THERMAL-BEHAVIOR AND CURED PRODUCTS OF MIXTURES OF 2 DIFFERENT BISMALEIMIDES

The thermal behavior of a new Bismaleimide, 2,2‐bis[4‐(4‐maleimidophenoxy)phenyl]propane (BBMI) and its mixtures with a conventional monomer, bis(4‐maleimidophenyl)methane (BMI) were investigated by differential scanning calorimetry. The melting point of BBMI was 142°C, lower than that of BMI, although its molecular weight is about twice that of BMI. Each of these bismaleimides and their mixtures showed a melting point when heating, but did not have a distinct freezing point when cooling because of vitrification. The unobserved freezing curve was estimated by calculation based on Schröder's equation using melting point and molar heats of fusion in both bismaleimides. The cured product of BBMI has thermal stability as good as that of BMI. Moreover, the cured product of BBMI has a high flexurai strength and a high flexural elongation owing to the introduction of flexible ether bonds and long phenoxy groups within the monomer structure. Copyright © 1990 John Wiley & Sons, Inc.