OPTOTHERMAL PROPERTIES OF FIBERS .6. EFFECT OF ANNEALING ON SOME OF THE OPTICAL AND DYNAMIC-MECHANICAL PARAMETERS OF POLYESTER FIBERS

Changes in the structure of annealed polyester fibers (Egyptian manufa cture) at a constant time of 5 h and different temperatures (80-190 de grees C) were studied interferometrically. The Pulta polarizing interf erence microscope was used for determining the mean refractive indices and mean birefringence of these fibers. The multiple-beam Fizeau frin ges in transmission was also used for determining the refractive indic es of the skin and core of these fibers. Also, the acoustic method was used for measuring the density and mechanical loss factor of these fi bers. Relations between the mean refractive indices, birefringences po larizabilities per unit volume, and mechanical parameters of annealed polyester fibers with different temperatures are discussed to clarify the thermal effects. Illustrations are given using graphs and microint erferograms. (C) 1996 John Wiley & Sons, Inc.