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

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1、Designation: D2196 15D2196 18Standard Test Methods forRheological Properties of Non-Newtonian Materials byRotational ViscometerViscountess1This standard is issued under the fixed designation D2196; the number immediately following the designation indicates the year oforiginal adoption or, in the cas

2、e of revision, the 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.1. Scope1.1 These

3、 test methods cover the determination of the apparent viscosity and the shear thinning and thixotropic properties ofnon-Newtonian materials in the shear rate range from 0.1 to 50 s1 using a rotational viscometer operating in a fluid of “infinite”dimensions.contained in a 600 mL low form Griffin beak

4、er.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establi

5、sh appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Princi

6、ples for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Summary of Test Method2.1 Test Method A consists of determining the apparent viscosity of coatings and related materials by measuring t

7、he torque ona spindle rotating at a constant speed in the material.a 600 mL low form Griffin beaker.2.2 Test Methods B and C consist of determining the shear thinning and thixotropic (time-dependent) rheological properties ofthe materials.2 The viscosities of these materials are determined at a seri

8、es of prescribed speeds of a rotational-type viscometerrotational viscometer with a spindle operating in a fluid of “infinite” dimensions. contained in a 600 mL low form Griffin beaker.The agitation of the material immediately preceding the viscosity measurements is carefully controlled.3. Significa

9、nce and Use3.1 Test MethodAis used for determining the apparent viscosity at a given rotational speed, although viscosities at two or morespeeds give better characterization of a non-Newtonian material than does a single viscosity measurement.3.2 With Test Methods B and C, the extent of shear thinni

10、ng is indicated by the drop in viscosity with increasing rotationalspeed. The degree of thixotropy is indicated by comparison of viscosities at increasing and decreasing rotational speeds (TestMethod B), viscosity recovery (Test Method B), or viscosities before and after high shear (combination of T

11、est Methods B andC). The high-shear treatment in Test Method C approximates shearing during paint application. The viscosity behavior measuredafter high shear is indicative of the characteristics of the paint soon after application.4. Apparatus4.1 Rotational ViscometerThe essential instrumentation r

12、equired providing the minimum rotational viscometer analyticalcapabilities for this method include:instrument will have the following capabilities at a minimum:1 These test methods are under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and are the

13、 direct responsibility ofSubcommittee D01.24 on Physical Properties of Liquid Paints a minimum of three speeds is recommended. Set theviscometer at the slowest rotational speed chosen for the test (Note 98). Initiate the spindle rotation and record the reading afterten revolutions (or other agreed-u

14、pon number of revolutions).NOTE 9A higher initial rotational speed may be used upon agreement between producer and user.12.4 Increase the rotational speed in steps and record the reading after ten revolutions (or equivalent time for each spindle/speedcombination) at each speed. After an observation

15、has been made at the top speed, decrease the rotational speed in steps to theslowest speed, recording the reading after ten revolutions (or equivalent time) at each speed.NOTE 11It is preferable to change speed when the motor is running.12.5 After the last reading has been taken at the slowest speed

16、, stop the rotation and allow the specimen to stand undisturbedfor an agreed-upon rest period typically 1 minute. At the end of the rest period, start the spindle rotation at the slowest speed andrecord the reading after ten revolutions (or other agreed-upon number of revolutions).13. Calculations a

17、nd Interpretation of Results13.1 Calculate the apparent viscosity at each speed as shown in Section 8. If using a dial reading viscometer, calculate theequivalent viscosity value for each torque value as shown in Section 10.13.2 If desired, determine the degree of shear thinning by the following met

18、hod:13.2.1 Shear Thinning Index (sometimes erroneously called the thixotropicthix index)Divide the apparent viscosity at a lowrotational speed by the viscosity at a speed ten times higher. Typical speed combinations are 0.2 and 2 rad/srpm (2 and 20r/min),rpm), 0.5 and 5 rad/s (5rpm (5 and 50 r/min),

19、rpm), 0.6 and 6 rad/s (6rpm (6 and 60 r/min)rpm) but selection is subjectto agreement between producer and user. The resultant viscosity ratio is an index of the degree of shear thinning over that rangeof rotational speed with higher ratios indicating greater shear thinning.13.2.2 A regular or log-l

20、og plot of viscosity versus rotational speed may also be useful in characterizing the shear-thinningbehavior of the material. Such plots may be used for making comparisons between paints or other materials.13.3 If desired, estimate the degree of thixotropy (under conditions of limited shearing-out o

21、f structure) by one of the followingmethods:13.3.1 Calculate the ratio of the viscosity at the slowest rotational speed with increasing speed to that with decreasing initialviscosity reading to the final viscosity reading. Note that both readings were taken at the same rotational speed. The higher t

22、heratio, the greater the thixotropy.13.3.2 Calculate the ratio of the viscosity at the slowest speed taken after the rest period to that viscosity before the rest period.The higher the ratio, the greater the thixotropy.14. Report14.1 Report the following information:14.1.1 The viscometer manufacture

23、r, model and spindle,14.1.2 The viscosities at increasing and decreasing spindle speeds,D2196 18514.1.3 The rest period time and the viscosity at the end of that time,14.1.4 The specimen temperature in degrees Celsius, and14.1.5 The shake time if other than that specified.14.2 Optional Reporting:14.

