The Mechanism by Which Oxidizing Agents Minimize Strength Losses in Wool Dyeing

Abstract

Introducing potasium bromate (KBrO3), an oxidizing agent, during wool dyeing minimizes the decrease in tensile failure properties of the wool. The effect is more pronounced when the fibers are in a highly curved state, such as when the wool is in fabric form. An explanation for the protective effect of KBrO3 is proposed in terms of the uneven distribution of stress that occurs when fibers, set in a curved configuration, are subjected to a tensile strain. The effects of curvature and set on the physical properties of single wool fibers have also been investigated, using tensile tests and scanning electron microscopy, and lend support to this theory. Tensile modulus values are relatively unaffected by setting operations but are highly sensitive to the degree of curvature in the fiber. The decreased stiffness of the curved fibers is attributed to the disruption of a stable network of secondary bonds between the polypeptide chains.