Surface-Chemical Aspects of Polymer Spreading and Adhesion to Wool Fibers

Attempts to shrink-resist unmodified wool sliver with liquid prepolymers are described. Only liquid prepolymers with surface tensions less than 30 mN/m spread spontaneously on unmodified wool fibers when applied from either an organic solvent or an oil-in-water emulsion. Such treatments give good shrink resistance when the sliver is washed in a liquor with high surface tension, but they fail in wash liquors of low surface tension, suggesting that adhesion at the wool/polymer interface is provided solely by van der Waal's forces. When the polymers are applied under conditions that facilitate diffusion of polymer molecules into the surface of the fibers, shrink resistance is improved, presumably because of enhanced adhesion.