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Polymers are very high molecular mass substance each POLYMERS
molecules of which consists of very large number of simple Structural unit joined together through covalent bond in a regular fashion.
HOMOPOLYMERS: Only one type of monomers unit are called homopolymers. For Polymers whose repeating structural unit is derived from
Example polyethylene polymer which is obtained by polymerization of ethylene.
n(CH Ethylene โ =CH โ ) โโโโ๏ข (-CHPolyethylene โ -CH โ -)n
COPOLYMERS: two or more type of Polymers whose repeating structural units are derived from monomers units are called Copolymers.
For Example NYLON โ 66
CLASSIFICATION BASED UPON STRUCTURE
LINEAR POLYMERS: over one another to give a well packed structure. In these polymers the various polymeric chains are stacked Because
of the close packing of polymers chains. have high boiling point. Linear polymers
BRANCHED CHAIN POLYMER: to produce the linear chain, but also form branches along the In these polymers, the monomers units not only combine
main chain.
THREE DIMENSIONAL NETWORK POLYMERS: chains are joined together to form a three dimensional network In these polymers, the initially formed linear polymers
structure. polymers are also called cross-linked polymers. Because of the presence of cross links, these
In this type of polymerization, a large number of monomers loss of molecule combine together usually with the to form a macro molecule in which the molecular formula^ simple molecules like water, alcohol, ammonia etc. of repeating structural unit is generally not the same as that of the monomers. The polymers thus formed are called condensation polymers.
n(H โ N-(CH โ ) โ -NH โ ) + n(HOOC-(CH โ ) โ -COOH)
CLASSIFICATION BASED UPON MOLECULAR FORCES
ELASTOMERS: between the polymer chain, are the weakest are called Polymers in which intermolecular force of attration
elastomers.
VOLCANIZATION:
- PolypropyleneStyron
- Buna โ S
POLYPROPYENE: Polypropylene is prepared by heating propylene in presence Starting material; Propylene() Reduction to
Of trace of Benzoyl peroxide as radical.
n(CH โ -CH=CH โ ) --------------- (-CH โ -CH-CH โ )n
USES: used for: It is harder and stronger polymer than polythene and it is
- For packing textiles and food.For making linears of bags and heat shrinkable wrans for record and other articles.
- For making automatic mouldings, seat covers, carpet, fibers rope.
- In the manufacture of stronger pipes and bottles.
BUNA โ S: Starting material: 1, 3 butadiene
(CH along with sodium, 4 styrene (C โ = CH โ CH = CH โ ) โ H โ
โCH = CH โ )
Styrene in the ratio of 3:1 in presence of sodium.^ It is obtained by copolymerization of 1,2 โ butadiene, 4
