Influence of γ irradiation on properties of composite structure UHMWPE+α -SiO₂

UHMWPE/SiO₂ composites have been obtained from a homogeneous mixture of ultra-high-molecular-weight polyethylene (UHMWPE) and nanodisperse silica dioxide ( α-SiO₂) powders by hot pressing method. Temperature dependence (20-170degree) of their specific electrical conductivity before and after γ-irradiation (D=200kGy), effect of absorbed dose on the value (dose dependence), and also behavior of the function ln σ_dc=f(T) have been studied under heating-cooling conditions. It is shown that, the dependence lnσ_dc=f(T) in both cases has a complex character: there observed ''breaks'', associated with phase transitions. It has also been studied the frequency dependence (25-106Hz) of the real and imaginary parts of complex electric module. Analysis of these dependencies showed the relaxation character in nanocomposites UHMWPE+ α-SiO₂ conditioned by interfacial polarization (Maxwell-Wagner effect) and that the dielectric properties of these composites and also their conductivity in high frequency range are determined by polymer matrix.With increasing concentration of -SiO2 in the matrix there is observed a growth in the values ε and ε⁽tgδ), and the dependence of these values on frequency corresponds to the exponential law.