A commercially available polyimide fiber was investigated as a possible precursor for the formation of carbon fibers. The
thermal response of the fiber was thoroughly investigated using DSC, TMA and TG. These responses were dependent on the atmosphere
and tension during scanning. The fiber was stabilized at high temperatures both in inert and oxidative environments and the
effect of these stabilization treatments on the structure and properties of the fiber was carefully followed. During heating,
the fiber showed shrinkage tendency at small tensions, but at higher tensions the fibers could be stretched. Among the two
environments investigated, air was more effective than nitrogen in getting a more stable fiber.