Influence of Plasticizers on Mechanical and Thermal Properties of Methyl Cellulose-Based Edible Films

Methyl cellulose (MC) films plasticized with malic acid (MA) and sorbitol (SOR) were prepared by casting solution and the influence of plasticizers at different concentrations (10, 20 and 30/100 g dry MC) on the mechanical and thermal properties were investigated. A decrease in tensile strength of the plasticized films was observed with increase in quantity of plasticizer. On the contrary, percentage elongation at break increased with an increase in plasticizer concentration that was more pronounced in SOR plasticized films. Films prepared with SOR exhibited higher water affinity and resulted in greater moisture absorption. Thermal stability was reduced with the addition of plasticizers and the SOR film samples were more thermally resistant as compared to MA-added films. FTIR analysis demonstrated the hydrogen bonding interactions between the functional groups of MC and plasticizers. The SEM micrographs of all the films showed a smooth and homogeneous surface morphology. The X-ray diffraction analysis suggested a semi-crystalline nature of the plasticized films.