Effect of Plasticizers and Fillers on PVC Insulation for LV Cables Used in Radiative Environments

This work investigates how the introduction of plasticizers and inorganic fillers affects the dielectric behavior of PVC insulation. Three formulations of increasing complexity were analyzed: unplasticized PVC, PVC plasticized with di-2-propilheptyl phthalate (DPHP), and a third formulation containing both DPHP and calcium carbonate. Broadband dielectric spectroscopy and breakdown voltage tests were conducted to assess electrical behavior, as a function of additive content. Results show that unplasticized PVC exhibits the most favorable dielectric response, with low conductivity and minimal losses, though its rigidity limits practical applicability. The addition of DPHP enhances flexibility but introduces a marked interfacial polarization peak at low frequencies. Conversely, calcium carbonate acts as an inert filler, producing no significant modification in the dielectric response. Breakdown voltage trends correlate well with the spectroscopy data, confirming the influence of formulation on electrical performance.