Determination of Viscosity Using A Brookfield Viscometer for Conditioning Polymers

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1 LUBRIZOL TEST PROCEDURE TP-N01004 Edition: December 2, 2013 Previous Editions: August 10, 2000 / November 1, 2011 Determination of Viscosity Using A Brookfield Scope A material's flow property is an important in-process and finished product parameter. It may be an indicator of a product's performance in a coating operation, its penetrating ability or ease of handling or use. The interrelationship between viscosity and other physical characteristics of a product e.g., color, solids content, etc., are useful indicators of product quality, acceptance and performance. Theory Viscosity is the measure of the internal friction of a fluid. This friction becomes apparent when a layer of fluid is made to move in relation to another layer. The greater the friction, the greater the amount of force required to cause its movement, which is called "shear". Shearing occurs whenever the fluid is physically moved as in pouring, mixing, etc. The measure of the speed at which these layers move with respect to each other is called the "shear rate." This has a unit of measurement called the "reciprocal second" (sec-i). Highly viscous materials thus require more force to move than less viscous materials. The force per unit area required to produce shearing action is called "shear stress." It has a unit of measure called "dynes per square centimeter" (dynes/cm2). Viscosity (n) can then be described by the following equation: shear stress n = shear rate The fundamental unit of viscosity measurement is the "poise." A material requiring a shear stress of one dyne per square centimeter to produce a shear rate of one reciprocal second has a viscosity of one poise (P), or 100 centipoise (mpa s). For this method, the units reported will be centipoise (mpa s). The Brookfield viscometer rotates a disc or cylinder in a fluid sample and measures the torque needed to overcome the viscous resistance to the induced movement. This is done by rotating the spindle with an electric motor, through a beryllium-copper spring. The degree to which the spring is wound, measured by a deflection of a needle on the viscometer's dial, is proportional to the viscosity of the fluid. For precision measurements between 0 and 100 centipoise, the UL Adapter is used in conjunction with the viscometer. It is important at this time to discuss Newtonian and non-newtonian fluids. A Newtonian fluid is a material which has, at a given temperature, a viscosity which is independent of the shear rate. In other words, when the "shear rate" is varied, the "shear stress" varies in the same proportion. Typical Newtonian fluids include water and thin motor oil. The Brookfield Viscosity Standards are also Newtonian fluids. In a non-newtonian fluid, when the "shear rate" is varied, the "shear stress" doesn't vary in the same proportion or even necessarily in the same direction. The viscosity of such fluids will change as the shear rate is varied. The most common Lubrizol Advanced Materials, Inc. / 9911 Brecksville Road, Cleveland, Ohio / TEL: or combination with other substances or in the User s process. Due to variations in methods, conditions and equipment used commercially in processing these materials, no warranties or guarantees are made as to the suitability of the information or products for the applications disclosed. Lubrizol shall not be liable and the User assumes all risk and responsibility for any use or handling of any material beyond Lubrizol's direct control. LUBRIZOL MAKES NO WARRANTIES, EXPRESS The information contained herein is being furnished for informational purposes only, upon the express condition that the User makes its own assessment of the appropriate use of such information. While the information contained herein is believed to be reliable, no representations, guarantees or warranties of any kind are made as to its accuracy, suitability for a particular application or the results to be obtained herefrom. Lubrizol Advanced Materials, Inc. ("Lubrizol") cannot guarantee how any products associated with this information will perform in Lubrizol Advanced Materials, Inc. is a wholly owned subsidiary of The Lubrizol Corporation All trademarks owned by The Lubrizol Corporation Copyright 2013 / The Lubrizol Corporation OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, For further information, please visit: THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. It is the User s sole responsibility to determine if there are any issues relating to patent infringement of any component or combination of components relating to the supplied information. Nothing contained herein is to be considered as permission, recommendation, nor as an inducement to practice any patented invention without permission of the patent owner.

