1、Designation: D1646 15D1646 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
2、 the case 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
3、.1 These test methods cover procedures for measuring a property called Mooney viscosity. Mooney viscosity is defined as theshearing torque resisting rotation of a cylindrical metal disk (or rotor) embedded in rubber within a cylindrical cavity. Thedimensions of the shearing disk viscometer, test tem
4、peratures, and procedures for determining Mooney viscosity are defined inthese test methods.1.2 When disk rotation is abruptly stopped, the torque or stress on the rotor decreases at some rate depending on the rubberbeing tested and the temperature of the test. This is called “stress relaxation” and
5、 these test methods describe a test method formeasuring this relaxation.NOTE 1Viscosity as used in these test methods is not a true viscosity and should be interpreted to mean Mooney viscosity, a measure of shearingtorque averaged over a range of shearing rates. Stress relaxation is also a function
6、of the test configuration and for these test methods the results are uniqueto the Mooney viscometer.1.3 When compounded rubber is placed in the Mooney viscometer at a temperature at which vulcanization may occur, thevulcanization reaction produces an increase in torque. These test methods include pr
7、ocedures for measuring the initial rate ofrubber vulcanization.1.4 ISO 289 Parts 1 and 2 also describes the determination of Mooney viscosity and pre-vulcanization characteristics. Inaddition to a few insignificant differences there are major technical differences between ISO 289 and this test metho
8、d in that ISO289 does not provide for sample preparation on a mill, while this test method allows milling sample preparation in some cases priorto running a Mooney viscosity test. This can result in different viscosity values for some rubbers.1.5 The values stated in SI units are to be regarded as t
9、he standard. The values given in parentheses are for information only.1.6 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 establish appropriate safety safety, health, and healthenvironmenta
10、l practices and determine theapplicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides
11、and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1349 Practice for RubberStandard Conditions for TestingD1418 Practice for Rubber and Rubber LaticesNomenclatureD1485 Practice for Rubber from Natural Sour
12、cesSampling and Sample PreparationD3182 Practice for RubberMaterials, Equipment, and Procedures for Mixing Standard Compounds and Preparing StandardVulcanized SheetsD3185 Test Methods for RubberEvaluation of SBR (Styrene-Butadiene Rubber) Including Mixtures With Oil1 These test methods are under the
13、 jurisdiction of ASTM Committee D11 on Rubber and Rubber-like Materials and are the direct responsibility of Subcommittee D11.12on Processability Tests.Current edition approved Dec. 15, 2015Dec. 1, 2017. Published January 2016January 2018. Originally approved in 1959. Last previous edition approved
14、in 20122015 asD1646 07 (2012).D1646 15. DOI: 10.1520/D1646-15.10.1520/D1646-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on
15、 the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users
16、 consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3186 Test Methods for RubberE
17、valuation of SBR (Styrene-Butadiene Rubber) Mixed With Carbon Black or Carbon Blackand OilD3896 Practice for Rubber From Synthetic SourcesSamplingD4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries2.2 ISO Standard:3ISO 289 Rubber,
18、 UnvulcanizedDeterminations Using the Shearing Disk Viscometer,Part 1 Determination of Mooney Viscosity, andPart 2 Determination of Prevulcanization Characteristics.3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Mooney viscosity, nmeasure of the viscosity of a rubber or rubbe
19、r compound determined in a Mooney shearing diskviscometer; viscosity is indicated by the torque required to rotate a disk embedded in a rubber specimen and enclosed in the diecavity under specified conditions.3.1.2 pre-vulcanization characteristics, nfor a vulcanizable compound, a measure of the tim
20、e to the incipient vulcanizationand the rate of cure during the early stages of vulcanization.3.1.3 stress relaxation, nresponse of a raw or compounded rubber to a rapid cessation of flow or a sudden deformation;specific to the use of the shearing disk viscometer, it takes the form of a decaying lev
21、el of stress initiated by suddenly stoppingthe rotation of the disk.3.1.4 test temperature, nsteady-state temperature of the closed dies with rotor in place and the cavity empty; this steady-statetemperature shall be measured within the dies as described in 6.1.3.4. Summary of Test Methods4.1 These
