Search

Electric cables play a crucial role in transmission and distribution systems. Polyvinyl chloride (PVC) is extensively used in cable insulation. In this work, PVC samples filled with nanosized ZnO and MgO particles are prepared. The effect of external electric field during sample preparation on the dielectric properties of PVC nanocomposites (NC) is evaluated. Accordingly, the samples are subjected to horizontal and vertical external electric fields during the preparation process. The evaluation is carried out considering different nanoparticle concentration levels. The studied concentration levels are 0.5, 1, 3 and 5 wt% for both adopted nanofiller types. Breakdown strength of the prepared NC samples is measured according to American society for testing and materials standard. Also, relative permittivity and dielectric loss of the prepared NC samples are measured. The evaluation is carried out considering horizontal and vertical electric fields. The obtained results show significant effects on the dielectric properties of the tested samples. Hence, the results show that the external electric field decreases relative permittivity and dielectric loss; however, it increases the breakdown strength of PVC NC. Applied horizontal electric field during sample preparation gives more improvement in dielectric properties of PVC NC compared to vertical electric field. Finally, the interpretation of the obtained results is highlighted and discussed. [ABSTRACT FROM AUTHOR]

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]