On the structural changes, mechanism and kinetics of stabilization of lignin blended polyacrylonitrile copolymer fiber

Abstract

Polyacrylonitrile(PAN)/lignin blend fiber prepared by continuous wet spinning process in dimethylsulfoxie(DMSO) was thermally stabilized under oxygen atmosphere in a continuous multizone oven at different heating temperature. The thermal behaviour of PAN/lignin fiber (PL fiber) stabilized were characterized by differential scanning calorimetry(DSC) under nitrogen atmosphere. The cyclization kinetics parameters such as activation energy(Ea), rate constant(k), pre-exponential factor(A) and extent of oxidation reaction (EOR) at different temperature were calculated from Kissinger and Ozawa method. FTIR analysis was used to investigate the structural changes and calculate the cyclization index and dehydrogenation index of stabilized PL fiber. The cyclization index values for the temperature of stabilization from 235 °C to 265 °C varied from 40 to 85%. The variation in density, elemental composition and mechanical properties of PL fiber stabilized at different temperature was determined. The density of the stabilized fiber varied from 1.225 to 1.385 g/cc as the stabilization temperature increased from 235 to 265 °C. The mechanism of thermal stabilization of and a set of temperature profile for a complete stabilization of PL fiber has been deduced from the various characterization