The Effect of Ultrasonic Etching on the Structure of Stabilized PAN Fibers

The effect of ultrasonic etching on the crystalline structure, fibrillar structure, skin-core structure of stabilized PAN fibers was studied by XRD and SEM. It has been found various degree of decrease occurs in the crystallite size and crystallinity of fibers heated at different temperatures after ultrasonic etching. Fibrillar structure of fibers heated at 195°C~245°C appear after ultrasonic etching in 90wt% DMSO solution for 6h. When the stabilization temperature is over 245°C, no separated fibrils or macrofibrils are found. When stabilized fibers were etched in pure DMSO, skin-core morphology was observed for the fibers heated at 235°C~265°C. The method of ultrasonic etching using pure DMSO confirms the structural difference between the skin and the core, also makes the difference visual.