A Novel Optical Method for Estimating the Dispersion of Carbon Black in Rubbers

Abstract

Abstract The work reported is part of a large program aimed at examining the internal mixing of rubbers and its effect on properties. The dispersion of carbon black in the compound is of primary importance. Standard microscopical methods used industrially to measure this parameter are either subjective or lack discrimination at the higher levels of dispersion. To study mixing behavior effectively it is necessary to be able to assess the property over a wide range of degrees of dispersion. A technique based on the analysis of the dark field image produced by a reflected light microscope has been developed. The specimen preparation is simple, and analysis is carried out using a standard T.V. system. The technique gives results which are sufficiently discriminating to allow correlation of black dispersion with processing and mechanical properties, even at extremely high levels of mixing. An additional advantage of the method is that unvulcanized samples may be used.