Polymers Test - 9

Nylon-6,6 is a fibre, not an elastomer, and cellulose is a polymer of glucose.

Neoprene is a synthetic polymer which resembles natural rubber.

Thermosetting plastics have three-dimensional cross-linked structure.

Linear polymers consist of long and straight chains. The examplesare high density polythene, polyvinyl chloride, etc. Melamine and vulcanized rubber are cross-linked polymers whereas glycogens are branched-chain polymers.

In chain growth type of polymerisation, the molecules of the same monomer or different monomers add together on a large scale to form a polymer. PVC is an example of chain growth polymer.

Step growth (condensation) polymerisation generally involves a repetitive condensation reaction between two bi-functional monomers. These polycondensation reactions may result in the loss of some simple molecules as water, alcohol, etc. and lead to the formation of high molecular mass condensation polymers. Nylon is an example of condensation polymer.

Diethyl phthalate is a low-boiling ester and is hence not used as a plasticiser, while all others are high-boiling esters and are hence used as plasticisers.

Nylon-6,6 is a polyamide which belongs to a group of polymers called fibres, that have the strongest forces of attraction between the molecules.

Polythene is a thermoplastic and has the forces of attraction intermediate between the fibres and elastomers.

Buna S is an elastomer, which is a group of polymers possessing a high degree of elasticity and having the weakest forces of attraction between the molecules.

Thus, the order is Y < Z < X.

Polymers which can be melted and reshaped time and again without any change in chemical composition and metallic strength are called thermoplastics, e.g. polyvinyl chloride.

Plexiglas is a polymer of methyl methacrylate.