Twin-screw Reactive Extrusion Preparation Of Carbon Fiber Reinforced Nylon 6 Composites

Carbon fiber reinforced polyamide 6 composite(CFRPA6) exhibits the properties of high strength,light weight,low water absorption and high dimensional accuracy,which is widely used in the field of aerospace,electronic and sports product,etc.since the methods manufacturing CFRPA composite of high strength are very rigorous and difficult to achieve continuous process and large-scale production,in this article,the process of carbon fiber reinforced PA6 composite in a twin-screw extruder were studied.The results showed that the carbon fibers with the average length-diameter ratio of 18:1 were dispersed homogeneously in the composite.We also studied the different technologies of the treatment of CF and the different process of extrusion,and the effects of CF on mechanical properties, processing properties,melting,crystallization and tensile fracture surface morphology of CFRPA6 composite.In this article,CFRPA6 composite was successfully prepared in the twin-screw extruder.The dispersion and length-diameter ratio of carbon fibers in CFRPA6 composite were characterized by SEM and optical microscope.The results showed that the CF were dispersed homogeneously in the composite and the distribution of length-diameter ratio accorded with the distribution rule of general reinforcing fiber. The average length-diameter ratio was about 18:1,and the best one could achieve 20:1.Treated CF with different technologies were characterized by SEM.The results showed that the surface of CF with oxidation treatment,as compared with the untreated one,became rough obviously,and the surface area was increased.The CF with nitric acid had the best effect.While the surface of CF with silane coupling agent compound treatment were smother than the untreated one,and the surface gully also became fewer.Analysis suggests that the surface of CF with silane coupling agent compound treatment has formed a layer of plastic interface,which could eliminate interface stress and attribute to the excellent bonding integrity.According to the analysis of the SEM of interface morphology,mechanical properties and retention of physical properties in humid environment,etc,the CFRPA6 composite that were prepared by the CF with silane coupling agent compound treatment in the twin-screw extruder displayed the excellent interface bonding and better properties compared with the untreated one.According to the analysis of interface crystallization morphology,DSC melting and crystallization,CF changed the nucleation mechanics,improved the crystalline rate and the onset crystallization temperature,the induction of CF could influence the melting behavior of PA6,CF could do crystalline nucleation to matrix,and form interfacial transcrystallization.