Size analysis of industrial carbon blacks by sedimentation and flow field-flow fractionation

Carbon black is one of the most useful particulate materials in the industrial field. Among the various physical properties of carbon black, size and size distribution are the most important properties to affect the quality of a final product. However, it is difficult to measure the exact particle size of carbon black since it suffers unavoidable interference from flocculation. In this study, the effects of various factors on the dispersion of industrial carbon blacks were investigated for the determination of size and size distribution of carbon black particles. Sedimentation and flow field-flow fractionations (FIFFF) were used to determine the size of carbon black, and their optimum analytical conditions were tested by changing surfactant, pH, ionic strength, and method of dispersion. The results showed that surfactant structure and its concentration played significant roles in dispersion stability. Carbon black was dispersed well with a nonionic surfactant with a pH of around 8 and an ionic strength of 0.003 M. The mean diameters measured from two types of FFF and photon correlation spectroscopy are in good agreement. This study demonstrates the potential of sedimentation and flow FFF for analyzing highly adsorptive industrial particles and guides for sample preparation.