Rotary Viscometers

Mirkamilov et have used a rheological method to study molecular interactions in a non-aqueous ionic copolymer solution. Ul yanova and Myasnikov studied phase separation in copolymer solutions and selective adsorption in mixed solvents. Pico and Williams have examined phase separation in plasticized tri-block copolymers. 

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The Cannon Instmment Company produces a line of rotational viscometers, most of which are quite specialized, eg. Cold Cranking Simulators (ASTM D5293) and Mini-Rotary viscometers (ASTM D3829 and D4684) for automotive engine oils. They also have a general use instmment similar to Brookfield s basic viscometer. 

As measured in the Cold Cranking Simulator (CCS). As measured in the Mini Rotary Viscometer (MRV). 

Fig. 6 Influence of the temperature on the consistency of 20% Lutrol F 127 in water (rotary viscometer, 250 rpm)...

Melt Viscosity. Figure 9 compares the relationship between melt viscosity and intrinsic viscosity of PET obtained by polycondensations using various additives and that of PET manufactured by the conventional method. The melt viscosity was measured with a rotary viscometer after the sample was melted at 280°C in a nitrogen stream. There is no difference in this relationship between the two kinds of PET. 

Schaub, H. Smith, M. F. and Murphy, C. K. SAE Paper 790732, June 1979, "Predicting Low Temperature Engine Oil Pumpability With the Mini-Rotary Viscometer. ... 

Concentric Cylinder Rotary Viscometer. These instruments are designed to have the test fluid in the annulus between two concentric... 

Viscosity measurement of the liquidized product using the Ostwald visometer was not successful because the solid particles in the product plugged the capillary. However, the viscosity of the product was too small for the rotary viscometer. The pressure drop caused by the delivery of the liquidization product through the stainless tubing will be measured to determine the effective viscosity in the hiture. 

The measurements were conducted on a rotary viscometer Viscoster UTS 50 of HAAKE. Applications software was used for treatment of the results. A Cone Board instrument was used. Radius = 25 mm Aperture angle = 3.49 x 10" rad kegel PK5 2.0 GRAD cone running clearance = 100 pm sample volume = 1.2 cm. The measurements were conducted at shear rate 30 - 2.2 X 10 s and within a temperature range from -20 to 50 °C. Sample holding time at preset temperature before measurements was 20 min. 

If the entire temperature dependence of viscosity is to be measured, it is necessary to use several methods based on different principles. In the viscosity range 10 —10 dPa s, use is mostly made of rotary viscometers. A platinum cylinder rotates around its axis in the glass melt in a crucible, and the force required for revolving the cylinder at a certain speed is measured. In another arrangement, the external crucible is rotated while the internal one is suspended on a torsion wire. Within the same viscosity region, it is possible to measure with a counterbalanced sphere viscometer a plat inum sphere suspended on a thin wire from the balance arm is immersed in the glass melt in a crucible. The other balance arm is loaded and the speed at which the sphere is withdrawn from the melt is measured. 

The rheological properties of slips are usually measured by rotary viscomete while capillary viscometers are used for routine checks. 

The unit of absolute viscosity is the pascal second (Pa.s), but centipoise (cP) is generally used as the alternative unit, where 1 Pa.s = 10 cP. Absolute viscosity is usually measured with rotary viscometers where a rotor spins in a container of the fluid to be measured and the resistance to rotation, torque, is measured. Absolute viscosity is an important measurement for the lubricating properties of oils used... 

Characteristic time ty is a function of the velocity gradient of hydrodynamic flow which is formed by the rotation of the working cyhnder into the rotary viscometer. So, it can be embed the ratio ... 

Rc Radius of the container in the coaxial cylinder rotary viscometer... 

Binding ratios of SDS (BHD Ltd.) and CPC (Tokyo Kasei Ltd.) to HPC (M.W. =11 -I5xl0 Tokyo Kasei Ltd.) were determined at 30 °C by an equilibrium dialysis method. Cloud point of an HPC solution was observed by the naked eye. Amounts of p-dimethylaminoazobenzene (Nakarai Ltd.) solubilized by the surfactant micelle and the surfactant-polymer complex were determined at 30 °C by colorimetry at 1 = 418 nm. Viscosity was measured by an Ubbelohde-type capillary viscometer, a cone-plate rotary viscometer, or a Brookfield-type rotary viscometer at 25 or 30 °C. Mean diameter of secondary particles of kaolinite in its dilute suspension (1 g/dl) was estimated by a Coulter counter (type TA-II) in 154 mmol/dm NaCl at room temperature. 

Fig. 5 Contour line of a Bingham-yield value of a concentrated kaolinite suspension (26.7 g/dl-medium) obtained by means of a Brookfield-type rotary viscometer in the presence of 154 mmol/dm NaCl at 25 °C as a function of the concentrations of added SDS and HPC. The digit on each curve represents the yield value in an arbitrary unit. Quoted from Ref. [7] after slight revision...

Flow curves for the concentrated kaolinite suspension (26.7 g/dl-medium) were obtained by a Brookfield-type rotary viscometer, from which the rheological parameters were estimated. The parameters such as Bingham yield values, apparent and plastic viscosities are the indication for flocculation/dispersion of the concentrated suspension, where their increases mean the interparticle bridging is pronouneed (i.e., flocculation/aggregation) while their decreases suggest the interparticle structure is ruined (i.e., dispersion). 

These MRl scans indicate the potential industrial importance of particle settling through viscoplastic media. The general trends had been investigated by Thomas [5] but further experimentation was clearly required. It was decided to construct a cup and bob similar to those of a conventional rotary viscometer, but modified so that the gap between them increases with depth, and thus the strain rate decreases with depth. This apparatus was constructed at Curtin University, Western Australia. A vertical section is shown on Fig. 1. A brief description, together with some preliminary results, was presented by Wilson [6]. Since that time, a second bob has been fabricated. It is also shown on Fig. 1. 

The preliminary estimation of the anisotropic viscosity coefficients Tiii and for solutions of an aromatic polyamide was performed in [57, 58]. Flow cells combined with an IR spectrophotometer were used in these studies to determine the values of angles 0 and (p. Angle (p was small (2-3°), and it was thus assumed that the molecules lie in the shear plane, and angle 6 was estimated with the dichroism of one of the n bands of poly-p-benzamide (PBA). Measurements of the torque in the moving cylinder of a rotary viscometer conducted in parallel with measurements of the velocity of fall of a ball along the axis of the cylinders in the space between them demonstrated the differences in the values of the longitudinal and transverse Tij viscosities. 

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