Effects of fabrication method of composite yarn intermediate material and resin melt viscosity on the impregnation properties and mechanical properties of PA66 fiber and glass fiber composites

Abstract

Continuous fiber-reinforced thermoplastic (c-FRTP) has received attention for reducing automobile weight. Hollow molded parts made by pultrusion molding of braided composites may improve the performance and reduce the weight of automotive parts. However, pultrusion molding of braided composites suffers from productivity problems. This research aimed to increase the productivity of pultrusion molding of braided fabrics to facilitate its practical application. The effects of the fiber intermediate fabrication method and the resin melt viscosity on the impregnation and mechanical properties of the composite were investigated. Glass fiber and polyamide 66 (PA66) were used as the fiber intermediates. Two types of fiber intermediates were used, one with interlace processing and one with the fibers lined up. PA66 fibers with high and low viscosity were used. A correlation was found between impregnation properties and mechanical properties of the molded products, which improved as the unimpregnated ratio decreased. Detailed observations revealed that impregnation of PA66 resin into glass fiber bundles started from interlaced points in the fiber intermediates introduced by interlace processing. Furthermore, low-viscosity PA66 resin had higher fluidity, which better promoted impregnation into glass fiber bundles. These results clarify design guidelines for fiber intermediates to realize better mechanical properties and shorter molding cycles.