Simultaneously enhancing processability and heat resistance for bismaleimide resins via eutectic-like blends

Simultaneously improving the processability and heat resistance of bismaleimide (BMI) resins remains a significant challenge. Herein, eutectic-like blends are constructed by combining traditional high-melting-point BMIs (including m-phenylene bismaleimide (MPD-BMI), 3,3'-diphenylsulfone bismaleimide (33DDS-BMI) and bisphenol A bismaleimide (BDM)) with two low-melting-point BMI monomers, indan bismaleimide (PIDA-BMI) and aliphatic trimethylhexane bismaleimide (SEM23), to optimize the processing performance of high-melting-point BMI systems. The results show that the PIDA-BMI/33DDS-BMI blend achieves a 64% reduction in melting point, coupled with a 6% increase in glass transition temperature ( T g), compared with neat 33DDS-BMI. For the SEM23/BDM blend system, the melting point is 14% lower than that of pure BDM, while its T g and flexural strength are increased by 13% and 10%, respectively. Rheological characterization confirms that the blended systems exhibit substantially reduced melt viscosity and widened processing windows, directly validating the enhanced processability. Mechanistic analysis suggests that inherent structural differences between BMI monomers induce amorphization and reduced crystallinity in the blending systems, which is proposed to be responsible for the synergistic optimization of melting behavior, heat resistance and mechanical properties. This work provides a practical strategy for improving the processability of high-melting-point BMI resins while maintaining or enhancing their thermal and mechanical performance.