mould, once a
thermoset has cured, they cannot be remoulded.
VISCOSITY: A fluids resistance to flow. In general, the hotter
a
resin is, the lower its viscosity.
2.6 FUNDAMENTALS
This section lays the foundation for this project, in the
following subsections are some useful definitions that formed
the
basis for further discussion on this project, it is deemed
very
necessary that the fundamental principles are discussed in
this
part of the project.
2.6.1 WHAT IS POLYETHYLENE?
Polythene is just a technical name for plastic, it was first
synthesized by the German chemist (Hans Von Pechmann, 1898)
while heating diazomethane. It is a type of polymer that is
thermoplastic meaning that it can be melted to a liquid and
remoulded as it returns to a solid state, it is chemically
synthesized from ethylene, a compound that is usually made
from petroleum or natural gas. Polyethylene is also
abbreviated
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as PE and its industrial application includes synthetic
fibre,
beverage, food containers and other household products.
2.6.2 WHAT IS RECYCLING AND PLASTIC RECYCLING?
Recycling is the practice of reusing items that would
otherwise be discarded as waste. It is a key component of
modern
waste reduction and is the third component of the ''Reduce,
Reuse, Recycle'' waste hierarchy. Plastic recycling as described
by
(Kutz, 2011) is the process of recovering scrap or waste
plastics
and reprocessing the material into useful products,
sometimes
completely different in form from their original state.
2.6.3 THE THREE R'S OF RECYCLING
Reduce, Reuse and Recycle (also known as R3) is a widely
accepted waste management method designed to reduce the use
of environmental resources and lessen humans' carbon
footprint
on earth. Reducing involves limited purchases and
accumulation:
consequently reducing the amount of waste produced.
Reduction
strategies include buying used product, avoiding disposable
products. Reusing products makes both environmental and
economical sense, reusing strategies include buying used
products instead of buying new ones. Recycling refers to
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processing, treating or converting an object into reusable
materials. Commercial products made from recyclable or
recycled
materials almost always contain a symbol on their packaging.
2.6.4 WHY THE NEED TO RECYCLE POLYTHENE?
There are several reasons for recycling Polythene as
enumerated
below:
1. Recycling reduces the need for raw materials such as
rubber, metals, oil and so reduces our impact on the
environment. Extracting virgin materials is a key cause of
global habitat loss (Friends of the Earth, 2008)
2. Recycling saves energy as recycling a material generally
uses far less energy than manufacturing from virgin
materials (WRAP, 2006).
3. Recycling saves cost. According to (Friedman, 2009) the
cost
of recycling is less than that of making new products.
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4. Recycling is one of the easiest ways to reduce impact on
the
environment, it introduces a ''green'' consciousness to
daily
life (Friends of the Earth, 2008).
5. Recycling reduces greenhouse gas emissions that
contribute
to global climate change.
6. Recycling reduces the amount of waste sent to landfills
and
incinerators.
7. Recycling creates wealth opportunities, Babajide Komolafe
(2004) stressed that on the introduction of the structural
adjustment programme (SAP) by the Babangida
administration, many Nigerians looked inwards for
opportunities of self employment and wealth opportunities.
2.6.5 PLASTICS IDENTIFICATION CODE
The identification coding system is a set of symbols placed
on plastics to identify the polymer type. It was developed by
the
Society of Plastics Industry (SPI) in 1998 and is used
internationally. The primary purpose of the code is to allow
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efficient separation of different polymer types for
recycling.
Separation must be efficient because the plastics must be
recycled separately. Even one item of the wrong type of resin
can
ruin a mix, the symbols used in the code consist of arrows
that
cycle clockwise to form a rounded triangle and enclosing a
number.
Figure 2.1: Plastic identification codes
2.6.6 CLASSIFICATION OF POLYETHYLENE
Polyethylene is classified into several categories based
mostly on its density and branching. The most important
polythene grades are HDPE, LLDPE and LDPE. Here, we will
discuss the two major grades based on density i.e HDPE and
LDPE
1. High density Polyethylene HDPE: This is a class of PE
thermoplastic made from petroleum. It is defined by a
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density of greater or equal to 0.941g/cm, HDPE has a low
degree of branching and thus stronger intermolecular forces
and tensile strength, it is four times stronger than LDPE ,
tougher, most chemical resistant and the least flexible of
the
types of polyethylene. HDPE is used in products and
packaging such as milk jugs, detergent bottles, garbage
containers and water pipes. One third of all toys are
manufactured from HDPE.
