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Measurement of shear or extension viscosity of fluids, especially polymers, by measuring pressure differences in two capillaries while subjecting to pure shear and shear and extension resistance
Measurement of shear or extension viscosity of fluids, especially polymers, by measuring pressure differences in two capillaries while subjecting to pure shear and shear and extension resistance
Fluid flows through a first (K1) and a second (K2) capillary in series. Fluid is merely sheared in the first capillary to determine the shear viscosity while in the second is sheared at the same or lower shear rate and also subjected to stretching flow so that the flow resistance comprises both shear and extension resistances. Flow resistance is determined by pressure measurement. An Independent claim is made for process equipment which comprises either: a) a first capillary (K1) with a continuously enlarging cross-section, a downstream second capillary (K2) with a continuously narrowing cross-section, either connected directly together or by a connecting piece (V) and two or more pressure sensors(P1,P2) in each capillary; b) a continuously narrowing capillary cross-section followed by a continuously enlarging cross-section either connected directly or by a connecting piece and two or more pressure sensors in each capillary;c) a first part capillary with constant cross-section, a second part capillary with a lower constant cross-section, but of a different size and a transition piece with a continuously varying cross-section between them forming a second capillary with a continuously varying cross-section and two or more pressure sensors in each part capillary. Preferred Features: For separating the extension viscosity the pressure component of the shear flow resistance is obtained by subtracting the part of the pressure difference corresponding to the shear flow resistance as a result of pressure measurement at the first capillary.
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