Research On The Properties Of Amphiphilic Modified Carbon Fiber And Its Carbon Paper

The proton exchange membrane fuel cell is a highly efficient and green energy conversion device,and the gas diffusion layer is one of its important components.Carbon paper is a common substrate material of gas diffusion layer.Its structure and performance affect the performance of proton exchange membrane fuel cells.In this paper,amphiphilic modification of carbon fibers was performed and the carbon papers were prepared from the modified carbon fibers.The effect of surface treatment on the properties of carbon papers was studied.In this paper,PAN-based carbon fibers are used as raw materials.Carbon fibers were washed with sodium hydroxide solution and then oxidized with chromic acid solution at room temperature to generate hydrophilic functional groups.Based on this treatment,some hydrophilic functional groups were retained.Meanwhile,the carbon fibers were further reacted to introduce lipophilic functional groups to get amphiphilic carbon fibers.The carbon paper for the proton exchange membrane fuel cell was prepared by using the above-mentioned some carbon fibers by processes such as dispersion,papermaking,resin impregnation,curing molding,carbonization and graphitization.The cold field-emission scanning electron microscope,the fourier transform infrared spectrometer and the X-ray photoelectron spectroscopy analyzed the effects of surface treatment on the surface morphology and functional groups of carbon fibers.The differential scanning calorimetry analyzed the thermal properties of the phenolic resin.The laser confocal roman electron spectroscope analyzed the degree of graphitization of carbon papers.The desktop scanning electron microscope analyzed the surface morphology of carbon papers.The universal tensile testing machine analyzed the mechanical properties of carbon papers.The four-point probe tester analyzed the electrical conductivity of carbon papers.The study found:(1)Chromic acid solution oxidized the alkali treated carbon fibers at room temperature for 10 minutes to introduce hydrophilic functional groups,and further reacted with octanol to introduce lipophilic functional groups.Because part of the hydrophilic functional groups did not participate in the reaction,an amphiphilic carbon fiber having both hydrophilic and lipophilic groups was obtained.(2)There were hydrophilic functional groups on the surface of both the oxidized carbon fibers and the amphiphilic modified carbon fibers,the dispersibility of the carbon fibers in water can meet the requirements for preparing carbon papers.(3)Amphiphilic carbon papers improved the interfacial bonding ability of carbon fiber and resin,which facilitates the transmission of electrons in carbon paper,and its resistivity decreases to 10.5 m? · cm.(4)After graphitization,the resistivity of carbon paper prepared with amphiphilic carbon fibers can be as low as 1.5 m? · cm.