Inter‐tow toughness modification of carbon fiber reinforced cyanate resin matrix composites

Abstract Carbon fiber‐reinforced cyanate ester resin matrix composites (CF/CE) are widely used in aerospace for their high‐temperature resistance and wave‐absorbing properties. However, CF/CE is prone to interlaminar delamination during the curing molding process or practical applications due to the brittleness of CE resin. In this study, we use polyether sulfone (PES) as a toughening layer through the inter‐tow toughening method to prepare PES inter‐tow toughened CF/CE (CF/CE‐P) and to investigate their thermal, mechanical, and microscopic morphology. We find that CF/CE‐P has a higher glass transition temperature ( T g ) and a lower coefficient of thermal expansion (CTE) than those of CF/CE composites. The flexural strength, flexural modulus, interlaminar shear strength (ILSS), and impact toughness of CF/CE‐P with 15 wt% PES is increased by 34%, 15%, 34%, and 45%, respectively, compared to CF/CE. In addition, the mode I interlaminar fracture toughness ( G IC ) of CF/CE‐P with 15 wt% PES is 1.86 times that of CF/CE. Highlights The inter‐tow toughening technique on a three‐dimensional scale is proposed. Model I interlaminar fracture toughness increased by 86% after inter‐tow toughness modification carbon fiber‐reinforced cyanate ester resin matrix composites. The composite material exhibits improved toughness and thermal performance. The prepreg preparation process is suitable for continuous industrial production.