Rheology

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Rheometer: MCR 301, Antron Paar, Graz, Austria.

Geometries: CP50-1 and PP10

Specialities: Peltier element (temperature control) and UV illumination.

Rheology is the science of deformation and flow of materials. Newtonian fluids have a certain viscosity at any given temperature independent of the shear forces applied. However, polymer solutions, particle pastes or other two component solutions are typically behaving non-newtonian i.e. they behave viscoelastic. By measuring the flow curve of a material we can determine the materials behavior under the shear stress conditions. Often the materials are exposed to different external forces such as shear forces, which are present when injecting material through an extrusion head or a needle. Understanding the material behavior in extrusion is important for the understanding and developing of biomaterials “bio-inks” for 3D bioprinting.

Another important behavior studied in our lab is the crosslinking or gelling behavior of hydrogels. The storage modulus G’, which describes the elastic properties and the loss modulus G”, which describes the viscous properties are measured to understand the viscoelastic behavior of the material. Sol-gel transition of hydrogels happens when G’ = G”. The figure illustrates the measurement of thermoresponsive hydrogel gelation from hyaluronan grafted with poly(N-isopropylacrylamine).

Temp Gelation  
Viscoelastic behavior of thermoresponsive hydrogel measured in 1% strain and 1 rad/s angular frequency.

Our Rheometer MCR 301 Anton Paar is compact system with air bearings and high-performance synchronous motor with continuous measuring environment control. The rheometer is equipped with a peltier element and a UV curing station. We are able to control the temperature during measurements and use UV light for the UV curing of materials. Any type of rheological test, both in rotational and oscillatory mode, is possible with the rheometer. Geometries we have available are a cone-plate 50mm diameter, 1º angle (CP50-1) and plate-plate 10mm diameter (PP10).

Rheometer  
Anton Paar MCR 301 rheometer on the left, CP50-1 geometry and the UV curing station on the right.

Technical data:

Torque:

  • Minimum torque 0.01 μNm,
  • maximum torque 200 μNm 
  • resolution 0.001 μNm.

Frequency:

  • Min. frequency 10E-5 Hz 
  • Max. frequency 100 Hz.

Speed:

  • Min. speed (measurement method: adjustable shear stress) 10E-7 1/min
  • Min speed (mode measurement: adjustable shear rate) 10E-6 1/min 
  • Max. speed 3000 1/min.
  • Range of normal forces of 0.01 to 50 N, resolution normal force of at least 0.002 N.
  • The set an angle of divergence of 0.1 μrad sensor and sensor resolution angle deviation 0.012 μrad.

  Documents:  

 
 
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Wed Jun 28 20:48:17 CEST 2017
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