CHAOS IN ROTATING LACTOSE POWDER BEDS

The flow properties of organic powders are of great significance for t he transfer, sampling and mixing of materials in the fine chemical, ph armaceutical, cosmetic, food, and agricultural fields. The following s tudies were performed to describe the complex flow behavior of lactose powders, a common pharmaceutical excipient. Pharmaceutical powder flo w is a crucial element of successful dosage form design and manufactur e. Three lactose samples, bulk (median diameter=52.3 mu m, sigma(g)=1. 9), 45-75 mu m and 125-180 mu m, were studied. Their flow patterns wer e analyzed and irregular oscillations of the dynamic angle of repose a round the mean were observed. Broad band frequency distributions were observed in the power spectra. Phase-space plots revealed complex non- overlapping trajectories. Return maps exhibited grouping of data point s with a well defined structure indicative of a chaotic system. The co mbined observations are consistent with underlying order, and were obs erved in all lactose samples. These studies are among the first demons trating chaos in organic powders. It is anticipated that powder specif ic chaotic inputs may be used to manipulate and improve powder flow at various stages in the pharmaceutical manufacturing process.