Rheometer
AssigneeThe Research Foundation of State University of New York
InventorsBenjamin Chu, Rolf Hilfiker
Life of this patent
Estimating the term…
Abstract
A magnetic sphere or needle rheometer which may be fully controlled by a personal computer is provided. The rheometer is capable of measuring viscosities in the range of 5.times.10.sup.-4 to 5.times.10.sup.4 Pas (0.5 cP to 5.times.10.sup.7 cP). It can operate at shear rates between 1 s.sup.-1 and 2.times.10.sup.-4 s.sup.-1 and measure relaxation times down to 100 ms. The rheometer includes a magnetic coil which is used to maintain the sphere or needle in a selected position within a sample cell. The current required to maintain the sphere or needle in this position as the sample cell is moved up or down is measured. The viscosity of the liquid can be calculated from the difference in current flowing through the coil when the cell is stationary and when it is moved at a constant velocity.
Claims23
A rheometer assembly for determining selected physical properties of liquids and gels, comprising:
- a sample cell;
- a magnetic needle which is positionable within said sample cell, said magnetic needle comprising a non-magnetic tube and magnetic material positioned within said tube;
- means for maintaining said magnetic needle at a selected position within said sample cell, said means for maintaining including means for generating a magnetic field;
- a laser source for directing a laser beam towards said sample cell;
- means for expanding a laser beam positioned between said laser source and said sample cell;
- a position detector aligned with said laser source and sample cell, said sample cell being positioned between said laser source and said position detector;
- means for moving said sample cell in a substantially vertical direction;
- and
- means for determining a physical characteristic proportional to the force necessary to maintain said magnetic needle at a selected position.
A rheometer assembly comprising:
- a sample cell;
- means for maintaining a magnetic needle at a selected positioned within said sample cell, said means for maintaining including means for generating a magnetic field;
- a conductive shield positioned about a selected portion of said sample cell, said shield including a pair of opposing windows;
- means for directing a light beam through said pair of opposing windows and said sample cell;
- a position detector aligned with said light source;
- means for controlling the temperature of said selected portion of said sample cell, said means for controlling including first and second separately controllable heating means, said first and second heating means being positioned, respectively, above and below said windows;
- means for moving said sample cell in a substantially vertical direction;
- and
- means for determining a physical characteristic proportional to the force necessary to maintain the magnetic needle at a selected position between said windows.
Dependencies are inferred from the claim text.