Oxidative stabilization studies on pretreated polyacrylonitrile precursor fiber suitable for carbon fiber production

Polyacrylonitrile (PAN) precursor fiber is the major precursor in demand for the production of carbon fiber. The conversion of PAN fiber to carbon fiber involves heat treatment of PAN fiber in different process condition at high temperatu re ranging from 200 to 1500 °C. The first step of heat treatment is oxidative stabilization of PAN fiber by controlled heating in air atmosphere at the temperature range 200-280 °C. Oxidative stabilization is a very slow process and the kinetics of stabilization depends on various parameters like comonomer composition in PAN copolymer, type of heat treatment atmosphere, heating rates, precursor fiber characteristics etc. The untreated and chemically treated precursor fiber characteristics are studied in detail during heat treatment under air atmosphere and effect of pretreatment on oxidative stabilization is studied using DSC, FTIR, elemental analysis and density measurements. Aqueous solution of Guanidine carbonate, ammonia and ammonium iodide are used for pretreating the precursor fiber prior to heat treatment. Chemical pretreatment of precursor fiber with guanidine carbonate and ammonia are found to help in achieving the optimum properties during oxidative stabilization.