2. Low density polyethylene LDPE: This class of PE is
defined by a density range of 0.910-0.940 g/cc. This results
in a lower tensile strength and increased ductility. LDPE is
used for both rigid containers and plastic film applications
such as plastic bags and film wrap. It was the first grade
of
polythene produced in 1933 by Imperial Chemical
Industries (ICI).
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2.6.7 SELECTED PROPERTIES OF POLYETHYLENE
Table 2.1: Properties of HDPE and LDPE(Source:
Academia.edu)
Properties HDPE LDPE
Melting Point 135C 115C
Crystallinity High
Crystalline(>90%
crystalline).
Low crystallinity(50-
60%).
Flexibility More rigid than
LDPE due to higher
crystallinity.
More flexible due to
lower crystallinity.
Strength Strong as a result of
regular packing of
polymer chains.
Not as strong as
HDPE due to
irregular packing.
Heat Resistance Useful above 100-
110C
Retains toughness
over a wide temp
range but density
drops off
dramatically above
room temp.
Transparency Less transparent
than LDPE.
Good transparency
since it is more
amorphous.
Density 0.95-0.97g/cm 0.91-0.94g/cm
Chemical Properties Chemically Inert
Tensile Strength
(MPa)
12.4 26.5
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CHAPTER THREE
3.0 MATERIALS AND METHODS
3.1 DESCRIPTION OF THE POLYTHENE RECYCLING
MACHINE
This machine is an ideal equipment for recycling plastics
e.g
High density polyethylene and Low density polyethylene. The
main components of the machine are: frame, extruder barrel,
heating compartment, screw shaft, hopper, drive shaft,
thermocouple, the die set with hole/opening diameter of 3mm
and 12 holes, belt, pulleys and electric motor. The outlet
is
located at the end of the die set where the conditioned
materials
are compressed and the content forced out through the outlet
slots. The heating compartment is where the material heats
up
and passed through an enclosed passage in the barrel. The
machine is powered by an electric motor via belt drive
connected
to the main shaft that turns the screw conveyor. The hopper
into
which the plastic material is fed is located at the top of
the
housing.
3.2 DESIGN CONSIDERATION AND MATERIAL SELECTION
To accomplish this, the following were taken into
consideration:
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1. Sizing of the shafts
2. Selection of the pulley and determination of transmitted
speed
3. Rating of the prime mover
4. Capacity of hopper
5. Volume of chamber
6. Choice of belt
7. Shear force and bending moment on shafts
8. Determination of torque acting on shafts
The factors which influenced the choice of materials
selected for this design include materials suitability,
strength,
local availability, corrosion, affordability and cost
effectiveness.
Also considered for the criteria of material selection for
the
various components of the machine is based on the type of
force
that will be acting on them, the work they are expected to
perform and their useful physical and mechanical properties.
The
bulk of the parts of the recycling machine were fabricated
using
mild steel, except for the extruder barrel, this is because it
is
easiest to be joined among all other metals. It is a very
versatile
metal, necessitating its use by many industries for fabrication
of
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process unit equipment. Apart from its versatility, it is also
very
cheap and readily compared to other metals.
3.2.1 SUPPORT FRAME
The main function of the machine frame is to support, guide
and
hold in accurate alignment all the moving members of the
operating machine. The frame was constructed from four 200mm
mild steel angle bar to give rigidity and stability that
will
withstand load and vibration.
3.2.2 HOPPER
The hopper is made of mild steel and it is the receptacle
through
which the polythene is accepted into the machine for recycling,
it
is attached to opening at the top of the extruder barrel
3.2.3 THE BARREL
The barrel is made with stainless steel which houses the
screw
conveyor. The fed polythene materials passes through the
barrel
from the hopper to the orifice at the exit. It is equally where
the
heating and melting of the materials take place.
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xxxv
3.2.4 HEATING ELEMENTS
These components are made of materials with very high
conductivity. The heater is adjustable and fixed to the
bored
metal (heating chamber) with the aid of clips. The heat from
these
heater is conducted through the bored metal which is used in
melting the polythene.
