Relative chemical resistance of solventless polyester and solventless epoxy resins

In the world of electrical insulation, many ideas and beliefs have been passed down through generations. Most of these beliefs are based on well documented data. Some are not well documented, however, because they have been repeated so many times they have become “cast in stone”. One such belief is that epoxies are more chemical resistant than polyesters. In fact, there are many possible chemistries for polyester resins and epoxy resins. Through this diversity, some epoxies are more chemical resistant than polyesters and vice versa. The author has exposed a variety of epoxy and polyester resin formulations to chemicals that may be present in various industrial environments, such as paper mills, mining and chemical manufacturing plants. The resulting data shows that all epoxies and all polyesters do not perform the same when exposed to different chemicals and the belief that epoxies are more chemical resistant than polyesters is not true in all cases