Quantitative analysis of the effects of comonomers and heating conditions on the stabilization reactions of polyacrylonitrile fibers as carbon fiber precursors

Thermal stabilization of polyacrylonitrile fibers is an important step in the production of carbon fibers. A detailed map of stabilization reactions is necessary to adjust the processing parameters - such as temperature and tension - that lead to high performance carbon fibers with minimum structural imperfections. We have investigated the effect of comonomer type and heating conditions on the thermal behavior of polyacrylonitrile fibers during stabilization process. In doing so, three types of PAN fibers having different chemical composition and characteristics were studied using Differential Scanning Calorimetry, Thermogravimetry Analysis and Thermomechanical Analysis. It was observed that chemical composition and characteristics of PAN fibers affect the initiation mechanism and temperature of the stabilization reactions, i.e. the sequence and temperature range of the stabilization reactions change in presence of different types of comonomers. However, heating rate as an important processing parameter does not affect the sequence of these reactions. An increase in the heating rate can only shift the reaction temperature to higher values. These results help the design of the processing unit and adjusting the tension.