An organic‐soluble bismaleimide‐grafted aminated para‐polyamide for the molecular reinforcement of bismaleimide/diallyl bisphenol A resin and its carbon fiber composites

Abstract Poly(p‐phenylene terephthamide) (PPTA) is an aromatic para‐polyamide with a rigid rod‐like main chain and superior intrinsic mechanical properties but is insoluble in all organic solvents. It has been demonstrated that introducing amino groups to the phenyl rings on the PPTA main chain yields organic‐soluble aminated para‐polyamide known as poly(p‐aminophenylene aminoterephthalamide) ((NH₂)₂‐PPTA). In this study, an organic‐soluble bismaleimide (BMI)‐grafted (NH₂)₂‐PPTA (BMI‐g‐(NH₂)₂‐PPTA) was synthesized by reacting the amino groups of (NH₂)₂‐PPTA with the double bonds of BMI via Michael addition reaction. BMI‐g‐(NH₂)₂‐PPTA was then employed as a new macromolecular reinforcing agent that significantly enhances the mechanical properties of BMI/2,2′‐diallyl bisphenol A (BD) resin. With the addition of merely 0.5 wt% of BMI‐g‐(NH₂)₂‐PPTA, the strength and toughness of both BD resin and BD/carbon fiber (CF) composite laminates are significantly improved without decreasing the heat resistance of the matrix. The uniform dispersion of BMI‐g‐(NH₂)₂‐PPTA in BD resin and its strong interaction with the matrix result in a more significant enhancement in the mechanical properties compared to directly incorporating (NH₂)₂‐PPTA into the matrix, providing a new and efficient method for enhancing the mechanical properties of BD resin and its CF composites. Highlights A novel BMI‐grafted aminated para‐polyamide, BMI‐g‐(NH₂)₂‐PPTA, is synthesized. BMI‐g‐(NH₂)₂‐PPTA is organic‐soluble and can disperse uniformly in BD resin. BMI‐g‐(NH₂)₂‐PPTA at 0.5 wt% enhances the strength of BD resin by 50.8%. BMI‐g‐(NH₂)₂‐PPTA is more efficient than (NH₂)₂‐PPTA in strengthening BD resin. Mechanical properties of BD/CF laminates are also enhanced by BMI‐g‐(NH₂)₂‐PPTA.