22、test methods are divided into three parts:4.1.1 Part A: ViscosityThis test method describes the measurement of the Mooney viscosity. The Mooney viscosity ismeasured by a metal disk embedded in a rubber specimen contained in a rigid cylindrical cavity maintained at a specified pressureand temperature
23、. The disk is slowly and continuously rotated in one direction for a specified time. The resistance to this rotationoffered by the rubber is measured in arbitrary torque units as the Mooney viscosity of the specimen.4.1.2 Part B: Stress RelaxationThis test method describes the procedure to measure s
24、tress relaxation.At the end of a Mooneyviscosity test, the rotation of the metal disk is suddenly stopped and the rate of decrease of torque is monitored as a function oftime.4.1.3 Part C: Pre-Vulcanization CharacteristicsThis test method describes how pre-vulcanization properties may bemeasured. Th
25、e viscosity of vulcanizable rubber compounds is recorded during heating at a specified temperature. The minimumviscosity and the times for the viscosity to increase by specified amounts are used as arbitrary measures of the start and rate ofvulcanization.5. Significance and Use5.1 ViscosityViscosity
26、 values determined by this test method depend on molecular structure, molecular weight, andnon-rubber constituents that may be present. Since rubber behaves as a non-Newtonian fluid, no simple relationship exists betweenthe molecular weight and the viscosity. Therefore, caution must be exercised in
27、interpreting viscosity values of rubber, particularlyin cases where molecular weight is very high. For example, as the molecular weight increases, the viscosity values for IIR polymers(butyl rubbers) reach an upper limit of about 80, at 100C (212F) using a large rotor at a rotation speed of 2 r/min,
28、 and may thendecrease to considerably lower values. For these higher molecular weight rubbers, better correlation between viscosity values andmolecular weight is obtained if the test temperature is increased.5.2 Stress RelaxationThe stress relaxation behavior of rubber is a combination of both an el
29、astic and a viscous response.Viscosity and stress relaxation behavior do not depend on such factors as molecular weight and non-rubber constituents in the sameway. Thus both of these tests are important and complement each other. A slow rate of relaxation indicates a higher elasticcomponent in the o
30、verall response, while a rapid rate of relaxation indicates a higher viscous component. The rate of stressrelaxation has been found to correlate with rubber structure characteristics such as molecular weight distribution, chain branching,and gel content.5.3 Pre-Vulcanization CharacteristicsThe onset
31、 of vulcanization can be detected with the Mooney viscometer as evidencedby an increase in viscosity. Therefore, this test method can be used to measure incipient cure (scorch) time and the rate of cureduring very early stages of vulcanization. This test method cannot be used to study complete vulca
32、nization because the continuousrotation of the disk will result in slippage when the specimen reaches a stiff consistency.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.D1646 1726. Apparatus6.1 Mooney ViscometerAn instrument consisting of
33、 a motor-driven rotating disk within a cylindrical die cavity formed by twodies maintained at specified conditions of temperature and die closure force. The Mooney viscometer measures the effect oftemperature and time on the viscosity of rubbers. If the stress relaxation test is to be performed, the
34、 instrument must be capableof quickly stopping the rotation of the disk and monitoring the relaxation of stress versus time. The die-rotor relationship of anexample design is shown in Fig. 1. The Mooney viscometer shall incorporate the following components:6.1.1 DiesThe dies and die holders forming
35、the die cavity shall be fabricated from a nondeforming tool steel, shall have anunplated finish, and shall be hardened to a Rockwell hardness of 60 HRC minimum. The dimensions of the die cavity, measuredfrom the highest surfaces, shall be 50.93 6 0.13 mm (2.005 6 0.005 in.) in diameter and 10.59 6 0
36、.03 mm (0.417 6 0.001 in.)in depth. The surfaces of the die cavity shall either be serrated or contain V-grooves to minimize slippage of the specimen.NOTE 2The two types of dies may not give the same results.6.1.1.1 Serrated DiesWhen the cavity is formed from four pieces of steel, serrations on the
37、surfaces of the dies and die holdersare used. These serrations consist of rectangular grooves 0.8 6 0.02 mm (0.031 6 0.0008 in.) wide with a uniform depth of notless than 0.25 mm (0.010 in.) nor more than 0.38 mm (0.015 in.). The grooves shall be vertical and shall be cut on 1.6 6 0.04mm (0.063 6 0.
