Studies on the Preparation of Strong/Stiff Polymeric Fibres

摘要

The thesis presents the results of several studies on the preparation of strong and/or stiff polymeric fibers. The emphasis in the studies lies in high strength fibers prepared from polyethylene and poly(L-lactide). In chapter 1 a brief review is given of the theoretical and practical strength of polymeric fibers, of the most important methods of preparation of strong polymeric fibers. Chapter 2 presents a study on the preparation of high-strength polyethylene fibers by a gel-spinning/hot-drawing technique. Chapter 3 is concerned with an electron microscopic study into the crazing phenomena observed during high-speed gel-spinning of ultra-high molecular weight polyethylene fibers. Chapter 4 deals with the effects of fiber diameter and skin-porosity on the drawing behavior of melt-spun polyethylene fibers. Chapter 5 reveals the results of a study of the chlorosulfonation of ultra-high strength polyethylene fibers, which made them applicable in composites. In chapter 6 the results described in chapter 5 are used to prepare carbon fibers in high yield, having high strength, modulus and elongation at break, starting from melt-spun linear low density polyethylene fibers. Chapters 7 to 9 are studies on the preparation of high strength poly(L-lactide) fibers by a dry-spinning/hot-drawing process.