3.2.5 SHAFT
A shaft is a rotating machine element which is used to
transmit
power or motion from one place to another and provides the
axis
of rotation of members such as pulley. Since the shaft is
subjected to bending and torsional deflection, mild steel was
used
in the design with the following considerations:
a. Rigidity, strength and stiffness.
b. Machinability.
c. High wear resistance.
d. Good heat treatment property.
The mechanical property of the grades of carbon steel are given
in
the table below
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xxxvi
Table 3.1 Mechanical properties of steels used for shafts
Indian Standard
Designation
Ultimate Tensile
Strength, MPA
Yield Strength, MPA
40 C 8 560-670 320
45 C 8 610-700 350
50 C 4 640-760 370
50 C 12 700 Minimum 390
Source: Khurmi & Gupta (2006) Machine Design
3.2.6 BEARINGS
Bearing is used to support moving element (shaft), also to
permit
the relative motion between the shaft and the pulley while
in
operation. The radial ball bearings with housing is used
because
of:
a. High wearing resistance.
b. Accuracy of shaft alignment.
c. good corrosion resistance properties.
d. Low cost of maintenance which involves greasing through
its nipples.
3.2.7 BELT
Flat belts are extensively used but the selection of the
belt
depends on:
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xxxvii
a. The power to be transmitted
b. The centre distance between shafts
c. The speed of the driving and driven shafts
3.2.8 ELECTRIC MOTOR
This is the machine component that transmits rotational
motion
and power from the pulley to the belt. The guiding selection
are
as follows:
a. Speed control
b. Starting and running characteristics
c. Noise level
d. Method of power transmission
Table 3.2 Coefficient of friction between belt and pulley
Belt
Material
Pulley Material
Cast Iron, Steel Wood Compressed
Paper
Leather
Face
Rubber
Face Dry Wet Greasy
Leather
oak
tanned
0.25 0.2 0.15 0.3 0.33 0.38 0.40
Leather
chrome
tanned
0.35 0.32 0.22 0.4 0.45 0.48 0.50
Convass-
stitched
0.20 0.15 0.12 0.23 0.25 0.27 0.30
Cotton
woven
0.22 0.15 0.12 0.25 0.28 0.27 0.30
Rubber 0.30 0.18 - 0.32 0.35 0.40 0.42
Walata 0.32 0.20 - 0.35 0.38 0.40 0.42
Source: Khurmi & Ghupta (2006) Machine Design
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xxxviii
3.3 PRINCIPLES OF OPERATION OF THE MACHINE
In the recycling of polythene, the polythene is gravity fed from
a
top mounted hopper into the barrel of the extruder. When the
material enters through the feed throat (an opening near the
rear
of the barrel) and comes into contact with the screw. The
rotating
screw forces the plastic material forward into the barrel which
is
heated to the desired melt temperature of the molten plastic.
A
heating profile is set for the barrel in which two or more
independent controlled heater zones gradually increase the
temperature of the barrel from the rear (where the plastic
enters)
to the front. This allows the plastic material to melt gradually
as
they are pushed through the barrel and lowers the risk of
over-
heating which may cause degradation in the polymer. Extra
heat
is contributed by the intense pressure and friction taking
place
inside the barrel. If the extrusion line is running a
certain
material fast enough, the heaters can be shut off by the
thermocouple and the melt temperature maintained by pressure
and friction alone inside the barrel. At the front of the
barrel, the
molten plastic leaves the screw and travels through a screen
pack
to remove any contaminants in the melt. The screens are
reinforced by a breaker plate (a thick metal puck with many
holes
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xxxix
drilled through it) since the pressure at this point could be
very
high. The breaker plate assembly also serves to create back
pressure in the barrel. Back pressure is required for
uniform
melting and proper mixing of the polymer, and how much
pressure is generated can be tweaked by varying screen pack
composition. After passing through the breaker plate, the
molten
plastic enters the die. The die is what gives the final product
its
profile and was designed so that the molten plastic evenly
flows
from a cylindrical profile, to the product's profile shape.
The
product must now be cooled and this is usually achieved by
pulling the extrudate through a water bath.
