why recycle plastics
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Plastic Recycling
Seminar copy submitted to
Visvesvaraya National Institute of Technology , Nagpur In partial fulfillment of requirement for the award of degree of
B.Tech.
(Chemical Engineering)
By
ROSHAN NINAWE
(BTO8CHE041)
Guide
PROF. S. M. KODAPE
Department of Chemical Engineering,
Visvesvaraya National Institute of Technology,
Nagpur 440010 (INDIA),
March 2012.
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DECLARATION
I, hereby declare that seminar titled “Plastic Recycling” submitted herein as a part of
course of Bachelor of Technology (Chemical Engineering) has been carried out by
me (accumulation of research data) in the department of Chemical Engineeering of
Visvesvaraya National Institute of Technology, Nagpur. The data so presented are
from the research carried out for which the references are provided at the end.
ROSHAN NINAWE
(BT08CHE041)
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CERTIFICATE
The seminar titled "Plastic Recycling” as per the course of Bachelor of Technology(Chemical Engineering), has been carried out under my supervision at department of
Chemical Engineering of Visvesvaraya National Institute of Technology, Nagpur.
The work is fit for evaluation.
Prof. S. M. Kodape
Assistant Professor,
Chemical Engineering,
VNIT, Nagpur.
Forwarded by-
Head of department,
Chemical Engineering,
VNIT, Nagpur.
Date:
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ABSTRACT
Disposal of plastic waste into landfills has become increasingly prohibitive due to high cost,
legislative and public option. Growing environmental awareness and reduction in availablelandfill capacity have prompted plastics recycling programs in most developed countries.
Currently, however only between 5 to 25% of plastic waste being recycled. This will have to
increase as worldwide consumption of plastics is set to expand sharply following treads in the
global population growth. At present, consumption of plastics per capita in developed counties is
five times that of non-industrialized countries such as china and India will contribute
significantly to plastic consumption and the increase of the plastic waste burden.
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Index
Sr No
Title……………………………………………………………………………………….1
Declaration………………………………………………………………………………..2
Certificate…………………………………………………………………………………3
Abstract…………………………………………………………………………………...4
Index……………………………………………………………………………………...5-6
Chapter 1
1.1 Introduction…………………………………………………………………………..7
Chapter 22.1 What is plastic?.............................................................................................................8
2.2 Classification…………………………………………………………………………. 8-9
2.3 Properties of Plastic……………………………………………………………………9
2.4 Uses of plastic…………………………………………………………………………10
2.5 Identification of different types of plastics…………………………………………...11
2.6 Collection……………………………………………………………………………...12
Chapter 3
3.1 Why recycle Plastic?.......................................................................................................13-14
3.2 GE Polymer Recovery Process………………………………………………………....15-16
3.3 Bayer Engineering Plastics Recycling Program………………………………………..16-19
3.4 Sources of waste plastics……………………………………………………………….19
Chapter 4
4.1 Manufacturing techniques………………………………………………………………20-21
Conclusion…………………………………………………………………………………..22
References…………………………………………………………………………………...23
Sr. No Contents Page No
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Index
Figures Page No
3.1 LINPAC Plastic Recycling Process………………………………………………………17
3.2 Consumed & discharged amount of plastic material in India…………………………….18
4.1 Extrusion………………………………………………………………………………….. 20
4.2 Injection moulding……………………………………………………… ...........................20
4.3 Blow moulding……………………………………………………………………………. 21
Tables
2.1 Identification of different types of plastics………………………………………………..11
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CHAPTER 1
1.1 Introduction:-Polymers constitute about 8% by weight of about 18 by volume of all materials going into
landfills. Of this steam about 40% comprises plastid packaging which due toits high visibility.
Voluminous nature, show biodegradability and hort use life has received a heightened profile in
public eye. Recent figures have shown that in Europe, recycling rates for post use plastic waste
were as follows: incineration with energy recovery (14%), mechanical recycling (6%) and
feedback or chemical (0.3%)
Incentives for using recycled plastics include ecological reasons, consumer demand, recycle-
content legislations and lower cost. Until recently these incentives have had to be weight against
variable material composition,, possibility of contamination ,loss of mechanical properties due
to degradation . Lack of standards and variations is supply. Now many of these problems have
been solved through such measures as the use of sophisticated automated sorting.
Restabilization, implementation of recyclate quality standards and integrated collection network.
