Polymers Test - 8

 PHBV is used in speciality packaging, orthopaedic devices and in controlled release of drugs. PHBV undergoes bacterial degradation in the environment.

Polystyrene is a thermosetting polymer which possesses intermolecular forces of attraction intermediate between elastomers and fibres.It is used in making wrapping material.

Gyptal is a polyester formed from condensation of ethylene glycol and phthalic acid. It is used in paints and lacquers.

PVC is a thermoplastic polymer which possesses intermolecular forces of attraction intermediate between elastomers and fibres. It is used in making rain coats, hand bags, water pipes etc.

Novolac (formed by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst)on heating with formaldehyde undergoes cross linking to form an infusible solid mass called bakelite which is a thermosetting plastic and cannot be remoulded once set. It is used for making combs, phonograph records, electrical switches and handles of various utensils.

Polystyrene is a thermoplastic polymers which are the linear or slightly branched long chain molecules capable of repeatedly softening on heating and hardening on cooling. It is used as an insulator.

Cellulose is a natural polymer of glucose. Its hydrolysis yields large number glucose molecules, so it's a polysaccharide.

Terylene or dacron is formed by the interaction of ethylene glycol and terephthalic acid by condensation polymerisation

Fibers have strong intermolecular forces. For example, Nylon. Elastomers have weakest intermolecular forces. For example Buna-S .Thermoplastic polymers have intermediate intermolecular forces between elastomers and fibers. For example polythene. Nylon has strongest intermolecular forces, polythene has intermediate and Buna-S has weakest.

The condensation polymers are formed by repeated condensation reaction between two different bi-functional or tri-functional monomeric units. In these polymerisation reactions, the elimination of small molecules such as water, alcohol, hydrogen chloride, etc. take place. Proteins are long chain polymers of amino acids which have both amino acid and a carboxylic acid groups. The linkage between two amino acids is called peptide linkage (-CO-NH-).