Bohlin VOR rheometer

Spccj/jfc Fluids Viscoela.stometers, The ATS RheoSystems Stresstech rheometer can carry out oscillatory measurements over a frequency range of 6.3 x 10 to 630 rad/s. The Bohlin VOR rheometer and the mechanical spectrometer both allow oscillatory measurements. The former has a frequency range of -10 Hz, the latter lO " -100 Hz. The maximum angular ampHtude is 0.02 rad for the VOR and 0.5 rad for the mechanical spectrometer. 

Measurements of the zero shear viscosity (20 °C) were made with a Bohlin VOR rheometer in the viscometry mode. If a Newtonian region was not found at the lowest measurable shear rates, the samples were characterized with a Bohlin-CS constant stress rheometer, with which it was possible to obtain extremely low shear rates. This approach was especially needed for highly viscous samples exhibiting pseudoplastic behavior on the VOR rheometer. Newtonian regions were found for each sample in this manner, yielding the zero shear viscosities reported. 

The particle size was determined using dynamic light scattering (also termed photon correlation spectroscopy PCS), using a Malvern PCS instrument. The equilibrium sediment and cream volumes were recorded using measuring cylinders at room temperature, and viscoelastic measurements were made using a Bohlin VOR rheometer. 

Rotational Rheometry. Two instruments were used for these measurements. An Instron model 3250 rheometer was used for measuring rotational viscometry and forced oscillation as a function of frequency with strains in the region of 0.5. A Bohlin VOR rheometer was used for dynamic measurements at smaller strains (i.e., 0.1). 

Forced-Oscillation Experiments. The dynamic moduli were measured as a function of frequency. At high strains (ca. 0.6), the Instron rheometer was used, whereas at lower strains (typically 0.16), the Bohlin VOR rheometer was used because of its greater sensitivity. Figure 6 shows the results obtained for the storage (G ) and loss (G") moduli for a 0.5-g dL" ... 

Rheological measurements on the slurry have been performed by Bohlin rheometer model VOR and constant stress rheometer C.. These two units combined are powerful enough to analyze slurries completely in viscometry, oscillatory and relaxation tests. Injection molding compound is fully characterized rheologically using capillary rheometer. 

C-VOR-200 Rheometer Bohlin Strain-controlled creep experiments... 

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