Effect of microcrystalline cellulose on the structure and performance of corn starch/rosin films for biodegradable packaging

The development of packaging materials derived from renewable resources presents a sustainable alternative to conventional petroleum-based plastics. This study focuses on the fabrication and comprehensive characterization of fully bio-based composite films made of corn starch, microcrystalline cellulose (MCC), and rosin. Systematic analysis using thermal (TGA, DSC), structural (XRD, FTIR), and morphological (SEM) techniques revealed that MCC significantly enhanced the crystallinity of the films -increasing from 28.65% to 40.13% through the formation of inter- and intra-molecular interactions, thereby reinforcing the composite matrix and enhancing the thermal stability. An MCC content of 10 wt% was found to optimally balance hydrophobicity and water vapor barrier properties in the starch–rosin films. The composites demonstrated superior biodegradability compared to both low-density polyethylene (LDPE) and native starch films. Furthermore, rheological (i.e. creep-recovery) and tensile tests indicated that a 20 wt% MCC loading yielded the best creep resistance, recovery performance and tensile strength, achieving an ideal equilibrium of flexibility (imparted by 5 wt% rosin and glycerol), mechanical strength, and structural integrity. Finally, meat preserving tests showed promising results in food storage applications. These results underscore the significant potential of Starch–MCC–Rosin composites as eco-friendly food packaging materials with customizable functional properties.