Study On The Correlation Between Surface Structures Of Carbon Fibers And The Interfacial Performance Of Composites

The structures on the surface of carbon fiber include the groove structure and chemical functional group structure.Above structures have important effects on the interfacial performance of composites.On the one hand,the groove structure can provide the meshing center between the carbon fiber and the resin matrix;On the other hand,the chemical bond or molecular chain entanglement can form between the carbon fiber and resin matrix.First of all,taking three kinds of carbon fiber as the research object,the method of quantitative characterization about the groove structure on the surface of carbon fiber was established by using SEM,Photoshop and Matlab.The structural parameters such as groove aspect ratio,groove density and surface irregularity were proposed.Because of inheritance of surface structure during the preparation of the PAN-based carbon fiber,the groove structure of carbon fiber can be adjusted by controlling the temperature of coagulation bath in spinning process.Secondly,the electrochemical oxidation was used to treat the surface of carbon fiber.It was found that carbon-containing functional groups on the surface of carbon fibers could be adjusted by changing the current density through the test of DCAT and XPS.Then,the mechanism of the formation of carbon-containing functional groups with the change of current density was analysed.Thirdly,the composites were produced using the carbon fibers with different surface structures as reinforcement.The test results of the interfacial performance of composites showed that the interfacial performance could be improved from the aspect of increasing the groove size of carbon fibers,but this method is only applicable to groove with small size.The influence of groove size on the interfacial performance of composites would be weakened with the further increase of groove size.The interfacial performance of composites would increase when the content of the active carbon-containing functional groups is not less than 31.24%.