Effect of stabilizing binder on void morphology and mechanical performance of wet compression molded rapid-curing non-crimp fabric composites

The use of binder-stabilized fabrics in wet compression molding (WCM) processes may be necessary to maintain fabric integrity and improve the bending stiffness of thick fabric stacks for improved resin management, particularly for unidirectional non-crimp fabrics (UD-NCFs). Therefore, it is essential to characterize the influence of stabilizing binder on the mechanical properties and quality of the final part. In this study, UD-NCF composite panels were manufactured with distinct processing conditions, including binder pre-activation and vacuum application during WCM, and extracted specimens were mechanically tested and microscopically assessed via optical microscopy and X-ray computed tomography. Pre-activation of the stabilizing binder reduced void content within the composite panels, thereby enhancing mechanical properties. Additionally, drawing vacuum for a duration of 20 s reduced the volume of large voids and increased the fiber volume fraction and interlaminar shear strength. This study provides valuable insights into the effects of a stabilizing binder and vacuum assistance on the mechanical properties of binder-stabilized UD-NCF composites.