ABSTRACT
The properties of polyamide products are not stable in the course of time. Aging occurs during their use, unfortunately in accord with the generally valid rule that quality loss is a much more frequent consequence of aging in nature than ripening to an improved state. The polymer is subject to thermal stress during polymerization itself where the reactions mostly occur in an inert medium. In an oxidative medium the polymer is subject to thermal energy effects, mostly during processing. Linear polyamides are not very resistant towards thermal energy. Within weeks to months, changes in their properties may be observed even at room temperature. The rate of radical formation in linear polyamides during their preparation, processing, storage, and current applications corresponds to the initiation rate of degradation processes. The polymer affects its own degradation processes by the chemical and physical structure of its chains, by the presence of some impurities, and finally by some intentionally present additives.
