Rotating spindle viscometer

2 Viscosity tests by rotational viscometers 4.8.2.1 Rotating spindle viscometer 

This rotating spindle viscometer is used for the determination of dynamic viscosity of a variety of bituminous binders modified and unmodified bituminous binders, bituminous emulsions, cut-back and fluxed bituminous binders by means of rotating spindle (coaxial viscometer) viscometer, at typical test conditions (temperatures and rate of shear). 

The principle of the test method is that the torque applied to a spindle (e.g. a cylinder), which is rotating in a special sample container containing the test sample, measures the relative resistance of the spindle to rotation and provides a measure of the dynamic viscosity of the sample. It may be necessary to apply a form factor to yield the actual dynamic viscosity at the test temperature. 

The typical test temperatures for unmodified or modified bitumens range from 90°C to 180°C. The test temperatures usually used when unmodified bitumens are tested are 90°C, 

105°C and 135°C, and when polymer-modified bitumens are tested, the test temperatures are 135°C, 150°C and 165°C. 

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Viscosity measurements were determined with a rotating spindle viscometer (Haake Model VT23) in a temperature-controlled medium. 

This test method determines the dynamic viscosity of bituminous emulsions by means of a rotating spindle viscometer. 

The dynamic viscosity test determined by a rotating spindle viscometer (rotational viscometer test) is also covered by ASTM D 2196 (2010). 

Viscosity measurements were carried out by two different methods. A rotating spindle viscometer was used to measure viscosities in the (10 -10 ) Pa-s range, whereas a beam biding viscometer was used for measurements in the (10 -10 ) Pa-s range. Combining data from ftiese two measurement series, viscosity of the glass in the (10 -10 ) Pa-s range was obtained by interpolation. 

For the rotating spindle viscometer experiments, approximately 320 g of fiit was melted in a platinum crucible for 2.5 h at 1450 °C in the viscometer furnace. The fiirnace temperature was then set to desired value and the rotating viscometer spindle was lowered into ftie melt The torque experienced by the spindle was measured and noted at defined time intervab. The viscosity of the melt was calculated fi-om the measured torque and spindle RPM and plotted as a function of time. A steady state value of this measurement provided the viscosity of the melt at that temperature. This process was repeated for different temperatures. The procedure for ftie vacuum processed samples was slightly different. Approximately 320 g of frit was melted in a platinum crucible for about 2.5 h at 1450°C in a laboratory furnace evacuated to between 13.3 kPa and 17.3 kPa. Alter the 2.5 h melting the crucible was transferred to the viscometer furnace. Viscosity measurements were then carried out using the procedure described above for the ambient sample. 

This work was funded by the R D organization at Owens-Illinois, Inc. Kathryn Perkins, Faith Workman, and Brett Hixson assisted in sample preparation and with several experiments. Daniel Ragland helped with the FTIR experiments. Carl Fayerweather provided support for the rotating spindle viscometer experiments. Richard Sipes help with UV-Vis experiments is greatly appreciated. Discussions with the 0-I s Glass Science Discipline members, both past and present, were helpful in the development of this project and in the preparation of this document. Comments fi-om several members of O-I R D, particularly Scott Weil, William Pine, Carol Click, and Ludovic Valette, improved the quality of this document and are greatly appreciated. 

When using simple rotating cup or spindle viscometers, the modified Cross equation can be simplified and rearranged (12) to the form ... 

Viscosities of liquid epoxy systems are usually measured with a rotating spindle instrument, such as a Brookfield viscometer. Solid resins are usually dissolved in solvent for viscosity measurement by these instruments. Temperature and spindle speed are important... 

The most popular viscosity test for products ranging in viscosity from 50 to 200,000 cP uses a rotating spindle instrument such as the Brookfield viscometer. The equipment used for this measurement is shown in Fig. 20.1. The instrument measures the resistance of the fluid to a spindle of certain size that is rotating at a predetermined rate. The method is relatively simple and quick. It can be adapted to either the laboratory or production floor. 

Measuring Viscosity Several common methods are available for measuring viscosity. Two very common ones are the use of capillary tubes such as Ubbelohde, Ostwald, or Cannon-Fenske viscometer tubes and the use of a rotating spindle such as the Brookfield viscometer. 

Stormer viscometers, concentric cylinder viscometers, rotating spindles, falling spheres, etc. Because these viscometers expend part of their energy in accelerating the particles, this produces change in their orientation, and because voidage in the bed is affected by the immersed objects, the data on apparent viscosity of fluidized beds have to be carefully examined. 