38、002 in.) centers. The serrations of the dies shall consist of two sets of such grooves at right angles to each other.6.1.1.2 Radial Grooved DiesWhen the die cavity is formed from two pieces of steel, radial V-grooves are used only on theflat surfaces of the die cavity. The grooves shall be spaced at
39、 20 intervals and shall form a 90 angle in the die surfaces with thebisector of the angle perpendicular to the surface. They shall extend from the 7-mm (0.281-in.) circle to the 47-mm (1.875-in.)circle in the upper die and from the 12-mm (0.472-in.) circle to the 47-mm circle in the lower die. The g
40、rooves shall be 1 6 0.1mm (0.04 6 0.004 in.) wide at the surface.NOTE 3Die wear can affect test results, usually to a lesser extent than rotor wear. As a general practice, many users replace dies every second timethey replace worn rotors (see 6.1.2.1). This practice may not apply to all materials te
41、sted, as wear is material dependent. The ultimate way to determineif die wear has affected test results is to replace the dies with a new set and determine if the test results are changed.6.1.1.3 Mounting of DiesThe dies shall be an integral part of or mounted on platens equipped with a heating devi
42、ce andcontrols capable of maintaining the die cavity at the specified test temperature with a tolerance of 60.5C (61F) at equilibriumconditions.6.1.1.4 Die ClosureThe viscometer shall have a suitable device for opening and closing the platens and dies and for holdingthem closed during a test. During
43、 a test it is extremely important that the die cavity be held closed with the correct force. To obtainthe correct closing force for the mechanical-type closures, follow explicitly either the manufacturers recommendation or otherFIG. 1 Relationship of Platens, Dies, and Rotor in a Typical Shearing Di
44、sk ViscometerD1646 173procedure of equal reliability.4 Pneumatically closed dies shall be held closed during the test with a force of 11.5 6 0.5 kN (25856 115 lbf). A greater force may be required to close the dies when testing extremely tough stocks. At least 10 s before the motoris started, the fo
45、rce should be set to 11.5 6 0.5 kN. The die closure shall be such that a piece of thin soft tissue (with a thicknessnot greater than 0.04 mm (0.0015 in.) placed between the meeting surfaces will retain a continuous pattern of uniform intensitywhen the dies are closed upon it.Anonuniform pattern indi
46、cates wear of the die holder surface, misalignment, or distortion of diesand die holders. Any of these situations will result in undue leakage and erroneous results.NOTE 4For mechanical-type closure viscometers, the pressure on the die cavities may change if the viscometer is used at a different tem
47、perature thanthat at which it is adjusted.6.1.2 RotorsTwo rotors are specified, differing only in their diameter. They shall be fabricated from a nondeforming tool steel,shall have an unplated finish and shall be hardened to a Rockwell hardness of 60 HRC minimum. The large rotor shall be 38.106 0.03
48、 mm (1.500 6 0.001 in.) in diameter and 5.54 6 0.03 mm (0.218 6 0.001 in.) in thickness as measured from the highestpoints. The small rotor shall conform to the large rotor except the diameter shall be 30.48 6 0.03 mm (1.200 6 0.001 in.). Theserrations on the face of the rotor shall conform to the r
49、equirements for the serrated dies given in 6.1.1.1 and the serrations on theedge of the rotor shall conform to the requirements specified for the serrated die holders. The rotor head shall be securely mountedperpendicularly to a suitable straight cylindrical stem not exceeding 11 mm (0.433 in.) in diameter. The rotor head shall bepositioned so that the top and bottom surfaces are 2.54 6 0.10 mm (0.100 6 0.005 in.) from the surfaces of the top and bottomdies, respectively, when the dies are closed. The wear tolerance from the center positio
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