Starch–Cellulose Ether Films: Microstructure and Water Resistance

Abstract

AbstractIn this study, composite films of corn starch, methylcellulose and carboxymethylcellulose plasticized by glycerol or polyethylene glycol (PEG) were prepared and the effects of blending level as well as the plasticizer type on the microstructure, water vapor permeability (WVP), opacity and solubility properties were investigated. Scanning electron Microscopy (SEM) observations showed homogeneous matrix of glycerol plasticized films and it was taken as an indicator of structural integrity. PEG plasticized films exhibited discontinuous surface, and this was attributed to phase separation. WVP of the films was found between 1.5 × 10−11 and 13.3 × 10−11 g/s m Pa and composite films were more resistant to water than starch film. However, WVP values were significantly higher than many of the synthetic films; as a result, one of the potential applications for presented films might be utility as a hydrophilic polymer layer in active food packaging applications. Among the factors studied, the plasticizer type was the most effective factor on the opacity of the films. Besides, differences in solubility were attributed to the differences in their structural integrity.Practical ApplicationsStarch films have good barrier properties to oxygen, carbon dioxide and lipids; however, they have limited mechanical properties and water vapor resistance. In the presented study, this problem is overcome by blending with cellulose ethers and water resistance is improved up to six folds. The developed films are in hydrophilic character when compared to conventional synthetic films such as PE and PP. Therefore, the developed films are quite appropriate to be used as a carrier polymer matrix for active hydrophilic and/or volatile compounds in active food packaging applications. Another potential applications of those films presented in this study is utilization as edible film layer where mechanical and permeability resistance needed.