Effects of using polyacrylonitrile on the thermal, morphological and mechanical properties of polyimide/polyacrylonitrile blend fibers

High-performance polyimide/polyacrylonitrile (PI/PAN) blend fibers were prepared through wet-spinning of the polymer blends of polyamide acid (PAA) and PAN solutions followed by a thermal treatment in air. During the heat treatment process, PAA was imidized into its final heteroaromatic PI form with the concomitant evolution of PAN into its ladder-like preoxidized form, thus yielding PI/PAN blend fibers with desirable properties. The structure evolution was traced by fourier transform infrared radiation spectrometer, differential scanning calorimetry and thermogravimetry, implying that the PAA moiety in the blend fibers played a role as initiator for the cyclization of PAN. The final PI/PAN blend fibers exhibited a single glass-transition peak at 326 °C and a smooth surface without any pores. Moreover, the PI/PAN blend fibers possessed the tensile strength of 1.06 GPa and modulus of 59.9 GPa.