13 - Tensile failure of polyester fibers

Abstract

Polyester fibers take a leading position among all chemical fibers. The unique properties of these fibers are due to the presence of aliphatic and aromatic parts in macromolecular chains and the regular molecular structure. Poly(ethylene terephthalate) (PET) is the predominant polyester used for fiber production, not only because of its good end-use properties and economy of production but in particular because of the ease of physical and chemical modification, suppressing negative and enhancing positive properties of PET. Despite the fact that PET and modified PET fibers have been widely investigated, there are still no fully described phenomena for predicting the mechanical behavior and tensile failure based on the structure or manufacturing parameters. One of the main reasons is the complex character of changes occurring during fiber manufacturing and modifications of structure due to the influence of stress, temperature, time, and environmental factors. This chapter provides basic information about chemistry, fabrication technology, and structure of PET and modified PET fibers. The structure evolution during fiber processing (spinning, drawing, and heat treatment) is discussed. The main approaches to the modeling of tensile behavior of polymeric fibers focused on PET are presented. The first part reviews manufacturing techniques of standard polyester fibers and their modifications. The basic routes for synthesizing and treatment of polyesters are discussed. In the second part, the technologies of spinning, drawing, heat setting, and corresponding complex changes in fibers are presented. The third part describes the mechanical behavior and tensile failure of polyester fibers. At the same time the influence of internal structure on the mechanical characteristics of polyester fibers is discussed. The influence of degradation processes due to environmental effects on strength and the fracture processes in PET fibers is described.