2. INTRODUCTION
Plastics are material consisting of a wide range of synthetic organic compounds that can
be moulded into solid objects.
Plastics are typically organic polymers of high molecular mass and often contain other
substances. They are usually synthetic, most commonly derived from petrochemicals.
Due to their low cost, ease of manufacture, versatility, durability and imperviousness to
water, plastics have an ever expanding range of applications.
They have replaced many traditional materials, suchas wood, stone, leather, metal, glass,
and ceramics.
3. Classifications of Plastics
Thermosetting/Thermosets Plastics:
Thermosets, or thermosetting polymers can melt and take shape only once. After they have
solidified, they stay solid. Once hardened a thermoset polymer cannot be re-melted in order to
be reshaped. Due to this Thermosetting plastics products can withstand high temperatures.
Thermoplastics:
A thermoplastic, or thermosoftening polymer are plastics which are thermo-formable
which means they can be melted or welded. This formability is reversible, means it can be
repeated as often as required as long as the material is not thermally damaged by
overheating. Thermoplastic materials have low melting points.
4. Thermosets vs Thermoplastics
Thermosets
Thermoset plastics contain polymers that
cross-link together during the curing process
to form an irreversible chemical bond. The
cross-linking process eliminates the risk of the
product remelting when heat is applied,
making thermosets ideal for high-heat
applications such as electronics and
appliances.
Pros: More resistant to high temperatures than
thermoplastics, Highly flexible design, Thick
to thin wall capabilities, Excellent aesthetic
appearance, High levels of dimensional
stability, Cost-effective.
Cons: Cannot be recycled, More difficult to
surface finish, Cannot be remolded or
reshaped
Thermoplastics
Thermoplastics pellets soften when heated and
become more fluid as additional heat is
applied. The curing process is completely
reversible as no chemical bonding takes place.
This characteristic allows thermoplastics to be
remolded and recycled without negatively
affecting the material’s physical properties.
Pros : Highly recyclable, Aesthetically-
superior finishes, High-impact resistance,
Remolding/reshaping capabilities, Chemical
resistant, Hard crystalline or rubbery surface
options, Eco-friendly manufacturing.
Cons: Generally more expensive than
thermoset, Can melt if heated
5. Thermosetting Plastics
The individual molecular chains of thermoset polymers are characterized by three
dimensional closely meshed crosslinking. This Property means that they can no
longer be shaped after hardening. They also cannot be melted. However , because of
their strong crosslinking, thermoset polymers do offer good chemical resistance and
a high level of thermal stability as well as being hard and brittle.
Thermosetting plastics are heated to curing temperature in a mould and pressed to
compactness in the cavity. Then they are allowed to cure and cool down to a
temperature suitable for ejecting the formed component from the cavity.
Once Thermosetting plastics are cured, they cannot be softened by re-heating as is
possible with thermoplastics. If they are re-heated to a high temperature , they
decompose to ashes.
Epoxy resin, Melamine formaldehyde (MF), Urea-formaldehyde (UF), Polyester are
the common thermosetting plastics
6. 1. Bakelite
Bakelite named after its inventor Leo Baekeland who invented this first thermosetting
Plastic in 1907, is a phenol formaldehyde resin.
Bakelite does not conduct electricity and heat and hence was used in electrical switches,
insulators for heat applications and jewellery after it was manufactured in various bright
colours. Bakelite is still used for making machine gun carbines and stocks.
7. 2. Epoxy resin
This is a class of reactive polymer which reacts with themselves.
The name epoxy resin denotes the basic components and th cured end product.
They have very good mechanical properties ,good adhesive performance and
chemical resistance.
Applications include Electrical Insulations, Electronic/LED components, Metal
coatings
8. 3. Melamine formaldehyde (MF)
Melamine resin or melamine formaldehyde or simply melamine is a
hard, thermosetting plastic material made from melamine and formaldehyde by
polymerization.
Melamine resin is the main constituent of laminates, such as Formica. It is
also used in Kitchen Utensils like plates. bowls.,etc
9. 4. Urea-formaldehyde (UF)
Urea-formaldehyde is a common chemical used in making sand moulds, used as a
wood adhesive (for plywood) and electrical switch housings.
