Method and device for simultaneous determination of shear viscosity and extensional viscosity

摘要

In a method for continuous or discontinuous measurement of shear and strain viscosities of Newtonian and non-Newtonian liquids, in particular structurally viscous liquids such as polymer melts and solutions and elastomers as well as other structural liquids, the liquid is passed through a first capillary or capillary configuration and through a second capillary connected in series therewith, wherein the liquid in the first capillary or capillary configuration shears only within a defined shear velocity range and the shear viscosity is determined, and, subsequently, the liquid in the second capillary having the same or somewhat smaller shear velocity range, shears and is additionally subjected to a strain-flow so that its flow-through resistance comprises shear as well as strain resistances. The flow-through resistance is determined by pressure measurements and, in order to separate out the strain viscosity, the pressure fraction of the shear flow resistance is extracted through subtraction of the portion of the pressure difference corresponding to this shear flow resistance using the measurements in the first capillary or capillary configuration.