Degradation of Polymers

the breakdown of macromolecules owing to heat, oxygen, moisture, light, penetrating radiation, mechanical stresses, biological agencies (for example, by the action of microorganisms), and other factors. Depending on the agent, the following forms of polymer degradation are distinguished: thermal, thermal oxidative, photochemical, hydrolytic, and radiation, among others. Usually several types of degradation processes take place simultaneously in a polymer; for example, making a polymer into a product, it undergoes thermal, thermal oxidation, and mechanical forms of degradation.

The degradation leads to a decrease in the polymer’s weight, and its structure and physical and chemical properties alter, that is, it ages and often becomes unsuitable for practical use. However, polymer degradation is not always undesirable. Thus, for example, the process is used in the mechanical synthesis of various block and graft copolymers, in the plasticization of rubber, and in the production of valuable low-molecular-weight substances (for example, glucose) from natural polymers. The study of degradation makes it possible to work out the scientific foundations and practical methods of stabilizing polymers.