Moisture absorption by cyanate ester modified epoxy resin matrices. Part IV: Effect of curing schedules

Abstract The cure schedule (time and temperature) has a profound effect on the physical properties of thermosetting materials. For hydrophilic systems, it can also influence the rate of diffusion of moisture and the equilibrium concentration. The effect of post‐cure time and temperature on the moisture sorption behavior and the viscoelastic properties of cyanate ester modified epoxy resin has been investigated. Moisture absorbed at 96% R.H. (relative humidity) and 50°C under isothermal conditions was found to increase with post‐cure temperature, but the diffusion coefficient decreased in line with the crosslink density. Resins of high crosslink density and high glass transition temperature appeared to exhibit a larger reduction in glass transition temperature on plasticization by moisture in comparison to those with lower crosslink density.