Chain-Extended bismaleimides. I. Preparation and characterization of maleimide-terminated resins

Starting from aromatic diamines, a series of bismaleimides (BMIs) and maleimide‐terminated structural resins were prepared in solution and characterized. Maleimide‐terminated resins were prepared through Michael addition reaction with 3/2 molar ratio of bismaleimide and aromatic diamine as reactants. The structural analysis was performed by FTIR and 1H‐NMR spectroscopy. Thermal properties are investigated by TGA, DTA, and DSC. Number‐average molecular‐weights of the resins were determined by cryoscopy. The presence of methylene (CH2) and ether (O) groups in the starting materials affect the reactivity and the degree of chain extension of the resins. From the viscosity measurements it was also found that thermal polymerization of BMIs could be taking place together with the Michael addition. © 1996 John Wiley & Sons, Inc.