Anisometry measurements in carbon black aggregate populations

Transmission electron microscopy with automated image analysis (TEM/AIA) was used to characterize the three-dimensional morphology and anisometry of carbon black aggregates. Individual carbon black aggregates were imaged at multiple goniometer angles, and their three-dimensional aggregate structure was modeled, yielding greatly enhanced morphological information. Aggregate size distributional properties were determined at multiple goniometer orientations for N300 and N600 series grades of varying aggregate structure levels. Aggregate projections were found to exhibit statistical decreases of 10 to 25% in area and perimeter with rotation. Decreases in other morphological parameters, including non-dimensional shape parameters, were also observed. In general, higher structure grades (aggregates) were found to display larger relative changes in morphological parameters with rotation than lower structure grades. Ramifications for conventional TEM/AIA and void-volume/polymer occlusion capacity measurements are addressed. Further analysis includes an assessment of aggregate anisometry on the TEM sample grid and new insights into the three dimensional nature of carbon black aggregate structure.