A Novel Modified Starch/Carboxymethyl Cellulose/Montmorillonite Bionanocomposite Film: Structural and Physical Properties

Abstract

Abstract A novel glycerol-plasticized and citric acid (CA)-modified starch/carboxymethyl cellulose (CMC)/montmorillonite (MMT) bionanocomposite films were prepared from corn starch by casting, to study the effect of the 10% CA, 10% CMC and four different loadings of MMT on the properties of starch films. Atomic force microscopy surface analysis showed that starch/CMC/MMT films had the highest roughness. X-ray diffraction test showed that the clay nanolayers formed an intercalated structure in the bionanocomposites. However, completely exfoliated structure formed only in the pure starch/MMT nanocomposites (without CA and CMC). CA, CMC and MMT improved mechanical properties of starch films. MMT had the greatest effect on the mechanical properties. The MMT addition at content of 7% caused to increase in ultimate tensile strength by more than threefold in comparison to modified starch/CMC films. The water vapor permeability (WVP) decreased significantly ( p < 0.05) by the addition of CA and CMC. When the MMT content of the starch films reached to 7%, the WVP decreased about 75% in comparison to the neat starch film. However, the hydrophilic character of bionanocomposites increased as the increasing of MMT content.