Relaxation in partially cured samples of an epoxy resin and of the same resin modified with a carboxyl-terminated rubber

This study examines the relaxation process at different temperatures in partially cured samples of an epoxy resin and of the same resin modified with 11.1% carboxyl-terminated butadiene acrylonitrile copolymer (CTBN). A differential scanning calorimeter (DSC) was used, which enabled the relaxation enthalpy, the glass transition temperature (T-g) and the relaxation peak temperature to be found. CTBN modifies the cure reaction and the relaxation process of the epoxy resin. The study of the relaxation process has a practical interest in addition to a theoretical one. It is known that, with these thermosets, a fully cured sample cannot be obtained at the first step. The introduction of an elastomeric modifier is a normal way of increasing the toughness of these materials. (C) 1999 Elsevier Science Ltd. All rights reserved.