Dynamic mechanical thermal analysis and dielectric thermal analysis of siloxane rubber-based composites filled with carbon black

Siloxane rubber-based composites filled with furnace carbon black N 220 at various concentrations were investigated bydynamic mechanical thermal analysis and dielectric thermal analysis. It was found that in the temperature interval from−30°C to 100°C the increase in the amount of carbon black results in the increase in the storage modulus (E′) values, as well as those of the mechanical loss angle tangent (tan δ). The decrease in E′ and the increase in tan δ in the interval from −40°C to −30°C was due to the process of the melting of the crystal structure of the siloxane rubber, formed during the cooling of the tested samples. Dielectric thermal analysis showed that the increase in the amount of carbon black lead to obtaining of vulcanizates with higher dielectric permittivity (ε′), whose values decrease with the increase of frequency. The research that was carried out showed that with the siloxane rubber-based composites the percolation threshold was reached when the concentration of carbon black was 20 wt%.