Aa. Hamza et al., OPTOTHERMAL PROPERTIES OF FIBERS .8. STRUCTURE ORIENTATION STUDY OF ANNEALED EGYPTIAN POLYESTER FIBERS, Journal of applied polymer science, 65(10), 1997, pp. 2031-2050
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.