Rheometer is a mechanical spectrometer that is capable of subjecting a sample to either a dynamic (sinusoidal) or steady (linear) shear strain (deformation). Then measuring the resultant torque expended by the sample in response to the shear strain (shear strain is applied by the motor- torque is measured by the transducer). In the dynamic mode, the motor begins all tests at the motor zero position, and drives symmetrically about motor zero to the strain commanded by the software. The motor is labeled with graduations indicating 0.1, 0.25, and 0.5 radians from motor zero. The maximum angular deflection of the motor is 0.5 radians from either side of motor zero. In the steady mode, the motor can begin a test from any position, rotating either clockwise or counterclockwise as specified by the user using software. Different geometry is available. Please see an overview:
|Cone/plate||Fluids, melts Viscosity > 10 mPas||True viscosity||Temperature ramp difficult|
|Parallel Plate||Fluids, melts Viscosity > 10 mPas||Easy handling, temperature ramp||Shear gradient across sample|
|Couette||Low Viscosity samples <10 mPas||High shear rate||Large sample volume|
Plates size: Low viscosity (milk)- 60 mm geometry, medium viscosity (honey)- 40 mm geometry, high viscosity (caramel)- 20 mm geometry.
Instrument: ARES-LS1 from TA Inst. Co.
Temperature: water bath 25oC - 80oC