ELECTRICALLY RESISTANT POLYMERIC HEATING BODY CONTAINING CONDUCTIVE CARBON BLACK

摘要

An electrically impedant article comprising an electrode embedded in a polymeric body having dispersed therein electrically conducting carbon black in which the body around the electrode contains a lower percentage of conductive carbon black than do other regions of the body further away from the electrode, the carbon black in said region around the electrode being of higher conductivity than the carbon black in said other regions. The polymeric body preferably comprises a silicone rubber. The article can be a heating tape having a pair of spaced parallel electrodes and may have a positive non-linear temperature co-efficient of impedance.