ANISOMETRY MEASUREMENTS IN CARBON-BLACK AGGREGATE POPULATIONS

Transmission electron microscopy with automated image analysis (TEM/AI A) was used to characterize the three-dimensional morphology and aniso metry of carbon black aggregates. Individual carbon black aggregates w ere imaged at multiple goniometer angles, and their three-dimensional aggregate structure was modeled, yielding greatly enhanced morphologic al information. Aggregate size distributional properties were determin ed at multiple goniometer orientations for N300 and N600 series grades of varying aggregate structure levels. Aggregate projections were fou nd 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, hig her structure grades (aggregates) were found to display larger relativ e changes in morphological parameters with rotation than lower structu re grades. Ramifications for conventional TEM/AIA and void-volume/poly mer occlusion capacity measurements are addressed. Further analysis in cludes an assessment of aggregate anisometry on the TEM sample grid an d new insights into the three dimensional nature of carbon black aggre gate structure.