1、Designation: D926 08 (Reapproved 2013)Standard Test Method forRubber PropertyPlasticity and Recovery (Parallel PlateMethod)1This standard is issued under the fixed designation D926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 This test method cove
3、rs the determination of plasticityand recovery of unvulcanized rubber by means of the parallelplate plastometer. Uncompounded, compounded, and reclaimrubber may be tested.NOTE 1ISO 2007 and Test Method D3194 use a principle similar tothis test method although the apparatus, test conditions, and proc
4、edure aredifferent.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 standar
5、d to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3194 Test Method for Rubber From Natural SourcesPlasticity Retention Index (PRI)D3767 Practice for RubberMeasurement of Dimensio
6、nsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesE145 Specification for Gravity-Convection and Forced-Ventilation Ovens2.2 ISO Standard:3ISO 2007 Rubber UnvulcanizedDetermination ofPlasticityRapid Plastimeter Method3. Summary of
7、 Test Method3.1 Plasticity:3.1.1 A specimen of specific volume and height is tested atroom temperature or heated to a specified test temperature for15 min and then subjected to a compressive force of 49 N fora specified time.3.1.2 At the end of this time, the height of the specimen ismeasured, and t
8、he plasticity number is calculated.3.2 RecoveryThere are two recovery procedures.3.2.1 Procedure AThe test specimen is removed from theplastometer immediately after the determination of plasticityand allowed to cool and recover some of its original height for1 min. The height is measured again and t
9、he recovery iscalculated.3.2.2 Procedure BThe test specimen is compressed to aheight of 5 mm for 30 s and then allowed to recover at the testtemperature for 5 min. The height is measured again and therecovery is calculated.4. Significance and Use4.1 The plasticity number and the recovery of the test
10、specimen are related to the flow properties and the elasticproperties, respectively, and may be useful in predictingprocessing characteristics, such as ease of forming and extru-sion characteristics.4.1.1 In this test method, plasticity is measured in an inversemanner, as noted by the final height o
11、f the specimen. Thus,high plasticity rubbers (high degree of flow during test) areindicated by a low plasticity number.5. Apparatus5.1 The essential features of the parallel plate plastometer,illustrated in Fig. 1, are as follows:5.1.1 Two metal plates, not less than 10 mm in thicknessand 40 mm in d
12、iameter, shall be mounted on a suitable frameso that one plate moves with respect to the other, and so that thetwo plates are parallel within 0.017 rad (1) at all times.5.1.2 The apparatus shall be so designed that a specimenbetween the parallel plates is subjected to a force of 49 6 0.5N, including
13、 the effect of the spring in the dial gauge duringtest.1This test method is under the jurisdiction of ASTM committee D11 on Rubberand is the direct responsibility of Subcommittee D11.12 in Processability Tests.Current edition approved Nov. 1, 2013. Published January 2014. Originallyapproved in 1956.
