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 sy stems used were mixes of iron oxide with either microcrystalline cellu lose (MCC), magnesium stearate or titanium dioxide. The spreading coef ficients as determined from the harmonic mean equation provided an ind ication as to which powder would predominantly spread over the other i n 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 th e above binary mixes and glass. Surface energy data obtained from cont act angle studies on the mixes were more accurate than estimates deriv ed from the surface energies of the individual powders at predicting s preading of the mixes onto glass. This work provides a model to predic t the mechanism of spreading and mixing of binary and ternary powder m ixes. (C) 1997 Elsevier Science B.V.