Effect of nozzle aperture on glass fiber reinforced polypropylene fabricated by DFFIM

Abstract

Fiber length and interfacial bonding properties are important factors in determining the mechanical properties of the composites. As an emerging fiber-reinforced thermoplastic molding method, DFFIM can reduce the fiber breakage during the molding process and thus improve the mechanical properties, while the fiber length and interfacial bonding properties of the composites fabricated by DFFIM are mainly affected by the equipment structure. This paper takes nozzle as the research object to investigate the effect of nozzle on the properties of glass fiber reinforced polypropylene (GF/PP) fabricated by DFFIM. First, GF/PP composites at three positions of nozzle flange, nozzle air-injection outlet and mold cavity were selected for fiber length detection, and it was found that the nozzle would lead to more severe fiber breakage in GF/PP composites; POLYFLOW was subsequently used to analyze the shear stress of GF/PP mixed flow fields in different aperture nozzles; DFFIM experiments were carried out to analyze the fiber length, micromorphology, and mechanical properties of GF/PP composites using the nozzle aperture as the test factor, and the results were consistent with the simulation results, as the nozzle aperture increased, the fiber length and interfacial bonding properties of GF/PP composites gradually increased, hence improving the mechanical properties.