ASTM D1646-17 Standard Test Methods for Rubber—Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer).pdf

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1、Designation: D1646 17Standard Test Methods forRubberViscosity, Stress Relaxation, and Pre-VulcanizationCharacteristics (Mooney Viscometer)1This standard is issued under the fixed designation D1646; 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 procedures for measuring aproperty called Mooney viscosity. Mooney viscosity is definedas the shearing torque resisting rotation of a cylindrical metaldisk (or rotor) embedded in rubber within a cylindrical cavity.The dimensions of the shearing disk viscometer, testtemperatures,

4、and procedures for determining Mooney viscos-ity are defined in these test methods.1.2 When disk rotation is abruptly stopped, the torque orstress on the rotor decreases at some rate depending on therubber being tested and the temperature of the test. This iscalled “stress relaxation” and these test

5、 methods describe a testmethod for measuring this relaxation.NOTE 1Viscosity as used in these test methods is not a true viscosityand should be interpreted to mean Mooney viscosity, a measure ofshearing torque averaged over a range of shearing rates. Stress relaxationis also a function of the test c

6、onfiguration and for these test methods theresults are unique to the Mooney viscometer.1.3 When compounded rubber is placed in the Mooneyviscometer at a temperature at which vulcanization may occur,the vulcanization reaction produces an increase in torque.These test methods include procedures for me

7、asuring the initialrate of rubber vulcanization.1.4 ISO 289 Parts 1 and 2 also describes the determinationof Mooney viscosity and pre-vulcanization characteristics. Inaddition to a few insignificant differences there are majortechnical differences between ISO 289 and this test method inthat ISO 289

8、does not provide for sample preparation on a mill,while this test method allows milling sample preparation insome cases prior to running a Mooney viscosity test. This canresult in different viscosity values for some rubbers.1.5 The values stated in SI units are to be regarded as thestandard. The val

9、ues given in parentheses are for informationonly.1.6 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 standard to establish appro-priate safety, health, and environmental practices and deter-mine the app

10、licability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by

11、 the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1349 Practice for RubberStandard Conditions for Test-ingD1418 Practice for Rubber and Rubber LaticesNomenclatureD1485 Practice for Rubber from Natural SourcesSampling and Sample Prepa

12、rationD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3185 Test Methods for RubberEvaluation of SBR(Styrene-Butadiene Rubber) Including Mixtures With OilD3186 Test Methods for RubberEvaluation of SBR(Styrene-Butadie

13、ne Rubber) Mixed With Carbon Black orCarbon Black and OilD3896 Practice for Rubber From Synthetic SourcesSampling1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and Rubber-like Materials and are the direct responsibility of SubcommitteeD11.12 on Processability Tests.Cur

14、rent edition approved Dec. 1, 2017. Published January 2018. Originallyapproved in 1959. Last previous edition approved in 2015 as D1646 15. DOI:10.1520/D1646-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o

15、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized

16、 principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1D4483 Practice for Evaluating Precision for Test MethodStandards in t

17、he Rubber and Carbon Black ManufacturingIndustries2.2 ISO Standard:3ISO 289 Rubber, UnvulcanizedDeterminations Using theShearing Disk Viscometer,Part 1 Determination of Mooney Viscosity, andPart 2 Determination of Prevulcanization Characteristics.3. Terminology3.1 Definitions of Terms Specific to Th

18、is Standard:3.1.1 Mooney viscosity, nmeasure of the viscosity of arubber or rubber compound determined in a Mooney shearingdisk viscometer; viscosity is indicated by the torque required torotate a disk embedded in a rubber specimen and enclosed inthe die cavity under specified conditions.3.1.2 pre-v

19、ulcanization characteristics, nfor a vulcaniz-able compound, a measure of the time to the incipientvulcanization and the rate of cure during the early stages ofvulcanization.3.1.3 stress relaxation, nresponse of a raw or com-pounded rubber to a rapid cessation of flow or a suddendeformation; specifi

20、c to the use of the shearing diskviscometer, it takes the form of a decaying level of stressinitiated by suddenly stopping the rotation of the disk.3.1.4 test temperature, nsteady-state temperature of theclosed dies with rotor in place and the cavity empty; thissteady-state temperature shall be meas

