Rheo-Optical Studies on the Deformation Mechanism of Semicrystalline Polymers. III. An Improved Technique for Oscillatory Measurements in Rheo-Optics and Its Application to Dynamic X-Ray Diffraction Measurements

Abstract

An improved technique, “Multi-Channel Narrow Sector Technique,” was presented for measuring rheo-optical responses of polymeric materials against oscillatory mechanical excitation. The technique is based on the Fourier expansion of the response accumulated at equally divided narrow phase intervals of the oscillatory excitation over many cycles of the oscillation, and is available for determination of the rheo-optical properties of the materials even under one or both of the following conditions: (i) the excitation being distorted from a genuine sinusoidal one, or/and (ii) the response being of nonlinear characteristics. The multi-channel narrow sector technique is applied to the dynamic X-ray diffraction measurements in association with the use of a microcomputer. Some results for two kinds of semicrystalline polymer films, a tubular-extruded film of a poly(butene-1) and a melt-crystallized isotropic film of a low-density polyethylene are demonstrated. Determination of the dynamic shift and the intensity variation of overlapped peaks of X-ray diffraction from crystal planes, which is necessary for evaluating the dynamic lattice deformation and orientation of the polymer crystals, is made by means of the least square method. Some typical results are further demonstrated for the dynamic behavior of the (110) and (200) crystal planes of the low-density polyethylene film.