Abstract
The fibers of Kevlar 29 and poly (3, 8-phenanthridinonediyl terephthalamide) made from the liquid crystalline solutions were hydrolyzed with 20wt% aqueous solution of sodium hydroxide at 100°C and 200°C to the considerable degrees of degradation and examined with an optical and a scanning electron microscope. The hydrolyzed fibers were found fractured both transversally and longitudinally along two different types of cleavage planes. The transverse cleavage planes with an average spacing of about 0.3μm were related to the zigzag-shaped fibrillar structure of fiber. The longitudinal cleavage planes consisted of cylindrical surface arranged coaxially one after another around fiber axis, contrary to the existing conception of the radially arranged pleated sheets. The spacing of longitudinal cleavage planes was estimated at 0.2-0.3μm. The etching of aromatic polyamide fibers by sodium hydroxide visualized the latent image of structure generated in the course of fiber formation by the wet-spinning of liquid crystals.