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xl
3.4 DESIGN ANALYSIS
3.4.1 DESIGN CALCULATION FOR HOPPER
The particular section where the polythene drops assumes the
shape of a frustum. To calculate the volume of the frustum, it
is
made to form a cone as shown below.
The top diameter should be three times the bottom diameter.
By
similarity
3d 3d=0.54m A B
h
C D h=0.22m
y
E
E d= 0.18m Figure 3.1 Frustum of a cone for the hopper
r
y =R
yh +
-------------------------------------------------------(3.1)
=09.0
y = 27.0
y22.0 + = 0.11
0.27y = 0.09 (0.22 + y)=0.11
y = 0.11
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xli
Hence the volume of the hopper = Volume of the big cone - the
Volume of the small cone
(Vh)max=
------------------------------------------------(3.2)
= [...
]-[...
] =0.0176m3
= [0.0167-0.000933]
= 0.0158m3
Assuming LDPE of the plastic type is to be gravity fed, then
mass
of the polythene to fill the volume of 0.0176 is given by
Mp=Vh [Density of LDPE is
0.91-0.94g/cm3]--------------------(3.3)
=9200.0158=14.53kg Weight of the polythene material required to
fill the hopper is
thus
Wp=Vhg---------------------------------------------------------(3.4)
=14.539.81=142.59N
3.4.2 LENGTH OF BELT
Diameter of driver pulley= 0.1m
Diameter of driven pulley= 0.065m
Pitch distance between driving shaft X=?
Length of belt L = + + 2 + !
" # ---------------(3.5)
The centre to centre distance was obtained using
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xlii
X=(2
2d1d +)+ 1d : X is the distance between the centre of 2
pulleys-
---------------------------------------------------------------------------(3.6)
Source: Khurmi and Gupta (2009) Theory of Machines
X= 1.02
065.01.0+
+
=0.1825m Length of belt (in terms of pulley diameter)
L= + + 2 + !
" #
= 3.1422 0.1 + 0.065 + 2 0.1825)0.1 0.0654 0.1825*
=0.625m 3.4.3 MAXIMUM TORQUE TRANSMITTED BY SHAFT
Tmax= + ,
d3--------------------------------------------------------(3.7)
Where , = Permissible shear stress of the shaft material,
42MPa
ds= Diameter of the shaft
Tmax= .-..
+
=201.15N
Tmax=1.2Tmean----------------------------------------------------------(3.8)
Tmean= ./. =167.6N
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xliii
3.4.4 VELOCITY RATIO OF BELT DRIVE
0
0 =
!1!1 1
2-------------------------------------------------(3.9)
Where t is thickness of belt
S is the slip and the result is to reduce the V.R
N1=speed of the driver in rpm
N2= speed of the driven in rpm
D1= diameter of the driver pulley
D2= diameter of the driven pulley
t= thickness of the belt
S= total percentage of slip (assume 2%) : Khurmi & Gupta
(2006)Machine Design
N2=
+
+
01.0065.0
01.01.01500
100
21
= 98.047.11500
= rpm9.2160
3.4.5 ANGLE OF WARP
sin 7 = 8" (in
radians)-------------------------------------------(3.10)
Where,
r1 is radius of driver pulley=0.05
r2 is radius of driven pulley=0.0325
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xliv
=1825.0
0325.005.0 =0.0959
7 = sin8 0.0959 =5.5
7 =180-5.5=174.5=3.05 radians (360= 2:;
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xlv
TB=(T1
T2)r2-------------------------------------------------------(3.13b)
Where r1 and r2 are radius of the driver and driven pulley
respectively
V= Linear velocity of the belt
V= @A B +
-----------------------------------------------------(3.14)
Source: Khurmi and Gupta (2006) Machine design
=60
15001.0142.3
=7.86m/s
Power of electric motor= 1.5HP=1.5746=1119W
T1T2=
CD-----------------------------------------------------(3.15)
T1T2=86.7
1119
T1T2=142.36N E E = e
GH(condition for transmission of maximum power)-----(3.16)
Source: Khurmi and Gupta (2009) Theory of Machines
I I = J
./ =2.117
T1=2.117T2 2.117T2T2=142.36N
T2=127.45N
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xlvi
T1=2.117127.45=269.81N
From equation 12: Power transmitted P=(T1 T2)vW
=(269.81127.41)7.86
=1119W From equation 3.13a & 3.13b:
Torque on the driving pulley TA=(T1T2)r1
= (269.81127.41)0.05
=7.12N
Torque on the driven pulley TB= (T1 T2)r2 = (269.81
127.41)0.0325
= 4.63N 3.4.8 ANALYSIS OF SHAFT
pulley bearing
shaft
Fig 3.3 Shaft support in bearing and carrying pulley
It is necessary to identify the forces acting on the shaft.
