OPTOTHERMAL PROPERTIES OF FIBERS - 12-INTERFEROMETRIC INVESTIGATION FOR THERMALLY TREATED VISCOSE FIBERS

The present article studies the structure of annealed viscose fibers i nterferometrically at a constant temperature of 100 +/- 1 degrees C at different times. The Pluta polarizing interference microscope has bee n used for determining the mean refractive indices and mean birefringe nce. The results were used to calculate the optical orientation functi on and the angle of orientation. The value (Delta alpha/3 alpha(0)), w hich depends on the molecular structure of the polymer, remains consta nt. Relationships between the mean refractive indices, birefringence, isotopic refgractive index, and polarizabilities per unit volume with different times were given for these fibers. The samples were subjecte d to X-ray diffraction to clarify the variation of crystallinity with the annealing conditions. Differential thermal analysis measurements w ere used to determine the glass transition temperature of viscose fibe r. Measurements of the volume swelling parameter of the viscose fibers with different liquids were given. Also, determinations of Cauchy's c onstants, dispersive power, and dielectric constant at infinity were c arried out. Illustrations are given using graphs and microinterferogra ms. (C) 1999 John Wiley & Sons, Inc.