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Mention the preparation, properties, uses and applications of the following polymers- Buna-S, PMMA, Kevlar, phenol formaldehyde.
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BUNA-S

Preparation: butadiene (about 75% by weight) and styrene (25% by weight) co-polymerize to give styrene butadiene rubber (SBR) as follows-

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The products formed by copolymerization show the specific properties of the monomers and hence is very useful in industry. Butadiene and styrene are called as primary monomer. This is nothing but a type of addition polymerization commonly known as co-polymerisation.

Properties and uses:

  • High abrasion resistance, high bearing capacity and resilience.

  • Gets oxidized in the presence of traces of ozone. Swells in oils and solvents.

  • Used for manufacture of car tyres, floor tiles, shoe soles, adhesives, and wire & cable insulations.

PMMA

It is prepared by polymerization of methyl-methacrylate which is an ester of methyl acrylic acid CH2 = C(CH3)-COOH in the presence of actyl peroxide. It is an acrylic polymer.

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Properties and uses:

  • Colorless, hard, thermoplastic and fairly rigid material.

  • High softening temperature 130-140o C, becomes rubbery above 65oC.

  • High optical transparency.

  • Has refractive index = 1.59.

  • Its drawbacks- low resistance to hot acids and alkalis & to scratches.

  • Used for protective coating and also for manufacturing safety glass.

  • Acrylic resin emulsion are used as textile and leather finish. Making lenses, artificial eyes, wind screens, TV screens etc.

KEVLAR

It is an aromatic polyamide with benzene rings attached to amide groups.

It is prepared by poly condensation between aromatic dichloride and aromatic diamines.

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Properties and uses:

  • High stability against heat.

  • Highly flexible it is 10 times stronger than aluminum and 5 times stronger than steel.

  • Used in aerospace and aircraft industries.

  • Making ropes, cables, protective clothing, bullet proof vests etc. helmets manufacturing, making car parts etc.

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