Resistance-expansion-temperature behavior of a disordered conductor-insulator composite

I have measured the resistance and linear expansion of a disordered carbon-black-polymer composite as a function of temperature from 25 to 180 degrees C. The sample resistance and thickness both increases monotonically as a function of temperature, with precipitous increases at the polymer melt temperature. The resistance versus thickness data show a monotonic increase with no precipitous changes at any point. These results suggest the electrical conduction mechanism is the same below, during, and above the polymer melt temperature. This casts doubt on some earlier models proposed to explain the resistance versus temperature behavior of these systems. These results also suggest a new approach to understanding the resistance versus temperature behavior by first developing a quantitative understanding of the resistance versus thickness behavior. (C) 1996 American Institute of Physics.