Grafted SiC nanocrystals: For enhanced optical, electrical and mechanical properties of polyvinyl alcohol

Abstract

Polyvinyl alcohol (PVA) grafted SiC (PVA-g-SiC)/PVA nanocomposite was synthesized by incorporating PVA grafted silicon carbide (SiC) nanocrystals inside PVA matrix. In-depth structural characterization of resulting nanocomposite was carried out using fourier transform infrared spectroscopy (FTIR), raman spectroscopy and X-ray diffraction (XRD) measurements. UV–Visible absorption spectroscopy was used to study optical properties such as optical energy gap (Eg), Urbach's energy (Eu), refractive index (n), real (ε1) and imaginary (ε2) parts of dielectric constant of PVA as well as PVA-g-SiC/PVA nanocomposite film. Refractive index of PVA increased from 1.5 to 2.0 for PVA-g-SiC/PVA nanocomposite film containing 0.015 wt% of PVA-g-SiC nanocrystals at 550 nm wavelength. Dispersion of refractive index was analyzed using the Wemple–DiDomenico single oscillator model and dispersion parameters (E0 and Ed) were determined. Microhardness measurements performed at an applied load of 9.8 mN showed an increase in the Knoop microhardness number (KHN) of PVA containing 0.015 wt% PVA-g-SiC nanocrystals. Detailed analysis of current-voltage data indicates that the conduction mechanism responsible for increase in conductivity of PVA-g-SiC/PVA nanocomposite film is voltage dependent and Schottky mechanism is the dominant conduction mechanism at medium and high voltage regions.