Effect of injection molding conditions on GF/PP connection properties

This study investigates polypropylene (PP) and different glass fiber-reinforced polypropylene composites (10% GF/PP, 20% GF/PP, and 30% GF/PP) to systematically examine the effects of injection molding parameters (mold temperature, injection temperature, and injection speed), as well as different GF content, on the welding strength in secondary injection molding of PP. The results indicate that when one injection molding parameter is fixed, welding strength significantly improves with an increase in the other parameters. Among them, the refusion of interface resin plays a dominant role in enhancing welding strength. Additionally, the distribution characteristics of glass fibers (GF) in the welding region and their effects on welding strength were observed and analyzed using a polarizing microscope. While GF contributes to the overall strength of the composite material, its impact on welding strength enhancement is limited. This study provides a robust theoretical foundation for optimizing the GF/PP secondary injection molding welding process.