Wednesday, January 16, 2008

Ch.33 Polymers - Core Points

JEE syllabus

Properties and uses of some important polymers:
Natural rubber,
teflon and

Objective 10 points

A polymer is a large molecule built by repetitive binding together of many small units called monomers.

Homopolymer: A polymer derived from a single repeating monomer. Only one type of monomer will have repetitive binding and a large molecule appears.

Copolymer: When two or more monomer bind together in a repetitive manner and give rise to a large polymer, it is called copolymer.

Chain growth polymers: Also called addition polymers.

Step Growth polymerss: Also called as condensation polymers

Classification based on physical properties: Elastomers, Fibre, Thermoplastics and
Thermosetting plastics

Rubber is a naturally occuring polymer of isoprene (2-methyl buta-1,3-diene)

Natural rubber is a thermoplastic and becomes soft and sticky when heated.The properties can be modified and improved by the process of vulcanization.


Nylon: The monomer of nylon 6 is caprolactum and for nylon 66, the monomers are hexamethylenediamine and adipic acid.

Teflon: It is an addition polymer of tetrafluoroethylene (nF2C=CF2).Under heat and pressure the double bond breaks and gets ready for bonding with a carbon on either side and the polymerisation takes place. (-F2C-CF2-)n

PVC: PVC is polyvinyl chloride and its monomer is vinyl chloride. CH2=CHCl

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