The
various shear forces and bending moment are calculated as
follows:
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xlvii
According to maximum shear stress theory, maximum shear
stress on the shaft
,max= KLM +
4,-----------------------------------------------------(3.17)
Neglecting the weight of the shaft total vertical load acting on
the
pulley
W= T1 +
T2------------------------------------------------------------(3.18)
Bending moment can be calculated using M= 4
LW ----------(3.19)
Where W= Total vertical load acting on pulley
L= Length of shaft= 0.704m
The equivalent twisting moment and bending moment can be
obtained from
Te= KN OP + Q
O1------------------------------------------(3.20)
Where,
Km= Combined shock and fatigue factor for bending=1.5
Kt= Combined shock and fatigue factor for torsion= 1.0 (Khurmi
et al, 2005)
Bending moment and shear force bending can occur as a result
of the applied loads on the shaft and belt tension.
From equation 3.18:
Total vertical load acting on the pulley, neglecting the weight
of
the shaft W= T1 + T2 = 269.81 + 127.41= 397.22N
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xlviii
From equation 20:
Bending moment M
M= 4
LW = 4
704.022.397 = 69.9N
Me= N + KN OP + Q O1--------------------------------(3.21)
Where Te=Equivalent twisting moment
Me= Equivalent bending moment
M=Bending moment
Equivalent twisting moment, Te= K69.9 1.5 + 1 7.12
= 105.09Nm
Equivalent bending moment, Me= 2
1 S69.9 + 105.09T = 87.4Nm
3.4.9 DIAMETER OF THE SHAFT
This is calculated from the relationship
Te= UVWXY.
+ ------------------------------------------(3.22)
Where ,PZ"[42MPa (Permissible shear stress of shaft
material)
LM[ 84MPa (Bending moment ASME code for design of transmission
haft with allowance for key, Khurmi & Gupta, 2008)
2 = /.+.-
= 0.023m
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xlix
Also from bending moment
87.4= .?-Y.
2 = 0.022m
chosen diameter of shaft= 0.02m
3.5.10 HEAT SOURCE
The processing temperature of most plastic is between
163C and 200C even though they melt between 108C and
121C. In this design, we have chosen 200C as the target
temperature of the heating chamber must be raised from room
temp (25C) to 200C. For LDPE of mass 14.53kg as calculated,
quantity of heat required to raise the temperature of this
mass
from 25C to 200C can be obtained from
Q= S\J
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l
Q25-200= (14.53 2.004 96)+(14.53 74.8)+(14.53 2.004 79)
= 6182.51KJ
3.5 ASSEMBLY PROCEDURE
First of all, the support frame was fabricated from four
equal
length of 200mm mild steel angle bar, the components were
welded together to form the support frame using arc welding.
The cylindrical barrel was then welded to the support frame
and
the feed throat was cut with an electric grinder.
The hopper plates from mild steel were marked, chiselled out
in
shapes, fitted together and welded with mild steel electrode
to
form a pyramidal shape.
The loader holes on the hopper were created using an
electrical
drill.
Then the designed hopper was welded to the feed throat of
the
cylinder using stainless steel electrode to give a better
grip.
The drive shaft was then designed with mild steel, 3mm round
bars were used in creating the screw pitch.
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li
Radial ball bearings were used for the drive shaft and stiff
bearings for the loader to permit relative motion between
shaft
and pulley.
The heating element was then attached to the cylindrical
barrel
(heating chamber), it is insulated with rock mat and
aluminium
surface coating to prevent heat loss.
The machine was sprayed green, reason being that recycling
represents green technology.
Finally, the motor was mounted and the machine ready for
use.
