Reduced graphene oxide catalytically enhances the rate of cyanate ester curing under variable frequency microwave heating

The curing of Lonza Primaset PT-30 novolac cyanate ester resin and EPON 826 bisphenol-A diglycidyl ether were investigated using convective thermal heating and variable frequency microwave (VFM) heating. The addition of 1 part per hundred reduced graphene oxide (r-GO) to PT-30 novolac cyanate ester increased the VFM cure rate compared to thermal heating. Curing it at 160 degrees C for 240 min with VFM heating resulted in a 55% degree of cure com-pared to a 26% degree of cure with thermal heating. This observed VFM rate enhancement is due to selective microwave heating of the r-GO particles in the resin resulting in increased r-GO catalytic activity toward cyanate ester curing. It is both a thermal and catalytic effect, the latter of which is absent when r-GO is added to a bisphenol-A diglycidyl ether resin with o- phenylenediamine hardener. Impurities present in the PT-30 matrix do not appear to contribute to its overall cure kinetics, nor do they participate in the observed VFM rate enhancement.