Surface Condition and Electrical Impedance in Rubber Friction

It is shown experimentally, by employing electrically conductive rubber, that during the frictional gliding of rubber a thin layer in contact with the track undergoes a deformation which considerably increases the electrical impedance of this layer. In the case of previously abraded rubber the layer is permanent. If a d.c. potential is applied between sample and track during sliding, electrostatic attraction between sample and track is produced which increases the frictional force. The thickness of the layer, as estimated from the magnitude of the electrostatic force, is a few thousandths of a centimetre.