Studies on skin-core structure of stabilized PAN fibers by ultrasonic etching method

After ultrasonic etching treatment,the morphology and the chemical constitution difference between the skin and the core of the stabilized fibers from different temperature zones were studied by SEM and Raman spectrum respectively.The fibers stabilized at 195-225℃ had low stability,in which almost no difference in structure appeared between the skin and the core.The core in the fibers stabilized at 235-265℃ was dissolved by ultrasonic etching due to lower stability compared with the skin,which led to significant morphology difference between the skin and the core.After stabilized at 275℃,the stabilization of the core was improved,and the skin and the core showed infusibility.The characteristic Raman-scattering peaks of graphite broadened in the final stabilized fibers,while the peaks of the skin was broader,indicating the chemical constitution difference between the skin and the core.