21、ured within the dies asdescribed in 6.1.3.4. Summary of Test Methods4.1 These test methods are divided into three parts:4.1.1 Part A: ViscosityThis test method describes themeasurement of the Mooney viscosity. The Mooney viscosityis measured by a metal disk embedded in a rubber specimencontained in

22、a rigid cylindrical cavity maintained at a specifiedpressure and temperature. The disk is slowly and continuouslyrotated in one direction for a specified time. The resistance tothis rotation offered by the rubber is measured in arbitrarytorque units as the Mooney viscosity of the specimen.4.1.2 Part

23、 B: Stress RelaxationThis test method describesthe procedure to measure stress relaxation. At the end of aMooney viscosity test, the rotation of the metal disk issuddenly stopped and the rate of decrease of torque ismonitored as a function of time.4.1.3 Part C: Pre-Vulcanization CharacteristicsThis

24、testmethod describes how pre-vulcanization properties may bemeasured. The viscosity of vulcanizable rubber compounds isrecorded during heating at a specified temperature. The mini-mum viscosity and the times for the viscosity to increase byspecified amounts are used as arbitrary measures of the star

25、tand rate of vulcanization.5. Significance and Use5.1 ViscosityViscosity values determined by this testmethod depend on molecular structure, molecular weight, andnon-rubber constituents that may be present. Since rubberbehaves as a non-Newtonian fluid, no simple relationshipexists between the molecu

26、lar weight and the viscosity.Therefore, caution must be exercised in interpreting viscosityvalues of rubber, particularly in cases where molecular weightis very high. For example, as the molecular weight increases,the viscosity values for IIR polymers (butyl rubbers) reach anupper limit of about 80,

27、 at 100C (212F) using a large rotor ata rotation speed of 2 r/min, and may then decrease toconsiderably lower values. For these higher molecular weightrubbers, better correlation between viscosity values and mo-lecular weight is obtained if the test temperature is increased.5.2 Stress RelaxationThe

28、stress relaxation behavior ofrubber is a combination of both an elastic and a viscousresponse. Viscosity and stress relaxation behavior do notdepend on such factors as molecular weight and non-rubberconstituents in the same way. Thus both of these tests areimportant and complement each other.Aslow r

29、ate of relaxationindicates a higher elastic component in the overall response,while a rapid rate of relaxation indicates a higher viscouscomponent. The rate of stress relaxation has been found tocorrelate with rubber structure characteristics such as molecu-lar weight distribution, chain branching,

30、and gel content.5.3 Pre-Vulcanization CharacteristicsThe onset of vulca-nization can be detected with the Mooney viscometer asevidenced by an increase in viscosity. Therefore, this testmethod can be used to measure incipient cure (scorch) time andthe rate of cure during very early stages of vulcaniz

31、ation. Thistest method cannot be used to study complete vulcanizationbecause the continuous rotation of the disk will result inslippage when the specimen reaches a stiff consistency.6. Apparatus6.1 Mooney ViscometerAn instrument consisting of amotor-driven rotating disk within a cylindrical die cavi

32、tyformed by two dies maintained at specified conditions oftemperature and die closure force. The Mooney viscometermeasures the effect of temperature and time on the viscosity ofrubbers. If the stress relaxation test is to be performed, theinstrument must be capable of quickly stopping the rotation o

33、fthe disk and monitoring the relaxation of stress versus time.The die-rotor relationship of an example design is shown inFig. 1. The Mooney viscometer shall incorporate the followingcomponents:6.1.1 DiesThe dies and die holders forming the die cavityshall be fabricated from a nondeforming tool steel

34、, shall havean unplated finish, and shall be hardened to a Rockwellhardness of 60 HRC minimum. The dimensions of the diecavity, measured from the highest surfaces, shall be 50.93 60.13 mm (2.005 6 0.005 in.) in diameter and 10.59 6 0.03 mm(0.417 6 0.001 in.) in depth. The surfaces of the die cavitys

35、hall either be serrated or contain V-grooves to minimizeslippage of the specimen.NOTE 2The two types of dies may not give the same results.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.D1646 1726.1.1.1 Serrated DiesWhen the cavity is forme

36、d from fourpieces of steel, serrations on the surfaces of the dies and dieholders are used. These serrations consist of rectangulargrooves 0.8 6 0.02 mm (0.031 6 0.0008 in.) wide with auniform depth of not less than 0.25 mm (0.010 in.) nor morethan 0.38 mm (0.015 in.). The grooves shall be vertical

