WEATHERING OF POLYMERS.

Examples are given of the weathering of polymeric materials of current or potential service use which demonstrate the importance and interaction of the elements of weather in degradation processes. The value of well-designed and conducted long-term exposure trials is stressed. The need for early evaluation of a material's weathering potential is highlighted and the methods for obtaining this information are reviewed. It is argued that the interpretation of the weathering data obtained on a material at one site to other sites is best approached by comparing the relevant meteorological data of the sites. In particular, for that large group of materials which weather primarily by photo-induced processes a knowledge of the ultra-violet (u. v. ) environment outdoors is required. The use of polysulphone and polyphenylene oxide films to obtain this information is reviewed and the results of a world-wide monitoring program, based on the use of polyphenylene oxide films are considered.