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lii
3.6 PROJECT DESIGN SPECIFICATION
Table 3.3: Design specification
Base height 605mm
Base length 700mm
Base width 415mm
Length of solid shaft 704mm
Diameter of the shaft 23mm
Diameter of loader pulley 65mm
Diameter of driver pulley 100mm
Diameter of driven pulley 70mm
Height of hopper 220mm
Diameter of extruder barrel 75mm
Length of extruder barrel 650mm
Feed throat 100mm by 40mm
Power of electric motor 1.5HP
Speed of electric motor, N 1500rpm
Steel used Mild steel & Stainless steel
Max allowable bending moment 84MPa
Max allowable tensile stress 42MPa
Insulation material thickness 62mm
Volume of hopper 0.0158m3
Coefficient of friction between
belt & pulley
0.25
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liii
3.7 COMPONENT SPECIFICATION
Table 3.4: Components
PART No DESCRIPTION SPECIFICATION MATERIAL
A Angle iron 3 full length Mild Steel
B Steel plate 1 full length Mild steel
C Driver pulley D 100mm Cast iron
D Driven pulley D 70mm Cast iron
E Shaft D23mm 704mm
long
Mild steel
F Extruder
Barrel
3 inches Stainless steel
G Bolts & nuts 12 and 10mm Mild steel
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liv
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION
4.1 SOURCES OF WASTE
The most abundant of these wastes were the table water
sachets,
these were followed by poly bags and other nylon wrappers.
Since
it was difficult to pick up the waste from sewers and
drainages
where they constitute a nuisance, they were recovered from
road
side, domestic bins and dumpsites around the school
environment. The experiment was carried out at a temperature
of
200C.
4.2 FABRICATION TESTING AND RESULT
The fabricated polythene recycling machine was tested to
evaluate its performance. First and foremost, polythene
materials
of various types, sizes and shapes were collected, sorted
out,
sliced and washed. The machine was prepared for the
recycling
operation by first switching on the heater (heating element),
a
stop watch was used to measure the time taken for recycling
per
batch and the heating lasted for about 30 minutes to enable
the
barrel reach the heating temperature of 200C, an innovation
that slashed the heating time of previous machines that
lasted
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lv
for about 1hr10mins . The hot zone of the barrel was
maintained
at this temperature. Then, the sorted polythene materials
were
fed into the machine through the hopper, the 1.5HP single
phase
electric motor which is the prime mover was simultaneously
switched on, the feed material was conveyed through the
barrel
by means of the screw positioned inside it. The material
eventually got softened and came out of the die's orifice at
the
end of the chamber. The material came out in strips and
dropped
into a bucket of water kept in place. The water medium helped
to
cool the resulted material fast. On subsequent testing of
the
recycling machine, it was discovered no remnant of the
softened
polythene inside the heating chamber had caked on cooling to
impede the rotation of the conveyor screw. In comparison to
existing recycling machines, the chamber had to be heated to
soften the remaining material before resuming operation and
still
not much progress was made. In an effort to effectively
discharge
the recycled polythene and improve output of yield,
stainless
steel barrel was used as opposed to mild steel because of
its
corrosion resistance properties. Another added advantage
over
mild steel is that it does not stick to the polythene in its
molten
state. It takes about 3mins to recycle a batch of plastics and
the
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lvi
average performance of the machine is estimated to be 95.6%
efficient and the capacity of the machine is approximately
285kg/hr.
Recycling efficiency, RE= mn1jn1PZ22mopqqrpsZ21p1tPp1Zupv
--------(4.1)
Specific mechanical energy= CmspCItPp1wn1jn1PZ22x
----------------(4.2)
Torque, Q =
+Cz-------------------------------------------------(4.3)
Where S= screw speed, putting equation 4.3 into 4.2, gives
T= +z{|xz1
---------------------------------------------------(4.4)
4.3 PERFORMANCE ANALYSIS
In actualizing the aims of this project, the performance test
was
carried out after the equipment has been assembled. The
machine was started and samples of equal weighted mass of
polythene nylon bags were fed through the hopper, each time.
