Glass fiber–reinforced polypropylene composites fabricated by direct fiber feeding injection molding

This article investigates the effect of process parameters on the mechanical properties of polypropylene-glass fiber (GF/PP) composites made using a new injection molding method known as direct fiber feeding injection molding (DFFIM). In the DFFIM process, continuous fibers are directly guided into the barrel of the injection molding machine through the designed vent and are fed into the polymer melt by the shearing motion of the screw of the injection molding machine during the plasticization process. The DFFIM process improves the fiber length and avoids excessive fiber attrition, resulting in enhanced mechanical properties in the composites. The effect of process parameters on the mechanical properties of manufactured composite specimens is discussed based on the results of tensile tests, three-point flexural tests, and Izod impact tests. Scanning electron microscopy was performed on the fracture surfaces to observe cross-section morphology. There is a fiber agglomeration phenomenon that occurs in the core layer of GF/PP composites made using DFFIM. The number of fiber rovings, number of fiber filaments, matrix feeding speed, and screw speed influence the GF content and distribution in the composites, ultimately affecting the mechanical properties.