Preparationand Characterization Of Sizing Agent For Pan-based Carbon Fiber Treated By Ozone

Currently vinyl ester resin has attracted more and more attention in the field of ship-usedcomposite material because of its excellent water resistance. However, the interfacial strengthbetween vinyl ester resin and carbon fiber is not enough high for application, which limits theapplication of vinyl ester resin. Based on the problems mentioned, this paper focuses on processand mechanism studies of ozone oxidation and preparation of sizing agent suitable to vinyl esterresin to improve the interfacial bond strength of CF/VE.Firstly, through soxhlet extraction original sizing agent of domestic carbon fiber and barecarbon fiber can be get. Using infrared spectroscopy, AFM,micro-destick test study, the effect ofthe original fiber sizing agents can be learned totally. The results show that:Although theroughness of T300is more moderate than domestic CCF300and the polar of original sizingagents of CCF300is lower,the original sizing agents still cannot strengthen the interfacial bondstrength between carbon and vinyl ester resin.The ILSS between CF and VE don’t changegreatly before and after removing the sizing agents of domestic CCF300and import T300. Sowe need more research on sizing agents only for vinyl ester resin.CCF300and T300are treated by ozone in high temperature respectively,and mulitifilamentfiber tensile strength test, AFM, micro-debonding, Raman Spectroscopy are used to study howthe process of ozone treatment to affact the multifilament fiber strength and CF/VE interface.Test results show that:ozone oxidation process should be controlled within a certain range, thatis to say, the processing temperature should not exceed160℃, processing time should notexceed9min, the concentration of ozone should not exceed45mg/L. The process parametersselected by this paper is oxidation treatment temperature120℃, oxidation treatment time6min,ozone concentration30mg/L. In this process parameters, the interfacial bond strength increaseby25%. The mechanism of ozone treatment is the following. There is a weak surface layer onCF that is the first part oxidated by ozone. The speed of etching amorphous carbon is more fastthan graphite crystallite, which leads to the irregular degree changing of graphitization of thefiber surface. So the optimum processing time period is very narrow and the process parametersshould be controlled strictly.A new sizing agen for carbon fiber is prepared through phase inversion emulsificationmethod using a kind of modified vinyl ester resin. The effects of type and content of emulsifieron emulsion can be get be using nanometer particle size analyzer, standing precipitation method.The test results show that when the polyoxyethylene castor oil ether (EL-40) is used, the sizingagent is more stable. The content of EL-40is10%by mass.Then different content ofpolyethylene glycol monomethyl ether(MPEG) is used to modify VE resin.To get the effects ofMPEG content on particle size of the emulsion, cure degree of VE, fiber surface morphology,CF/VE interfacial strength, we use nanometer particle size analyzer, SEM, AFM, DSC and micro-debonding test. The test results show that with the increase of the MPEG content, particlesize of emulsion gradually increases, stiffness of the coated CCF300decreased, the curingdegree of VE decreased, and the interfacial bond strength increased from30.29MPa to37.29MPa. The optimum amount of MPEG is20%.The mechanism of improving the CF/VE interfacial bond strength is studied throughtesting the interfacial bond strength of three CFRPs which use polystyrene, styrene-containingVE802, styrene-free VE as based resin. The test results show that: partilly crosslinked VE resinsizing agent can improve interfacial bond strength because it contains active carbon-carbondouble bonds which can react with the matrix to form crosslinked network through styrene.