Mechanism of heat aging of silicone resins

Silicone resins are used as dipping, varnishes and coatings for glass cloth and glass covered magnet wire, primarily in applications in which high ambient or operating temperatures obtain. The silicone resins often must be depended upon to maintain electrical and mechanical properties required in the specific application for long periods at temperatures as high as 180°C or even higher. The physical and electrical properties of silicones change both as a function of temperature and aging. A knowledge of the reasons for these changes should help both in the development of superior materials and in application to specific problems.