Effect of poly(vinyl pyrrolidone ) on the morph ology and physical properties of poly(vinyl alcohol) /sodium montmorill onite nanocompos ite films

Nanocomposites of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP) and sodium montmorillonite (NatMMT) were prepared by solution mixing and then cast into films. X-ray diffraction analysis and images of transmission electron microscopy establish the formation of PVA/NatMMT intercalated nanocomposite. Exfoliated and highly intercalated PVA/PVP/Na tMMT nanocomposite formed in the presence of PVP. Inclusion of PVP in PVA/NatMMT matrix enhances the hydrogen bonding interactions between PVA and NatMMT and thus increases the mechanical properties and thermal stability of PVA/PVP/NatMMT nanocomposites compared to PVA/NatMMT nanocomposite. The interactions between PVA, PVP and NatMMT were established by the Fourier transform infrared spectroscopy. The moisture absorption tendency of both the PVA and PVA/PVP films reduced after the incorporation of NatMMT at 75% constant relative humidity. Differential scanning calorimetry studies show that the presence of PVP and NatMMT both are responsible for reducing the heat of fusion, and crystallinity of PVA. The flow behavior of the PVA, PVA/PVP and its nanocomposite solutions has been also studied. Water vapor permeability of PVA/PVP/NatMMT composite films decreased in the presence of nanoclay due to increasing tortuous paths for diffusion.