Author:

Keywords:

rheology, thixotropy, suspensions, 0904 Chemical Engineering, 0915 Interdisciplinary Engineering, 0913 Mechanical Engineering, Polymers

Abstract:

The rheological behaviour of a thixotropic system has been investigated in terms of the instantaneous structure. The system consists of magnesium silicate fibres, dispersed in a Newtonian. alkyd resin. The application of low frequency oscillatory measurements in the analysis of such materials is discussed. As the characteristic time for thixotropic recovery proved to be several orders of magnitude larger than the average relaxation time, the viscoelastic response of the instantaneous structures can be measured under vibrations of a suitable frequency. Using this technique changes in the relaxation spectrum due to stationary shearing are measured. Equilibrium structures under stationary and oscillatory flow are compared and the similarity principle between both types of measurements is tested for thixotropic systems. The rate of change of thixotropic recovery under rest and under vibrations is considered. © 1972 Dr. Dietrich Steinkopff Verlag.