Abstract: Aiming at the problems of lower fiber volume content, difficult to control thickness and poorer interlaminar toughness of fiber reinforced composites prepared by Vacuum Assisted Resin Infusion process(VARI), the non-woven copolyesterveils were introduced into the preforms of carbon fiber fabric and then they were pretreated by hot-pressing process in the vacuum bag. Finally, carbon fiber/epoxy composite laminates were prepared by VARI process. The changes of composite thickness, short-beam shear strength, three-point bending behavior and ModeⅠ interlaminar fracture toughness were studied by comparison of the composite laminates before and after modification. The results showed that the thickness of the modified laminate decreased, the fiber volume content increased from 57.9% to 62.2%, the G_ⅠC value of interlaminar fracture toughness increased by 144.7%, and the shear strength and bending performance were basically equal to the unmodified laminate. The significant increase of ModeⅠ interlaminar fracture toughness of the modified composites were mainly based on the following three mechanisms. The first is the fiber bridging between interlaminar fracture surfaces. The second is the dispersion of thermoplastic particles at interlayer interface which hinders the crack propagation. The third is that the interfacial phases need to dissipate additional fracture energy due to shear plastic deformation.

Key words: vacuum assisted resin infusion process, copolyester non-woven veils, carbon fibre, composite, fiber volume content, mode Ⅰ interlaminar fracture toughness