抄録
According to the phenomenological theory for thixotropy presented by Cheng and Evans, an equilibrium curve and constant-structure curves can be determined as characteristic shearing stress vs. rate of shear relations for a thixotropic liquid. These curves were obtained by measuring the shearing stress at various rates of shear with a Weissenberg rheogoniometer using two solutions of polyvinylchloride in dibutylphthalate. Solutions of constant structure are non-Newtonian; shearing stress goes to zero as rate of shear approaches zero. Solutions in equilibrium state of structure are suggested to have yield stress. Relaxation spectra of these solutions at various rates of shear were determined from stress relaxation after cessation of steady flow. These results were discussed in relation to the hypothetical formation and destruction of structure in the solution. An empirical equation for the shear-rate dependence of shearing stress of these solutions was derived by analysing the data. This equation is consistent with the Cheng-Evans' constitutive relation for thixotropic liquids.