2 Page 2 of 5 type of non-newtonian fluids are called Pseudoplastic (the viscosity decreases as the "shear rate" increases), Dilatent (viscosity increases as the "shear rate" increases), and Plastic (this type of fluid will behave as a solid under static conditions). The most common non-newtonian fluids (paints, emulsions and dispersions) are of the Pseudoplastic type. Some non-newtonian fluids display a change in viscosity with time under constant shear rate. There are two categories of this type of fluid: Thixotropic (the fluid's viscosity decreases with time as it is sheared at a constant rate); and Rheopectic (the fluid's viscosity increases with time as it is sheared at a constant rate). The information in this section is taken from "MORE SOLUTIONS TO STICKY PROBLEMS" BROOK- FIELD ENGINEERING LABORATORIES, INC. Stoughton, Massachusetts. Equipment 1. Brookfield Viscometer with UL Adapter, Model LVF, or equivalent, or as specified in Routine Product Control or Corporate Routine Raw Material Control. 2. Mercury immersion thermometer, glass, 0 to 220 F graduated in at least 2 F increments, or equivalent temperature indicator. 3. Constant temperature water bath or an equivalent system for adjusting the measurement temperature of a sample. 4. Griffin beakers, 600 ml, or larger, or any similar container with a minimum inside diameter of 3 1/4 inches (83 mm). Containers of other sizes may be required by Routine Product Controls, Corporate Routine Raw Material Controls, an addendum, or a Site Specific SOP or Policy. 5. Brookfield FACTOR FINDER (contains conversion factors to convert dial readings to viscosities in centipoise (mpa s). Reagents 1. Various Brookfield Viscosity Standards (such as nominal 5, 10, 100, 1000, 5000, mpa s), or equivalent with NlST Traceable Certificates of actual analysis. 2. For Merquat 2200 polymer: a. Obazoline 662N. b. Deionized water. Method Standardization 1. Refer to Site SOP or Site Calibration Procedure. Instrument Operating Conditions 1. lnstrument Operating Conditions will vary depending on the Model (Analog or Digital). Refer to Site SOP or lnstrument Operation Manual for current lnstrument Operating Conditions. 2. The Viscometer must be level and the spindle suitably centered in the test sample container. 3. The spindle must be properly immersed to the groove found on its shaft. a. To prevent the formation of bubbles under and around the spindle, the spindle should be immersed into the sample at a slight angle before attaching to the viscometer. This is especially true for viscous materials. b. All Brookfield Viscometers are calibrated at the factory. The calibration of all Brookfield Viscometers is based on immersion of the spindle in a 600 cc low form Griffin beaker (approximately 3 1/4" internal diameter). Viscometer ranges will generally change if smaller vessels are used. They will also change as the spindle is brought near the walls of the container. Guard legs must be attached if furnished FACTOR FINDER is used, particularly with the first two spindles (#1 and #2). c. The use of a container smaller than the 600 ml low form Griffen beaker will result in an increase in viscosity readings, particularly with the #1 and #2 spindles.

3 Page 3 of 5 d. If specified, use a container smaller than the 600 ml Griffen beaker, the simplest approach is to report the dimensions of the container and ignore the probable effect on calibration. As long as the same size container is used for all subsequent test, there will be no correlation problem. Alternately, the viscometer can be recalibrated to compensate for the smaller container. Procedure 1. Consult the Product Specifications for the proper model spindle number, speed of rotation (rpm), sample size, sample temperature and, if necessary, the container size. If not stated there, determine the sample viscosity at the highest speed of rotation which will give a reading toward full scale. (The precision of the instrument increases at this end of the scale). 2. Unless otherwise specified, transfer approximately 400 ml of sample to a 600 ml beaker and adjust sample to the required measurement temperature. Unless otherwise specified on the Product Specification, this temperature adjustment should be done to within +I C or +2 F. Use a water bath, if necessary. 3. Insert spindle in the test material until the fluid's level is at the immersion groove cut in the spindle's shaft. With disc type spindles, care should be taken to avoid trapping air bubbles on its surface. Tilt the beaker while immersing the spindle or immerse spindle at an angle before attaching to the viscometer. 4. Thread spindle to the instrument shaft in a clockwise direction. Finger tighten the connection. 5. Position the sample so that the spindle is centered in the test sample container. The Brookfield factory calibration procedure uses guard legs. Unless the instrument has been recalibrated without the guard legs or the guard legs are not required by Site Specific SOP or Policy, it will be necessary to use guard legs for viscosity measurements. 6. Check the level of the viscometer with the bubble level. For accurate results, it is very important that the leveling bubble is exactly centered. 7. Unless otherwise instructed, take a reading when the pointer or the digital display is stable. Record this reading, and, if necessary, consult the Factor Finder to obtain the proper factor for the viscometer model, speed and spindle number that was used. a. The viscosity specification itself must be met and reported using the speed, spindle, and temperature listed in the appropriate document. Any viscosity measurement not meeting these requirements (spindle, speed and temperature) will be deemed off-spec. b. If the viscosity measurement is off-scale high, go to the next higher spindle number but do not change the rpm setting. If the viscosity measurement is off-scale low, go to the next lower spindle number but do not change the rpm setting. This is for reporting purposes only. The measured value will be considered out of specification even if the measured value lies within the specification range when using different spindle and/or speed.

