SOME STUDIES ON THERMAL TREATMENTS OF POLYESTER FIBERS - STRUCTURAL-CHANGES

The development of the changes of structure during thermal treatment o f polyester fiber is studied. Critical dissolution time (CDT) was eval uated to trace the changes in crystallinity and crystal morphology of polyester fibers. CDT increased as the time of thermal treatment was i ncreased. The change in CDT was less effective for samples thermally t reated at temperatures up to 160 degrees C, which may indicate a nucle ation tendency of tiny crystals. CDT of polyester treated at 200 degre es C in air was found to be relatively high, while silicon oil medium can affect both amorphous and crystalline regions, increasing the stru cture disorder. The effect of treatment under constant length revealed smaller CDT values than those attained by samples treated in free con ditions. An indication to crystal size increase was traced by a decrea se in peak width in X-ray diffraction pattern. Thermal treatment incre ased the crystallinity of polyester fibers up to 160 degrees C. Dry ai r medium was more effective in increasing the disorder in amorphous re gions than silicon oil medium. (C) 1997 John Wiley & Sons, Inc.