Carbon Blacks and Their Use in Rubber. I—Comparative Properties of Blacks and Tests in Uncured Rubber

Abstract

Abstract The physical and chemical characteristics of several carbon blacks and of rubber stocks containing them have been investigated in order to determine their suitability as pigments in tire-tread stocks. Five blacks have been studied—Charlton lampblack, Micronex, Super Spectra, Thermatomic, and Goodwin. Part I represents a study of the properties of the blacks themselves and their use in raw rubber. Part II, to be published in a subsequent issue, will describe tests on various cured rubber stocks containing the same blacks. OUR knowledge regarding the physical and chemical characteristics of pigments which make them more or less suitable as reenforcing agents in cured rubber goods is very incomplete. In spite of several brilliant contributions in the field, we are still far from a satisfactory understanding of the principles involved in the preparation of coin-pounds. Lack of systematically arranged information is perhaps partly responsible for this state of affairs. The object of this paper was to assemble more detailed and well-organized information in a small field. It is believed that a sufficient number of systematic efforts will place us in a position to understand more completely the colloidal behavior of pigments in rubber and perhaps in other media.