Preparation and optimization of guar-based rolling films with enhanced physicochemical properties

The escalating concerns over plastic pollution have spurred interest in exploring bio-based sustainable alternatives. This research aims to develop guar galactomannan films through a cast-drying approach and enhance their mechanical and functional properties through incorporation of cellulose nanocrystals (CNC), microcrystalline cellulose (MCC), and glycerol in various concentrations. The resulting guar-based films exhibit remarkable flexibility, strength, smoothness, and uniformity with self-rolling and unfolding behavior when sequentially exposed to acetone and water. The neat guar films exhibit light transmittance of ∼ 61 % at 600 nm, thermal stability up to ∼ 290°C, tensile strength of ∼ 63.0 MPa, and strain capacity of ∼ 2.6 %. The incorporation of 30 % CNC leads to a significant improvement in tensile strength, reaching 87.4 ± 2.1 MPa, while the incorporation of MCC leads to a substantial improvement in strain. The incorporation of CNC and MCC enhances the thermal stability of guar films, with a significant improvement at 30 % CNC loading, while glycerol-plasticized films also exhibit significantly improved stability. Incorporating 20 % and 30 % MCC and CNC leads to a marked improvement in thermal stability. Additionally, glycerol plasticization exhibits a concentration-dependent increase in percent strain and work-to-break, reaching up to 75 % strain and over a four-fold increase in work-to-break. Moisture absorption is significantly reduced with MCC and CNC, with 30 % CNC yielding the lowest uptake (∼ 8.5 %) due to increased hydrogen bonding. In contrast, glycerol enhances moisture sensitivity by disrupting polymer interactions. This study also reports distinctive self-rolling and unfolding behavior of guar films when sequentially exposed to acetone and water, attributed to differential swelling at the top and bottom surfaces of the films. These findings underscore the novel self-rolling capability of guar-based films, alongside their tunable properties, offering a promising avenue to mitigate the environmental impact of conventional plastics.