1994 年 43 巻 490 号 p. 895-901
Electrical conductivity and mechanical tanδ of poly (alkyl methacrylate) (PRMA) composites filled with carbon black (CB) were measured as functions of CB content and temperature. The dispersion of CB particles was investigated by means of the optical photograph. The critical volume fraction Vc, at which the electrical conductivity increases rapidly, and the rate of electrical conductivity increase at the parcolation threshold differed depending upon the kind of matrix polymer. It was found that CB particles easily aggregated and formed the fine electro-conductive network in the composites with matrix polymers having lower surface tention and lower miscibility for CB particles, resulting in the higher rate of electrical conductivity increase at the threshold as well as the higher value of Vc. For the composites with polymers having the high Tg, the plasticizing effect appeared strongly owing to the presence of CB particles, so that Tg shifted to a lower temperature side as much as 25°C.