A
stop watch was used to monitor the time taken for recycling
per
batch. A 1.5HP single phase electric motor and from the test
result, the average performance of the machine is estimated to
be
95.6% efficient and the capacity of the machine is
approximately
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lvii
285kg/hr. The test runs were carried out 6 times to obtain
the
performance of the machine in table 4.1
Table 4.1: Performance test for the machine
S/N Input
mass
(kg) (I)
Continuous
variables/parameters
Responses
Screw
speed
(rpm)
Torque
(Nm)
(T)
Time
(secs)
(t)
SME
(kj/kg)
Total
mass
output
(kg) (Q)
Recycling
efficiency
(%) (RE)
1 7 53 201.51 105 17.80 6.6 95.6
2 7 106 100.79 116 23.60 5.5 83.5
3 7 106 100.79 120 24.86 5.4 81.0
4 7 106 100.79 113 22.18 5.7 87.3
5 7 53 201.51 110 19.23 6.4 90
6 7 106 100.79 108 18.59 6.5 92.4
Equations above show that speed and torque is inversely
proportional to recycling time as demonstrated in figures
above
drawn from the plots of table 4.1. Often, screw length is
referenced to its diameter in terms of an L:D ratio, it was
observed that the length per unit diameter L/D affects the
mixing
shear and the resistance time of the polythene material in
the
extruder, the higher the ratio, the indication of a longer
extrusion
-
lviii
barrel and the higher the mixing of the polythene inside the
barrel.
To save running cost and high energy consumption, figure
4.1(appendix) illustrates that the higher the output mass,
the
lower the SME at low speed(S1). Similarly, experiments show
that
for a batch process in fig 4.2 (appendix), the effect of
recycling
time on the efficiency on the efficiency of the machine under
the
influence of the screw speed(rpm) and torque. Decreasing
screw
speed and increasing the torque while maintaining a constant
temperature results to a plot of increase in efficiency with
corresponding decrease in recycling time. This shows that
the
dependence of the efficiency could be examined as a function
of
time.
4.4 DISCUSION OF RESULT
During the testing of the project, it was observed that the
recycling efficiency was higher with the shaft maintaining a
steady and uniform speed as compared to previous work by
Odior
et al where knife penetration first causes compaction
accompanied by frictional heat. A heater profile was set up in
this
design for required heating of the blend thereby eliminating
the
-
lix
process of cutting and heating action which partially melts
the
compacted waste to produce only thick shreds.
4.5 MAINTENANCE
In order to maintain the waste polythene recycling machine,
the
following guidelines are recommended:
I. The machine should not be overloaded or its design
capacity
exceeded and it must be ensured that the machine attains
sufficient speed before loading.
II. Sufficient and proper lubrication of the bearings should
be
carried out since insufficient lubricant will cause noise
and
high operation temperature.
III. The machine should not be exposed to rainfall to
minimize
corrosion of the components.
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lx
4.6 COST ANALYSIS OF MATERIALS AND PRODUCTION OF
MACHINE
Table 4.2: Bill of engineering measurement and estimation
S/N ITEM
DESCRIPTION
UNIT QTY UNIT
PRICE
(N)
TOTAL
PRICE
(N)
1 Shaft 1 1 3000 3000
2 Angle iron 3 3 1900 5700
3 Sheet of
plates
1 1 5000 5000
4 Stainless pipe 1 1 3500 3500
5 Bearing 3 3 500 1500
6 Electric motor 1 1 30000 30000
7 Pulley 3 3 1500 4500
8 Belt 2 2 700 1400
9 Heating
element
1 2 3500 3500
10 Thermocouple 1 1 4000 4000
11 Labour 20000 20000
12 Miscellaneous 9000 15000
Total 97,100
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lxi
CHAPTER FIVE
5.1 CONCLUSION
A low technology, low cost machine designed specifically for
recycling low-density polythene for use in particular
applications.
The low-density polythene recycling machine performs
satisfactorily in these conditions. It is efficient, cheap, easy
to
operate and cheap to maintain. These features make it
particularly suitable for the informal sector where there is
little or
no technical knowledge. Its low cost when compared to
existing
machinery also makes it competitive. It removes the
restrictions
posed to recycling by the high cost of existing machinery,
consequently increasing recycling activities. One great
advantage
to be derived from the use of this machine is that the cost
of
running it is minimal compared to what it takes to a full
imported plant. The simplicity of operation of the machine
ensures that no too much technical skill is needed to operate
it.
