THE USE OF SKELETONIZATION FOR THE SHAPE CLASSIFICATION OF CARBON-BLACK AGGREGATES

A specialized image analysis erosion technique, termed skeletonization , has been used for the first quantitative and direct measurement of b ranching in carbon-black aggregates. Twenty different carbon-black gra des were analyzed using transmission-electron-microscopy/automated-ima ge analysis (TEM/AIA). The skeletonization data were used in a discrim ination analysis program for detailed shape classification of carbon-b lack aggregates into four different shape categories that included: sp heroidal (Type 1), ellipsoidal (Type 2), linear (Type 3) and branched (Type 4). These data were used to examine differences in the aggregate shape distributions between and within grades. Skeletonization and co nventional TEM/AIA analyses were also conducted to examine aggregate b reakdown as a result of high-shear mixing in rubber (SBR) and cellulos e acetate butyrate (CAB) paint chip compounds. It was found that the n umber of aggregate branches decreased by as much as 50% in rubber and 70% in CAB compounds, and the distributions became narrower. Aggregate breakdown increases in the direction of the larger particle size carb on blacks which contain more linear (Type 3) aggregates. In rubber, an N650 (131 DBPA) and N330 (102 DBPA) carbon blacks were found to be si milar in overall aggregate shape properties. Therefore, the significan tly higher vulcanizate modulus for N650 appears to be related to a hig her level of carbon-black-polymer interaction, as opposed to high amou nts of polymer occluded and immobilized within the aggregate structure .