OPTOTHERMAL PROPERTIES OF FIBERS .7. OPTICAL INVESTIGATION OF ANNEALED NYLON-6 FIBERS

The influence of annealing on the birefringence of nylon-6 fibers was examined. These fibers were found to show considerable optical anisotr opy. Three independent techniques were used to study the optical aniso tropy in these fibers. The first technique to determine the diameter o f the fiber from the diffraction pattern was using a He-Ne laser beam. The second technique was the application of the Becke-line technique to study the effect of annealing on the skin layer of these fibers at different temperatures for a constant time of 5 h. The third is the ap plication of a double-refracting interference microscope (the Pluta po larizing interference microscope). The double-beam technique is consid ered as the most suitable technique for determining the mean refractiv e indices and the double refraction of the annealed samples at differe nt temperatures. (155 and 175 degrees C and at two constant times 7 an d 9 h). Microinterferograms and curves are given for illustration. (C) 1997 John Wiley & Sons, Inc.