- 1 Thermo plastics
- 1.1 Cellulose derivatives
- 1.2 Synthetic resins
These kinds of plastics have long separate and large molecules arranged side by side. The various types of thermoplastics are discussed below.
Cellulose nitrate is generally obtained by treating the cellulose with a mixture of nitric acid and sulphuric acid. It has high toughness, good resistance to moisture and it is highly inflammable. It is mostly used for making spectacle frames, toilet wares, pen bodies, etc.
It is obtained by treating the cellulose with acetic acid. It is inserted and compressed in the mould for better stability and for obtaining high mechanical strength. It has the tendency to absorb moisture and is less in weight. It is used for manufacturing photographic films, buttons, radio panels, sheets, tubes, toys, etc.
It is the most lightest of all cellulose derivatives. It has very good electrical properties, chemical resistance, surface hardness and strength. Generally used for making jigs, fixtures, nozzles and moulded articles.
Cellulose acetate – butyrate
It is obtained by treating cellulose with acetic acid and butoric acid. It has a good stability against light and heat and moisture absorption tendency. Cellulose acetate can also be used for injection moulding. It is used for making radio cabinets, pipes, steering wheels, handles and coating.
It is generally available in extruded form. It has an attractive appearance and good resistance to moisture, solvents and fire. Generally used for making curtains and packaging materials.
It has low tendency for moisture absorption. Cellulose propionate can withstand temperatures upto 93°C and can be easily moulded. Used for making fountain pens, telephones and flashlight cases.
The following are the synthetic resin.
It has very high resistance to acids, alkalizes and the solvents can also be made flexible, tough and good insulators. It has low water absorption. It is used for making fabrics, trays, pipes and for corrosion resistant coatings and packaging works.
it is available in any form and any color.it has good dimensional stabilities and strain resistance. Polystyrenes are easily joined by cementing. It is used for making boxes, cases, radio parts, table ware and insulation parts.
It has a high transparency tendency. It is made in any color with high dielectric properties, good strength, and resistance to moisture and very good light transmitting power. This material can be casted, injection moulded, extruded and can be stretched into sheets. It is used for manufacturing tubes, plates, lamination, display cases, helmets and valves.
It is generally called as PVC. They are flexible and rigid. It has good electrical and weather resistance. These are resistant to water and available in variety of colors.
It is named after Teflon. It has good chemical resistance and can withstand temperatures upto 288°C. it cannot be dissolved in any solvent. It has high electrical resistance, low friction and very low adhesion to other substances. It mostly available in the form of sheets, rods and tubes. It is used for making gaskets, electrical insulators, etc.
It is also known as polyamide. It has high strength, toughness and elasticity. It can be moulded and extruded into rods. The powder metallurgy methods can also be used for this type of plastics. It is a good insulator and has good wear resistance. Used for making Yarn for making clothes, insulation wires and combs.
Its trade name is Lucite and plexiglass. It is easily formed at temperatures around 120°C. it is known for its clear color and high light transmission ability. Used or manufacturing aircraft parts, bowls, contact lenses and various surgical instruments.