Curing Behavior of 4,4′-Diglycidyloxybiphenyl with p-Phenylene Diamine Derivatives

To expand the applicability of 4,4′-diglycidyloxybiphenyl (BP), the simplest liquid crystalline epoxy derivative, the curing reaction mechanism with p-phenylenediamine (p-PDA) derivatives under various stereoscopic conditions was investigated through kinetic analyses. Specifically, curing factors such as the starting temperature, heat, and activation energy were studied and analyzed. In particular, the effect of steric hindrance of the hardeners on the mechanism of curing reactions was explored by analyzing isothermal kinetics. It was found that the larger steric hindrance of the curing agents induced the slower curing reaction, and the contribution of the reduction in the self-catalytic curing was more pronounced than the S_N2 reaction. To determine the optimized curing conditions, cured BP materials were fabricated and their glass-transition temperatures and thermal conductivities, which significantly improved over general-purpose epoxy resins owing to the characteristics of the liquid crystal, were investigated. [Figure not available: see fulltext.].