| With the development of the aerospace industry, the demand for high-temperature resistant carbon fiber composite increases day by day, carbon fiber need sizing processing before made into composite, and the heat-resisting performance of sizing agent will have a direct impact on the interface properties of the composite materials. The sizing agents for carbon fiber are epoxy resin dominated at present, which can resist 180℃in the maximum limit, but many materials need to work under the environment of 250℃high temperature, and there is no report on 250℃high-temperature resistant carbon fiber sizing agent at present, so it has important significance that this paper developed a kind of 250℃high-temperature resistant carbon fiber sizing agent.This paper uses polyamide imide(PAI) solution as sizing agent, which is analyzed by high performance liquid chromatography and infrared spectrum, the results shows that the sizing agent only contains one main component which is polyamide imide; The heat resistance of sizing agent is analyzed, the results shows that the curing process that room temperature→110℃(5h)→210℃(10h) can make the sizing agent resist more than 250℃; Sizing by different concentrations of sizing agent, the results showed that the mass fraction of 0.1% is the best sizing concentration, and the fiber has good surface characteristics after sizing, the loss weight of the fiber only 4‰after 250℃treated for 24h.The morphology of unsized and sized fiber was characterized by scanning electron microscopy and atom forced microscopy, the results shows sizing can improve fiber surface morphology; the fiber is analyzed by contact angle test in different solvents, the result shows that the sizing fiber enhance more than unsized fiber in surface energy; XPS test results show that the polarity of the fiber surface enhance after sizing, and thereby enhance the infiltrating ability in the resin; sized fibers with epoxy resin and bismaleimide single fiber composites process 24h under 250℃, and interface shear strength only decrease by 2.15% and 1.93% respectively, this means that the two composites have a good high-temperature resistant behavior; the resistance to muggy test is done for the above two single fibre composites, because of water infiltration, interface shear strength desease by 30.78% and 25.92% respectively, but interface shear strength have been certain restored after the removal of water, which can explain that single fiber composite interface fails to completely craze after boiled 72h in water. |
