Effect of gamma radiation on carbamoylethylated cotton

Carbamoylethylated cotton samples having 0·392, 0·524, 0·725, 1·379 and 1·546% N were prepared by reacting cotton cellulose in the fabric form with different concentrations of acrylamide in the presence of NaOH. The behaviour of these samples towards gamma radiation was investigated and compared with untreated cotton and alkali-treated cotton which was prepared under conditions similar to those of carbamoylethylation but in the absence of acrylamide. Irradiation was performed at different radiation doses (3·307–29·766 Mrad). Results of copper number and carboxyl content indicated that the carbamoylethylated cotton samples exhibited higher resistance to irradiation than the alkali-treated and untreated cotton samples. Furthermore, this resistance was higher the greater the extent of carbamoylethylation, expressed as % N. With respect to degree of polymerization, results suggested that the presence of the carbamoylethyl groups in the molecular structure of cotton cellulose impeded glucosidic bond scission, provided that these groups were present in relatively small amounts. This and the indication of differences between the tensile strength and elongation at break among the substrates examined were interpreted in terms of differences in microstructural features which, in turn, determine the susceptibility of each substrate to irradiation irrespective of the radiation dose used.