The application of a modified MacMichael viscometer in rheologic studies of montmorillonite clays

Available instruments for viscosity and rheologic measurements necessitate disruption of the system under test prior to observations. Generally, the gel structure of a thixotropic clay must be disturbed by shaking, pouring into a container for testing, and again upon insertion into the sample of the bob, spindle or paddle of the instrument. Also, these instruments yield a single point reading which is only a final or average value, depending upon the instrument. The occurrences during the test itself cannot be observed. Accordingly? it seemed feasible to determine, if possible, what other rheologic factors are involved in the breakdown of ·the gel structure of a thixotropic clay dispersion. The objective of the study was to design and test an instrument which would not require disturbing the sample before testing, which would give minimal destruction of the sample upon entry of the test probe into the sample, and which would give complete permanent recordings throughout the time of testing