The Relation Of The Pourability Of Suspension Concentrates To Their Viscoelasticity

The pouring characteristics from 1 liter HDPE containers have been determined for a number of commercially available suspension concentrates and model solutions with controlled rheology. The pouring phenomenon was observed to occur in two phases: a rapid continuous stream over approximately the first 30 seconds, followed by a slower, dropwise drainage. The rheology of the fluids was measured using a Rheometrics RFS II variable strain rheometer in the dynamic mode. It was found that the weight of formulation remaining in the container after 1 minute's pour out correlated well with the viscous modulus of the fluid. The subsequent rate of drainage of the formulation from the container was dependent upon the elastic modulus of the formulation. Guidelines for development of formulations with efficient pour properties are given.