Abstract: Compared with the traditional method to improve interlaminar fracture toughness of laminates, non-woven veils interlayer toughening technology is more convenient, more flexible and has the advantage of low cost. In this paper, three non-woven veils, PPS, PEI and PI, were added to the carbon fiber laminates and compared with the non-toughened specimens. The results show that the addition of PPS non-woven veils has the most significant effect on the interlaminar fracture toughness energy release rate of mode-Ⅰ. The fiber bridging effect was observed under mode-Ⅰ loading at the crack tip of the specimens. Microstructure information of laminates was obtained by SEM, and it is proved that the short fiber non-woven veils interlayer forms a three-dimensional interlaced fiber network in the matrix. The debonding and pulling out of the fiber play an important role to hinder the delamination crack. Thus, the interlaminar fracture toughness is improved.

Key words: composite, composite laminates, interlaminar toughness, non-woven veils