Synthesis of carbamoylethyl Cassia angustifolia seed gum in an aqueous medium.

The Cassia angustifolia seed gum (CAG), a galactomannan, isolated from the seeds of C. angustifolia was subjected to the carbamoylethylation which involved the reaction of CAG with acrylamide in an aqueous medium (water) in the presence of alkali (NaOH) as a catalyst. Alkali concentration, acrylamide concentration, liquor:gum ratio as well as reaction temperature and time were found to affect the extent of carbamoylethylation of CAG (expressed in terms of nitrogen content) and so, these were optimized. Degree of substitution (DS) and reaction efficiency was also determined. FTIR revealed the successful carbamoylethylation of CAG and rheological study conducted on 1 and 2% (w/w) solutions of the carbamoylethyl-CAG not only brought out the non-Newtonian pseudoplastic behaviour, but also high stability of carbamoylethyl-CAG solutions in comparison to solutions of the unmodified CAG.