Polymers:
- The fibres have strong hydrogen bond.
- Examples of elastomers :- buna-s , buna - N , neoprene.
- Examples of the fibres:-polyamide ( nylon 6,6) , polyester ( terelyne).
- Concept of thermoplastic:- which substance which is soft on heating and hardening on cooling.
- Examples of thermoplastic are polythene , polystyrene , polyvinyl .
- Thermoplastic are not heavily branched.
- Trend of force of attraction i.e bond attraction : fibre > thermoplastic > elastomers.
- Thermosetting plastic are heavily branched.
- Examples of thermosetting plastic are bakelite , urea - formaldehyde resins etc.
- Thermosetting plastic are not soften on heating .
- Addition or chain growth polymers are having free radicals mechanism. In these mechanisms the initiator use are benzoyl peroxide , tert butyl peroxide , acetyl peroxide are used.
- For formation of Low density polyethene peroxide is use as the catalyst .
- Low density polymer (LDP) are chemically inerts and they are poor conductor of electricity ,so they are used as insulators .
- High density polymer is form in presence of the zigler natta catalyst . The zigler natta catalyst is the triethyl aluminium and titanium tetrachloride .
- Polyacryonitrile is use for substitution of wool and also use for preparation of Orlon fibre.
- Terelyene is a condensation polymer and it has monomers are ethylene glycol , terephatahallic acid.
- Chloroprene is converted in to neoprene in presence of oxygen benzoyl peroxide.
- Some important structures and reactions:
- 1) terelyene:
2) nylon 6,6
3) nylon 6
4) PHBV:
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