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.