Evaluation Method of Local Orientation of Polymer Chain Using an Interference Microscopic Technique

Abstract

An attempt is made to establish a method for evaluating the distribution functions of the local molecular orientation (LMO) and the local crystallinity (LC) in a fiber by optical microscopy. The LMO distributions were typically classified into two models in an actual case ; one-dimensional anisotropic model (model I) and two-dimensional anisotropic model (model II). A theoretical equations relating to refractive index and molecular orientation in both models have been derived from the generalized Lorenz-Lorentz equation as basic tenet. The refractive indexes corresponding the two different polarized lights, whose electric field vectors oscillated parallel and perpendicular to the fiber axis were analyzed on the basis of the above theoretical equations. The prerequisite para meters are the densities of crystalline, amorphous regions and three principal refactive indexes of the crystal. In addition to the distribution functions of LMO and LC, this method enables us to determine the refractive index of an amorphous region and also the ratio of orientation between crystalline and amorphous regions. The best fit model between models I and II. can be chosen by judging from the polarized microscopic observation of the cross section of a fiber and from the side view of a fiber by an interference microscopy. Polyester fibers belong to the model I and Kevlar 49 to model II. The degree of LMO of both fibers shows larger at the periphery than at the center of a fiber.