Electrical Conductivity and Dielectric Permittivity of γ-Irradiated Nanocomposites Based on Ultrahigh-Molecular-Weight Polyethylene Filled with α-SiO2

Abstract

UHMWPE/SiO₂ composites were obtained from a homogeneous mixture of ultrahigh-molecular- weight polyethylene (UHMWPE) and silicon dioxide (α-SiO₂) by hot pressing. The temperature dependence (20–170°C) of their conductivities σdс prior to and after γ irradiation (D = 200 kGy), the effect of absorbed dose on the σ_dс value (dose dependence), the behavior of the function logσ_dc = f(T) under heating–cooling conditions, and the frequency dependences (25–106 Hz) of the real (ε') and imaginary (ε'') parts of the complex dielectric constant were studied. The logσ_dc = f(T) dependence was shown to have in both cases a complex pattern: “breaks” due to phase transitions were observed. With an increase in the concentration of α-SiO₂, the ε' and ε'' (tanδ) values in the matrix increased and the frequency dependences of these values corresponded to an exponential rule.