Effect Of Filler Treatment On The Electrical Behavior Of CB/HDPE Composites

The performance of conductive polymeric composites is related not only to the kinds and the structure of the matrix, but also to the behavior of the filler. In this thesis, the electrical and dynamic rheological properties of oxidative carbon black (o-CB) filled high-density polyethylene (HDPE) composites were investigated, in order to reveal the relationship between carbon black (CB) modification and the performance of the materials.The resistivity-temperature characteristic of o-CB/HDPE composites was investigated. Results showed that composites filled with o-CB have perfect conductivity and the electrical percolation threshold was about the same as the system of CB/HDPE, but the percolation region was narrower than that of CB/HDPE. It was also revealed that the NTC effect was decreased, the electrical reproducibility was improved, the PTC intensity was enhanced and even the room temperature resistivity of o-CB /HDPE was increased by only 0.3 order compared with CB/HDPE, but was lower by 0.9 order than that of crosslinked CB/HDPE. It was said that the change of the behavior of the materials was due to the oxidation of CB.In order to deeply understand the relationship between CB modification and NTC behavior, the resistivity relaxation behavior and dynamic rheological behaviors for o-CB /HDPE composites were investigated. Results showed that composites filled with o-CB have longer relaxation time and the dynamic storage modulus G' lower than CB/HDPE, which indicates the strong physical adsorption interaction between o-CB particles and HDPE for the forming of new pores decreases the reagglomeration of o-CB to form new conducting network.