GLASS-TRANSITION TEMPERATURES IN BISMALEIMIDE-BASED RESIN SYSTEMS

The glass transition temperatures in bismaleimide-based resins were investigated using different stoichiometric ratios of 1,1'-(methylenedi-4,1-phenylene)bismaleimide (BMI) and 4,4'-methylenedianiline (MDA). The resin cure involves a low temperature primary amine addition to the maleimide double bonds and a high temperature homopolymerization of the maleimide double bonds. The network topology and the glass transition temperature changes with resin composition and curing conditions were determined using differential scanning calorimetry (DSC). An empirical model was used to relate the glass transition temperature to the extents of the amine addition and the homopolymerization reactions in 1:1 and 2:1 BMI:MDA resins. The changes in thermal properties with resin post-cure were also examined.