Poly(vinyl alcohol) nanocomposite films: Thermooptical properties, morphology, and gas permeability

Poly(vinyl alcohol) (PVA)/saponite nanocomposites were prepared with various clay concentrations with the solution intercalation method. The intercalations of the polymer chains in the clay were examined with wide-angle X-ray diffraction and transmission electron microscopy. The variations of the dispersion, morphology, thermal properties, and gas permeability of the nanocomposites with clay concentrations in the range of 0-10 wt % were examined. Up to a 5 wt % clay loading, the clay particles were highly dispersed in the PVA matrix without any agglomeration of particles. However, some agglomerated structures formed in the polymer matrix above a 7 wt % clay concentration. The thermal stability of the hybrids increased linearly with increases in the clay loading up to 10 wt %. To measure the oxygen permeability and optical properties of the PVA hybrid films, the PVA hybrid solutions were coated onto both biaxially oriented polypropylene and poly(ethylene terephthalate) films, which were used as polymer substrates. The oxygen permeability values monotonically decreased with increases in the clay loading in the range of 0-10 wt %. The optical properties, such as the haze and gloss of the hybrid films when coated onto the matrix films, were nearly constant, that is, independent of the clay loading. These improvements arose because of the largely nanometer-scale dispersion of the clay layers. (c) 2006 Wiley Periodicals, Inc.