Synthesis and characterization of swelling properties superabsorbent Hydrogel Carboxymethylcellulose-g-Poly (Acrylic Acid)/Natrium Alginate cross-linked by gamma-ray irradiation technique

Superabsorbent hydrogel (SAH) is a hydrophilic polymer network that can absorb and retain a large amount of water in swelling conditions. SAH has been synthesized from Carboxymethylcellulose (CMC) with variations in weight (1.0 g, 1.5 g, 2.0 g, 2.5 g) grafted by poly (acrylic acid) (PAA) and composited with natrium alginate (NaAlg). Samples were cross-linked using gamma-ray irradiation technique in a dose 10 kGy (at a dose rate of 5 kGy/hour). CMC can increase porosity and influence swelling properties. Characteristics of swelling properties in aqueous solutions which are influenced by weight variations of the CMC were evaluated, such as aquadest, urea solution with various concentrations (0.25%, 0.50%, 0.75%, and 1.00%) and salt solution of NaCl and CaCl₂ with variation of concentrations (0.09%, 0.9%, and 1.9%). The Swelling ratio in salt solutions decreased significantly compared to in aquadest. Swelling capacity increased with decreasing cation content (Ca²⁺+). A different phenomenon occurs in urea solution, because urea is a neutral molecule, so the presence of urea molecules are not influenced by the electrostatic repulsion of COO⁻ groups in the polymer chain. FTIR measurement showed PAA grafting reaction on CMC and NaAlg cross-linked with gamma-ray irradiation. From SEM measurement the SAH had heterogeneous porosity. (paper)