Thixotropic plastic viscoelastic fluid

Suetsugu, Y. and White, J.L. (1984) A theory of thixotropic plastic viscoelastic fluids with a time-dependent yield surface and its comparison to transient and steady state experiments on small particle filled polymer melts, /. Non-Newtonian Fluid Mech., 14,121-40. 

If the shear rates are constants, the non-Newtonian fluids can also be classified according to their viscosity dependence on time. This classification has been widely applied to describe the rheological characteristics of coatings. For the development of deformation, the time evolution corresponds to the effect of the increase of shear rate. Three typical cases occur with the time evolution the thixotropic fluids exhibit the decrease of viscosity, corresponding to pseudo-plastic fluids the rheopectic fluids exhibit the increase of viscosity, corresponding to dilatant fluids while the viscoelastic fluids exhibit partial recovery of the deformation of pseudo-plastic fluids after the removal of the stress. Since polymers can perform a large scale of elastic deformation, this character appears extremely significant. 

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