Bismaleimide and Bispropargyl Ether Blends: Curing Kinetics—model Free Approach

Two structurally different bismaleimides, namely 2,2-bis[4-(4-maleimidophenoxy-phenyl)]propane (BMIX) and 5(6)-maleimide-1(4′-maleimidophenyl)-1,3,3′-trimethyl indane (BMII) and bispropargyl ether of bisphenol A (BPEBPA) were prepared. The two bismaleimides were separately blended with BPEBPA in different mole ratios [BMIX/BMII: BPEBPA = 100: 0, 75: 25, 50: 50, 25: 75, 0: 100%] and the materials were thermally polymerized at 230°C. The curing studies of the monomers and blends reveal that the blending of BMIX and BMII with BPEBPA decreases the curing temperature window. Blending of 25% of either BMIX or BMII with BPEBPA drastically reduces the curing enthalpy and was nearly half the value of pure BPEBPA. The FTIR spectra of the cured materials show that the chromene ring stretching frequency of BPEBPA decreases as the bismaleimide content increases and new absorption peaks corresponding to cyclopentane (941 cm−1) and cyclohexane (1018 cm−1) appeared. The curing kinetics of the monomers and blends were studied using three model free kinetic methods. The trend noted for the variation of apparent activation energies for curing of 25% BMIX + 75% BPEBPA blend is different compared to the monomers and other blends.