Brookfield type viscometer

Lastly, viscosity plays an important role in the manufacture of a polyurethane from a prepolymer. A Brookfield-type viscometer is a convenient method of analysis. 

D 2196 Standard Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield type) Viscometer... 

EN 302-7 (2004) [12] deals with the determination of the conventional adhesive duration of use. The viscosity of a specified volume of adhesive at 20°C is monitored using a Brookfield type viscometer until a viscosity exceeding 25 000 mPa s is found. 

ASTM D 2196. 2010. Standard test methods for rheological properties of non-newtonian materials by rotational (Brookfield type) viscometer. West Conshohocken, PA ASTM International. 

Although the international system of units (SI vmit) for viscosity is Pa-s, cps is also used often for raw materials of adhesives and PSAs. For viscous liquids, Brookfield-type viscometers or coaxial-cylinder-type viscometers, shown in Fig. 40.8, are usually used. For higher viscous... 

For elastomers and rubbers, Mooney viscometers are used, which are documented in standards ISO 289 and JIS K 6300. Brookfield-type viscometers can also be used for elastomers. Elastomers should be dissolved in a solvent in content of 10-20 wt.% before measuring with Brookfield-type viscometer. 

Figure 2. Viscosity of HPMC solution. 20% of HPMC solution was slowly refrigerated from 60°C to 27°C and slowly heated to 41 C. The viscosity was measured by Brookfield type viscometer.

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 pH is measured using a 4% aqueous solution. Viscosity is normally measured using Brookfield viscometer. Alternatively, a capillary-type viscometer or falling ball such as Hxppler may be employed. The type of viscometer used must always be noted. 

Apparatus Use a Brookfield Model LV series viscometer, analog or digital, or equivalent type viscometer for the determination of viscosity of aqueous solutions of cellulose gum within the range of 25 to 10,000 centipoises at 25°. Rotational viscometers of this type have spindles for use in determining the viscosity of different viscosity types of cellulose gum. The spindles and speeds for determining viscosity within different ranges are tabulated below. 

Probably the most widely used type of viscometer in the food industry is the Brookfield rotational viscometer. An example of this instrument s application to a non-Newtonian food product is given in the work of Sarava-cos and Moyer (1967) on fruit purees. Viscometer scale readings were plotted against rotational speed on a logarithmic scale, and the slope of the straight line obtained was taken as the exponent n in the following equation for pseudoplastic materials ... 

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. 

Figure 18. Solubility characteristics of a hydroxyl containing vinyl terpolymer in Rule 66-type solvents (Brookfield LVF viscometer)...

Norsodyne Resin, Isophthalic type (high resistance to hydrolysis and organic solvents) acid index, 13 styrene content, 50 wt % viscosity (Brookfield-type rotational viscometer) at 25 °C, 160 mPa s (cP) and volumetric shrinkage, 9%. 

The method and type of equipment used also vary with the type of adhesive. As an example, the viscosity of electrically conductive adhesives is measured according to ASTM D1824, Apparent Viscosity of Plastisols and Organosols at Low-Shear Rates by Brookfield Viscosity The viscosity of typical electrically conductive die-attach adhesives is measured with a Brookfield HBT viscometer with Spindle TB and Speed 5. For higher-viscosity conductive adhesives and for underfill adhesives, a Brookfield RVT or RVF viscometer is used with Spindles 6 or 7 at speeds of 4—10.4 rpm. Another Brookfield viscometer, the Cone-and-plate viscometer with a CP-51 spindle is used for low-to-intermediate viscosity adhesives. Finally, the Brookfield HAT and HBT instruments are used for the high-viscosity (1-2 million cP at 1 rpm) adhesives typically used in SMT applications. ... 

Procedmes for extracting valid shear stress versus shear rate data from measurements involving wide gap coaxial cylinder systems (the Brookfield viscometer being an extreme example of wide gap devices) are therefore of considerable interest in making quantitative measurements of the flow properties of non-Newtonian process products. Most of these data-treatment procedures necessarily involve some assumption regarding the functional form of the flow curve of the material. One example is that made in the derivation of data from the Brookfield-type instrument, which assumes that the speed of rotation of the cylinder or spindle is proportional to the shear rate experienced by the fluid. This assumption implies that the flow curve is adequately described by a simple power-law (which for many shear-thinning non-Newtonian fluids may be acceptable), but this assiunption is widely taken to exclude all fluids which display an apparent yield stress and/or non-power law type behaviour. 

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). 

Types include Cyanabond Textile Adhesive U-270, U-271, U-251, U-253, U-273, U-274, U-255, and U-275 whose viscosities vary from water-thin liquids to mobile pastes of 90,000-95,000 cps viscosity (Brookfield LVF viscometer, No. 4 spindle, 6 rpm, 72°F). Storage stability is good for at least 6 months at 72°F. 

The Brookfield type of viscometer, in which one of a number of different spindle types (RV, LV and so forth) is rotated in the sample dispersion, also enjoys widespread use for viscosity measurements (see ISO 2555 and 1652). The disadvantages associated with this type of viscometer are that the shear rate is not well defined and that the results of measurements made using different spindle types cannot be compared with one another. 

Slurry Viscosity. Viscosities of magnesium hydroxide slurries are determined by the Brookfield Viscometer in which viscosity is measured using various combinations of spindles and spindle speeds, or other common methods of viscometry. Viscosity decreases with increasing rate of shear. Fluids, such as magnesium hydroxide slurry, that exhibit this type of rheological behavior are termed pseudoplastic. The viscosities obtained can be correlated with product or process parameters. Details of viscosity deterrnination for slurries are well covered in the Hterature (85,86). 

Solution Polymers. Methacryhc solution polymers are usually characterized by thek composition, soHds content, viscosity, molecular weight, glass-transition temperature, and solvent type. The compositions of methacryhc polymers are most readily determined by physicochemical methods such as spectroscopy, pyrolytic gas—Hquid chromatography, and refractive index measurements. The soHds content is determined by dilution followed by solvent evaporation to constant weight. Solution viscosities are most conveniendy determined with a Brookfield viscometer. Methods for estimating molecular weights by intrinsic viscosity are available (103). 

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 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. 

Different grades of Methocel and Metolose are supplied, with nominal viscosities of 4000 mPa s (measured with a Brookfield viscometer on a 2% w/v solution). Methocel 4M types E and are different in their hydration rates, type being the quickest. Metoloses SH4000 differ in their gel temperature. Grades 60 and 90 were used. Another polymer of 4000 mPa s viscosity was used hydroxyethylcellulose, in order to observe effects on the dissolution rate. 

For the studies presented in this chapter, samples of peanut and cottonseed meal suspensions were evaluated for foam capacity, stability, and viscosity measurements as described by Cherry and coworkers (23, 24, 22). Vegetable protein suspensions at the appropriate concentration and pH were whipped in a Waring-type blender. After blending, the whipped products were transferred to a graduated cyclinder. Milliliters of foam were recorded immediately and at various time intervals to determine capacity and stability. A Brookfield viscometer and... 

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