Brookfield Viscosity Test

All the oligo-polyols are used to build the polyurethane high MW structure in a reactive process, as a consequence of the oligo-polyols terminal hydroxyl group reaction with polyisocyanates. The reactivity of oligo-polyols in polyurethane fabrication is a very important practical characteristic. Reactivity is a measure of the reaction rate of an oligo-polyol with an isocyanate in order to make the final polyurethane polymer. One practical method is the measurement of viscosity, in time, by Brookfield Viscosity Test (BVT), especially used to determine the reactivity of ethylene oxide capped polyether polyols. Figure 3.12 shows the effect of the primary hydroxyl content upon the reactivity of ethylene-oxide capped polyether triols of MW of 5,000 daltons. 

Oligomer and Film Characterization. Brookfield viscosity measurements were taken on a Model RVTD digital readout viscometer. Samples for Instron testing were prepared on glass plates using 25 or 75 pm (1.0 or 3.0 mil) Byrd film applicator. Coatings for cure speed and MEK double rub (MEKDR) studies were prepared on aluminum Q-Panels using a 40 wire wound rod (100 pm or 4.0 mil). 

Brookfield viscosity measurement is a way to estimate the quality of a fresh dispersion. The ageing test controls the evolution of the viscosity over time. It is... 

Frequently used single-point viscosity tests in the starch plant are orifice pipettes,56 orifice funnels,57 the Hot Scott viscometer, and various methods to determine alkaline fluidity.58 For absolute measurements of the rheological properties, rotating viscometers with coaxial cylinders are used.59 The paper industry uses mainly the Brookfield viscometer and the Hercules viscometer for determining shear-dependent viscosity, pseudoplasticity, and thixotropy. Oscillatory and capillary viscometers are used for more detailed viscosity characterization, such as yield value, elastic properties, and viscoelasticity.60... 

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. 

These methods determine the viscosities of polyols in the range from 10 to 10,000 cP at 25 C and 50 C. Test Method A (Brookfield Viscosity) also applies to more viscous samples soluble in n-butyl acetate. Test Method B is the Cannon Fenske method. 

The Brool eld viscosity test measures the low-temperature viscosity of gear oils and hydraulic fluids under low shear conditions. Brookfield viscosities are measured in centipoise units using a motor-driven spindle immersed in the cooled oil sample, ASTM D2983. 

Standard Test Method for Apparent Viscosity of Plastisols and Organosols at Low Shear Rates by Brookfield Viscosity, ASTM D1824, Am Soc. Testing and Materials. 2002. 

Since cellulases are commercially available, we looked at this reaction further. A number of several commercial cellulases were screened for their ability to reduce the Brookfield viscosity of xanthan solution. Mannosidase and glucosidase were also used in combination with cellulase with the hope of exposing the cellulose backbone by removing the side chains. All of the cellulases tested were found to be somewhat active toward r ucing the molecular weight of xanthan gum (Table 3). 

BROOKFIELD recently announced it offers two hands-on courses that can help users of its instruments to get the most out of their viscosity test methods. These one-day training sessions can be scheduled to take place at Brookfield s Middleboro, MA, headquarters and at major metropolitan areas across the U.S. Courses can also be conducted at customers facilities, where content can be adapted to specific product applications. For more information, call (800) 628-8139 or (508) 946-6200, or visit www.brookfieldengineering.com/ser-vices/educational-programs. 

Both laboratory and field tests with polysaccharide polymers showed that the effective viscosity of a polymer solution in Ten-sleep rock was much lower than the Brookfield viscosity. Laboratory results indicated that this effect was primarily because of the presence of residual oil. 

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. 

These two instmments form a relatively inexpensive package that allows the characterization of a large number of materials over a wide range of viscosities and shear rates. Brookfield has also developed a digital Stormer-type viscometer (ASTM D562), Model KU-1, which is an improvement over the old manual Stormer. This low shear (- 50 ) viscometer is commonly used to test house paints. 

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. ... 

Apples were chopped and mashed to a fine puree. Apple mash was treated with enzyme preparation and incubated for 2 hours at 55°C. Viscosity of mash was measured several times using a Brookfield DC3 viscometer with Helipath stand attachment and TD spindle. After two hours of incubation sanple was coitriftig for 20 minutes at 10.000 rpm. Volume, clarity, pH and brix of the juices were measured. The pectin level of the juices was assessed by a standard alcohol test. 

