Process And Properties Of Carbon Nanofibres By Electrospinning

Carbon nanofibres have many outstanding performance based on itsone-dimensional structure，which make them be the optimal candinate for a broad rangeof important applications in widely different areas. Although there are many methods offabricating nanofibres, electrospinning is perhaps the most versatile process. Traditionalpreparation methods are difficult to get carbon nanofibres easily. The method ofelectrostatic spinning has gained popularity with its simple equipment preparationconveniently in last20years. This technique allows for the operation of continuouscarbon nanofibres with diameters in the range from several mircometers down to tens ofnanometers. At present, the electrostatic spinning method is hard to broaden itsindustrial applications because of its low yield. Although many researchers have mademany explorations from the aspects of improving nozzle to the receiver in terms ofnanofibres production, they have not solved this problem fundamentally. Therefore,once the problem of mass production electrostatic spinning method is solved, thepreparation of nanometer fiber will have a big leap.The most direct solution to improve the mass production is to increase the numberof the effective jet nozzles. On the basis of single nozzle electrospinning, this thesisgives the research of spinning process parameters which affects fiber output in differentsprinkler spacing in circular distribution. The experiment solves the problem of slowsolvent evaporation. Based on ANSYS simulation analysis result, this paper finds outwhy the productivity drops as the sprinkler spacing decreases and it gives reasonableexplaination of Suspended uneven phenomenon. When the sprinkler spacing is12cmand the solvent is vapored in time, multiple nozzles electrospinning method can realizeproportional enlargement. We obtains PAN nanofibre mats with length of1m and widthof35cm which have uniform distribution with a range of200nm~300nm whose specificstrength is.500.98N·m/kg.The research of pre-oxidation process at different temperatures and heating ratesand carbonization process at different temperatures, is shown that polyacrylonitrileprecursor fiber mat turns to be the pre-oxidized fiber web with good mechanicalproperties. Followed by carbonization at different temperature，nano-carbon fibres with uniform morphology can be gained. The effect of pre-oxidation and carbonization tofibres web structure and properties are analysed by DTA-TG, FT-IR and SEM. Thetensile test results of pre-oxidation web reveals that it is fractured gradually, the highestspecific strength is241.9N m/kg, the BET result is top8.24m~2/g at250℃for1h at therate of1℃/min. Carbon fiber structure which is treated in N2atmosphere at differenttemperature is analysed by FT-IR. The CV capacitive performance of nano-carbon fiberat1000℃is optimal. With the increase of scan rate (100mV/s), the CV area is larger.The charge and discharge performance with high current is good, and the good chargeand discharge cycle stability performs best after10times.