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:  

 

Geometry	Application	Advantage	Disadvantage
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.

Equipment

Instrument: ARES-LS1 from TA Inst. Co.

Temperature: water bath 25^oC - 80^oC