OPTOTHERMAL PROPERTIES OF FIBERS .2. ANNEALING EFFECT ON THE BIREFRINGENCE VARIATIONS OF POLYESTER FIBERS

The variation of refractive indices and birefringences of Egyptian-man ufactured polyester fibers with different annealing times at constant temperature 160 degrees C are studied by interferometry. The polarizin g interference microscope is used for determining the mean refractive indices and mean birefringence of these fibers. The results are used t o calculate optical orientation function and the angle of orientation. Also, the acoustic method has been used for measuring the density and the mechanical loss factor of these fibers. Relations between the mea n refractive indices, birefringence, polarizabilities, mechanical loss factors, and densities with annealing time are given for these fibers . Illustrations are given using graphs and microinterferograms. (C) 19 96 John Wiley & Sons, Inc.