It has low water absorption, High tensile strength and high surface hardness and is
non-poisonous.
Examples include decorative laminates, foundry sand molds. It is also used to glue
wood together.
Iron handle made of UF
10. 5. Polyester
Polyester is commonly used to make synthetic fibres used extensively in woven fabric
Shirts , trousers, jackets, bedsheets, blankets, furniture upholsteries, computer mats and
pillows are some its common applications.
Belts for pulleys/conveyors, tyre reinforcements, safety belts, safety ropes, films, are some
of its industrial applications.
Polyester fibre is very strong, tear resistant and if used in fabric can make it wrinkle free.
11. Thermoplastics
A thermoplastic, or thermosoftening polymer are plastics which are thermo-formable
which means they can be melted or welded. This formability is reversible, means it can be
repeated as often as required as long as the material is not thermally damaged by
overheating. Thermoplastic materials have low melting points.
Common Thermoplastics used:
1. Polymethyl methacrylate (PMMA) - Acrylic 11. Polyoxymethylene (POM) – Acetal
2. Polycarbonate (PC) 12. Styrene Acro-Nitrile (SAN)
3. Polyamides (PA) - Nylons 13. Polybutylene Teraphthalate (PBT)
4. Polyvinyl chloride (PVC)
5. Acrylonitrile butadiene styrene (ABS)
6. Polystyrene (PS)
7. Polypropylene (PP)
8. Polyethylene (PE)
9. Polyethylene terephthalate (PET)
10. Polytetrafluoroethylene (PTFE) - Teflon
12. 1.Polymethyl Methacrylate - Acrylic
Polymethyl methacrylate (PMMA), also known as by the trade
names Crylux, Plexiglas, Acrylite, Lucite, and Perspex.
It serves as a sturdy substitute for glass for items such as aquariums, motorcycle
helmet visors, aircraft windows and lenses of exterior lights of automobiles.
It is extensively used to make display signs including lettering and logos.
Acrylic Paints consist of PMMA particles suspended in water.
13. 2. Polycarbonate (PC)
Polycarbonates are strong, tough materials, and some grades are optically transparent. They
are dimensionally stable but costly.
PC is easily moulded and thermoformed for many applications such as electric
components, electrical switches, data storage devices, automotive parts, light covers,
industrial housings and reflectors.
PC sheeting in GreenhouseLaboratory Safety GogglesCd’s & Dvd’s
14. 3. Polyamides
Polyamides (PA) is commonly known by trade names like Nylon, Akulon or Grilon. In India,
GSFC (Gujrat State Fertilizers and Chemical) is the largest manufacturer of PA.
Nylon has high strength, high fatigue resistance, high chemical resistance, low friction.
Nylon fibres are useful in making fabrics, ropes, carpets, parachutes, sails protective vests and
musical strings.
Nylon is also used in mechanical parts including machine screws, gears, rollers, handles, levers,
air filters, safety mask and power tool casings.
Nylon Cable Ties Toothbrush Bristles Polyamide Gears Nylon Tubes
15. 4. Polyvinyl chloride
Polyvinyl chloride (PVC) is the world's third-most widely produced
synthetic plastic polymer.
PVC comes in two basic forms: rigid and flexible. The rigid form of PVC is used in
construction for pipe. It is also used in making bottles, non-food packaging, and cards.
It is converted to flexible forms with the addition of plasticizers. In this form, it is used in
plumbing, electrical cable insulation, shoe soles, hoses, tubing, flooring, phonograph
records, inflatable products like water beds and pool toys.
It is tough, flexible, lightweight and cheap material that is flexible and resistant to flame,
acids and base.
Commonly used in the construction industry for vinyl siding, drainpipes, gutters and
roofing sheets.
17. 5. Acrylonitrile butadiene styrene (ABS)
ABS is an impact-resistant engineering thermoplastic & amorphous polymer. ABS is
made up of three monomers: acrylonitrile, butadiene and styrene
It is a light weight material with good mechanical toughness, High surface brightness and
excellent surface aspect but it cannot survive extreme difference of weather.
ABS can be electroplated and is hence used in consumer products such as toys, appliances,
decorative interiors, ceiling fan decorative rings and cell phone bodies.
