Swelling Capacity in Carboxymethylcellulose-Cellulose Hybrid Hydrogels: The Effects of Oxidation with Zinc Chloride and Refining on Cellulose Used as Reinforcement

The focus of the study was to address the issue of hydrogels based on carboxymethyl cellulose having poor gelation strengths when in contact with liquids. In order to enhance this characteristic, cellulose was added to the hydrogels, and their characteristics were examined. Unlike previous studies, cellulose was modified mechanically and chemically before its addition. The pulp was refined using a traditional PFI mill or a supermasscolloider as part of the mechanical modification process. The combination of H2O2 and ZnCl2 was also chosen for chemical modification of the pulp due to their synergistic effect, where ZnCl2 facilitates fiber swelling, and H2O2 enhances Zn²⁺ ions' reactivity, further promoting cellulose oxidation. By creating a cellulosic backbone with higher resistance properties, it is intended to prevent the cellulose-carboxymethyl cellulose complex from dispersing in water. Epichlorohydrin was utilized in different ratios to crosslink modified cellulose and carboxymethyl cellulose in the hydrogel-making process. Fourier transform infrared spectroscopy, Differential scanning calorimetry, and Scanning electron microscopy were used to examine the hydrogels' structural, thermal, and surface characteristics. The results showed that with the modified cellulose addition, the loss of swelling and water absorption properties of the hydrogel due to the increase in cellulose content can be minimized. The swelling capacity of the samples was significantly preserved by refining the cellulose using a PFI mill. However, refining using supermasscolloider did not give satisfactory results. In summary, the study showed that modified cellulose reinforcement may be used to produce hydrogels without significantly altering the swelling capacity of carboxymethyl cellulose-based hydrogels.