Reinforcement and Toughening of Thermo-Compressed Guar Gum Films with Untreated Rice Husk for Eco-Friendly Packaging Applications

This study investigates the fabrication of eco-friendly composite films based on guar gum (GG) reinforced with untreated rice husk (URH) powder (5–30 wt%) via a thermocompression process. To the best of our knowledge, this is one of the first demonstrations of directly utilizing untreated rice husk as a multifunctional reinforcing filler in GG-based bioplastics without any chemical or surface modification, thereby eliminating energy-intensive pretreatment steps. Particle dispersion and interfacial adhesion were optimal up to 10 wt% loading, above which agglomeration occurred. The incorporation of URH enhanced the thermal stability of the matrix. Mechanical performance peaked at 10 wt% URH, exhibiting a 90% increase in tensile strength, a 32% increase in elongation at break, and a 246% improvement in toughness compared to the neat GG film. Furthermore, URH addition reduced moisture content and water vapor permeability while increasing the water contact angle. Although film opacity increased, the results demonstrate that URH acts as an effective multifunctional filler. These GG/URH composite films exhibit strong potential for scalable industrial applications in eco-friendly food packaging, including disposable pouches and trays, offering a sustainable alternative to petroleum-based plastic materials.