Effects of crystallization and thermal degradation behavior on mechanical properties of fiber‐reinforced composites during post‐annealing

Abstract Post‐annealing treatment is one of the most effective methods for enhancing the mechanical properties of composite materials. This study focuses on carbon fiber reinforced nylon 6 (CF/PA6) composites via injection molding, specifically investigating the effects of high‐temperature post‐annealing duration on their mechanical properties, crystallization and thermal degradation behavior. The findings indicate that the tensile strength and modulus of CF/PA6 composites exhibit a complex trend with varying annealing times, attributed to the combined effect of crystallization and thermal degradation behavior. Notably, samples annealed for 24 h exhibited the best tensile strength and modulus, with significant improvements of 14.7% and 21.4%, respectively, compared to the original samples. This work holds significant implications for enhancing the performance of composites. Highlights Mechanical properties of composites change complicatedly during post‐annealing. Combined effect of crystallization and thermal degradation behavior. The process method enables high‐performance and controllable manufacturing.