OPTOTHERMAL PROPERTIES OF FIBERS .3. OPTICAL ANISOTROPY IN NYLON-66 FIBERS AS A FUNCTION OF ANNEALING PROCESS

Nylon 66 (ICI Polyamide 66, Carded & Combed Top) fibers were annealed in the temperature range 80-180 degrees C for 1-10 h. Refractive indic es and birefringence were measured interferometrically. Two independen t techniques were used to study the optical anisotropy in these fibers . The first technique was to study the effect of annealing on the swel ling properties of fibers from its diffraction pattern using a He-Ne l aser beam. The second was the application of multiple-beam Fizeau frin ges in transmission to determine the skin and core refractive indices and double refraction of annealing samples. The application was carrie d out using multiple-beam Fizeau fringes in transmission to determine Cauchy's constants and the dispersive coefficient for the fiber layers . The resulting data were used to calculate the mean polarizability pe r unit volume and the isotropic refractive indices. Behavior of optica l properties at different annealing conditions is discussed. The resul ts obtained clarify the new reorientation, and each layer change occur red due to annealing at different conditions. Microinterferograms and curves are given for illustration. (C) 1996 John Wiley & Sons, Inc.