Evaluating Ester Crosslinking of Cotton Fabric by a Polycarboxylic Acid Using Acid-Base Titration

Polycarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid (BTCA) have been the most promising nonformaldehyde durable press finishing agents to replace the traditional N-methylol reagents. High levels of smooth fabric appearance are the direct result of ester crosslinking of cotton cellulose by a polycarboxylic acid, and appearance is therefore determined by the amount of ester crosslinks formed on the fabric. In this research, we use acid-base titration to evaluate ester crosslinking by measuring the concentrations of the ester and the free carboxylic acid and the percent of carboxyl groups forming crosslinks on the cotton treated with BTCA. We correlate the wrinkle resistance of the treated cotton with the ester concentration on the fabric. The linear correlation between wrinkle-recovery angle and ester concentration indicates that ester concentration determined by titration can be used as the basis for evaluating the effectiveness of crosslinking for durable press finished cottons.