An important aspects of most polymer recycling process is the sorting of the plastics waste
stream into its constituents polymer types. Mixed plastics generating have lower value and
produce products with poor and variable properties, whereas sorted streams can be used in higher
value application. The first chapter describes automated sorting and identification technologies
for effective separation of waste plastics including flotation-sedimentation air classification,
hydro cyclone form flotation, and selective dissolution as well as mid and near infrared
spectroscopy, X-ray analysis, and optical scanning using photodiodes of CD cameras.
Size reduction techniques, which are integral part of almost all plastic recycling process. These
can be classified as cutting techniques, densification processes and pulverization processes. Size
reduction process is also frequently used for material liberation from composite of multilayer
products. For example communication in combination with air elutriation can enable the
classification and separation of plastic multi component materials such as textile reinforced
plastic hose ,fiber reinforced foam backed mats and waste carpet.
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CHAPTER 2
2.1 What is Plastic?
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids that aremoldable. Plastics are typically organic polymers of high molecular mass, but they often contain
other substances. They are usually synthetic, most commonly derived from petrochemicals, but
many are partially natural.[7]
2.2 Classification:-
Plastics are usually classified by their chemical structure of the polymer's backbone and side
chains. Some important groups in these classifications are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can also be classified by the chemical process
used in their synthesis, such as condensation, polyaddition, and cross-linking.[7]
Thermoplastics and thermosetting polymers
There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are
the plastics that do not undergo chemical change in their composition when heated and can be
moulded again and again. Examples include polyethylene, polypropylene, polystyrene, polyvinylchloride, and polytetrafluoroethylene (PTFE). Common thermoplastics range from 20,000 to
500,000 amu, while thermosets are assumed to have infinite molecular weight. These chains are
made up of many repeating molecular units, known as repeat units, derived from monomers;
each polymer chain will have several thousand repeating units.
Thermosets can melt and take shape once; after they have solidified, they stay solid. In the
thermosetting process, a chemical reaction occurs that is irreversible. The vulcanization of rubberis a thermosetting process. Before heating with sulfur, the polyisoprene is a tacky, slightly runny
material, but after vulcanization the product is rigid and non-tacky.[7]
Other classifications
Other classifications are based on qualities that are relevant for manufacturing or product design.
Examples of such classes are the thermoplastic and thermoset, elastomer, structural,
biodegradable, and electrically conductive. Plastics can also be classified by various physical
properties, such as density, tensile strength, glass transition temperature, and resistance tovarious chemical products.[7]
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Biodegradability
Main article: Biodegradable plastic
Biodegradable plastics break down (degrade) upon exposure to sunlight (e.g., ultra-violet
radiation), water or dampness, bacteria, enzymes, wind abrasion, and in some instances rodentpest or insect attack are also included as forms of biodegradation or environmental degradation. Some modes of degradation require that the plastic be exposed at the surface, whereas other
modes will only be effective if certain conditions exist in landfill or composting systems. Starch
powder has been mixed with plastic as a filler to allow it to degrade more easily, but it still doesnot lead to complete breakdown of the plastic. Some researchers have actually genetically
engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as
Biopol, is expensive at present. The German chemical company BASF makes Ecoflex, a fully
biodegradable polyester for food packaging applications.[7]
Natural vs synthetic
Main article: Bioplastic
Most plastics are produced from petrochemicals. Motivated by the finiteness of petrochemical
reserves and possibility of global warming, bioplastics are being developed. Bioplastics are madesubstantially from renewable plant materials such as cellulose and starch.
In comparison to the global consumption of all flexible packaging, estimated at 12.3 milliontonnes, estimates put global production capacity at 327,000 tonnes for related bio-derived
materials.[7]
Crystalline vs amorphous
Some plastics are partially crystalline and partially amorphous in molecular structure, giving
them both a melting point (the temperature at which the attractive intermolecular forces are
overcome) and one or more glass transitions (temperatures above which the extent of localizedmolecular flexibility is substantially increased). The so-called semi-crystalline plastics include
polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some
polyurethanes. Many plastics are completely amorphous, such as polystyrene and its copolymers,poly (methyl methacrylate), and all thermosets.[7]
2.3 Properties of plastics
The properties of plastics is defined chiefly by the organic chemistry of the polymer. such as
hardness, density, and resistance to heat, organic solvents, oxidation, and ionizing radiation. Inparticular, most plastics will melt upon heating to a few hundred degrees celsius.While plastics
can be made electrically conductive, with the conductivity of up to 80 kS/cm in stretch-oriented
polyacetylene, they are still no match for most metals like copper which have conductivities of several hundreds kS/cm.[7]
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2.4 Uses of plastic:-
Computers & Electrical Equipment Housings
Computers are a targeted product for recycling of their plastic components the high rate of
innovation in the computer industry means that current computers have only the short time in themarket. This makes computers recycling a growing industry. Improve design measures to
facilitate simplified disassembly have already come in to practice, accelerating the acceptance of
computer recycling further. Computer companies that are particularly active in this area include
Hewlett-Packard, IBM Xerox and Siemens Nixdorf etc. these companies take back old models
and incorporate recyclate in their new products. In the United kingdom, the Ray Company has
been recycling electronics equipment computers sciences 1985.
