AN ASSESSMENT OF SUBSTRATE-BINDER INTERACTIONS IN MODEL WET MASSES .1. MIXER TORQUE RHEOMETRY

Recent work has shown the importance of physical interactions between materials during size enlargement processes (e.g., wet granulation). I n this study several model substrates and binder solutions were select ed, their particulate, solution and energetic properties determined an d the potential physical interactions of the solid and liquid phases a ssessed. Considerable differences were noted in the wetting, spreading and adhesion tendencies of the various substrate-binder combinations. The rheological properties of the wet massed solid-liquid systems wer e then measured using an instrumented mixer torque rheometer. The resu lts confirmed that solid-liquid physical interactions (especially spre ading) are important in determining wet massing behaviour. The most im portant influences appeared to be on the stability of the wet masses a t elevated liquid levels and theories were developed to explain this o bservation in terms of the accepted models of wet granule structure.