Reactive Modification of Fluorinated Phthalonitrile Resin With Aminophenylacetylene–Bismaleimide Adducts: Processing Behavior, Molecular Interactions, and Glass‐Fiber Composite Properties

To improve the processability of fluorinated phthalonitrile (BFPH) resin, three reactive modifiers, BMIA11, BMIA12, and BMIA21, were synthesized from m‐aminophenylacetylene and bismaleimide at different feed ratios and blended with BFPH. Their chemical structures, curing behavior, processability, thermal stability, and composite properties were investigated experimentally, while molecular dynamics simulations were used to analyze intermolecular interactions and molecular packing. Among the three modifiers, BMIA12 showed the most pronounced effect. The BMIA12/BFPH system exhibited relatively high binding energy, lower cohesive energy density, and higher fractional free volume. DMA showed that BMIA12 broadened the low‐modulus flow region and reduced the curing onset temperature from 296.6°C to 251.1°C. At 10 wt% BMIA12, the DSC curing peak temperature decreased from 303.3°C to 254.5°C. At 5 wt% BMIA12, the glass‐fiber composite retained a glass‐transition temperature of approximately 420°C, while the interlaminar shear strength and flexural strength reached 61.5 and 589.6 MPa, corresponding to increases of 6.2% and 6.8%, respectively. The modified resins maintained char yields of 63.6%–64.8% at 800°C. These results show that BMIA12 improves BFPH processability while maintaining favorable thermal and mechanical performance.