4 Page 4 of 5 8. UL Adapter - If specified, the UL Adapter (1-100 mpa s) must be installed following the instruction in the lnstrument Operations Manual. a. Two UL Adapter tubes are available, an open tube for measurements in tanks or beakers and a closed tube which holds 16.0 mls of sample. The open tube can be converted to a closed tube using a plastic end cap provided by Brookfield. The closed tubes can be immersed in a constant temperature bath. When using an open tube, immerse to the groove in the side of the UL Adapter. NOTE: Check the operating instructions for the model used for the current UL Adapter equipment available. This will also give the correct sample size for measuring viscosity on a UL Adapter. 9. Adjust viscometer to the proper rpm setting as stated in the appropriate document. When using the UL Adapter, the proper rpm setting is determined by the expected viscosity range of the sample: RPM Range (mpa s) If the UL Adapter was used on the Analog Viscometer, obtain appropriate factor from the following chart. This factor compensates for the windage resistance encountered by the needle indicate. THIS MAY NOT APPLY TO THE MODELS WITH A DIGITAL READOUT. CHECK THE OPERATING INSTRUCTIONS FOR THE MODEL USED. Multiply scale reading by this factor to get correct viscosity. RPM Range (mpa s) Factor * ** * Deduct 0.4 from reading off 100 scale before multiplying to correct for air resistance to rotation at 60 rpm. **Deduct 0.1 from reading off 100 scale before multiplying to correct for air resistance to rotation at 30 rpm. 11. If the UL Adapter dial reading is off-scale high, go to the next lower rpm setting. The UL Adapter is supplied with one spindle. 12. For Merquat 2200 polymer: a. Pour 380 g of deionized water into a 600 ml beaker. b. Add 20 g of Merquat 2200 while stirring the solution with a propeller-type stirrer. Mix for 1 hour. c. Add 100 g of Obazoline 662N and mix for 30 minutes. d. Measure the solution viscosity at 30 C using a Brookfield viscometer, spindle #2 at 12 rpm. Calculation and Data Reporting 1. Report viscosity, temperature, spindle number and speed of rotation used. Remember that the speed and spindle values as well as the measurement temperature are part of the product or raw material specification. For a viscosity measurement to be in specification, it must be made at the speed, spindle and temperature specified. It is possible, therefore, to have a viscosity measurement which meets the centipoise range but be off spec if the wrong spindle and speed have been used in the measurement of that value. 2. Viscosity in mpa s = Dial Reading x Factor. Newer models (Digital) can be programmed to read viscosity directly. Performance Data 1. Range: 0-100,000 mpa s. 2. Accuracy: The results obtained agree with theoretical to within 1%. Brookfield viscometers are guaranteed to be accurate to within +I% of its full scale range. 3. Precision: The original performance data is based on duplicate analyses of five samples performed by each of three operators. Pooled Standard Deviation: mpa s. Therefore, the precision without the UL adapter is estimated to be 282 mpa s.

5 Page 5 of 5 The standard deviation using the UL Adapter is mpa s as determined by one operator on one sample of a Newtonian fluid (average 4.81 mpa s) with a total of nine replicates yielding eight degrees of freedom. The precision of the test method is three times the standard deviation and therefore estimated to be plus or minus mpa s. The method has percent relative standard deviation (%RSD) of 1.2%. The standard deviation using a #2 spindle at 30 rpms is 1.I3 mpa s as determined by one operator on one sample of a Newtonian fluid (average mpa s) with a total of nine replicates yielding eight degrees of freedom. The precision of the test method is three times the standard deviation, and therefore, estimated to be k3.39 mpa s. The method has percent relative standard deviation (%RSD) of 0.36%. 4. Detection Limit: If you chose a spindle and speed such that your full scale range is mpa s, the Viscometer will measure any viscosity in this region to 1.0 mpa s. 5. Elapsed Time: 10 minutes 6. Operator Time: 10 minutes References See Restricted Page. 1. F. Daniels, R. A. Alberty, PHYSICAL CHEMISTRY, 4th Edition, John Wiley & Sons, lnc., NY, "Brookfield Synchro-Lectric Viscometer Instruction Manual". 3. More Solutions to Sticky Problems, A Guide To Getting More From Your Brookfield Viscometer, Brookfield Engineering Labs, Inc. 4. Brookfield Engineering Laboratories Data Sheet 034-c, The Brookfield U.L. Adapter. 5. Brookfield Engineering Laboratories maintains a library of technical papers on viscosity measurement and control. Reprints are available upon request at no charge. A current listing of available papers and an order form are provided in the booklet, TECHNICAL PAPERS ON VISCOSITY MEASUREMENT AND CONTROL (Data Sheet 091-C).