The Role of Tension and Temperature for Efficient Carbonization of Polyacrylonitrile Fibers: Toward Low Cost Carbon Fibers

We report the production of automotive grade carbon fibers in a low temperature carbonization furnace by making use of the influence of various levels of tensions and temperatures on polyacrylonitrile (PAN) precursor fibers. The experiments were performed at two different temperatures during a low temperature carbonization process to understand the effect of differences in temperature as well as tension. The effect of oxidative stabilization and carbonization processes on the structure, mass retention, and mechanical properties of precursor fibers was analyzed. Fibers were collected from each zone of the low and high temperature furnaces, and physical properties were measured for carbon fibers along with precursor and oxidized fibers. The infrared studies revealed the variation in the chemical structure of the fibers during the stabilization, and the aromatization index of 65.5% was calculated from thermal studies of the stabilized fibers. It was found that an increase in tension during low temperature (LT) carbonization has increased fiber density and produced a higher modulus and high tensile strength fiber up to 2200 cN. It was also seen that increasing the temperatures during the initial carbonization did not affect tensile strength and produced lower modulus fiber once high temperature (HT) carbonization was completed. However, this study revealed that it is possible to produce fibers with a tensile strength of 3.28 GPa and tensile modulus of 222 GPa just within LT carbonization, which are desirable for automotive applications. Moreover, by eliminating the HT carbonization, additional energy consumption and manufacturing time can be reduced, which further lowers the cost of the final carbon fibers.