Dielectric and thermo-kinetic properties of SiC/PS composite: Depending on the filler concentration

Abstract

In this study, the structural, dielectric, electrical, thermal, and thermo-kinetic properties of silicon carbide (SiC)/polystyrene (PS) nanocomposites containing 1–10% SiC were systematically investigated. Degradation kinetics were analyzed using the Coats–Redfern method. Pure PS exhibited low dielectric loss (tan δ ≈ 0.01–0.02) with weak frequency and temperature dependence, indicating efficient energy storage and minimal dissipation. Incorporation of SiC progressively increased low-frequency dielectric loss, reaching 0.12–0.15 at 7–10% loading. This behavior is attributed to Maxwell–Wagner–Sillars interfacial polarization and the gradual formation of quasi-conductive pathways near the percolation threshold. Temperature effects became more pronounced at higher SiC concentrations, reflecting thermally activated carrier transport and reduced interfacial relaxation times. AC conductivity (σac) evolved from polarization-limited conduction in pure PS (10⁻¹²–10⁻¹¹ S cm⁻¹) to enhanced hopping and tunneling transport with increasing SiC content. At intermediate loadings (3–5%), conductivity increased by one to two orders of magnitude, while 7–10% composites exhibited strong frequency-dependent behavior and elevated plateau conductivity, indicating the formation of quasi-continuous conductive networks separated by thin insulating barriers. These results are consistent with Jonscher’s universal power law. Thermal analysis revealed a non-linear dependence of glass transition temperature (T_g) and degradation behavior on SiC concentration. The 7% SiC/PS composite showed the highest thermal stability, whereas the 10% composite displayed decreased and broadened T_g, indicating structural heterogeneity and agglomeration at high filler loading. Activation energy decreased from 288 kJ mol⁻¹ for pure PS to 194 kJ mol⁻¹ at 7% SiC (α = 0.4), suggesting modified degradation pathways associated with increased free volume and altered intermolecular interactions. In contrast, Gibbs free energy remained nearly constant, indicating preservation of the overall thermodynamic degradation barrier. Overall, the 5–7 % SiC/PS range provided the best balance between enhanced dielectric performance and thermal stability.