Effects of processing steps and hygrothermal ageing on mechanical performance of PA6GF30 composite: Interfacial shear strength

Polyamide 6 reinforced with glass fiber was prepared using extrusion compounding and injection molding processes. The effect of processing steps on the orientation and the fiber length were investigated. Optical observations shows that the fibers are predominantly orientated parallel to the main mold flow direction. In addition, the measurements of fiber length after both extrusion and injection molding reveal a clear shortening effect of these techniques on their length. Such reduction results probably from the fiber–machine, fiber–fiber, and fiber–polymer interactions. Afterwards, mechanical characterizations were performed on samples before and after ageing in distilled water and glycol–water mixture. The mechanical characteristics were then used as input parameters in the Kelly–Tyson model. Subsequently, the evolution of mechanical properties, the fiber/matrix bond strengths and reinforcement efficiency of the studied material were deeply discussed in both states. Results reveal that a full immersion in either distilled water or glycol–water mixture, affects significantly the interfacial fiber/matrix region as obviously confirmed by SEM observations. So, a decrease of the interfacial shear strength value was recorded. Accordingly, the reinforcement efficiency is extremely reduced after hygrothermal ageing leading to an overall fall in mechanical parameters. POLYM. COMPOS., 39:504–512, 2018.