Evaluation of dielectric properties for PVC/SiO2 nanocomposites under the effect of water absorption.

Adding nanoparticles (NPs) to a base polymer matrix which is known as nanocomposites results in improving its dielectric properties. In this paper, the evaluation of polyvinyl chloride (PVC)/silica nanoparticles (SiO₂) nanocomposites is carried out considering the effect of water absorption. PVC nanocomposites are prepared considering different filler loadings of SiO₂ NPs (1, 2.5, 5, and 7.5 wt%). The preparation of PVC/SiO₂ nanocomposites is chemically carried out by casting the solution. The chemical structure of PVC/SiO₂ nanocomposites after water adsorption is investigated by Fourier transform infrared (FTIR) spectroscopy. The effect of water absorption is carried out by immersing nanocomposite samples in tap water. The AC breakdown strength of PVC/SiO₂ nanocomposites is measured before and after water immersion. In addition, both dielectric constant (έ) and loss tangent (tan δ) are measured considering different frequencies before and after the water immersion. The results show that the dielectric properties of PVC/SiO₂ nanocomposites are significantly affected by water absorption, where PVC/SiO₂ nanocomposite sample with filler loading of 7.5 wt% is found to have lower water absorption compared to the other adopted filler loadings. Under the effect of water absorption, the breakdown strength of the base and PVC nanocomposite samples is decreased, and its value for PVC nanocomposite still exceeds the base polymer. Finally, the dielectric constant and dielectric loss of PVC samples are increased under the effect of water absorption. The increase in dielectric constant and dielectric loss is small at the higher filler loadings. [ABSTRACT FROM AUTHOR]