In the United States recycling of electronic equipment is on the rise, fueled by international and
US regulatory developments and heightened interest in managing both the asset value and waste
stream created by the growing use of electronic equipment. Waste management objectives targetboth the hazardous constituents in electronic waste and waste diversion goals. Electronic product
recovery and recycling directives have been on the international agenda for several years, most
notably in Europe and Asia. In 1998, the European Union raised the stakes with its draft proposal
on electronic waste with stipulations on new product design, including restrictions on the use of
heavy metals and requirements for the use of recycled plastic in new products. This directive is
certain to have a "ripple effect" in the US. At the same time, regulatory activity in the US has
picked up with several states actively pursuing electronic waste policies.[5]
Automotive Plastics
The product life cycling of engineering plastics used in the automotive industry is app.2
to 3 times that of product in the computer industry. Thus design improvements relating it
disassembly and recycling will only make a contribution in about ten years time is the most
recycled automotive plastic contribution in about ten years time is the PC-PBT blend obtained
from reclaimed bumpers. A promising strategy in automotive engineering plastics recycling is to
use polymers that are chemically compatible within complete sub-assemblies. This allows such
modules to be easily recycled by simply granulating them to produce an alloy that still has
engineering domain properties.[5]
Compact Discs
It has been estimated that app. 10% of all CDs, manufactured are rejects and are disposed in
landfills. In the US alone, more than two billion polyearbinate compact disks are manufactured
year and between150-200 million CDs are crapped annually due to rejects. CDs are also
destroyed due to aspects of artist‟s rights. These together with some post consumer CDs are
currently being reclaimed to produce grades of recycled PC. The main problem with recycling of
polycorbanate compact disks is removal of the aluminum and acrylic lacquer coatings.[5]
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2.5 Identification of different types of plastics:-
There are several simple tests that can be used to distinguish between the common types of
polymers so that they may be separated for processing. The water test. After adding a few drops
of liquid detergent to some water put in a small piece of plastic and see if it floats. Burning test.
Hold a piece of the plastic in a tweezers or on the back of a knife and apply a flame. Dose the
plastic burn? If so, what colour? Fingernail test. Can a sample of the plastic be scratched with a
fingernail?
Test PE PP PS PVC*
Water burning Floats Blue
flame withyellow tip, melts
and drips.
Floats Yellow
flame with bluebase.
Sinks Yellow,
sootyflame – drips.
Sinks yellow,
sooty smoke.Does not
continue to burnif flame is
removed
Smell after
burning
Like candle wax. Like candle wax
– less strong
Sweet hydrochloric acid
Scratch Yes No No No
Table 2.1 Identification of different types of plastics
*To confirm PVC, touch the sample with a red-hot piece of copper wire and then hold the wire
to the flame. A green flame from the presence of chlorine confirms that it is PVC.
Source: Vogler. 1984
To determine if a plastic is a thermoplastic or a thermoset, take a piece of wire just below red
heat and press it into the material. If the wire penetrates the material, it is a thermoplastic; if it
does not it is a thermoset.
A cooling system has also been introduced in the United States to aid identification of plastics
for reclamation. It is based on the „Recycle Triangle‟ with a series of numbers and letters to help
with identification. More information is available from the Association of Plastic Manufacturers
in Europe (APME). See useful addresses section later in this brief.[2]
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Plastics fact file
• More than 20,000 plastic bottles are needed to obtain 1 tonne of plastic.
• It is estimated that 100 million tonnes of plastics are produced each year.
• The average European throws away 36kg of plastics each year.
• 4% of oil consumption in Europe is used for the manufacture of plastic products.
• Some plastic waste sacks are made from 64% recycled plastic.
