RETRACTED ARTICLE: Effect of temperature on the dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold

The temperature dependence of dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold was studied based on the effect medium approximation theory (EMA theory). Although the literature on calculation based on the EMA theory by changing the parameters is vast, an overall discussion taking into account the EMA theory is required to explain the dielectric properties of the composites and their temperature dependence. Changes of the dielectric properties of carbon black-filled PMC and their temperature dependence below the percolation threshold for the volume fraction of carbon black have been discussed based on the EMA theory. The composites satisfy the universal law of conductivity above the percolation threshold, whereas it gives the critical exponent of s = 1 for dielectric constant below percolation threshold. The rates of the decrement of both % changes of dielectric constant and dielectric loss factor for temperature become larger with an increase in the volume fraction below percolation threshold. By incorporating the effect of thermal expansion into the EMA theory, the temperature dependence of dielectric properties is successfully explained.