ASTM D2196-2018e1 Standard Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational Viscometer.pdf

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1、Designation: D2196 181Standard Test Methods forRheological Properties of Non-Newtonian Materials byRotational Viscometer1This standard is issued under the fixed designation D2196; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the

2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1NOTEEditorial corrections were mad

3、e throughout in September 2018.1. Scope1.1 These test methods cover the determination of theapparent viscosity and the shear thinning and thixotropicproperties of non-Newtonian materials in the shear rate rangefrom 0.1 to 50 s1using a rotational viscometer operating in afluid contained in a 600 mL l

4、ow form Griffin beaker.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this st

5、andard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision

6、 on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Summary of Test Method2.1 Test Method A consists of determining the apparentviscosity of coatings and related materials by me

7、asuring thetorque on a spindle rotating at a constant speed in a 600 mLlow form Griffin beaker.2.2 Test Methods B and C consist of determining the shearthinning and thixotropic (time-dependent) rheological proper-ties of the materials.2The viscosities of these materials aredetermined at a series of

8、prescribed speeds of a rotationalviscometer with a spindle operating in a fluid contained in a600 mL low form Griffin beaker. The agitation of the materialimmediately preceding the viscosity measurements is carefullycontrolled.3. Significance and Use3.1 Test Method A is used for determining the appa

9、rentviscosity at a given rotational speed, although viscosities at twoor more speeds give better characterization of a non-Newtonianmaterial than does a single viscosity measurement.3.2 With Test Methods B and C, the extent of shear thinningis indicated by the drop in viscosity with increasing rotat

10、ionalspeed. The degree of thixotropy is indicated by comparison ofviscosities at increasing and decreasing rotational speeds (TestMethod B), viscosity recovery (Test Method B), or viscositiesbefore and after high shear (combination of Test Methods Band C). The high-shear treatment in Test Method C a

11、pproxi-mates shearing during paint application. The viscosity behaviormeasured after high shear is indicative of the characteristics ofthe paint soon after application.4. Apparatus4.1 Rotational ViscometerThe essential instrument willhave the following capabilities at a minimum:4.1.1 A drive motor,

12、to apply a unidirectional rotationaldisplacement to the spindle immersed in the specimen forrotational speeds between 0.307 and 10.24 rad/sec (0.3 and 100rpm) constant to within 0.01%.4.1.2 A force sensor to measure the torque required to drivethe spindle immersed in the specimen at each of the defi

13、nedspeed settings to within 0.1%.4.1.3 A coupling shaft, or other means, to transmit therotational displacement from the motor to the spindle.4.1.4 A rotational element, spindle, or tool, such as theshapes shown in Fig. 1 to fix the specimen between the spindleand a stationary surface. The protectiv

14、e bracket, which attachesto the viscometer and protects the spindle, provides thestationary surface described in the preceding sentence.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of S

15、ubcommittee D01.24 on Physical Properties of Liquid Paints a minimum of three speeds is recommended. Setthe viscometer at the slowest rotational speed chosen for thetest (Note 8). Initiate the spindle rotation and record thereading after ten revolutions (or other agreed-upon number ofrevolutions).NO

16、TE 9A higher initial rotational speed may be used upon agreementbetween producer and user.12.4 Increase the rotational speed in steps and record thereading after ten revolutions (or equivalent time for eachspindle/speed combination) at each speed.After an observationhas been made at the top speed, d

17、ecrease the rotational speedin steps to the slowest speed, recording the reading after tenrevolutions (or equivalent time) at each speed.12.5 After the last reading has been taken at the slowestspeed, stop the rotation and allow the specimen to standundisturbed for an agreed-upon rest period typical

18、ly 1 minute.At the end of the rest period, start the spindle rotation at theslowest speed and record the reading after ten revolutions (orother agreed-upon number of revolutions).13. Calculations and Interpretation of Results13.1 Calculate the apparent viscosity at each speed asshown in Section 8. I

19、f using a dial reading viscometer,calculate the equivalent viscosity value for each torque value asshown in Section 10.13.2 If desired, determine the degree of shear thinning bythe following method:13.2.1 Shear Thinning Index (sometimes called the thixindex)Divide the apparent viscosity at a low rot

20、ational speedby the viscosity at a speed ten times higher. Typical speedcombinations are 0.2 and 2 rpm (2 and 20 rpm), 0.5 and 5 rpm(5 and 50 rpm), 0.6 and 6 rpm (6 and 60 rpm) but selection issubject to agreement between producer and user. The resultantviscosity ratio is an index of the degree of s

21、hear thinning overthat range of rotational speed with higher ratios indicatinggreater shear thinning.13.2.2 A regular or log-log plot of viscosity versus rota-tional speed may also be useful in characterizing the shear-thinning behavior of the material. Such plots may be used formaking comparisons b

22、etween paints or other materials.13.3 If desired, estimate the degree of thixotropy (underconditions of limited shearing-out of structure) by one of thefollowing methods:13.3.1 Calculate the ratio of the initial viscosity reading tothe final viscosity reading. Note that both readings were takenat th

23、e same rotational speed. The higher the ratio, the greaterthe thixotropy.D2196 181313.3.2 Calculate the ratio of the viscosity at the slowestspeed taken after the rest period to that viscosity before the restperiod. The higher the ratio, the greater the thixotropy.14. Report14.1 Report the following

24、 information:14.1.1 The viscometer manufacturer, model and spindle,14.1.2 The viscosities at increasing and decreasing spindlespeeds,14.1.3 The rest period time and the viscosity at the end ofthat time,14.1.4 The specimen temperature in degrees Celsius, and14.1.5 The shake time if other than that sp