• Plastics packaging totals 42% of total consumption and very little of this is recycled.[2]
2.6 Collection
When thinking about setting up a small-scale recycling enterprise, it is advisable to first carry out
a survey to ascertain the types of plastics available for collection, the type of plastics used bymanufacturers (who will be willing to buy the reclaimed material), and the economic viability of
collection.
The method of collection can vary. The following gives some ideas;
• House to house collection of plastics and other materials (e.g. paper).
• House to house collection of plastics only (but all types of polymer).
• House to house collection of certain objects only.
• Collection at a central point e.g. market or church.
• Collection from street boys in return for payment.
• Regular collection from shops, hotels, factories, etc.
• Purchase from scavengers on the municipal dump.
• Scavenging or collecting oneself.
The method will depend upon the scale of the operation, the capital available for set-up, transport
availability, etc.[1]
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CHAPTER 3
3.1 Why recycle plastics?
In „western‟ countries, plastic consumption has grown at a tremendous rate over the past two or
three decades. In the „consumer‟ societies of Europe and America, scarce petroleum resources
are used for producing an enormous variety of plastics for an even wider variety of products.
Many of the applications are for products with a life-cycle of less than one year and then the vast
majority of these plastics are then discarded. In most instances reclamation of this plastic waste
is simply not economically viable. In industry (the automotive industry for example) there is a
growing move towards reuse and reprocessing of plastics for economic, as well as environmental
reasons, with many praiseworthy examples of companies developing technologies and strategies
for recycling of plastics. Not only is plastic made from a non-renewable resource, but it is
generally non-biodegradable (or the biodegradation process is very slow). This means that plastic
litter is often the most objectionable kind of litter and will be visible for weeks or months, and
waste will sit in landfill sites for years without degrading. Although there is also a rapid growth
in plastics consumption in the developing world, plastics consumption per capita in developing
countries is much lower than in the industrialised countries. These plastics are, however, often
produced from expensive imported raw materials. There is a much wider scope for recycling in
developing countries
due to several factors:
• Labour costs are lower.
• In many countries there is an existing culture of reuse and recycling, with the associated system
of collection, sorting, cleaning and reuse of „waste‟ or used materials.
• There is often an „informal sector‟ which is ideally suited to taking on small-scale recycling
activities. Such opportunities to earn a small income are rarely missed by members of the urban
poor.
• There are fewer laws to control the standards of recycled materials. (This is not to say that
standards can be low – the consumer will always demand a certain level of quality).
• Transportation costs are often lower, with hand or ox carts often being used.
• Low cost raw materials give an edge in the competitive manufacturing world.
• Innovative use of scrap machinery often leads to low entry costs for processing or manufacture.
In developing countries the scope for recycling of plastics is growing as the amount of plastic
being consumed increases.[3]
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Plastics fact file
• More than 20,000 plastic bottles are needed to obtain 1 tonne of plastic.
• It is estimated that 100 million tonnes of plastics are produced each year.
• The average European throws away 36kg of plastics each year.
• 4% of oil consumption in Europe is used for the manufacture of plastic products.
• Some plastic waste sacks are made from 64% recycled plastic.
• Plastics packaging totals 42% of total consumption and very little of this is recycled[7]
Plastics for recycling
Not all plastics are recyclable. There are 4 types of plastic which are commonly recycled:
• Polyethylene (PE) - both high density and low-density polyethylene.
• Polypropylene (PP)
• Polystyrene (PS)
• Polyvinyl chloride (PVC)
A common problem with recycling plastics is that plastics are often made up of more than
one kind of polymer or there may be some sort of fibre added to the plastic (a composite) to
give added strength. This can make recovery difficult.[4]
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3.2 GE Polymer Recovery Process:-
GE has developed a polymer recovery scheme for the recycling of engineering thermoplastics.
Approved recycles disassembled, shred, and grind and purify engineering thermoplastic
components from application such as automotive bumpers. Large volume water bottles, compactdiscs, computer housings and telephones.
GE plastics buys back this material in clean flank from adds virgin resins and additives such as
stabillzers, modifiers and pigments to create upgraded recycled content materials.
As an important part of the GE recycle strategy is recycle designs, in order that the engineering
plastics are prepared for easy recycling after their product life is over. This makes them faster
and easier to disassemble segregate and clean.
GE corn plastic builds a market and provides justification to expand GE acreage. Expansion is
certain to have negative economic, social and environmental consequences for PCC and manyothers. Crop diversity slowly but surely will be reduced, putting the entire food system at risk.
