Investigation of thermal and dielectric behaviour of PVA–ZnO nanocomposite films.

The aim of the work is to study the impact of different concentration of zinc oxide (ZnO) nanofillers on the thermal, molecular dynamics and dielectric properties of poly(vinyl alcohol) (PVA) nanocomposites. The PVA–ZnO nanocomposite films are prepared by varying the loading of ZnO ranging from 0.5 to 2 wt% by solution casting method. The films are characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, UV–visible absorption spectroscopy. In PVA–ZnO nanocomposite film, hexagonal phase (P63-mc) of ZnO with PVA peak at 19.91 is found. The calculated size of ZnO is 21 nm. Further, Thermogravimetric, differential scanning calorimetry and dielectric measurement of PVA–ZnO nanocomposite films are showing good results at 1wt.% ZnO nanofillers in PVA. Improved thermal stability with about 45% residual weight at 325 °C and crystallinity (16.5%) at 300 °C are obtained for1wt% ZnO in PVA. Integration of ZnO nanoparticles into PVA exhibit greater effect on optical, thermal, and dielectric properties due to large surface area and availability of more interfacial sites for interactions. FTIR study confirms the chemical interaction of OH and C–O groups of PVA with surface of ZnO. At 1wt% ZnO nanofillers in poly (vinyl alcohol) has shown higher optical band gap, melting temperature, and change in enthalpy. Dielectric properties are evaluated at frequency ranging from 100 to 5 MHz. Among all PVA–ZnO nanocomposite films, 1wt% ZnO in PVA has presented relatively high dielectric constant (12.46) at 4 MHz with low tangent loss. It is attributed to accumulation of charges between boundaries of ZnO and PVA. Thus, the present comprehensive study provides an insight into the fabrication of PVA–ZnO nanocomposites for polymeric electronic device in microwave frequencies and optical sensor. [ABSTRACT FROM AUTHOR]