Electrical and thermal studies of the distribution of carbon black in a polyester matrix in the presence of aluminum oxide

• Published in: Journal of applied polymer science 2008-08, Vol.109 (4), p.2250-2258
• Main Authors: Mansour, S.H, Abd-El-Messieh, S.L, Abd-El-Nour, K.N
• Format: Article
• Language: English
• Subjects: activation energy; Applied sciences; Composites; dielectric properties; Exact sciences and technology; fillers; Forms of application and semi-finished materials; polyesters; Polymer industry, paints, wood; Technology of polymers; thermal properties
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.28268

The distribution of a filler in a polymeric matrix is one of the most important factors affecting the physical properties of the final product. For this reason, the main objective of this study was to introduce aluminum oxide (Al₂O₃), acting as a dispersing agent, to reduce the filler-filler interaction and enhance the filler-polymer interaction. To achieve this aim, the electrical behavior of a styrenated polyester resin filled with different amounts of high-abrasion furnace black in the presence of 5% Al₂O₃ was studied in the vicinity of the percolation threshold to evaluate the effect of the addition of Al₂O₃ in an attempt to reduce the filler-filler interaction through the polyester matrix. At a certain concentration of carbon black, an abrupt increase was noticed through electrical conductivity, permittivity, and dielectric loss investigations. With this increase, the tendency of conductive chain formation increased through the aggregation of a carbon black particle network. The addition of 5% Al₂O₃ improved the filler distribution by lowering the aggregate size and consequently enhanced the formation of the network. From the Arrhenius temperature dependence of the electrical conductivity, the activation energy and pre-exponential factor were obtained, and they confirmed the validity of the compensation law for the semiconducting composite systems. The composites were also analyzed by thermogravimetric analysis. Al₂O₃ improved the thermal stability of the composites in comparison with that of a sample free of Al₂O₃.