14、 Last previous edition approved in 2008 as D926 08. DOI:10.1520/D0926-08R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onth
15、e ASTM website.3Available from American National Standards Institute, 25 West 43rd St., 4thFloor, New York, NY 10036.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.1.3 A digital or dial indicator gauge calibrated in hun-dredths of
16、a millimetre (0.01 mm) shall be mounted on theapparatus in such a manner that the distance between the platescan be determined at all times.5.1.4 When required, the apparatus shall be operated in anyoven, as described in Specification E145, that is capable ofcontaining the plastometer.5.1.5 A separa
17、te dimensional measurement gauge is re-quired for performing recovery measurements. The apparatusand methodology described in Practice D3767, Procedure A,shall be employed when performing these measurements.5.2 Test SurfacesFilms or material with low coefficients offriction shall be used to prevent
18、sticking of the test specimen tothe plates. The most commonly used test surface is polyesterfilm. Other films such as cellophane or nylon may be used. Thetest surface film shall have a thickness of 0.25 6 0.005 mm.NOTE 2The test surface used can affect the plasticity number. Evendifferent grades of
19、the same type of film can cause different results. Whencomparing results, the same test surface must be used.6. Sampling6.1 Samples may be taken from raw rubber or unvulcanizedrubber compounds undergoing processing operations.7. Test Specimens7.1 The specimen shall be a right cylinder 2.00 6 0.02 cm
20、3in volume and be free from air pockets. (A cylinder 16 mm indiameter and 10 mm in height is appropriate.) The specimenmay be prepared from either a solid piece or plied sheets ofunvulcanized rubber approximately 1.5 mm in thickness, carebeing taken to exclude air pockets in the sheet. The specimens
21、may be cut from the sheet either by means of two mating diesconforming to Fig. 2, which produce cylinders of the correctvolume, or a rotating die having an internal diameter ofapproximately 16 mm. If a rotating die is used, the height of thecylinder shall be adjusted until the volume is 2.00 6 0.02
22、cm3.If the density is known, weighing may be used to adjust to thecorrect volume. If necessary, the specimen shall be placed in asuitable holder so that it is not appreciably deformed beforetesting.8. Test Conditions8.1 The plasticity and recovery values obtained for a givensample will depend largel
23、y upon the manner in which the testspecimen is prepared. It is therefore imperative that whencomparisons are made between similar materials, the testspecimen preparation should be in accordance with somerigidly specified method. This is necessary because the plas-ticity and recovery may be affected
24、by the amount of mechani-cal working and the conditions under which such work is done.This effect is not constant for all materials. The time intervalbetween test specimen preparation and testing is important andshould be the same for test specimens between which com-parisons are to be made.8.2 The
25、test temperature shall be 23 (room temperature), 40,70, 85, or 100C unless another temperature is agreed upon.The most frequently used temperature is 23C.8.3 Readings may be taken at any desired interval followingthe application of the load. The most frequently used intervalsare between 3 and 10 min
26、.9. Plasticity Procedure9.1 Set the indicator to read zero with two thicknesses of thetest surface between the plates. Condition the plastometer atthe test temperature until temperature equilibrium is achieved.9.2 Place the test specimen between the two test surfaces toprevent sticking of the test s
27、pecimen to the plates.9.3 If required, condition the test specimen at the testtemperature for 15 6 0.5 min.FIG. 1 One Type of Parallel Plate PlastometerFIG. 2 Die for Forming Test SpecimenD926 08 (2013)29.4 Quickly place the test specimen between the two paral-lel plates, lower the mass, and at the
28、end of the required timeinterval, read the thickness gauge to hundredths of a millime-tre. Record the height of the specimen in millimetres as h1.9.5 Calculate plasticity, P, as follows:P 5 100h1(1)10. Recovery Procedures10.1 Recovery values may be determined by the proceduredescribed in either 10.2
29、 or 10.3, but the results will differ.10.2 Procedure A:10.2.1 After determining the plasticity as described inSection 9, immediately remove the test specimen from theplastometer and allow it to cool exactly 1 min at 23 6 2C.Then measure the height of the specimen with the two testsurfaces using the
