Water Permeation In Polylactide and Polylactice/Montmorillonite Composites: Experimental Results Versus Theoretical Prediction

Polylactide (PLA) is a well-known renewable and biodegradable polymer that has been widely used in medical and pharmaceutical applications. Uses of PLA in packaging are expanding but are limited by insufficient moisture barrier properties. PLA-clay nanocomposites produced by solvent-casting and melt-blending made a significant improvement in the moisture barrier properties of PLA. For example, a nanocomposite of PLA with 10 wt% motmorillonite reduced the water permeability in PLA by 35%. In this research, water permeation in PLA-montmorillonite composites at different concentrations of montmorillonite was investigated to compare experimental results with theoretical prediction. Specifically, a three-phase model that takes into account the interface region between montmorillonite and the polymer matrix was developed to determine the water permeability of the mixed matrix membrane. By fitting the model to the experimental results, the shape and orientation of montmorillonite particles were estimated and compared with results from wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) techniques.