Tailoring carboxymethyl cellulose-based food packaging films blended with polyvinyl alcohol and nano-MMT for enhanced performance and shelf life

This study investigated the impact of glycerin plasticization, polyvinyl alcohol (PVA) and nano-montmorillonite (MMT) compounding, and organic acid cross-linking agent on the mechanical, microstructural, crystallinity, water absorption, and thermal characteristics of carboxymethyl cellulose (CMC)-based films. The developed manufacturing technique resulted in substantial improvements in the film's tensile strength and Young's modulus, which increased by 240% and 840%, respectively. However, there was a 27% reduction in elongation at break. Scanning electron microscopy revealed that the optimal MMT concentration, which prevented agglomeration within the polymer matrix, was 4 wt.%. Evaluations of hydrophilicity/hydrophobicity demonstrated a 24% reduction in moisture absorption and a 41% decrease in water vapor permeability for the CMC-based films. This reduction significantly lowered the solubility and swelling degree of the films by 63% and 93%, respectively. Notably, beyond a cross-linker concentration of 15 wt.%, this contribution diminished slightly. Thermal analysis indicated that glycerin reduced the film's glass transition temperature from 76.2 °C to 68.9 °C, while the addition of PVA and MMT increased this temperature by 22% and 53%, respectively. The optimal formulation for an effective food packaging film was identified as CMC/PVA/glycerin at a 1/1/2 ratio, with 4 wt.% MMT and 15 wt.% cross-linker. The resulting film demonstrated an improved shelf life for food products compared to polyethylene alternatives.