Cycloaliphatic epoxy resin cured with anhydride in the absence of catalyst

Understanding mechanisms of cycloaliphatic epoxy resin curing with anhydride is important for the preparation of new thermosetting polymer materials. In this paper, the curing of commercial epoxy monomer 4-epoxycyclohexylmethyl-3,4-epoxycyclohexane-carboxylate ERL-4221 with 4-methylhexahydrophthalic anhydride in the absence of catalyst was studied by two complementary methods: Fourier-transform infrared spectroscopy and differential scanning calorimetry. Different reaction pathways were examined, and the most probable curing mechanism was proposed. It was shown that the synthesized polymer network possesses glass transition temperature of 222 °C, which is among the highest values for cured epoxy resin obtained so far.