The Surface Treatment Of Fiber And Fiber Reinforced Epoxy Composites

The interface and arrangement of reinforcement are important factors of the properties of composite. The properties of the ramie fiber after heat treatment and 3D carbon fiber network reinforced epoxy resin were studied.The properties of ramie fibers treated by thermal processes under nitrogen and air atmospheres, including thermal stability, crystal property, chemical structure, longitudinal thermal deformation behavior and surface performance, were studied. Thermo-gravimetric analysis (TG) showed that the fibers treated at or below 200? under air had a similar thermal stability as those treated under nitrogen, whose weight loss was less than 8%. Therefore, a proper thermal treatment temperature of 200? was suggested. The amount of-OH in fibers was decreased by thermal treatments, proved by infrared spectroscopy analysis. It is indicated by X-ray diffraction analysis that thermal treatments were harm to the crystalline index of ramie fibers, and moisture absorption did greatly affect the crystalline structure of cellulose, leading to a decrease of crystalline interplanar spacing. The longitudinal thermal deformation behavior of ramie fibers were further measured by thermo mechanical analyzer. The results showed that the ramie fibers with moisture absorption after thermal treatment was of thermal expansion properties, those without moisture absorption after treatment under dry air exhibited thermal shrinkage in the temperature range below 100? and thermal expansion above 100?, and those without moisture absorption after treatment under nitrogen displayed thermal shrinkage in the whole temperature range. The fracture morphology of ramie fibers/epoxy resin composites was observed by scanning electron microscopy, which disclosed the compatibility between fibers and resin matrix was enhanced through thermal treatments under nitrogen or air, and the interfacial adhesion of composites was improved.3D carbon fiber network reinforcement (CFNR) was fabricated based on short carbon fibers bonded and carbonized with phenolic resin. The original CFNR/epoxy composite was prepared by vacuum bag molding. The microstructure of CFNR and CFNR/epoxy composites were examined by POM and SEM. The mechanical properties and electrical properties of composites samples were evaluated by universal testing machine and DC resistance tester, respectively. The results indicated that the chopped carbon fibers were bonded into continuous 3D network by carbonised phenolic resin, and there are obvious network nodes of carbon-based adhesive points in CFNR/Epoxy composites; the bending strength of CFNR/Epoxy composites had increased by 33% and 29% than chopped carbon fiber composites and pure epoxy samples, the compression strength had increased by 23% and 10%. Additionally the electrical conductivity of CFNR/Epoxy composites was as 45 times as chopped carbon fiber composites.