Synthesis of carboxylated locust bean gum hydrogels by ionizing radiation

•Carboxylation of LBG by TEMPO mediated oxidation described.•Preparation of CLBG hydrogels in paste like conditions, and in the presence of acetylene gas explained.•Influences of the degree of carboxylation and dose rate on the gelation of CLBG examined.

In the present study, a locust bean gum (LBG) was carboxylated by a technique known as TEMPO mediated oxidation. Characterization of the carboxylated LBG (CLBG) was performed by spectroscopic and chromatographic techniques. The CLBG was then irradiated with gamma rays utilizing a 60Co gamma-ray source at the dose rates of 30 Gy/h and 300 Gy/h up to 10 kGy in very concentrated solutions called as “paste-like” and in the presence of acetylene. Sol–gel analysis was carried out in order to determine the polymer-to-gel conversion ratios. It was found that the swelling capacity of the hydrogels prepared in the presence of acetylene increased with dose from 19,000% to 34,000%. The gelation percentage was observed to increase rapidly up to 5.0 kGy, which then continued to increase at a slower rate. Despite low gelation, the crosslink density of the CLBG hydrogels prepared in the paste-like state was observed to be high.