Preparation and Study of Physical Properties of Starch-CMC Biodegradable Composite Film Containing Montmorillonite Nanoparticles

Novel citric acid modified starch-carboxy methyl cellulose (CMC) -montmorillonite (MMT) bionanocomposite films were prepared by casting method and the effect of MMT on the structural and physical properties of the starch-CMC biocomposites was studied. X-ray diffraction test showed that strong polar interactions between the hydroxyl groups present in the starch and CMC chains and in the silicate layers led to intercalation of biopolymer chains into MMT layers galleries. The water vapor permeability decreased from 2.44 to 1.13×10-7 g/mhPa as the MMT percentage increased from 0 to 7%. At the level of 7% MMT, the composite films showed the highest ultimate tensile strength (27.55 MPa) and lowest strain-to-break (18.25%). The DSC tests showed that, the temperature position of the melting peak increased from 221.5°C to 243.0°C as MMT content increased from 1 to 7 %, but the glass transition decreased and gradually disappeared.