37、andshall be cut on 1.6 6 0.04 mm (0.063 6 0.002 in.) centers. Theserrations of the dies shall consist of two sets of such groovesat right angles to each other.6.1.1.2 Radial Grooved DiesWhen the die cavity isformed from two pieces of steel, radialV-grooves are used onlyon the flat surfaces of the di

38、e cavity. The grooves shall bespaced at 20 intervals and shall form a 90 angle in the diesurfaces with the bisector of the angle perpendicular to thesurface. They shall extend from the 7-mm (0.281-in.) circle tothe 47-mm (1.875-in.) circle in the upper die and from the12-mm (0.472-in.) circle to the

39、 47-mm circle in the lower die.The grooves shall be 1 6 0.1 mm (0.04 6 0.004 in.) wide atthe surface.NOTE 3Die wear can affect test results, usually to a lesser extent thanrotor wear. As a general practice, many users replace dies every secondtime they replace worn rotors (see 6.1.2.1). This practic

40、e may not apply toall materials tested, as wear is material dependent. The ultimate way todetermine if die wear has affected test results is to replace the dies with anew set and determine if the test results are changed.6.1.1.3 Mounting of DiesThe dies shall be an integral partof or mounted on plat

41、ens equipped with a heating device andcontrols capable of maintaining the die cavity at the specifiedtest temperature with a tolerance of 60.5C (61F) at equi-librium conditions.6.1.1.4 Die ClosureThe viscometer shall have a suitabledevice for opening and closing the platens and dies and forholding t

42、hem closed during a test. During a test it is extremelyimportant that the die cavity be held closed with the correctforce. To obtain the correct closing force for the mechanical-type closures, follow explicitly either the manufacturers rec-ommendation or other procedure of equal reliability.4Pneu-ma

43、tically closed dies shall be held closed during the test witha force of 11.5 6 0.5 kN (2585 6 115 lbf).Agreater force maybe required to close the dies when testing extremely toughstocks. At least 10 s before the motor is started, the forceshould be set to 11.5 6 0.5 kN. The die closure shall be such

44、that a piece of thin soft tissue (with a thickness not greater than0.04 mm (0.0015 in.) placed between the meeting surfaceswill retain a continuous pattern of uniform intensity when thedies are closed upon it.Anonuniform pattern indicates wear ofthe die holder surface, misalignment, or distortion of

45、 dies anddie holders.Any of these situations will result in undue leakageand erroneous results.NOTE 4For mechanical-type closure viscometers, the pressure on thedie cavities may change if the viscometer is used at a different temperaturethan that at which it is adjusted.6.1.2 RotorsTwo rotors are sp

46、ecified, differing only intheir diameter. They shall be fabricated from a nondeformingtool steel, shall have an unplated finish and shall be hardenedto a Rockwell hardness of 60 HRC minimum. The large rotorshall be 38.10 6 0.03 mm (1.500 6 0.001 in.) in diameter and5.54 6 0.03 mm (0.218 6 0.001 in.)

47、 in thickness as measuredfrom the highest points. The small rotor shall conform to thelarge rotor except the diameter shall be 30.48 6 0.03 mm4Decker, G. E., “Note on the Adjustment of the Mooney Viscometer DieClosure,” ASTM Bulletin, No. 195, January 1954, p. 51.FIG. 1 Relationship of Platens, Dies

48、, and Rotor in a Typical Shearing Disk ViscometerD1646 173(1.200 6 0.001 in.). The serrations on the face of the rotor shallconform to the requirements for the serrated dies given in6.1.1.1 and the serrations on the edge of the rotor shall conformto the requirements specified for the serrated die ho

49、lders. Therotor head shall be securely mounted perpendicularly to asuitable straight cylindrical stem not exceeding 11 mm(0.433 in.) in diameter. The rotor head shall be positioned sothat the top and bottom surfaces are 2.54 6 0.10 mm (0.100 60.005 in.) from the surfaces of the top and bottom dies,respectively, when the dies are closed. The wear tolerance fromthe center position should not exceed 60.25 mm (60.010 in.).A suitable seal shall be provided in the lower die having aminimum clearance and constant torque when the machin