Study On The Interface Properties Between Carbon Fibers And Epoxy Resin

The interfacial properties of FRP (fiber-reinforced polymer composite) is the keyfactors that affect effective performance of fibers and resin matrix and mechanicalproperties, thermal properties and durability et. The research of interfacial properties ofFRP composite is the foundation to study and improve the performance of FRPcomposite. In civil engineering environment, FRP composite is inevitably influenced bythe role of a variety of harsh environments, such as water, alkali solution immersion,and high-temperature environments. In harsh environments, the interface of FRPcomposite between the fiber and resin matrix prone to degradation, leading to thedegeneration of long-term durability.In this paper, microbonding test and other methods was used to study the influencingfactors, laws and mechanisms of interfacial properties between the carbon fiber andepoxy matrix.First of all, based on the combination of theoretical analysis and practical operation,the microbonding test was utilized to study the interfacial propoerties of carbon fiberand epoxy resin.Secondly, the morphology, sizing agent element content and functional groups on thecarbon fiber surface were characterized, and the results showed that: after the sizingagent on the carbon fiber surface were eliminated, the gully of the fiber surface wasmore obvious, roughness increased, oxygen content and reactive functional groupsdecreased; After high-temperature oxidation was completed, the roughness of thecarbon fiber surface increased, the oxygen content increased.Thirdly, the microbonding test was used to evaluate the inflouce of sizing agent tocarbon fiber and epoxy resin adhesive performance, and results showd: after the sizingagent of carbon fiber was got rid, the interfacial bond strength decreased; the sensitivitydegree of matching between the different sizing agents of carbon fiber and differentresin systems were different; after the treatment of high-temperature, although thesurface oxidation increase, the interfacial bond strength decreased because of thedecomposition of the sizing agent.Finally, the law of carbon fiber-epoxy interfacial bond strength was gained that wasaffected by harsh environments such as heat, water, alkali solution, salt solution, andthe results showed that: interfacial adhesion was a certain degree of weakened followedwith the improvement of the treatment temperature; however, with the extension of thetreatment time, the interface was enhanced, which is due to the after-solidification of theresin matrix; in the three kinds of solution the interfacial bond strength between carbonfiber and resin matrix was rapid degradated, but with the immersion time increasing, thedegradation rate was slowed down; compared with waterand the salt solution, in the alkaline solution, the carbon fiber-resin interface degraded the most seriously.