Preparation And Properties Of Carbon Fiber Conductive Composites

Carbon fiber reinforced thermoplastic composite(CFRP)has the advantages of light weight,corrosion resistance and good fatigue resistance,it has broad application prospects in high-end manufacturing fields such as aerospace and electronic information.With the development and application of CFRP products,the requirements for materials are increasing day by day.In addition to excellent mechanical properties,CFRP also needs to have good electrical,thermal,electromagnetic shielding and other special properties.Although carbon fiber(CF)has the characteristics of high specific strength,high modulus,electrical conductivity,thermal conductivity,etc.,the electrical conductivity of CFRP composite with carbon fiber and resin matrix is not good.How to make CFRP have good electrical conductivity and better mechanical properties has become a research hotspot in the field of composite materials.Therefore,CF/PA6 composite is proposed as the research object to solve the problem of composite material functionalization.In order to achieve excellent electrical conductivity and mechanical properties of CF/PA6 composites,this topic firstly treated CF with surface treatment and quantitatively grafted carbon nanotube(CNT)on the surface.Secondly,CF/CF was prepared by melt impregnation combined with hot pressing.Based on the above PA6 conductive composites,the effects of CF surface treatment,grafted CNT and grafted CNT density on the properties of CF/PA6 conductive composites were investigated.The research content mainly includes the following three parts:(1)Preparation of CF/CNT hybrid reinforcement.CF and CNT were surface treated with concentrated nitric acid,and the quantitative CNT were grafted onto CF by controlling the grafting reaction time of the coupling agent to prepare CF/CNT hybrid reinforcement.CF was tested and characterized by scanning electron microscopy,X-ray photoelectron spectroscopy and the like.The results show that the surface roughness of CF after surface treatment increases.After CF and CNT are grafted by chemical coupling of coupling agent,CNT will form a network structure on the surface of CF,which will increase the interfacialwettability of the composite and improve the interfacial adhesion..(2)Preparation of a single layer of CF/PA6 conductive composite.The CF/PA6 conductive composite monolayer was prepared by melt impregnation combined with hot press forming.The electrical conductivity,thermal conductivity and electromagnetic shielding of the composites were characterized by means of resistivity tester and vector network analyzer.The effects of different CF treatments on the composites were analyzed.The results show that the presence of CF has a significant enhancement to the conductivity of PA6 matrix.Surface treatment and grafted CNT can effectively improve the conductivity,thermal conductivity and electromagnetic shielding properties of the composite.With the increase of grafting content,the electrical conductivity and thermal conductivity of the composites continue to increase,but when the grafting content is 0.4wt%,although the electrical conductivity and thermal conductivity of the composites reach the maximum,the mechanical properties reduce.(3)Preparation of CF/PA6 conductive composite laminates.The mechanical properties of CF/PA6 conductive composites were tested by pre-lamination and compression molding.The mechanical properties and fracture morphology of the composites were tested by universal electronic testing machine and scanning electron microscope.The results show that CF surface treatment and quantitative grafting of CNT can improve the mechanical properties of the composites.With the increase of CNT grafting density,the mechanical properties of the composites increased first and then decreased,and reached the maximum when the CNT grafting content was 0.25wt%,which was obvious compared with the untreated CF/PA6 composites.improve.The interface bonding ability of the composites was verified by H-type samples.The results show that the interface bonding conditions match the mechanical properties test results.The stress transfer mechanism is used to demonstrate that the grafting of a certain amount of CNT can increase the bonding ability of the fibers to the matrix,and the stress transmission to the matrix is prevented by the network structure formed by the CNT and CF laps,which prevents the interfacial crack propagation of the composites.This improves the mechanical properties of the composite.