Its applications in automotive and transportation includes instrument panels, Dashboard
components, Door liners & handles, Seat backs and seat belt components.
Lego brick toys
18. 6. Polystyrene (PS)
Polystyrene (PS) is a synthetic aromatic hydrocarbon polymer made from
the monomer styrene. Polystyrene can be solid or foamed
It is an inexpensive resin per unit weight and is one of the most widely used plastics.
PS is used in manufacture of disposable cutlery, CD’s & DVD’s, Plastic models of cars and
boats, pens, cosmetics.
Expanded Polystyrene (EPS) known by the trade names Styrofoam/ Thermocol, is used to
make architectural models, packing appliances and drinking cups for heated beverages.
19. 7. Polypropylene (PP)
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in. a
wide variety of applications
PP is useful for diverse products as reusable plastic food containers, casings,
microwave/dishwasher safe plastic containers, toys, ropes, piping systems, insulation for
electric cables, filter element for water purifiers and other liquids.
In Medicine, it is used to make heat-resistant medical equipment and injections.
The wide color range, durability, low cost, and resistance to dirt make it ideal as a
protective cover for papers and other materials. (used in Rubik's cube stickers)
20. Polypropylene (contd.)
A major percentage of plastic components in refrigerators and washing machines are made
of PP.
PP sheets are used for bags, stationary folders and packaging and clear storage bins.
Although relatively inert, it is vulnerable to ultraviolet radiation and can degrade
considerably in direct sunlight.
Polypropylene is tough and stiff, scratch resistant, cheap but not as impact resistant as
polyethylene
21. 8. Polyethylene (PE)
PE Is Polyethylene or polythene or polyethene is the most common plastic. It is a family
of of similar materials categorized according to their density and molecular structure.
Ultra-high molecular weight polyethylene (UHMWPE) is tough and resistant to chemicals.
It is used to manufacture moving machine parts, bearings, gears, artificial joints and some
bulletproof vests.
High-density Polyethylene (HDPE) is commonly used in milk jugs, liquid laundry
detergent bottles, outdoor furniture, portable gasoline cans, water drainage pipes, and
grocery bags.
22. Polyethylene (cont.)
Medium-density Polyethylene (MDPE) is used for packaging film, sacks and gas pipes and
fittings.
Low-density Polyethylene (LDPE) is flexible and is used in the manufacture of squeeze
bottles, milk jug caps, buckets, tumblers, retail store bags and linear low density
polyethylene (LLDPE) as stretch wrap in transporting and handling of durable goods and
as the common household food covering.
23. 9. Polyethylene terephthalate (PET)
Tis is clear and tough plastic suitable for bottles and jars of beverages and food products.
Suitably designed and dimensioned preforms are injection moulded and then stretch blow
moulded to get the desired shape of the respective jar or bottle.
24. 10. Polytetrafluoroethylene (PTFE) - Teflon
PTFE is known as Teflon (Dupont) or infolon and belongs to a class of thermoplastics
known as fluoropolymers.
The most common application of PTFE is as a coating for non stick cookware.
Being chemically inert, it is used in making containers and pipes that come in contact with
reactive compounds.
It ha the lowest coefficient of friction of any substance manufactured and is used in
applications where there is sliding between parts such as gears, bearings and bushings.
25. 11. Styrene Acro-Nitrile
SAN is similar to polystyrene and is known by trade name Tyril. Like Polystyrene it is
transparent and brittle.
SAN is chemically resistant and is used to manufacture syringes.
SAN is resistant to boiling water and hence finds applications in food containers and
kitchenware.
Other applications include computer products, packaging material, battery cases, knobs and
plastic optical fibres.
Owing to acro-nitrile content, it has a yellowish tint rather than the normal transparent
plastic.
26. Decoding of Plastics
In 1988, The Society of the Plastic Industry (SPI) established a classification system to
help customers and recyclers properly recycle and dispose of each different type based on
its chemical makeup.
Today, manufacturers follow a coding system and place a number , or SPI code on each
plastic product, usually moulded into the bottom.
Although you should always verify the plastic classification number of each product you
use, especially if you plan on recycling it, this guide provides a basic outline of the
different plastic types associated with each code number.
PET HDPE PVC LDPE PP PS OTHER
