Nylon 6,6 composites with carbon fiber covalently bonded to functionalized carbon nanotubes fabricated by reactive extrusion

Abstract

To produce nylon 6,6 (N66)-based composites with carbon fiber (CF) having extremely high mechanical strength, CF covalently bonded with carbon nanotube (CNT), CF–c–CNT, was first produced by reacting functionalized CF and CNT and then a composite of N66 and CF–c–CNT was produced by melt extrusion. Two types of CF–c–CNT were prepared: CF and CNT functionalized with acyl chloride (COCl) and amine group (NH2), respectively (COCl–CF–c–CNT–NH2), and CF and CNT functionalized with NH2 and COCl, respectively (NH2–CF–c–CNT–COCl). N66 bonding to CF–c–CNT occurred during extrusion by the reaction of COCl with amine groups in N66. Thus, N66 bonded to CF (N66–CF–c–CNT) and N66 bonded to CNT (CF–c–CNT–N66) were formed. The N66/CF–c–CNT–N66 composite exhibited the highest interfacial adhesion, the best filler dispersion, and the greatest amount of N66 bonding to filler among the composites tested. As a result, the N66/CF–c–CNT–N66 composite had the highest tensile strength and fatigue life among the composites. The tensile strength and fatigue life of the N66/CF–c–CNT–N66 composite were 20% higher and five times longer than those of the N66/CF composite, respectively.