Preparation and characterization of chitosan/montmorillonite-K10 nanocomposites films for food packaging applications

Chitosan (CS)/montmorillonite-K10 (MMTK-10) clay composite films with different amounts of the clay MMTK-10 (0.5, 1, 2.5, and 5%) were prepared using a solution-casting method, and their properties were determined. The objective of this study is to prepare CS/clay nanocomposites and then to investigate the effects of clay content on mechanical, barrier, and thermal properties of these nanocomposites. The prepared films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, and scanning electron microscopy. Barrier properties (oxygen and water permeability), mechanical properties (tensile strength and elongation), and thermal behaviors (thermogravimetric analysis) were investigated and compared. The water vapor and gas permeability values of the composite films decreased significantly with increasing filler concentration. Tensile strength of the composites increased significantly with the addition of clay, and elongation at break decreased with increasing clay concentration. The tensile strength of nanocomposites is up to 34.82 MPa for 5 wt% clay content, and the tensile modulus shows a 74.63% higher value than that of neat CS. The resulting films had an opaque appearance, which depended on the amount of MMTK-10 added. The oxygen permeability decreased with the increase in MMTK-10. The minimum oxygen permeability (1.54 cm3/m2 day atm) was recorded for film with 5% MMTK-10. The water permeability of the composite films decreased significantly between 13 and 22% when clay was added. The dispersed clay improves the thermal stability and enhances the hardness and elastic modulus of the matrix systematically with the increased loading of clay. POLYM. COMPOS., 33:18741882, 2012. (C) 2012 Society of Plastics Engineers