過酸化ジクミルによって網状化されたカーボンブラック・ポリマ複合体の電気的特性

抄録

Carbon black was mixed or co-grafted in solution with acrylic or methacrylic copolymers containing double bonds which were introduced by copolymerization of 2, 3-dimethy 1-1, 3-butadiene (DMB). Then, a variety of resistors with different degrees of crosslinking were made by coating the mixed pastes on porcelain plates and curing them with dicumyl peroxide for a given time at a given temperature. Their degree of crosslinking was estimated by the measurement of gel fraction, and its value for the most crosslinked resistor was more than 90%.
For the resistors containing n-butyl acrylate (BA), acrylic acid, or DMB as a polymer component, the volume resistivities of the mixing type (the weight ratio of polymer/carbon black: 1/1) and the grafting type (the weight ratio of polymer/carbon black: 0.62-0.85/1) were in the range of 1.5-2.3Ω·cm and in the range of 2.8-3.9Ω·cm, respectively. Apparently, the volume resistivity of the mixed type was smaller than that of the grafting type. The resistance change with temperature was slightly positive for the samples except the highly crosslinked grafting type, and the reproducibility on the temperature cycle was improved with increasing crosslinking.
On the other hand, the volume resistivity of the resistors containing lauryl methacrylate instead of BA was in the range of 3.8-5.4Ω·cm which was larger than that of BA type resistors. Especially, the mixing type resistors crosslinked with DCP showed a positive temperature coefficient against temperature cycle (40-140°C), and the resistance change at 140°C became more than 200%.