OBSERVATION OF BANDS IN HIGH-MODULUS ARAMID FIBERS BY POLARIZATION MICROSCOPY

Experimental data are presented which show that the examination of the highly oriented aramid fiber, Kevlar, at high magnification in an optical microscope in the extinction position between crossed polars gives an image with regions of regular fine bands. The diffraction pattern shows first order but no zero order. This is interpreted as being due to the passage of depolarized scattered light from a material with regularly spaced discontinuities. This is identified with the pleated structure proposed by Dobb et al.