(i) Polymethyl methacrylate (PMMA)

Acrylic PMMA (Polymethyl Methacrylate) is both a thermoplastic and transparent plastic. Two of the most common brand names are Plexiglass and Lucite and it is also commonly known as acrylic glass, acrylic, perspex or plexiglas. It is often used as an alternative to glass and is preferred for many applications because of its moderate properties, easy handling, easy processing and low cost. However, acrylic is not recommended for use in structural applications because of its poor impact resistance.

Common Uses:

• Industrial Uses: water tank liner, hand-held computer case, liquid chemical pump, conveyor rollers, soap dispensers hatch covers, bumper guards.
• Automotive Industry: lenses of exterior lights, trunk release handles, master cylinder, dashboard lighting.
• Consumer products: aquariums, motorcycle helmet lenses, paint, furniture, picture framing, umbrella clamps, cell phone antennas, bicycle air pumps, AV wall outlets, visors.

• Medical applications: lens implants, hard contact lenses, dentures, fillings,

   

Physical Properties:

• Specific Gravity - 1.18 g/cm
• Tensile Strength - 9400 psi
• Flexural Strength - 1300 psi

• Impact Strength - 0.4 ft-lb/in

   

General Properties:

• Good Weatherabiity
• Clear/colorable – excellent clarity
• Good Insulation Properties
• UV resistant
• Good abrasion resistance
• Good stiffness
• Low smoke emission

• Low water absorption

   

Processing:

• Injection Molding

• Extrusion

   

   

(ii) Buna-S

Synthesis of Buna S

It is a random co-polymer formed by the emulsion polymerization of a mixture of 1:3 butadiene and styrene in the presence of peroxide catalyst at 5 degree Celsius and therefore the product is called as cold rubber. The rubber obtained is also called Styrene butadiene rubber (SBR).

In Buna-S, Bu stands for butadiene and, Na for sodium and S for styrene. It is vulcanized with sulphur. The rubber is slightly inferior to natural rubber in its physical properties.

Properties of Buna–S:

• It is very tough and a good substitute for natural rubber.
• It possesses high abrasion resistance.

• It has high load bearing capacity.

   

Uses of Buna–S:

• It is used for manufacturing automobile tyres.

• It is used for making floor tiles, footwear components, cable insulation etc.

   

Applications:

• It finds application due to its high resistance to abrasion.
• It is used for the manufacture of passenger car tyres and treads,motor cycle and scooter tyres, cycle tyres and tubes.
• They are also used for the manufacture of conveyor belts, foot-wares, shoe soles, hoses and electrical insulation.