OPTOTHERMAL PROPERTIES OF FIBERS - XI - THE EFFECT OF THERMAL ANNEALING OF DRAWING BEHAVIOR FOR EGYPTIAN POLYESTER FIBERS ON THE CRYSTALLINITY AND SOME OPTICAL-PARAMETERS

The structure developed of annealed Egyptain poly(ethyleneterephthalat e) (PET) fibers is studied interferometerically due to the drawing pro cess. Using a two-beam Pluta polarizing interference microscope connec ted to a device to dynamically study the draw ratio with the birefring ence changes, the relations of drawing changes with some optical param eters are given. The evaluation of density, the mean square density fl uctuation [eta(2)], crystallinity, amorphous orientation, crystalline orientation functions, number of chains per unit volume N-c, and numbe r of random links between the network junction points N has been found . The results obtained clarify the effect of annealing time and temper ature with different draw ratios on the structure of PET fibers. Empir ical formula is suggested to correlate the changes in f(theta), theta, Delta n(a), and A with the draw ratio. Microinterferograms and curves are given for illustration. (C) 1998 John Wiley & Sons, Inc.