Investigation of applied compression on the adhesion of powders to a substrate surface

Abstract

The influence of applied forces on the adhesion of classified pharmaceutical polyethyleneglycol(PEG) 4000, Starch 1500, spray-dried lactose and heavy precipitated calcium carbonate onto a characterized stainless steel substrate has been investigated using a centrifuge technique. The particles of each powder were initially forced onto the substrate surface by centrifuging at a particular speed, and immediately after this stage, the adhesion profile was determined. Once a minimum value for the adhesion force had been achieved, over the range of the applied forces, all powders displayed a statistical log—normal distribution of the percentage of adherent particles with respect to the adhesion forces. The geometric median force of adhesion for all powders was found to increase linearly with the preliminary applied force. The slope of each regression line indicated quantitatively the change of the median adhesion force per unit increase of the applied force. This value was dimensionless and that evaluated for PEG 4000 was 33.3 × 10 −1, Starch 1500 7.57 × 10 −2, spray-dried lactose 1.72 × 10 −2 and calcium carbonate 1.63 × 10 −2.