24、2.1 Degree of Shear ThinningShear thinning index and speeds over which it was measured (13.2).14.2.2 Estimated Degree of Thixotropy (under conditions of shearing-out of structure)Ratio of the viscosities at the lowestspeed, for both increasing and decreasing speeds; or ratio of the viscosity at the

25、lowest speeds before and after the rest period, andspeed at which they were measured (13.3).15. Precision and Bias15.1 PrecisionSee Section 22 for precision, including that for measurement of the shear thinning index (ratio of viscosity at0.5 rad/srpm to that at 5 rad/s (5 r/min to that at 50 r/min)

26、. rpm. It has not been possible to devise a method for determiningprecision for viscosities at increasing and decreasing speeds other than as individual measurements. No attempt was made todetermine the precision of the measurement of the degree of thixotropy because this parameter is dependent on t

27、he material, thetime of the test, and other variables.15.2 BiasNo statement of bias is possible with this test method.TEST METHOD CVISCOSITY AND SHEAR THINNING OF A SHEARED MATERIAL16. Apparatus16.1 High-speed laboratory stirrer with speeds of at least 200 rad/s (2000 r/min) and equipped with a 50-m

28、m (2-in.) diametercircular dispersion blade.317. Preparation of Specimen17.1 Insert the 50-mm (2-in.) blade into the center of the container (7.1) so that the blade is about 25 mm (1 in.) from the bottom.Run the mixer at 200 rad/s (2000 r/min) (Note 1210) for 1 min.NOTE 10Materials may be sheared at

29、 other speeds using other size blades upon agreement between producer and user.18. Procedure18.1 Immediately insert the same spindle used in Test Method B into the sheared material in the same manner as in Section 8.18.2 Initiate the spindle rotation at the highest speed used in Test Method B (12.5)

30、. Record the scale reading after ten revolutions(or other agreed-upon number of revolutions).18.3 Decrease the rotational speed (Note 11) in steps and record the readings at each speed down to the lowest speed used inTest Method B, recording the reading after ten revolutions at each speed (or other

31、agreed-upon number of revolutions).19. Calculations and Interpretation of Results19.1 As in Test Method B, calculate the viscosities at each decreasing speed.speed if you are using a dial reading viscometer.19.2 If desired, calculate the degree of shear thinning by the method given in Test Method B,

32、 13.2. The measured viscositybehavior after shearing is essentially that of the paint immediately after application (disregarding changes in solids).19.3 If desired, estimate the degree of thixotropy (under conditions of complete shearing-out of structure) by calculating theratio of the viscosities

33、at the lowest speeds before and after shear. The viscosity at the lowest speed before-shearing is taken fromTest Method B, 13.1, at the lowest increasing speed. The viscosity at lowest speed after-shear is taken from 19.1. The higher theratio, the greater the thixotropy.20. Report20.1 Report the fol

34、lowing information:20.1.1 The viscometer manufacturer, 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, and time of mixing if different from method.20.2 Optional Repor

35、ting:20.2.1 Degree of Shear ThinningShear thinning index and speed over which it was measured (13.2).3 Cowles or Shar type mixer/disperser.D2196 18620.2.2 Estimated ThixotropyRatio of viscosities at lowest speed viscosities before and after shearing and the rotational speedat which they were measure

36、d.21. Precision and Bias21.1 PrecisionThe precision for individual viscosity measurements is the same as for Test MethodAin Section 22. No attempthas been made to determine the precision of the shear thinning index or degree of thixotropy for Test Method C for the reasonsgiven in 15.1.21.2 BiasNo st

37、atement of bias is possible with this test method.22. Summary of Precision22.1 In an interlaboratory study of Test Methods A and B, eight operators in six laboratories using dial reading apparatus froma single supplier (Brookfield Engineering) measured on two days the viscosities of four architectur

38、al paints comprising a latex flat,a latex semi-gloss, a water-reducible gloss enamel, and an alkyd semi-gloss, that covered a reasonable range in viscosities and wereshear thinning. Measurements at increasing speeds of 0.5, 1.0, 2.0, and 5.0 rad/s (5, 10, 20, and 50 r/min) (equivalent to eightoperat

39、ors testing 16 samples) were used to obtain the precision of Test Method A. The within-laboratory coefficient of variationfor Test Method A (single speed) was found to be 2.5 % with 121 df and for Test Method B (Shear Thinning Index) 3.3 % with31 df. The corresponding between-laboratories coefficien

40、ts are 7.7 % with 105 df and 7.6 % with 27 df. Based on these coefficientsthe following criteria should be used for judging the acceptability of results at the 95 % confidence level:22.1.1 RepeatabilityTwo results obtained by the same operator at different times should be considered suspect if they

41、differby more than 7.0 % relative for single speed viscosity and 9.5 % relative for shear thinning index.22.1.2 ReproducibilityTwo results obtained by operators in different laboratories should be considered suspect if they differby more than 22 % relative, respectively, for the same two test method

42、s.NOTE 11Measurements made by digital apparatus from the same supplier or apparatus from other suppliers may have different precision23. Keywords23.1 non-Newtonian; rheological properties; rheology; rotational viscometer; rotational viscosity; shear thinning; thix index;thixotropic; thixotropy; visc

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