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 proposed in continuous glass fiber reinforced polypropylene composites. Two types of binding agents modified with maleic anhydride, i.e. low- and high-molecular-weight PP binders were employed. Amino silane coupling agent was also used for the sizing of the glass fibers. In the first step, the sizing conditions with non-binding, low- and high-molecular-weight PP binders were compared for bending properties. According to the near infra-red (NIR) analysis of the sized glass fibers, the glass fiber finished with the low-molecular-weight PP binders greatly indicated the existence of the amide bond between 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 consequence, low-molecular-weight PP binder specimens gave the highest bending strength. Furthermore, the concentration ratio of the low molecular-weight PP binder was varied with three steps. Matrix PP modified with maleic anhydride was also used in order to investigate the effect of matrix modification on bending properties. The interphase structure formed by a binder agent and a silane coupling agent in the continuous glass fiber reinforced polypropylene composites was discussed in detail. (C) 2000 Published by Elsevier Science Ltd.