Influence of TiO2 Nanoparticles on the Morphological, Thermal and Solution Properties of PVA/TiO2 Nanocomposite Membranes

Polyvinylalcohol/titanium dioxide (PVA/TiO2) nanocomposite membranes were prepared by dispersing hydrophilic fumed TiO2 nanoparticles into the polymer matrix. The influence of TiO2 nanoparticles on the morphological, thermal and solution properties of PVA/TiO2 nanocomposite membranes was investigated using FESEM, XRD, DSC, TGA, rheometer, zeta sizer and contact angle meter. FESEM analysis shows that TiO2 nanoparticles up to 30wt% are dispersed homogeneously in the membranes without aggregation and covered by PVA polymeric chains. Above 30wt% TiO2 content, the level of aggregation increases, and at 50wt%, it was significant. The incorporation of TiO2 nanoparticles into the PVA matrix lowers the primary crystallinity of PVA and by inducing new crystalline regions due to TiO2; the overall crystallinity of the nanocomposite membranes is modified. Thermal stability of the composite membrane is improved by the addition of TiO2 nanoparticles. The increase of TiO2 concentration in PVA/TiO2 suspension has shown a transition in the regime of suspension from Newtonian to shear thinning starting at 10wt% TiO2. At low concentration of nanoparticles, the shear thinning behavior at lower shear rate is less. The shear thinning behavior increases as the concentration of TiO2 is increased. The conductivity of PVA/TiO2 dispersions is lower than PVA which indicates the formation of clusters, leading to decrease in number of charge carriers and their mobility. The zeta potential increases with increasing TiO2 content, which shows that PVA/TiO2 suspension is stable at higher content of TiO2. The hydrophilicity of PVA/TiO2 nanocomposite membranes increases as the loading of TiO2 is increased in the membrane.