Polymers Test - 7

The process of vulcanisation consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K. On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened.

Copolymerisation of 1,3-butadiene and acrylonitrile to give Buna-N requires a peroxide catalyst.

nCH₂ = CH − CH = CH₂ + nCH₂ = CH − CN → Buna − N

Nylon 2–nylon 6 is an alternating polyamide copolymer of glycine (H₂N–CH₂–COOH) and amino caproic acid [H₂N (CH₂)₅ COOH] and is biodegradable. 

Rubber is a natural polymer and possesses elastic properties. It is manufactured from rubber latex which is a colloidal dispersion of rubber in water. Natural rubber may be considered as a linear polymer of isoprene.

Branched chain polymers contain linear chains having some branches, e.g., low density polythene.

Teflon has CF₂ = CF₂ (tetrafluoroethene) as monomer unit. Teflon is manufactured by heating tetrafluoroethene with a free radical or persulphate catalyst at high pressures.

Teflon is chemically inert and resistant to attack by corrosive reagents. It is used in making oil seals and gaskets and also used for non – stick surface coated utensils.

High density polythene is formed when addition polymerisation of ethene takes place in a hydrocarbon solvent in the presence of a catalyst such as triethylaluminium and titanium tetrachloride (Ziegler-Natta catalyst) at a temperature of 333 K to 343 K and under a pressure of 6-7 atmospheres.

Buna –N is obtained by the copolymerisation of 1, 3 – butadiene and acrylonitrile in the presence of a peroxide catalyst. It is resistant to the action of petrol, lubricating oil and organic solvents. It is used in making oil seals, tank lining. etc.