In the preparation of carbon fiber

In the preparation of carbon fiber reinforced composites, CF surfaceparticipates in forming an interfacial region between CF and the resinmatrix which could dramatically affect the properties of composites[32]. According to literature [2,34,61], the interfacial properties of CFreinforced polymer composites to a large extent depend on the wettability and functionality of CFs. Our previous research also showed thatimprovements in surface roughness and increases in the relative contentof oxygen-containing functional groups of HSCFs after the electrochemical surface oxidation could result in the significant increase in theILSS values [9]. Above SEM, XPS and Raman results showed that greatchanges in morphology structure and chemical composition happenedto UHMCF surfaces after electrochemical oxidation. Especially for thesurface chemistry of UHMCFs, a large extent of increases happened tothe relative content of the oxygen-containing functional groups duringelectrochemical surface oxidation. As a widely used epoxy resin,DGEBA is synthesized from bisphenol A and epichlorohydrin and epoxygroups are its functional groups which can react with –COOH and –OHgroups. Therefore, in the preparation of UHMCF reinforced epoxy resincomposites, oxygen-containing groups react with the epoxy groups ofepoxy resin. The introduction of oxygen-containing groups on the surfaces of UHMCFs and its chemical reaction with the epoxy groups ofepoxy resin is shown in Fig. 10. With increases in the relative content ofoxygen-containing groups introduced onto the surfaces of UHMCFs, theILSS values of corresponding composites gradually increased afterelectrochemical surface oxidation.