effect of nanoclay (montmorillonite) on water vapour permeability, contact angle and thermal properties of carboxymethyl cellulose-polyvinyl alcohol based nanocomposite films

the high hydrophilic property of biopolymer based plastics is one of the most important defects of them. blending biopolymers with compatible synthetic polymers and using nano particles such as nanoclay as nanofiller are improving methods that have been extensively considered in recent years. carboxymethyl cellulose (cmc) is one of the lowest cost biopolymers that have enormous applications in different industries and polyvinyl alcohol (pva) is a synthetic polymer which has a high compatibility with biopolymers. in this research, cmc-pva nanocomposites containing 3-10% montmorillonite (w/w cmc) were prepared by casting method. the x-ray diffraction (xrd) results indicated the formation of an exfoliated nanostructure in all mmt content samples. nanocomposites containing 10% mmt exhibited 29.06% reduction in water vapor permeability (wvp) compared to the blend film without nanoclay. samples with 10% mmt, showed the lowest surface hydrophilisity (contact angle = 65.1o). the differential scanning calorimetry (dsc) results indicate that by increasing of mmt contents, the glass transition disappeared gradually and no glass transition was observed in the thermograms of the films containing 5, 7 and 10% mmt.