Abstract
The nonohmic behavior of carbon black-loaded natural rubber vulcanizates was studied. Three samples contained high-abrasion furnace black (HAF) in good, moderate, and poor dispersion. Another sample contained a good dispersion of medium thermal black (MT). The nonohmic behavior of the poor HAF dispersion and that of the MT dispersion could be interpreted as due to internal field emission across insulating gap widths of 2 and 2.5 µ. The existence of such gaps was confirmed by electron micrographs. No clear evidence of internal field emission could be obtained for the good and moderate HAF dispersions where, according to electron micrographs, the gaps are much narrower. There is some indication that the degree of dispersion can be correlated with field emission characteristics.