Synthesis of a new superabsorbent copolymer based on acrylic acid grafted onto carboxymethyl tragacanth.

In this research, a new superabsorbent copolymer was synthesized based on the tragacanth gum (TG) via graft polymerization of the acrylic acid onto the carboxymethyl tragacanth (CMT) in the aqueous solution. For this purpose firstly, the carboxymethyl tragacanth was synthesized by reaction of the tragacanth gum and the monochlroroacetic acid in basic conditions. Then the acrylic acid was grafted on the carboxymethyl tragacanth via free radical polymerization. The characterization of the products was carried out by FT-IR, TGA, and SEM analyses. The effects of reaction conditions such as different values of the initiator, monomer and crosslinking agent on water absorbency were investigated. Furthermore, the swelling behavior of the synthesized polymer was evaluated in normal saline, tap water, distilled water, at different pHs and in various degrees of neutralization of the acrylic acid. Finally, by studying the obtained results, optimum conditions for the copolymer with the highest swelling ratio were obtained.