OPTOTHERMAL PROPERTIES OF FIBERS .8. STRUCTURE ORIENTATION STUDY OF ANNEALED EGYPTIAN POLYESTER FIBERS

A two-beam interferometric method is used to study the change of optic al orientation functions and the molecular structure of annealed Egypt ian poly( ethylene terephthalate) (PET) fibers. The acoustic method wa s used for measuring the density. The density results were used to cal culate the degree of crystallinity of PET. It was found that annealing causes alignment to the fiber chains in the directions of the fiber a xis. This alignment gives an increase in the optical orientation funct ion and decrease in orientation angle. The value of Delta alpha/3 alph a(0), which depends upon the molecular structure of the polymer, remai ns constant. The obtained results of the optical and the density clari fy that new reorientations occurred due to annealing at different cond itions. The changes of the refractive index profile of annealed PET fi bers are given. Microinterferograms and curves are given for illustrat ion. (C) 1997 John Wiley & Sons, Inc.