Biodegradable nanocomposites obtained by ball milling of pectin and montmorillonites.

Two composites of apple peel pectin with 3% of either a natural or an organically modified montmorillonite clay, were prepared using a new alternative method, that relies on solid-state mixing at room temperature high energy ball, milling(HEBM). This technique involves an efficient mixing of the organic and inorganic components by mechanical grinding. The milled powders were cast by water as films and characterized. The absence of the peak, corresponding to the basal spacing of the clay, in the X-ray diffractograms of the composite samples allowed us to suggest that the dispersion of the clay inside the pectin matrix takes place with the exfoliation of the clay sheets. The physical properties such as thermal degradation, elastic modulus, sorption and diffusion of water vapour and oxygen were analysed. It was found that they all were improved in the nanocomposites, in particular in the sample containing the natural sodium montmorillonite.