Chemical modification of cotton cellulose in supercritical carbon dioxide: Synthesis and characterization of cellulose carbamate

Chemical modification of cotton cellulose in supercritical carbon dioxide has been studied and cellulose carbamate has been successfully synthesized. Compared with the conventional carbamate process, the supercritical method had remarkably increased the nitrogen content of the modified cellulose. The effects of impregnating pressure, esterification temperature and esterification time on the nitrogen content of the products were discussed. The modified cellulose was characterized by Fourier transform infrared spectroscopy (FTIR), NMR spectrometer, X-ray diffraction (XRD), and thermogravimetry (TG). In addition, the surface morphology of modified cellulose fibers was investigated using scanning electron micrographs (SEM).