The polymers described in this article used in a wide variety of applications that have contributed to many R&D investigation in US universities, industry, national laboratories, utilities, and organizations such as EPRI. A significant decline in such R&D has Occurred gradually over the past 20 to 30 years, as many of the end products have Matured and funds have declined. It is not planned to cover the detailed properties of these polymer; however, many of the basic properties and their importance have changed little since the 1960s. Some of the relevant references are as follows.