Network formation in bismaleimide resins

Heated cell FTIR spectroscopy was used to study the kinetics of the amine addition and the homopolymerization reactions. BMI:MDA formulations with stoichiometric ratios of 1:0, 1:2, 1:1, and 2:1 were used to determine the composition dependence of the curing reactions. The results from the spectroscopic studies were compared with the kinetic data obtained using DSC. The glass transition temperatures of the networks, which were measured using DSC under isothermal and dynamic curing conditions, were used to demonstrate the cure-path dependence of the thermal properties of the network. The experimental results indicate that for resins with cure-path dependent network properties, the reaction kinetics determine the development of network properties during the early stages of cure. The post-cure properties, however, are strongly influenced by the resin composition. Hence, by controlling the composition and curing conditions, it is possible to build the desired thermal properties into the network.