Wool Felting and Electrostatic Interaction Between Wool Fibers in Salt and Detergent Solutions

Abstract

The Derjaguin-Verwey-Overbeek theory of the ionic double layer is applied to problems in wool felting. The electro static repulsion between ionized wool fibers in aqueous salt solutions is shown to range from a very small value for natural wool to over 30 ergs/cm² of contact area between chemically modified fibers with a high surface charge. In the latter case, such repulsion may reduce significantly the hydrophobic attraction beteeen the fibers and thus reduce or eliminate their felting tendency. The theory is applied to results by Meichelbeck and Knittel on modified wool with a high con centration of either acidic or basic groups. The effects of fiber modification, of solution pH, and of fiber blending on felting follow predicted trends. The influence of ionic detergents on felting is understood in terms of strong adsorption of detergent ions at oppositely charged sites at the fiber surface, or weak adsorption at hydrophobic surface sites.

Keywords

Wool fibers. Chemically modified wool. Washing pH DCCA-sulfite;carboxymethylation;aminoethylation. Surface charges electrostatic repulsion ionic double layer hydrophobic interaction salt solutions detergent adsorption. Wool felting. Shrink resist.

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