The electric self-heating behavior of graphite-filled high-density polyethylene composites

The electric self-heating behavior of graphite-powder-filled high-density p olyethylene is studied. Two equations are proposed to describe the electric -field dependence of the self-heating temperature and resistance dependence of the critical field. Based on Ohmic and non-Ohmic approximations and the heat-dissipation model, the self-heating equations are also derived theore tically. The equations show that self-heating is determined by the initial resistance and true positive temperature coefficient (PTC) effect under fie lds. Design and application principles for polymer PTC heaters are suggeste d on the basis of the experimental results and proposed equations. (C) 2000 John Wiley & Sons, Inc.