Assays. Nitrogen assays to determine 1-amidoethylene unit content were done by Kjeldahl method. Limiting viscosity numbers were determined from 4 or more viscosity measurements made on a Cannon-Fenske capillary viscometer at 30°C. Data was extrapolated to 0 g/dL polymer concentration using the Huggins equation(44) for nonionic polymers and the Fuoss equation(45) for polyelectrolytes. Equipment. Viscosities were measured using Cannon-Fenske capillary viscometers and a Brookfield LV Microvis, cone and plate viscometer with a CP-40, 0.8° cone. Capillary viscometers received 10 mL of a sample for testing while the cone and plate viscometer received 0.50 mL. 

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. 

Another well documented, but less widely used method for formulation development is the measurement of electrokinetic properties [14]. These tests require more disdnc-tive/elaborate sample preparation and are mosdy restricted to use during development. Also widely used and relied on are rheological measurements. The scope of rheological measurements ranges from viscosity measurements to the determination of yield points or oscillatory properties, such as the G and G -modules [15]. Since suspoemulsions are not ideal viscous but mostly viscoelastic or dilatant, a wide range of characterization techniques exists. Instrumentation required for this are simple rotary viscosimeters (Brookfield) or more sophisticated stress or shear controlled rotational viscosimeters. 

Dense-phase flow properties can be predicted by measuring the viscosity and deaeration rate of a fluidized bed in a laboratory test (117). This method appears to be especially useful for evaluating the flow characteristics in standpipes. The viscosity is measured by means of a Brookfield viscometer, which consists of a cylindrical wire-screen spindle rotated about its axis by an electric motor through a torsion spring. The torque required to rotate the spindle is measured by displacement of the... 

Linear and radial core flood tests were conducted to determine the polymer concentration for mobility control requirement. Figure 13.39 shows Brookfield (UL adapter) viscosity properties for the Alcoflood 1275A polymer in injection water and in an alkaline-surfactant solution. Note that the AS dramatically decreased the viscosity, and a higher polymer concentration was required to provide the same viscosity. 

Texture analyzers are also used to assess deformability of a fluid, using penetration force vs. depth profiles, etc. These instruments in addition to Brookfield and Haake viscometers are common QC metrics. Other methods include viscosity flow cups and bubble or falling ball viscometers, and several relevant standard test methods include ASTM D1200, DIN/ISO 2431, ASTM D5125, BS3900 Part A6, ASTM D1545, and ASTM D1725. 

The viscosity is typically measured by a viscometer. The SI unit of viscosity is the pascal second (Pa s). However, the widely used unit is poise (P) or centipoise (cP) (1 cP = 1 mPa s). The routine laboratory testing of viscosity is typically done using Brookfield viscometers and reported in cP. For non-Newtonian fluids such as those discussed above, the viscosity is dependent on the spindle size and type (number) and speed of rotation (rotation per minute or r/min) of the viscometer. 

The oligo-polyol s viscosity is determined using a Brookfield viscosimeter. The Standard Test Method for oligo-polyol viscosity determination is ASTM D4878 [37]. There are two test methods, A and B, applicable for viscosities between 0.01 to 1000 Pa-s, at 25 °C, or for solid polyols (such as polytetrahydrofuran), at 50 °C. Test method A is indicated for oligo-polyols of very high viscosities. 

The Brookfield DV-II+-series rotational viscometers and DV-IIl-series rheometers have a built-in Time-to-Torque feature. The selected instrument is run in stand-alone mode, at one constant speed with one spindle. The motor rotation automatically stops at a user-selected torque reading that is a percent of full-scale range or "FSR." The elapsed time and the setpoint torque are then shown on the instrument s display. This system can therefore be used as a type of gel timer - the instrument monitors the torque increase to 90 % of full-scale range, for example, as the sample s viscosity increases during gelation. However, it is a "one-point" test - that is, only one data point is acquired. If the instrument s "continuous printing" mode is selected and a... 

Viscosity may be tested by numerous methods using standard equipment. In siniplest form the test for viscosity is carried out by allowing a measured volume of the gum solution to flow by gravity from a pipet provided with a capillary oriflce and noting the time of flow. Viscosity can also be expressed as millipoises or centi-poises, depending upon the type of equipment used. Bloom pipets, Oswald pipets, and Dudley pipets are utilized to determine viscosity, as well as such instruments as the Brookfield, Stormer, and MacMichael viscometers. 

While various methods and equipment can be used to measure viscosity, the most common uses the Brookfield viscometer (Fig. 7.1). ASTM D2196, Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield) Viscometer, covers this method for Model LVF and Model RVF viscometers. Brookfield LV viscometers are used for low-viscosity materials, RV for medium-viscosity formulations, and HV for high-viscosity formulations. Test Method ASTM D2556, Apparent Viscosity of Adhesives HavingShear-Rate Dependent Flow Properties also specifies... 

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