High‐performance hierarchical composites based on polyamide 6, carbon fiber and graphene oxide

Abstract This study reports the effect of graphene oxide (GO) coating on carbon fiber (CF) surface on the mechanical and thermal properties and morphology of CF‐reinforced polyamide 6 (PA6) composites containing 7.5 wt% of short CFs. GO was coated on the CF surface by a physical absorption method with concentrations ranging from 0.05 to 0.5 wt% GO. The PA6/CF composites were prepared by extrusion, and the specimens were obtained by injection molding. Their morphology (SEM, XRD tests), mechanical (tensile, flexural, impact, and fatigue tests), and thermal properties (DSC, TG and HDT tests) were analyzed. A significant change in the preferential (growth) crystal planes of PA6 was observed upon the incorporation of CFs containing GO, favoring the formation of α crystals in PA6. GO coating on CFs was effective and provided an increase in tensile strength and Young's modulus up to 12% and 24%, flexural strength and flexural modulus up to 22% and 25%, and a decrease in impact strength and fatigue life up to 30% and 23%, respectively, when compared to unmodified PA6/CF composites. Fracture micrographs indicated an increase in the PA6/CF interaction and the effectiveness of GO as a coupling agent for the composite.