Internal antiplasticization in diglycidyl ether of bisphenol A diamino diphenyl methane non‐stoichiometric epoxy networks

Abstract

DGEBA‐DDM (diglycicyl ether of bisphenol‐A‐diamino diphenyl methane) networks of various epoxide/amine molar ratios ranging from 0.7 to 1.4, were studied by density, quasi static (10⁻⁴ s⁻¹), and ultrasonic (5 10⁶ s⁻¹) modulus, and thermostimulated creep measurements. Any step aside stoichiometry leads to an antiplasticization, e.g. an increase of the quasi static modulus, whereas T_g decreases. The previous interpretations (based on volumetric property considerations), of this phenomenon are questionable. The only common feature of all the antiplasticized systems is an unexplained decrease of the population of macro‐molecular segments involved in beta motions.