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Controlled strain, for steady shear measurements of viscosity in a concentric cylinder geometry. This highly sensitive instrument can measure the viscosity of air to three significant figures, and can measure the shear rate dependence of viscosity for fluids with viscosities less than 2 Poise, between 0 oC and 80 oC. This rheometer requires 2 ml of liquid sample, and has a shear rate range between 10-2 s-1 and 102 s-1.
The outer cup rotates at a prescribed speed, and the inner bob is connected to a torsion wire. The deflection of the torsion wire determines the torque. This rheometer is currently used to study polyelectrolyte solutions, which are strongly shear thinning at low concentrations. It has been interfaced to a computer using LabViewTM. |
