Polyarylsulfones as electrical insulation

The polyarylsulfones are a unique class among thermoplastic dielectric materials in that their electrical and mechanical properties are very stable over the temperature range −100°C to over 150°C and even after extended periods at the maximum temperature. Continuous use at 150°C is UL rated for polysulfone and 180°C is reasonable for polyphenyl-sulfone. Data is presented to show the effects of time and temperature upon the dielectric strength, dielectric loss, and mechanical properties of these polyarylsulf ones. The frequency and temperature dispersions of dielectric properties are presented. The high oxidation state of the normal polymer is suggested as an explanation of very great resistance to failure by electrical treeing and for the good flammability ratings.