Predicting mixing performance using surface energy measurements

Surface energy data determined by contact angle studies were useful in predicting interactions in binary and tertiary systems. The binary systems used were mixes of iron oxide with either microcrystalline cellulose (MCC), magnesium stearate or titanium dioxide. The spreading coefficients as determined from the harmonic mean equation provided an indication as to which powder would predominantly spread over the other in the binary mix. The predicted spreading: behaviour was compared with actual performance based upon visual inspection and scanning electron micrographs of the mixes. The ternary systems studied consisted of the above binary mixes and glass. Surface energy data obtained from contact angle studies on the mixes were more accurate than estimates derived from the surface energies of the individual powders at predicting spreading of the mixes onto glass. This work provides a model to predict the mechanism of spreading and mixing of binary and ternary powder mixes. (C) 1997 Elsevier Science B.V.