Surface Treatment And Mechanical Properties Of T300 Carbon Fiber

With the development of new industries,carbon fiber materials have been widely used in the fields of aerospace,rail transit,wind power generations and medical devices due to its excellent mechanical properties,low density,corrosion resistance and high temperature resistance.However,the surface of carbon fiber is highly chemically inert and smooth,resulting in poor interfacial adhesion properties.At the same time,carbon fibers have low elongation which is prone to rupture due to repeated bending and friction in the weaving process.Therefore,it is necessary to perform surface treatment on carbon fibers to increase the activity of the fiber surface and improve the surface roughness and the interfacial properties of the carbon fiber reinforced epoxy resin composites.In addition,the strand integrity of carbon fiber bundles is improved by sizing,so as to improve its weaving performance.In this paper,the surface treatment of carbon fiber materials in three dimensions?carbon single fiber,carbon fiber bundle and carbon fiber fabric?were carried out,modified with polypyrrole?PPy?,carbon nanotubes?CNT?or sizing agent.The properties of carbon fiber materials before and after treatment were tested and analyzed.The details are as follows:In the first part,carbon fiber monofilaments were treated with PPy and PPy-CNT respectively.The properties of interface,surface morphology and surface chemistry were tested and analyzed.The results showed that PPy was formed from pyrrole oxide by ferric chloride and deposited well on the surface of carbon fibers.Compared with untreated one,the interfacial shear strength of single carbon fibers modified by PPy and PPy-CNT were increased by 35.8%and 55.7%,respectively.Scanning electron microscope?SEM?images showed that the surface of single carbon fiber was coated with PPy and CNT.In addition,atomic force microscopy?AFM?showed that the surface roughness of treated carbon single fiber was increased by 1.65 and 2.38 times.In the second part,different solid content waterborne epoxy resins were used to sizing the carbon fiber bundles,and the systematic and detailed comparison of characterization before and after sizing was performed.The results showed that the overall performance of carbon fiber bundles was the best after sizing with a 2%solid content waterborne epoxy resin sizing agent:the interfacial shear strength of carbon fiber bundles was increased by 35.6%,the tensile strength was increased by 65.3%,the fuzzes weight was decreased by 76.2%,the abrasion performance of carbon fiber bundles was increased to 2571 times.Besides,the 2%solid content waterborne epoxy resin was combined with PPy and PPy-CNT respectively for the surface treatment of carbon fiber bundles.The results showed that the tensile strength of carbon fiber bundles reinforced epoxy resin composites were increased by 29.7%and 42.6%,indicating the interface between carbon fiber bundles and epoxy resin was significantly improved.The tensile strength of fiber bundles was increased by 89.7%and 86.9%respectively.The carbon fiber bundle maintained good abrasion performance,and the weight of fuzzes was significantly reduced by 67.5%and 65.9%.In the third part,the surface treatment of carbon fiber fabrics and the preparation of the carbon fiber fabric reinforced epoxy resin composites were carried out,and the mechanical and wave absorbing properties of the final composites were tested,characterized and analyzed.Specifically,the carbon fiber fabrics were treated with 2%solid centent epoxy sizing agent combined with PPy,PPy-CNT,and pure epoxy sizing agent to prepare composites.The results of mechanical tests showed that after the PPy-CNT and epoxy resin sizing system treatment,the tensile strength of the composite reached 677.7Mpa,which was 44.0%higher than that of the untreated material;The bending strength of the composite after treatment was increased by 18.8%.The effectiveness of surface treatment in improving the mechanical properties of the final composites was verified from the macroscopic scale.At the same time,due to the active role of the PPy and CNT in absorbing materials,the carbon fiber fabric treated by the above system reinforced epoxy resin composites also had good absorbing ability.In the 8GHz-12GHz frequency range,S₂₁ reached-28dB and the absorption efficiency reached 99.8%.