Effects of coupling agents on the impact fracture behaviors of T-ZnOw/PA6 composites

The impact fracture behaviors of polyamide 6 (PA6) composites with tetra-needle-shaped zinc oxide whisker (T-ZnOw) are studied in this work. Two different silane coupling agents, KH-550 with amino groups and KH-560 with epoxy groups, are used to treat T-ZnOw. The results show that the coupling agent types, content as well as the T-ZnOw content have much influence on the impact fracture behaviors of T-ZnOw/PA6 composites. Compared with the composites filled with untreated T-ZnOw, in which the impact strength decreases linearly with the increasing content of filler, chemical treated T-ZnOw improves the impact strength of the composites apparently due to the improved interfacial interaction between T-ZnOw and matrix. Further results show that the main toughening mechanisms of treated T-ZnOw in PA6 composites include the pullout of T-ZnOw from matrix, the anchoring role of other three needles when one of the four needles of T-ZnOw is pulled out from matrix, and the local yielding or deformation of matrix around the T-ZnOw.