Polymer degradation is a change in the properties—
tensile strength,
colour, 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,
alkalis and some
salts. These changes are usually undesirable, such as cracking and chemical disintegration of products or, more rarely, desirable, as in
biodegradation, or deliberately lowering the
molecular weight of a polymer for
recycling. The changes in properties are often termed "aging".