30、dial micrometer gauge specified in 5.1.5.Record this reading as h2.10.2.2 Calculate recovery, RA, as follows:RA5 100 h22 h1! (2)10.3 Procedure B:10.3.1 Follow the procedure described in Section 9 fordetermining plasticity, except that the test specimen shall becompressed to a height of 5 mm for 30 s
31、. This may be done byplacing three spacers 5.00 6 0.01 mm in thickness on twothicknesses of test surface at suitable positions between theplates to ensure parallelism and prevent misalignment of theplates.10.3.2 At the end of the compression period, remove thespecimen from between the plates and per
32、mit it to recover for5 min at the test temperature.10.3.3 At the end of the 5-min recovery period, measure theheight of the specimen with the micrometer gauge specified in5.1.5. Record as h3.10.3.4 Calculate recovery, RB, as follows:RB5 100 h32 5! (3)11. Report11.1 Report the following information:1
33、1.1.1 Sample Identification:11.1.1.1 A full description of the sample and its origin,11.1.1.2 Compound details, where appropriate,11.1.1.3 Preparation method of the test piece (plied orsolid), and11.1.1.4 Time between preparation and test.11.1.2 Test Conditions:11.1.2.1 Test surface used,11.1.2.2 Te
34、st temperature,11.1.2.3 Time, in minutes, the force was applied to the testpiece,11.1.2.4 Recovery time, in minutes, and11.1.2.5 Date of the test.11.1.3 Test Results:11.1.3.1 Plasticity number, P, and11.1.3.2 Recovery number, RAor RB.12. Precision and Bias12.1 These precision and bias statements hav
35、e been pre-pared in accordance with Practice D4483. Please refer toPractice D4483 for terminology and other testing and statisticalconcept explanations.12.2 The Type 1 precision was determined from an inter-laboratory study of three compounds that were mixed in onelaboratory. Four laboratories prepa
36、red samples and tested eachcompound.12.3 A “test result” for this plasticity and recovery testingrepresents one measurement with a parallel plate plastometer.12.4 Table 1 lists the precision data. A Type 1 precision, asdefined in Practice D4483, includes as components ofvariation, the specimen prepa
37、ration and testing operationwithin each laboratory, but not the mixing or compoundpreparation components of variation.12.5 The precision of this test method may be expressed inthe format of the following statements which use an “appro-priate value” of r, R,(r), or (R), that is, that value to be used
38、 indecisions about test results (obtained with the test method).The appropriate value is that value of r or R associated with amean level in Table 1 closest to the mean level underconsideration (at any given time, for any given material) inroutine testing operations.12.6 RepeatabilityThe repeatabili
39、ty, r, of this test methodhas been established as the appropriate value tabulated in Table1. Two single test results, obtained under normal test methodTABLE 1 Type 1 PrecisionTestTest Tem-perature, CRangeof ValuesAWithin LaboratoryBBetween LaboratoryBSrr (r)BSRR (R)CPlasticity 70 415755 22.7 64.2 11
40、.0 64.2 181.7 31.1Plasticity 100 350630 17.7 50.1 10.2 25.5 72.2 14.7Recovery 70 50250 28.6 80.9 54.0 55.7 157.6 105.0Recovery 100 30190 15.8 44.7 40.6 21.0 59.4 54.0AUnits = mm 100.BSr= repeatability standard deviation, in measurement units.r = repeatability in measurement units.(r) = repeatability
41、 (relative) percent.SR= reproducibility standard deviation, in measurement units.R = reproducibility in measurement units.(R) = reproducibility (relative) percent.CMidpoint of range used to calculate (r) and (R).D926 08 (2013)3procedures, that differ by more than this tabulated r (for anygiven level
42、) must be considered as derived from different ornon-identical sample populations.12.7 ReproducibilityThe reproducibility, R, of this testmethod has been established as the appropriate value tabulatedin Table 1. Two single test results obtained in two differentlaboratories, under normal test method
43、procedures, that differby more than the tabulated R (for any given level) must beconsidered to have come from different or non-identical samplepopulations.12.8 Repeatability and reproducibility expressed as a per-cent of the mean level, (r) and (R), have equivalent applicationstatements as above for
44、 r and R. For the (r) and (R) statements,the difference in the two single test results is expressed as apercent of the arithmetic mean of the two test results.12.9 BiasIn test method terminology, bias is the differencebetween an average test value and the reference (or true) testproperty value. Refe
45、rence values do not exist for this testmethod since the values of plasticity and recovery are exclu-sively defined by the test method. Bias, therefore, cannot bedetermined.13. Keywords13.1 elastic properties; flow properties; parallel plate plas-tometer; plasticity; plasticity and recovery; plastome
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