Relation between the Structure and Mechanical Properties of Epoxy Resins

Abstract

Relation between the molecular structure and dynamic mechanical properties has been studied for various epoxy resins cured with typical curing agents such as diaminodiphenylmethane and methylhexahydrophthalic anhydride. The modulus in rubber region and the front factor in the equation of state for rubber elasticity increased with the increase of crosslinking density, phenyl group contents, and especially structural symmetry in the crosslinking resins. The glass transition temperature (T_g) increased with the increase of the crosslinking density, polarity, and especially phenyl group contents of the cured resins. The relation between the modulus in glassy region and molecular structure of epoxy resin was somewhat obscure, but the glassy modulus might be related to T_g of the cured resins. Bending stress and maximum strain of the resins were also discussed.