Evaluation of potting compounds by electrical resistivity techniques

The Continuous Current Monitoring Device (CCMD) for evaluating potting compounds was first reported in 1956¹. It was developed at the Naval Ordnance Laboratory by R. W. Warfield and associates, and is based upon electrical resistivity measurement techniques. Studies were made initially on the polymerization of various cross-linked resin systems to determine curing characteristics, exothermic effects, proper cure temperatures, and the overall activation energies (E_a) for the polymerization process². The CCMD was then applied to the cured systems to measure electrical resistivity properties as a function of temperature. From this data the nature of the cross-linked structure and activation energy (E_c) for the electrical conduction process were derived, and the presence of second order transitions (T_g) within the temperature range studied were noted.^{3, 4}