Polymer Degradation.

Polymer Degradation.

• Polymer degradation is a change in the properties (color, shape, etc) of a polymer or polymer- based product under the influence of one or more environmental factors such as heat, light or chemicals such as acids, alkalies and some salts.
• These changes are usually undesirable.

Types of degradation in polymer

1)Photoinduced degradation.

2)Thermal degradation.

3)Chemical degradation.

4)Biological degradation.

Photoinduced degradation

Most polymers can be degraded by photolysis to give lower molecular weight molecules. Electromagnetic waves with energy of visible light or higher, such as ultraviolet light rays and gamma rays are usually involved in such reaction.

Thermal degradation

Chain growth polymers like poly(methyl methacrylate) can be degraded by thermolysis at high temperature to give monomers, oils, gases and water.

Chemical degradation

It is a type of polymer degradation that involves a change of the polymer properties due to a chemical reaction with the polymer surrounding.

Biological degradation

Biological plastics can be biologically degraded by microorganisms to give lower molecular weight molecules. 

Examples;

Polyethylene, polypropylene and poly(methyl methacrylate) are sensitive to oxidation and UV radiation, while PVC may discolor at high temperature due to loss of hydrogen chloride gas and become very brittle. PET is sensitive to hydrolysis and attack by strong acid, while polycarbonate depolymerises rapidly when exposed to strong alkalies.