1) Vulcanization of Rubber: Vulcanization is a process where natural rubber is boiled with sulphur to make it harder.
2) Thermosetting Polymer: They are made from relatively low molecular mass semi-fluid polymers which on heating become hard and infusible. This is due to extensive cross-linking between various chains. They have three dimensional network of bonds. Thermosetting polymer is irreversible. It cannot be melt again. E.g. Bakelite, melamine.
3) Thermoplastic Polymer: Thermoplastic polymers soften on heating and harden on cooling. There is no cross-linking between the chains. Thus, they undergo reversible change when heated and cooled. E.g. PVC, Polyethylene, polypropylene, Polystyrene, etc.
4) Elastomers (Rubber/ Rubber like substance): In these the chains are held by weakest intermolecular forces, due to these weak forces, the polymers can be stretched. A few cross-links present between the chains permit the polymer to attain its original form when the forces ceases. E.g. vulcanized rubber, Buna-N, neoprene, Buna-S, etc.
5) Fibres: They possess high tensile strength and high modulus due to strong intermolecular forces like H-bonding. For examples, Nylon-66, Nylon-6, Dacron/ Terylene.
6) Buna-S (Styrene Butadiene Rubber): It is prepared by the polymerization of butadiene and styrene in the presence of sodium metal.
n CH2=CH- CH=CH2 + x CH(C6H5)=CH2 ——-> (-CH2-CH=CH-CH2)n–(CH(C6H5)-CH2)x
1,3-Butadiene Styrene Buna-S
7) Buna-N: It is prepared by the polymerization of butadiene and acrylonitrile in the presence of sodium metal.
n CH2=CH- CH=CH2 + x CH(CN)=CH2 ——-> (-CH2-CH=CH-CH2)n–(CH(CN)-CH2)x
1,3-Butadiene Acrylonitrile Buna-N
Uses: For making tyres, floor tiles, foot wear component, cable insulation / for making oil seals, tank linings to keep petrol.
8) PVC: By polymerization of vinyl chloride (CH2=CH-Cl) in presence of peroxide.
9) Teflon (Polytetrafluoroethylene, PTFE): It is prepared by the polymerisation of tetrafluroethylene.
nCF2=CF2 ——-> (CF2-CF2)n
Uses: It is used for making oil seal, gaskets, non-sticky pan.
10) Polyacrylonitrile (PAN): It is prepared by the polymerisation of acryonitrile.
n CH(CN)=CH2 ——–> -(CH(CN) –CH2)n
Acrylonitrile Polyacrylonitrile
Uses: It is used as a substitute of wool, for making cloths, carpets and Blankets.
11) Polystyrene: It is prepared by the polymerisation of styrene.
nCH(C6H5)=CH2 ———> –(CH(C6H5)-CH2)n
Uses: It is used to make hot drink cups, toys, radio-TV bodies, etc.