Influence of injection molding on the flexural strength and surface quality of long glass fiber-reinforced polyamide 6.6 composites

The objective of this paper was to process a polyamide 6.6 composite reinforced with long glass fibers (50 wt.%) using a design of experiments to determine the processing conditions that simultaneously maximize the flexural strength and the surface quality of the molded composite. The analyzed factors were the barrel temperature profile, the injection speed and the screw speed. To maximize the flexural strength response variable and the surface quality, all studied parameters should be maintained at the higher levels. The analysis of microstructure of composites molded demonstrates that this combination of parameters promotes a greater orientation of the fibers in the outer layers, as well as prevents the migration of glass fiber to surface of the composite. This kind of microstructure is favorable to a better surface quality, and a greater flexural strength. (C) 2015 Elsevier Ltd. All rights reserved.