Structural Characterization of Wool by Thermal Mechanical Analysis of Yarns

A thermomechanical analysis of yarns in a tensile mode is used to characterize wool fibers modified to show the β-crystal form in comparison with native untreated wool retaining the α-crystal form. The TMA curves show that fiber extension causes significant structural modification of the wool samples. In particular, melting of the α-form crystallites in native wool can be detected at around 215°C, with supercontraction prior to effective crystallite melting. But extended wool yarn shows no thermal mechanical event corresponding to melting of the β-form crystallites. Extended wool has a thermal mechanical behavior similar to that of silk yarn.