Testa Analytical Solutions e.K has published a technical report that describes how accurate particle size measurements can be made on carbon black samples using their BI series disc centrifuge photosedimentometer.
Carbon black is a widely used abrasion-resistant filler employed in the manufacture of tires and in the production of many other rubber materials. Carbon black is also used as a pigment in coatings and lacquers, plastics, printing inks, and tinting blacks.
Since the particle size distribution (PSD) of aggregates of carbon black is strongly correlated with the thermal and mechanical properties of dispersions, the measurement of a carbon black PSD is an important part of its quality control. Although often unimodal, the typical particle size range for non-agglomerated carbon black is very broad covering from 10 nm to over 500 nm.
The authors provide an informative introduction to the principles of particle sizing using a disc centrifuge photosedimentometer and they demonstrate the importance of extinction correction in order to make accurate measurements.
Results on the ASTM series of Carbon black reference materials (A4 - F4) is presented and comparisons between different reference materials made. Different sample preparations are discussed and the stability of such preparations with time shown.
The report concludes given the small particle sizes involved, and the breadth of a typical distribution, the BI series disc centrifuge photosedimentometer is the instrument of choice for measuring carbon black particle size distribution. Not only is the BI disc centrifuge photosedimentometer a rugged instrument, but its theory of operation is well developed. Provided all corrections are made, the accuracy of particle size distribution measurements on carbon black samples using the BI disc centrifuge photosedimentometer is unsurpassed.