The influence of sizing conditions on bending properties of continuous glass fiber reinforced polypropylene composites

In this study, the interphase construction by using binding agents was prop osed in continuous glass fiber reinforced polypropylene composites. Two typ es of binding agents modified with maleic anhydride, i.e. low- and high-mol ecular-weight PP binders were employed. Amino silane coupling agent was als o used for the sizing of the glass fibers. In the first step, the sizing co nditions with non-binding, low- and high-molecular-weight PP binders were c ompared for bending properties. According to the near infra-red (NIR) analy sis of the sized glass fibers, the glass fiber finished with the low-molecu lar-weight PP binders greatly indicated the existence of the amide bond bet ween the PP binder and the silane coupling agent. This result implies that the matrix PP chain tends to entwine with the PP binder chain. As a consequ ence, low-molecular-weight PP binder specimens gave the highest bending str ength. Furthermore, the concentration ratio of the low molecular-weight PP binder was varied with three steps. Matrix PP modified with maleic anhydrid e was also used in order to investigate the effect of matrix modification o n bending properties. The interphase structure formed by a binder agent and a silane coupling agent in the continuous glass fiber reinforced polypropy lene composites was discussed in detail. (C) 2000 Published by Elsevier Sci ence Ltd.