Large industrial ag corporations will exert even greater control over production and distribution,
which increasingly will threaten small farmers and organic food production. This will lead to
increased prices because there‟ll be fewer suppliers controlling the market. In short, use of the
product now may help in the short run, but harm PCC‟s business in the future. While GE corn
plastic might seem to make sense in the short term, its many negative consequences could make
it harder or even impossible ever to return to sustainable solutions.[3]
Thermoplastics make up 80% of the plastics produced today. Examples of thermoplastics
include;
• high density polyethylene (HDPE) used in piping, automotive fuel tanks, bottles, toys,
• low density polyethylene (LDPE) used in plastic bags, cling film, flexible containers;
• polyethylene terephthalate (PET) used in bottles, carpets and food packaging;
• polypropylene (PP) used in food containers, battery cases, bottle crates, automotive parts and
fibres;
• polystyrene (PS) used in dairy product containers, tape cassettes, cups and plates;
• polyvinyl chloride (PVC) used in window frames, flooring, bottles , packaging film, cable
insulation, credit cards and medical products.
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There are hundreds of types of thermoplastic polymer, and new variations are regularly being
developed. In developing countries the number of plastics in common use, however, tends to be
much lower.
Thermosets make up the remaining 20% of plastics produced. They are hardened by curing and
cannot be re-melted or re-moulded and are therefore difficult to recycle. They are sometimesground and used as a filler material. They include: polyurethane (PU) – coatings, finishes, gears,
diaphragms, cushions, mattresses and car seats; epoxy – adhesives, sports equipment, electrical
and automotive equipment; phenolics – ovens, handles for cutlery, automotive parts and circuit
boards (The World Resource Foundation).[3]
3.3 Bayer Engineering Plastics Recycling Program:-
Bayer ag has developed programs to recycle a range of engineering plastics including PC
compact discs and milk bottles. ABS vacuum cleaner housings and automotive radiator grills and
polyamide coach seats.
Computer housings form the majority of the ABS recyclate, while the Bay blend is comprised of
appliance housings and the Makolon is derived from CDs. It is significant to note that flame
retard ABS products of unknown origin are excluded in the Bayer process for recycling
engineering plastics. This is because such grades may contain environmentally harmful flame-
retardant such retardant is their ABS grades since 1986.Instead their ABS grades use additives
based on a phosphate PTFE mixture.[6]
MRC Polymers
An MRC polymer is plastics recycling company specializing in quality engineering resins. The
company products recycled PC under the Noxell tm trademark for use in printer ribbon
cartridges. They also after PC-PET blends with post consumer recycle content under the stanuloy
tm trade name. These resins come in both glasses reinforced and UV stabilizes forms.
Typical applications for which MRC supplies recycled resign include Xerox copier covers,
computer keyboards etc. the improved performance achieved through the use of recycled
engineering resins, which are available at a lower cost than some virgin resins with inferior
physical properties, allows these recycled resins to make inroads into a variety of applications.
For example replacing a virgin high heat resistant ABS grade with recycled PC grade can
preserve cost yet gives significantly improved performance.
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LINPAC Plastic Packing
At Linpac Plastics recycling we deal with post consumer and post industrial rigid plastics,
mainly polypropylene, polystyrene, and polyethylene. This is purchased from manufacturers or
collection schemes and brought into our factory at Allerton By water by road transport.
. Fig 3.1: - LINPAC Plastic Recycling Process
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The material is sorted as to type and colour.
Depending on the condition of the material, it is then either dry granulated, or washed
and granulated. During these processes the plastic is chopped into flake or granules and
any contamination is removed, resulting in the output of high quality flake or granules.
Laboratory tests are also carried out at this stage to assess the exact properties of theplastic, this is important for the next stage of the process.
Fig 3.2: - Consumed & discharged amount of plastic material in India
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Once an order from a customer has been received, material is chosen from our large stock
of flakes and regrind, and then blended together to give the exact specification of that
required by the customer.
The blend is then fed through our extruders. It is at this stage when the colour is added in
the form of master batch. The blend of plastic chips and colorings agent are fusedtogether by heat and pressure in the extruder and the resulting molten plastic is then
forced out through a multi-holed die.
As the material emerges from the die, it is then chopped into small pellets by revolving
blades and cooled in a water stream.
During the extrusion of any blend, samples are taken at regular intervals and are
su bjected to various QC checks to ensure the customer‟s requirements are met.
