Introduction

Fibers are produced globally in quantities exceeding 100 million tons with about 60% being synthetic fibers. If one were to choose a single technique to characterize fibers, thermal analysis (TA) would be the technique of choice. The critical issues, controlling fiber performance and the parameters, are conveniently measured by TA overlap. Fiber performance is controlled by the total fiber process history and the key structural elements, nano through micro, imparted to the fiber by this history—crystal morphology, crystallinity, molecular orientation, and phase connectivity are all parameters available through TA techniques. In synthetic fiber manufacture, polymer melts or solutions are converted to fibers by the process called spinning—the conversion of a fluid polymer pool to a continuous, highly uniform filament or yarn (yarn is a multiplicity of filaments) by forcing the polymer liquid through a plate with holes (spinneret), cooling the filament (heat transfer) to the solid state (melt spinning), or by a combination of solvent removal (mass transfer) and cooling. Then, this filamentary product can be further modified structurally by stretching in the solid state (process called drawing), annealing at elevated temperatures, and other related processing steps to provide a product with the desired end-use characteristics through precise control of molecular orientation, crystal morphology, and connectivity between ordered and disordered phases. TA is the characterization technique best suited to define fiber structure and properties and, with a knowledge of fiber manufacturing parameters, fiber processing. Once the parametric correlations of fiber structural features and TA are established, TA provides a rapid and accurate technique for a detailed description of fiber morphology, molecular orientation, and, in some cases, phase interconnectivity. The purpose of this book is to provide the fiber scientist and thermal analyst, focused on fiber materials, an in-depth understanding of how the careful application of TA techniques to fiber problems allows the accurate measurement of key fiber parameters.