An easy and accurate method for determining degree of substitution on carboxymethylated cotton fabric

Carboxymethyl cellulose (CMC) is a common cellulose ether used in many industries including food, pharmaceuticals and personal care, chemicals, drilling fluids, paper as well as textile. The degree of substitution (DS) affects final CMC properties primarily, and thus it must be precisely measured before use. There are various methods for determination of DS when CMC is in powder form, however, methods for determination on the fabric are limited to back titration. Conventional titrimetric methods include reactions with a variety of chemicals and timely titration practices whose accuracy depend mainly on high level of expertise of the operator. An easy-to-apply alternative method with high repeatability is thus needed. In this study, a quick method comprising staining with a well-known dyestuff, namely Methylene Blue, followed by short rinsing-drying, and K/S measurement with spectrometer is offered for determination of degree of substitution of CMC. A precisely followed titration procedure is also carried out. It is shown that the results of newly offered method correlates very well with those of titration method. This alternative method is easier to apply, offers visual evidence and dyeing solution can be used again by addition of expended chemicals and dyestuff, if desired.