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What are the different ways of classification of polymers ? |
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Answer» Solution :(1) Classification based on source :(a) Natural polymers : Obtained from chemical substance , prepared in a laboratory or industries . E.g. Nylon , terylene , polyethene. (c) Semisynthetic polymers : obtained from natural polymers by some chemical treatment e.g. acetate rayon, CUPRAMMONIUM silk. (2)Classification based on structure: (a) Linear polymer : It is made up of long continuous chain without any branches. e.g. polyethese, PVC (b) Branched polymer : It is made up of main chain with small chains as branches of main chain e.g. polypropylene . (c) Network or cross-linked polymers : The chain polymers linked by strong covalent bonds leads to network structure. e.g. Bakelite, melamine. (3) Classification based on polymerisation : (a) Addition polymers : The addition of a LARGE number of monomers like alkenes or alkynes and the polymers are formed by chain growth polymerization .e.g. Orlon, teflon. (b) Condensation polymers : The two monomers combine to form a polymers by elimimation of a small molecules like water oralcohol. e.g. nylons, polyesters, etc. (4) Classification based on molecular forces: (a) Elastomers : In these polymers , the INTERMOLECULAR forces of attraction between the polymer chains are the weakest . They have high degree fo elasticity . e.g. vulcanised rubber, Buna-S (b) Fibres : In these polymers , the intermolecular forces of attraction between the polymer chains are the strongest . They have high TENSILE strenght . e.g. Orlon, terylene . (c) Thermoplastic polymers : In these polymers , the intermolecular forces of attraction in the polymer chains in between those of elastomers and fibres . e.g. Polythene, polystyrene. (d) Thermosetting polymers : These polymers are cross linked or branched molecules which do not become soft on heating under pressure, hence cannot be remoulded and recycled . e.g. Bakelite. (5) Classification based on growth polymerisation : (a) Chain growth polymer:Alkenes undergo growth chain polymerisation when treated with small quantity suitable initiators. e.g. polyethene, PVC. (b) Step growth polymer : These polymers are called condesation polymers . e.g. Nylon , Bakelite. |
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