Thermo-sensitive properties of carbon-black-loaded styrene butadiene rubber composite membranes

摘要

Some conducting polymer composite membranes were prepared by using styrene butadiene rubber as matrices and incorporating carbon blacks and a kind of organic crystal (2,6-di-tert-butyl-4-methyl phenol, BMP). Several composite membranes whose resistivities showed a critical percolation threshold at room temperature exhibited a thermo-sensitive property and their resistivities increased with increasing temperature, that is, a positive temperature coefficient (PTC) effect for these membranes was observed. The switching temperature of these composite membranes, which was associated with a sharp variation in resistivity within a certain temperature range, was quite well matched to the melting point of the BMP crystal. A few membranes, loaded with an appropriate amount of Sterling SO-N550 carbon black and the BMP crystal, showed a relatively high PTC intensity.