Investigation On The Mechanism Of Rapid Activation Of Carbon Fiber By Microwave And Its Application In The Modification Of Composite Material Interface

Carbon fiber reinforced polymers(CFRPs)are used in various fields due to their outstanding properties.However,the surface of carbon fiber(CF)is smooth and inert with poor wettability between the resin and fiber,resulting in weak interfacial bonding and poor cycle life.Finding an effective modification method with wide applicability and low cost has become a challenging topic.Compared with traditional modification methods,microwave has the benefits of high activation efficiency,simple operation and environment friendly.This paper is based on the method of microwave activation,and uses the differences in responsiveness of T800,M40X,and M55J under microwave.By introducing copper phthalocyanine on the surface of carbon fiber to alleviate the damage caused by microwave,the activation,modification and construction of high temperature resistant interfaces of carbon fibers are achieved.The main work is as follows:(1)The microwave method was used to activate and modify T800 with different modification times,and the competitive mechanism of microwave activating-etching on carbon fiber was studied comparatively.Combined with the analysis of X-ray photoelectron spectroscopy(XPS),atomic force microscopy(AFM),interfacial shear strength(IFSS)and contact angle test results,it could be seen that with the increase of microwave modification times,the O/C on the surface of CF increased,the wettability between the resin and CF increased,and the interfacial bonding ability was enhanced.The results of scanning electron microscopy(SEM),Raman scattering(Raman)and single-filament tensile tests showed that the microwave modification can oxidize and etch the surface of CF,which reduced a decrease in the tensile properties of CF.(2)The microwave activation mechanism was explored by comparing the responsiveness of T800,M40X,and M55J to microwaves.SEM,AFM,and XPS results confirm the microwave responsiveness of the carbon fibers as good conductor.The graphite structure of carbon fibers was characterized by X-ray diffraction analysis(XRD),Raman and XPS tests,and the results showed that the graphite structure of M55J had the highest degree of regularity and orderliness.The influence of different graphitized carbon fibers on the microwave response was systematically investigated.The results of XPS,single fiber tensile strength test,micro-debonding and mechanics mode-AFM(f-AFM)tests showed that compared with M40X and T800,M55J had the strongest microwave responsiveness and was easier to form micro-plasma on its surface and realize efficient modification effect under the same microwave modification times.(3)The influence of the introduced copper phthalocyanine(CuPc)on the interfacial properties of the composites was analyzed by transverse fiber bundle tensile test(TFBT),interfacial shear strength(IFSS),and f-AFM.The submerged arc discharge method(SAD)proved that CuPc can reduce the damage to M55J surface and improve the retention of carbon fiber tensile strength.The interface high temperature resistance of carbon fiber reinforced polymers was enhanced due to the large benzene ring rigid structure of CuPc.Compared with M55J/EP,mM55J-CuPc/EP had better performance,especially at the temperature of 175 ℃,the TFBT and IFSS of mM55J-CuPc/EP were improved by 247.4% and 72.5%,respectively.This demonstrated that the structural modification of CuPc constructed a high temperature resistant and high strength interface.