IN-SITU OBSERVATION OF ELECTRIC-FIELD-INDUCED AGGLOMERATION OF CARBON-BLACK IN EPOXY-RESIN

This letter reports on the influence of a static electric field applie d by metal electrodes on the agglomeration process of carbon black (CB ) in epoxy resin. The growth of dendrites from the anode into the mate rial is observed in situ by optical transmission microscopy, A percola ting network is seen to form, combined with a drastic reduction in the sample resistivity. This behavior can be explained by taking into acc ount the electrostatic interaction of the charged CB particles. The fi nal resistance for composites with a given CB content can be controlle d within a range of several decades by varying the applied voltage and the curing temperature of the mixture. (C) 1998 American Institute of Physics.