MEASUREMENT OF THIXOTROPY OF MODEL FOOD COLLOIDAL SUSPENSIONS WITH STEP CHANGE SHEAR RATE

An experimental study of the measurement of thixotropy of concentrated monodisperse latex suspensions with the step change in shear rate method was conducted. The size of the latices varied between 125 and 423 nm. The step change in shear rate method gave reproducible results provided that the sample was sheared to an equilibriun stress at a reference shear rate before a step change in shear rate was made. The experimental data from the step change in shear experiments are presented in the form of constant structure curves. The degree of thixotropy was found to be related to latex concentration, size, and surface charge. Thixotropy increased with increases in concentration, size, or surface charge of a monodisperse latex suspension.