Electrical and mechanical stress responses for carbon black loaded rubber

The major objective of this study was to determine the relations between certain electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) for carbon black loaded rubber. Resistance and capacitance were measured under constant strain and constant stress conditions in an effort to determine these relations for rubber filled with 30 to 70 parts carbon black per hundred parts rubber.

Seven materials for making electrical contact were investigated. Silver paint was found to result in low contact resistance, to be reliable, and fairly inexpensive.

Electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) were found to exhibit similar trends as functions of carbon black content. This is in agreement with previous theories of the conduction network and electron percolation. Resistance and stress relaxation equations were quantitatively determined. These follow a power law time dependence, with relaxation rates depending mainly on carbon black content and temperature.