When the machine is well maintained, its durability is
guaranteed. The machine is compact, less complex and
requires
no special expertise. Its maintenance cost is also lower
when
compared with existing imported machinery. The machine will
also contribute favourably to environmental and economic
issues.
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lxii
It is affordable for small scale plastic recycling business.
The
modifications introduced in the design and operation of the
plastic recycling machine, if implemented will be beneficial
and
advantageous in the following:
I. The processing of waste plastic materials will be
enhanced
to achieve the production of high quality plastic products
on
relatively large scale for domestic and industrial uses.
II. The national economy will be boosted since adoption of
such
machines will help in reducing the importation of similar
machines, maximize the use of local materials, save cost
and conserve foreign exchange.
III. The machine is recommended for local entrepreneur
because of its cost effectiveness, simplicity and
availability
of parts. It reduces drastically the labour, fatigue and
cost
involved in the production of plastic products under
environmentally friendly conditions.
5.2 RECOMMENDATIONS
This machine is very suitable for the developing economy and
environment. It is not only helpful to the setting up of
recycling
activities which in turn affect the environment and economy, it
is
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lxiii
also a very good source of self employment. It has the capacity
to
reduce employment in developing countries like ours. I
recommend this machine to the informal sector of the
Nigerian
economy and other developing nations. I also recommend it to
the young entrepreneur and those who are unemployed. It is
cheap to obtain, easy to maintain and possess ability to
generate
substantial income in a period of time. I therefore
recommend
that subsequent work on plastic recycling should be focused
on
further improvement and incorporation of this machine. The
following suggestions can be adopted:
1. A cooling system should be incorporated in the design to
automatically cool the pellets of the plastic materials
recycled.
2. The use of diesel or petrol powered engine to eliminated
dependency on the epileptic electric power supply.
3. A feedback system that automatically re-feeds plastic
which
have not been recycled.
4. The process of sorting and cleaning that precedes the
recycling should be efficient so that the plastics will be
dried
before recycling to aid easy recycling.
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lxiv
REFERENCES
Anaekwe E. N, (2010), Nylon and Plastic Recycling Plants in
Nigeria, development report, 29th July.
Babajide. K (2004): ''Polythene Products and our
Environment''
Vanguard Newspaper, 15th July, P. 20.
Bamisaiye O. P (2010) Design and Development of a Low
Density
Polythene Recycling Machine, P. VIII.
Callister W. D JR. & Rethwisch D. G, (2012) fundamentals
of
Materials Science and Engineering: An Integrated approach,
4th
Edition, John Wiley and Sons Inc.
Friedman L. S, (2009), Garbage and Recycling, Green haven
Press, Cengage Learning.
Friends of the Earth (2000), Beyond the Bin, Economics of
Waste
Management Option, a summary option, P. 27.
Khanna O. P. (2005): ''A Textbook of Production Technology''
New
Delhi, Dhanpat Rai Publications Ltd P. 87.
Khurmi, R.S & Gupta, J.K. (2005), A textbook of Machine
Design,
New Delhi-110055, Eurasia Publishing House.
Khurmi R. S & J.K. Gupta (2010), Theory of Machines,
Eurasia
Publishing House, Pvt, Ltd.
Myer. K, (2011) Applied Plastics Engineering Handbook,
Elsevier
Inc.
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lxv
Odior A.O., Oyawale F. A. and Odusote J. K. (2012)
Development
of a Polythene Recycling Machine from Locally Sourced
Materials
Vol 2, No. 6.
Onibokun A. G. and Kumuyi A. J. (1981), ''Clean up Nigeria'',
A
research paper available on recycling.
Rajput, R, (2008) Fluid Mechanics & Hydraulics Mechanics:
S.
Chand & Company Limited.
Ugoamadi C. C., Ihesiulor O. K. (2011) Optimization of the
development of a plastic recycling machine Nigerian Journal
of
Technology Vol 30, No. 3.
Waste and Resource Action Programme, WRAP (2010), Final
report on Environmental benefits of recycling, March 2010.
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lxvi
APPENDIX A
Belts Electric motor
Stainless steel extruder barrel and hopper
-
lxvii
APPENDIX B
The designed polythene recycling machine with extruder
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lxviii