Assuming that the QC checks serve to confirm the quality, the product can then be
packaged to the customer‟s requirements.
Finished product is usually dispatched to the customer within hours of the production run
finishing. The pellet will then start its life cycle again in the manufacture of new items.
3.4 Sources of waste plastics:-
Industrial waste (or primary waste) can often be obtained from the large plastics processing,
manufacturing and packaging industries. Rejected or waste material usually has good
characteristics for recycling and will be clean. Although the quantity of material available is
sometimes small, the quantities tend to be growing as consumption, and therefore production,
increases. Commercial waste is often available from workshops, craftsmen, shops, supermarkets
and wholesalers. A lot of the plastics available from these sources will be PE, often
contaminated. Agricultural waste can be obtained from farms and nursery gardens outside the
urban areas. This is usually in the form of packaging (plastic containers or sheets) or construction
materials (irrigation or hosepipes). Municipal waste can be collected from residential areas
(domestic or household waste), streets, parks, collection depots and waste dumps. In Asian cities
this type of waste is common and can either be collected from the streets or can be collected
from households by arrangement with the householders. (Lardinois 1995) [7]
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CHAPTER 4
4.1 Manufacturing techniques:- • Extrusion:-
The extrusion process used for manufacturing new products is similar to that outlined above for
the process preceding pelletisation, except that the product is usually in the form of a continuous
„tube‟ of plastic such as piping or hose. The main components of the extrusion machine are
shown in Fig. The reclaimed plastic is forced along the heated tube by an archimedes screw and
the plastic polymer is shaped around a die. The die is designed to give the required dimensions to
the product and can be interchanged.[4]
Fig 4.1 Extrusion
• Injection moulding:-
The first stage of this manufacturing process is identical to that of extrusion, but then the plastic
polymer emerges through a nozzle into a split mould. The quantity of polymer being forced out
is carefully controlled, usually by moving the screw forward in the heated barrel. A series of
moulds would be used to allow continual production while cooling takes place. See Figure 2
below. This type of production technique is used to produce moulded products such as plates,
bowls, buckets, etc.[4]
Fig 4.2 Injection moulding
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• Blow moulding:-
Again the spiral screw forces the plasticised polymer through a die. A short piece of tube, or
„parison‟ is then enclosed between a split die -which is the final shape of the product - and
compressed air is used to expand the parison until it fills the mould and achieves its required
shape. This manufacturing technique is used for manufacturing closed vessels such as bottles and
other containers. See Figure [4]
Fig 4.3 Blow moulding
• Film blowing:-
Film blowing is a process used to manufacture such items as garbage bags. It is a technically
more complex process than the others described in this brief and requires high quality raw
material input. The process involves blowing compressed air into a thin tube of polymer to
expand it to the point where it becomes a thin film tube. One end can then be sealed and the bag
or sack is formed. Sheet plastic can also be manufactured using a variation of the process
described [4]
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Conclusion:-
It has been found by going through this seminar report that PLASTIC RECYCLING is not only
helpful in prevention of environmental pollution but also helpful in energy conservation by
recycling of industrial as well as household based plastic.
It has been found that a lot of energy has been conserved by PLASTIC RECYCLING in the
production of various commodities. More ever it has been found that there are some reductions
in some properties of the recyclate it still has significantly higher properties than the virgin
version.
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References
1. B.Baum & C.H.Parker
„PLASTICS WASTE MANAGEMENT MANUFACTURING CHEMISTS
ASSOCIATION”, WASHINGTON D.C.May 1990
2. A.J.Warner , C.H.Parker & B.Baum
“SOLID WASTE MANAGEMENT OF PLASTICS MANUFACTURING CHEMISTS
ASSOCIATION WASHINGTON” D.C. 1990
3. J. Milgrom
“CONSERVATION RECYCLING”
4. R. Liang and R.K. Gupta, Rheological properties of recycled polycarbonate and ABS
melts, Proc. XIIIth Int. Congress on Rheology, Cambridge, U.K., vol. 1, 216-218 (2000).
5. K. Boudreau, R. Malloy and A. Tayebi., A method for the recovery of polycarbonate
from compact disks. University of Massachusetts, ANTEC (1993).
6. E.R. Kaiser & A.A.Carotti“MUNCIPAL INCINERATION OF REUSE WITH 2% & 4% ADDITION OF
PLASTICS”. Society of Plastic Industries, New York 1971.
7. Wikipedia.com