Hydrogel of biodegradable cellulose derivatives. II. Effect of some factors on radiation-induced crosslinking of CMC

The effects of high‐energy radiation on sodium carboxymethylcellulose (CMC) with a degree of substitution of 2.2 were investigated. Moderate CMC concentrations formed hydrogels by intermolecular crosslinking. Significant influences on the results of irradiation, in addition to the concentration, were the dose and dose rate and the presence of oxygen in the surrounding atmosphere. Up to a 95% gel fraction was obtained from 50 and 60% CMC solutions irradiated by an electron beam. CMC hydrogels swelled by absorbing more than 800 g of water per gram of dry gel at a low applied dose. Swelling tests of CMC hydrogels in salt solutions and in media of various pHs showed that the swelling decreased with the salt concentration and was lower at acidic pH values. Radiation yields of crosslinking and scission were calculated on the basis of gel–sol analysis. Crosslinked CMC, in the form of the hydrogel, was degraded by the action of cellulase enzyme, thereby entering the class of environmentally friendly polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3030–3037, 2001