Effect of preswelling on radiation degradation of cotton cellulose

Complete text of publication follows. Cotton cellulose was swollen in sodium hydroxide (1, 3, and 6 M) and tetramethylammonium hydroxide (TMAH, 1, and 3M), respectively, in the presence of air. Samples after neutralization and drying were irradiated in open air (3, and 10 kGy). Effect of swelling alone and that of the combined treatment were studied. Swelling: At higher alkali concentrations cellulose I-cellulose II transition was observed by X ray diffraction, the ratio of amorphous phase did not change significantly. Degradation during swelling, characterized by the degree of polymerization (DP), the FTIR spectra of polymer, and the amount of small molecular products, was higher in solution of TMAH than in NaOH. It seems to be the consequence of the higher swelling ability of TMAH observed in previous works. This result was attributed to the large size and non-polar part of tetramethylammonium cation able to penetrate into the non-polar sheets of cellulose, furthermore, to the extremely high activity of TMAH in aqueous solution. Irradiation: Samples were irradiated in dry form (water content about 8-10 %). Irradiation can result in degradation and crosslinking of macromolecules simultaneously. The viscosity of the polymer solution measured after irradiation should be the resultant of these two effects. According to viscosity data more crosslinks were developed during irradiation in samples preswollen in TMAH than in the corresponding samples preswollen in NaOH. This phenomenon can be explained by the higher mobility of the molecules, which causes a higher probability of recombination of radicals and formation of crosslinks meanwhile. This is a new proof for higher swelling ability of TMAH in comparison with NaOH