1、Designation: D2196 15Standard 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.1. Scope1.1 These test methods cover
3、 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 of “infinite” dimensions.1.2 The values stated in SI units are to be regarded as thestanda
4、rd. The values given in parentheses are for informationonly.1.3 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of r
5、egulatorylimitations prior to use.2. Summary of Test Method2.1 Test Method A consists of determining the apparentviscosity of coatings and related materials by measuring thetorque on a spindle rotating at a constant speed in the material.2.2 Test Methods B and C consist of determining the shearthinn
6、ing and thixotropic (time-dependent) rheological proper-ties of the materials.2The viscosities of these materials aredetermined at a series of prescribed speeds of a rotational-typeviscometer operating in a fluid of “infinite” dimensions. Theagitation of the material immediately preceding the viscos
7、itymeasurements is carefully controlled.3. Significance and Use3.1 Test Method A is used for determining the apparentviscosity 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 W
8、ith Test Methods B and C, the extent of shear thinningis indicated by the drop in viscosity with increasing rotationalspeed. The degree of thixotropy is indicated by comparison ofviscosities at increasing and decreasing rotational speeds (TestMethod B), viscosity recovery (Test Method B), or viscosi
9、tiesbefore and after high shear (combination of Test Methods Band C). The high-shear treatment in Test Method C approxi-mates shearing during paint application. The viscosity behaviormeasured after high shear is indicative of the characteristics ofthe paint soon after application.4. Apparatus4.1 Rot
10、ational ViscometerThe essential instrumentationrequired providing the minimum rotational viscometer analyti-cal capabilities for this method include:4.1.1 A drive motor, to apply a unidirectional rotationaldisplacement to the specimen at at least for rotational speedsbetween 0.05 and 6 rad/s (0.5 an
11、d 60 r/min) constant to within1%.4.1.2 Aforce sensor to measure the torque developed by thespecimen to the rotational displacement of the rotationalelement to within 1 %.4.1.3 A coupling shaft, or other means, to transmit therotational displacement from the motor to the rotational ele-ment.4.1.4 A r
12、otational element, spindle, or tool, such as thecylindrical shape shown in Fig. 1, to fix the specimen betweenthe drive shaft and a stationary position.NOTE 1Each rotational element covers a range of about 1.5 decadesof viscosity. The rotational element is selected so that the measuredviscosity (or
13、torque) is between 10 and 90 % of the range of the rotationalelement.4.1.5 A data collection device, to provide a means ofacquiring, storing, and displaying measured or calculatedsignals, or both. The minimum output signals required forrotational viscosity are torque, rotational speed, temperature,a
14、nd time.NOTE 2Manual observation and recording of data are acceptable.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.24 on Physical Properties of Liquid Paints orratio
15、 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 rad/s to that at 5 rad/s (5 r/min
16、 to that at 50 r/min). It hasnot been possible to devise a method for determining precisionfor viscosities at increasing and decreasing speeds other than asD2196 153individual measurements. No attempt was made to determinethe precision of the measurement of the degree of thixotropybecause this param
17、eter is dependent on the material, the time ofthe test, and other variables.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 e
18、quipped with a 50-mm (2-in.)diameter 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 12) for1 min.NOTE 12Materials ma
19、y be sheared at other speeds using 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 Meth
20、od B (12.5). Record the scale reading after tenrevolutions (or other agreed-upon number of revolutions).18.3 Decrease the rotational speed (Note 11) in steps andrecord the readings at each speed down to the lowest speedused in Test Method B, recording the reading after tenrevolutions at each speed (
21、or other agreed-upon number ofrevolutions).19. Calculations and Interpretation of Results19.1 As in Test Method B, calculate the viscosities at eachdecreasing speed.19.2 If desired, calculate the degree of shear thinning by themethod given in Test Method B, 13.2. The measured viscositybehavior after
22、 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.
23、 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
24、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
25、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
26、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
27、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
28、 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) wereused to obtain the precision of Test Method A. The within-laboratory
29、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 on these coefficients the followingcriteria sho
30、uld 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 viscosityand 9.5 % relative for shear thinning inde
31、x.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 13Measurements made by digital apparatus from the samesupplier or apparatus from other suppliers m
32、ay have different precision23. Keywords23.1 non-Newtonian; rheological properties; rheology; rota-tional viscometer; rotational viscosity; shear thinning; thixo-tropic; thixotropy; viscometer; viscosity3Cowles or Shar type mixer/disperser.D2196 154ASTM International takes no position respecting the
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