Reaction Kinetics and Physical Properties of Carboxymethyl Cellulose-Based Hydrogel Blends for Food Packaging

Carboxymethyl cellulose (CMC) is a commonly studied polymer made by chemically modifying cellulose to increase water dispersability. CMC is widely used in hydrogel applications because of its biocompatibility and biodegradability. CMC hydrogels are used as absorbents, for food packaging, as additives in pharmaceutical formulations, and for other applications. CMC hydrogels can be synthesized using a variety of chemical and physical crosslinking agents. Here, ethylene glycol diglycidyl ether (EGDE) is used as a chemical crosslinker. The optimal cross-linking temperature and EGDE concentration were determined using <i>in-situ</i> oscillatory shear rheology, and other properties, such as the water vapor permeability, swelling ratio, tensile strength, and % elongation at break of the hydrogels were also measured to assess their usefulness for food packaging applications. These hydrogels were found to have unsatisfactory bulk and mechanical properties for food packaging materials, so blends of CMC with various polysaccharides have been investigated to search for synergy between the different biopolymers. In particular, κ-Carrageenan and Xanthan gum were chosen for this study; both are common anionic polysaccharides with excellent gelling, stabilizing ability, emulsifying, and thickening properties. These blends were chosen due to CMC being easy to use, readily available, and cheap. Additionally, this study focuses on finding a correlation between rheology, and bulk properties, such as tensile strength, water vapor permeability, and % elongation at break.