Another method (ASTM D-2669) is suitable for blends of wax and additives with apparent viscosities up to 20,000 cP at 177°C (350°F). Apparent viscosity is the measurement of drag produced on a rotating spindle immersed in the test liquid. A suitable viscometer is equipped to use interchangeable spindles and adjustable rates of rotation. The wax blend is... 

Viscosity measurements used to describe polymer solubility are based on the Brookfield model LVF, at 60 rpm after 1 min spindle revolution. This is a rotational type viscometer which can vary its shear rate by spindle speed changes. Only one-point (shear rate) measurements were made however. This type of reporting puts it on a par with the efflux type viscometers used in the coating industry in that only one shear rate is used. 

The determination of viscosity from the couple exerted on concentric cylinders is used in many viscometers. For silicate glasses, a wide range of techniques are used for measuring viscosity. For low viscosities (1 Pa s to 1 MPa s), a rotating spindle technique, based on the above principle, is often used. For higher viscosities, techniques based on fiber elongation, compression of a cylinder and be im-bending are utilized. 

Viscosity property of a material to increasingly resist deformation with increasing rate of deformation. This property is quantitatively defined as dynamic viscosity or coefficient of viscosity and is often used synonymously with apparent viscosity. The viscosity of adhesives is primarily determined by means of rotational or throughflow viscometers (DIN cup. Ford cup, Zahn cup). Adhesives generally show non-Newtonian behavior. In addition to temperature, any expression of viscosity must also refer to the measuring instrument and measurement parameters (rotating spindle, rate of shear, nozzle diameter). 

The spindle viscometer (ASTMD2393) is one of the simplest instruments to operate. It measures torque required to rotate an immersed element (the spindle) in a fluid. The spindle is driven by a motor through a calibrated spring the deflection of the spring is measured and mathematically converted into a viscosity value in units of centipoise. By utilizing multiple rotational speeds and interchangeable spindles, a variety of viscosity ranges can be measured. 

Two main types of viscosity tests are performed on solder paste. The first method utilizes a T shaped spindle that is spun inside a container of paste in a helical path. The T spindle viscometer is also known as a Brookfield viscometer. The bar is rotated at 5 20 revolutions per minute (RPM) in 5 RPM increments. The viscosity is recorded at each speed for several minutes. The bar moves up and down in the Z axis (perpendicular to the surface of the paste sample jar) as the bar rotates. The helical path ensures the paste is shear thinned excessively by the bar during the viscosity test. 

The Nametre Rotary B rotational viscometer measures torque in terms of the current needed to drive the d-c motor at a given speed while a material is under test. The standard sensors are coaxial cylinders or Brookfield disk-type spindles, but a cone—plate system is also available. The viscosity range for the coaxial cylinder sensors is 5 to 5 x 1(T mPa-s, and the maximum shear rate is 200. ... 

The viscosity of a liquid can also be determined by measuring the torque needed to rotate a cylinder in the liquid. Brookfield viscometers and rheometers fall into this class of instrument (Fig. 3.7). The viscometer measures the torque produced when a spindle is rotated at constant velocity in a liquid. The Rheometer produces a constant torque... 

Prepare 500 mL of a 2% solution of carboxymethylcellulose, sodium salt, in water in the manner described in the U.S. Pharmacopeia reference above. Since the solution preparation is time-consuming, your instructor may prepare it ahead of time. Using a rotational viscometer with an appropriate spindle and a constant temperature bath, measure the viscosity of this solution at various temperatures. Plot viscosity vs. temperature. 

The ageing test measures the torque necessary to induce the rotation of a special spindle in the slurry. The measure must be done before the first rotation is completed in order to prevent destruction of the gel network. We measure gel after 25 seconds using a Brookfield viscometer with a special spindle (Helipath type), rotating at 1 rpm. 

Since the apparent viscosity of a non-Newtonian fluid holds only for the shear rate (as weii as temperature) at which it is determined, the Brookfield viscometer provides a known rate of shear by means of a spindle of specified configuration that rotates at a known constant speed in the fluid. The torque imposed by fluid friction can be converted to absolute viscosity units (centipoises) by a multiplication factor. See viscosity, shear stress. The viscosities of certain petroleum waxes and wax-polymer blends in the molten state can also be determined by the Brookfield test method ASTM D 2669. 

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