Evaluation of Fracture Toughness of Epoxy Resin for Cryogenic Use

To establish guidelines for the molecular design of epoxy for cryogenic use, mechanical and thermal properties of epoxies were measured at cryogenic temperatures. The fracture toughness at cryogenic temperatures was thought to be one of the most important factors as the selection standard of epoxies. Resins with larger epoxide equivalents and that with flexible molecular structures exhibited higher fracture toughness at cryogenic temperatures. It is thought that the fracture toughness of epoxies is dependent on the intermolecular force and the stress relaxation at the crack tip. This can be used as a guideline for molecular design of epoxies with high fracture toughness at cryogenic temperatures.