Applications of Particle Sizing by Ultracentrifugation

The following examples illustrate the applicability of ultracentrifugal sedimentation to particle size distribution of HPOP. Ultracentrifugal sedimentation has been used to determine the cause of the color strength loss of C.I. PR254 powder 

The large particle size sample is the starting crude pigment with the median diameter near 750 nm. The smaller particle size sample is the finished pigment with the median particle diameter near 130 nm. 

PB15 1 sample has smaller crystals as indicated by the lower peak intensities in the XRD pattern. The TEM and disc centrifuge show that this sample has small primary particles in the range of 20-40 nm. The smaller primary particles being more surface active formed aggregates as shown by TEM. This is consistent with the larger median diameter (536 nm) found by disc centrifuge and by the lower surface area of 46 m g for this sample. 

By contrast, the C.l. PB15 3 sample has large crystals and larger primary particles (70-150 nm) which are more stable and did not aggregate as much as shown by TEM, disc centrifuge (median diameter 153 nm) and the larger surface area of 58 mVg. 

Yes P No I I P Height C Area C Fined P Manual I I ( None P Coarse P Fine P Cu  

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