Modification Of Carbon Fiber And Its Application In The Paper For Fuel Cell

Carbon fiber papers have been widely used in modern society as a high-performance carbon fiber composite material. The development status of carbon fiber and carbon fiber paper at home and abroad was reviewed and new investigation on carbon fiber paper was analyzed. Researches comprising of carbon fiber modification, dispersion and forming technology were carried out according to difficulties in scattering during paper forming and lower strength in detail. Concrete work and major achievements included were as follows:1 The modification of carbon fiberGas-phase oxidation, liquid-phase oxidation and polymer-coated methods were adopted to improve hydrophilic and dispersion properties. The work reached the following conclusions:(1) Heat treatment temperature and time were studied to see their effects on the properties of carbon fiber and the optimum conditions were 800℃, 1h respectively.(2) The effects of oxidants on carbon fiber in liquid-phase oxidation were discussed. Concentrated nitric acid was preferable to other oxidants and the carbon fiber can be well scattered in 4min when the treatment temperature and time were 60℃and 90min respectively. Simultaneously, the index of tensile strength of carbon fiber paper was 14.23 N·m·g-1and the resistance rate was 0.151 ?·cm.(3) Aniline and CPAM were applied in the process of polymer-coated modification. Results showed that the optimizing concentration of polymer-coated modification applied with aniline was 1.5%, and the preferable treat conditions of polymer-coated modification applied with CPAM were at ordinary temperature, for 12min. According to the experiments results that the carbon fiber properties with different modification methods. Liquid-phase oxidation is preferable with the reagent of nitric acid, at 60℃, for 90min.2 The dispersion performance of carbon fiber pulp(1) Pulping performance of carbon fiberThe beating degree of the pulp was maintained in about 8°SR through repeated measurements of carbon fiber pulp. The final pH value was 7.4-7.6 and the surface charge of carbon fiber was-14.7μeq/L when the concentration of carbon fiber was 0.5%. Consequence, the best beating conditions were considered to be low-speed, for 3min according to the length and yield of carbon fiber paper. (2) Dispersion performance of carbon fiber pulp Factors such as concentration, length distribution of carbon fiber, pH of the system, surfactant, dispersant and so on were discussed in our work to see their effects on the dispersion performance of carbon fiber pulp.3 The forming process of carbon fiber paperThe forming process of carbon fiber paper applied with CMC, cationic starch and PVA was studied. CMC (9S-A) was turned out to be the best adhesive and the dosage was determined to be 30% added in the former.4 Mechanism of sheet structure and strength formation were discussedThe sheet structures and the strength formation mechanism of carbon fiber paper were analyzed. The differences of the mechanism between carbon fiber paper and plant fiber paper were compared.