SOLUBILITY TESTS AS A MEASURE OF WOOL MODIFICATION

Abstract

The sensibilities of some solubility tests were examined to estimate the degree of damage to wool during the textile processing.
Merino tops were used as samples. The residual grease on wool was removed by Soxhlet extraction with methylene chloride in order to minimize a possible damage due to the rise of temperature. The samples were then rinsed thoroughly in distilled water and dried at the room temperature. Samples subjected to alkaline treatments of increasing severity were prepared by treating the above-mentioned Merino tops in sodium carbonate solution.
The amounts of cystine, lanthionine and total sulphur in wool modified by the alkaline treatment were determined by phospho sodium tungstate method proposed by Zahn, paper chromatography proposed by Dowling, and Calius method. The time of half-dyeing of each sample was then measured to find the relations between the degree of damage and the rate of dyeing.
Urea-bisulfite solubility tests proposed by Lees and Elsworth is very sensible to the alkaline treated wool. In the present paper, the sensibilities were examined using thiourea, thiodiglycol and ε-caprolactum in place of urea. It was found that thiourea-bisulfite solubility test is more sensible than to urea-bisulfite solubility test and that the results by the former showed smaller dispersion values than by the latter. The time of half-dyeing and the urea-bisulfite solubility were decreased by the alkaline treatment.
A part of cystine in wool is transformed into lanthionine by the alkaline treatment, and this reaction proceeds in a fairly short time and markedly at temperatures above 50°C.