Abstract
Useful applications of charging phenomena occuring during scanning electron microscopy (SEM) of conductor-insulator composites have been investigated. Unlike the charging of insulating particles in conventional SEM techniques, the local field effect in a conductive composite enhances the relative secondary electron emission in the isolated conductive grains. This ‘‘reverse’’ charging characteristic was utilized for the mapping of dispersion, orientation and segregation characterization in conductor-insulator composite systems. The charging phenomenon directly reflects the relative electrical continuity of the conductive filler particles in the insulating matrix. The photographic display of the conductive filler arrangement in the composite using this charging phenomenon is termed a SEM charging micrograph. Carbon black/polyvinyl chloride composites with both spherical and chain-like carbon blacks were used in this study. The structural aspects of such composites as revealed by charge display techniques were found to be directly correlatable with the electrical properties of the composites. This technique is applicable to composites with both small (100 Å) and large (over 10 μ) fillers.
Published Version
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