The Chemical Modification of Wool—Treatment with Formaldehyde Solutions

Abstract

A study was made of the reaction of formaldehyde with wool in order to determine optimal conditions for the production of wool that is more stable to alkali, as measured by the alkali- solubility test. Extremely mild treatments with dilute formaldehyde solutions confer an appre ciable degree of alkali-resistance to the wool, presumably by the formation of cross-links, and optimal alkali-resistance was obtained by treatment with 0.5% formaldehyde solutions at pH 6 to 8 for 6 hrs. at 50° C. Under these conditions, cystine linkages are not involved to any appre ciable extent, and the acid-combining capacity of the wool is changed only slightly. Although loss of sulfur from formaldehyde-treated wool occurs readily on treatment with hot alkaline solutions, the rate of loss of both sulfur and weight is less than in the case of untreated wool. The chemical evidence cited is in agreement with the view expressed elsewhere that additional cross-linkages are introduced in the wool molecule as a result of treatment with formaldehyde solutions. The lability of these new cross-linkages on exposure to acidic or hydrolytic condi tions is noted, and this behavior is compared with that of wool modified by other chemical reactions. Some comparisons are made with the use of the formaldehyde reaction in the regen erated protein-fiber field.