A study on cure kinetics and time-temperature-transformation cure diagram of epoxy/cyanate ester co-curing system

Abstract

Copolymerization of epoxy resin and cyanate ester combines the advantages of both epoxy thermosets and cyanate esters, taking important roles in the field of electronic packaging and aerospace applications. However, optimal cure control is essential to achieve outstanding performance, due to its complex reaction mechanism and step growth of network polymer. Although many groups investigated the cure behaviors of epoxy/cyanate ester co-curing system, those works are mainly focused on applying different models to obtain various curing kinetic parameters. Herein, in addition to obtaining curing kinetic parameters using Kissinger equation and Ozawa equation, diffusion factor was purposely introduced into Kamal model to successfully describe the whole cure process, including both kinetically controlled stage and diffusion controlled stage. Meanwhile, the applicability of DiBenedetto equation to T_g vs. conversion plots of epoxy/cyanate ester co-curing system was confirmed regardless of its complex reaction mechanism, and the one-to-one relationship between T_g and conversion of this co-curing system was observed. In addition, time-temperature-superposition kinetic was studied, and corresponding T_g ∼ lnt master curve was obtained. Moreover, time-temperature-transformation cure diagram, with vitrification curve and iso-conversion curves, was constructed for the first time in the case of epoxy/cyanate ester co-curing system.