CHARACTERIZATION OF CARBON BLACK FILLED POLYMERS USING SMALL ANGLE X-RAY SCATTERING AND TRANSMISSION ELECTRON MICROSCOPY: A COMPARATIVE STUDY

Abstract

Carbon black (CB) is often incorporated in polymeric materials in order to modify their properties. The final properties of composite materials containing CB depend on, among other things, the nature of the carbon black, its concentration and its degree of dispersion. Therefore, there is a need to accurately characterize the degree of dispersion of carbon black in polymers. Although techniques based on optical microscopy can be used for detecting large agglomerates, they do not have the resolution to accurately quantify dispersions of particles having diameters less than 0.25 microns. Small angle X-ray scattering (SAXS) has the potential of being a useful and efficient tool for characterizing dispersions on length scales ranging from the order of 0.01 to 0.1 micron. The method is quick and provides an average value of the average agglomerate size through indirect measurements of the correlation length and the inner specific surface area. On the other hand. Transmission Electron Microscopy (TEM) allows for the direct visualization of the dispersion and measurements of each individual agglomerate. When coupled with computerized image analysis, size distributions of the agglomerates can be generated. In this article, characterization of model dispersions of carbon black using both SAXS and TEM are presented and a correlation between the two techniques are discussed.

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Mark D. Whitmore

Permanent Address: Department of Physics, Memorial University of Newfoundland, St. Johns, Nfld., Canada A1B 3X7