25、ecified.14.2 Optional Reporting:14.2.1 Degree of Shear ThinningShear thinning index andspeeds over which it was measured (13.2).14.2.2 Estimated Degree of Thixotropy (under conditions ofshearing-out of structure)Ratio of the viscosities at thelowest speed, for both increasing and decreasing speeds;

26、orratio of the viscosity at the lowest speeds before and after therest period, and speed at which they were measured (13.3).15. Precision and Bias15.1 PrecisionSee Section 22 for precision, including thatfor measurement of the shear thinning index (ratio of viscosityat 0.5 rpm to that at 5 rpm. It h

27、as not been possible to devisea method for determining precision for viscosities at increasingand decreasing speeds other than as individual measurements.No attempt was made to determine the precision of themeasurement of the degree of thixotropy because this param-eter is dependent on the material,

28、 the time of the test, and othervariables.15.2 BiasNo statement of bias is possible with this testmethod.TEST METHOD CVISCOSITY AND SHEARTHINNING OF A SHEARED MATERIAL16. Apparatus16.1 High-speed laboratory stirrer with speeds of at least200 rad/s (2000 r/min) and equipped with a 50-mm (2-in.)diamet

29、er circular dispersion blade.317. Preparation of Specimen17.1 Insert the 50-mm (2-in.) blade into the center of thecontainer (7.1) so that the blade is about 25 mm (1 in.) from thebottom. Run the mixer at 200 rad/s (2000 r/min) (Note 10) for1 min.NOTE 10Materials may be sheared at other speeds using

30、 other sizeblades upon agreement between producer and user.18. Procedure18.1 Immediately insert the same spindle used in TestMethod B into the sheared material in the same manner as inSection 8.18.2 Initiate the spindle rotation at the highest speed used inTest Method B (12.5). Record the scale read

31、ing after tenrevolutions (or other agreed-upon number of revolutions).18.3 Decrease the rotational speed in steps and record thereadings at each speed down to the lowest speed used in TestMethod B, recording the reading after ten revolutions at eachspeed (or other agreed-upon number of revolutions).

32、19. Calculations and Interpretation of Results19.1 As in Test Method B, calculate the viscosities at eachdecreasing speed if you are using a dial reading viscometer.19.2 If desired, calculate the degree of shear thinning by themethod given in Test Method B, 13.2. The measured viscositybehavior after

33、 shearing is essentially that of the paint immedi-ately after application (disregarding changes in solids).19.3 If desired, estimate the degree of thixotropy (underconditions of complete shearing-out of structure) by calculatingthe ratio of the viscosities at the lowest speeds before and aftershear.

34、 The viscosity at the lowest speed before-shearing istaken from Test Method B, 13.1, at the lowest increasing speed.The viscosity at lowest speed after-shear is taken from 19.1.The higher the ratio, the greater the thixotropy.20. Report20.1 Report the following information:20.1.1 The viscometer manu

35、facturer, model and spindle,20.1.2 The viscosities at decreasing spindle speeds,20.1.3 The specimen temperature in degrees Celsius, and20.1.4 The speed of the high-speed mixer, size of blade, andtime of mixing if different from method.20.2 Optional Reporting:20.2.1 Degree of Shear ThinningShear thin

36、ning index andspeed over which it was measured (13.2).20.2.2 Estimated ThixotropyRatio of viscosities at lowestspeed viscosities before and after shearing and the rotationalspeed at which they were measured.21. Precision and Bias21.1 PrecisionThe precision for individual viscosity mea-surements is t

37、he same as for Test Method A in Section 22.Noattempt has been made to determine the precision of the shearthinning index or degree of thixotropy for Test Method C forthe reasons given in 15.1.21.2 BiasNo statement of bias is possible with this testmethod.22. Summary of Precision22.1 In an interlabor

38、atory study of Test Methods A and B,eight operators in six laboratories using dial reading apparatusfrom a single supplier (Brookfield Engineering) measured ontwo days the viscosities of four architectural paints comprisinga latex flat, a latex semi-gloss, a water-reducible gloss enamel,and an alkyd

39、 semi-gloss, that covered a reasonable range inviscosities and were shear thinning. Measurements at increas-ing speeds of 0.5, 1.0, 2.0, and 5.0 rad/s (5, 10, 20, and 50r/min) (equivalent to eight operators testing 16 samples) were3Cowles or Shar type mixer/disperser.D2196 1814used to obtain the pre

40、cision of Test Method A. The within-laboratory coefficient of variation for Test Method A (singlespeed) was found to be 2.5 % with 121 df and for Test MethodB (Shear Thinning Index) 3.3 % with 31 df. The correspondingbetween-laboratories coefficients are 7.7 % with 105 df and7.6 % with 27 df. Based

41、on these coefficients the followingcriteria should be used for judging the acceptability of resultsat the 95 % confidence level:22.1.1 RepeatabilityTwo results obtained by the sameoperator at different times should be considered suspect if theydiffer by more than 7.0 % relative for single speed visc

42、osityand 9.5 % relative for shear thinning index.22.1.2 ReproducibilityTwo results obtained by operatorsin different laboratories should be considered suspect if theydiffer by more than 22 % relative, respectively, for the sametwo test methods.NOTE 11Measurements made by digital apparatus from the s

43、amesupplier or apparatus from other suppliers may have different precision23. Keywords23.1 non-Newtonian; rheological properties; rheology; rota-tional viscometer; rotational viscosity; shear thinning; thixindex; thixotropic; thixotropy; viscometer; viscosityASTM International takes no position resp

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