ASTM D624-2000(2012) Standard Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers 《硫化橡胶 热塑性弹性体拉伸性能的标准试验方法》.pdf

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1、Designation: D624 00 (Reapproved 2012)Standard Test Method forTear Strength of Conventional Vulcanized Rubber andThermoplastic Elastomers1This standard is issued under the fixed designation D624; the number immediately following the designation indicates the year oforiginal adoption or, in the case

2、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 Department of Defense.1. Scope1.1 This test me

3、thod describes procedures for measuring aproperty of conventional vulcanized rubber and thermoplasticelastomers called tear strength.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to addr

4、ess all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard 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:2D412 Test Meth

5、ods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD1349 Practice for RubberStandard Temperatures forTestingD3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces fo

6、r TestPurposes from ProductsD3767 Practice for RubberMeasurement of DimensionsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2 ISO Standard:ISO/34 Rubber, Vulcanized Determination of TearStrength (Trouser, Angle, and Crescent

7、Tear Pieces)33. Terminology3.1 The tear of rubber is a mechanical rupture processinitiated and propagated at a site of high stress concentrationcaused a cut, defect, or localized deformation. The followingdefinitions define different techniques for measuring the resis-tance to tear, i.e. the tear st

8、rength, required for use with thisstandard.3.2 Definitions of Terms Specific to this Standard:3.2.1 Type A tear strengththe maximum force required tocause a nick or cut in a Type A (nicked crescent) test piece togrow by tearing the rubber, divided by the thickness of the testpiece.3.2.2 Type B tear

9、strengththe maximum force required tocause a nick or cut in a Type B (nicked tab end) test piece togrow by tearing the rubber, divided by the thickness of the testpiece.3.2.3 Type C tear strengththe maximum force required tocause a rupture of a Type C (right angle) test piece, divided bythe thicknes

10、s of the test piece.3.2.4 Type T or trouser tear strengththe mean or medianforce, calculated in accordance with procedures in this method,required to propagate a tear in a Type T (trouser) test piece,divided by the thickness of the test piece.3.2.5 Type CP or constrained path tear strengththe meanor

11、 median force, calculated in accordance with procedures inthis method, required to propagate a tear in a type CP(constrained path) test piece, divided by the thickness of thetorn section.3.2.6 complete tracethe section of a graphical plot offorce versus jaw separation distance between the point at w

12、hichthe first peak occurs and the point at which the test isterminated.3.2.7 peaka point at which the slope of a trace changesfrom positive to negative.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.10 on Physical Testi

13、ng.Current edition approved Jan. 1, 2012. Published March 2012. Originallyapproved in 1941. Last previous edition approved in 2007 as D624 00 (2007).DOI: 10.1520/D0624-00R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For

14、Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute, 11 West 42ndSt., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,

15、 PA 19428-2959, United States.3.2.8 rangethe difference between the greatest and thesmallest observed test values.3.2.9 valleya point at which the slope of a trace changesfrom negative to positive.4. Summary of Test Method4.1 A tearing strain (and stress) is applied to a test specimenby means of a t

16、ensile testing machine operated withoutinterruption at a constant rate of crosshead traverse until thespecimen is completely torn.4.2 This test method measures the force per unit thicknessrequired to rupture, initiate, or propagate a tear through a sheetof rubber in the form of one of several test p

17、iece geometries:4.2.1 Type A, a razor-nicked test piece with a crescentshape, as shown in Fig. 1, Die A. The force in this test pieceacts in a direction substantially along the major axis (length)FIG. 1 Type A, B and C Tear Test Specimen Cutting DiesD624 00 (2012)2and perpendicular to the “nick”, or

18、 razor cut. Type A is used tomeasure tear propagation and is normally cut from smaller testspecimens that can not accommodate other test types.4.2.2 Type B, a razor-nicked test piece with a crescent shapeand with tab ends, as shown in Fig. 1, Die B. The force in thistest piece acts in a direction su

19、bstantially along the major axis(length) and perpendicular to the “nick”, or razor cut. Type Balso measures tear propagation and is preferred over Type Awhen the test sample allows.4.2.3 Type C, an un-nicked test piece with a 90 angle onone side and with tab ends, as shown in Fig. 1, Die C. The forc

20、eacts on the test piece in a direction substantially parallel to thetab ends of the specimen (45 to the 90 center angle) in thedirection of grip separation. Type C measures rupture, or tearinitiation strength at the stress concentration located at the 90apex. If tear initiation does not occur at the

21、 apex, the results aremore indicative of tensile strength than tear strength.4.2.4 Type T, a trouser tear test piece, as shown in Fig. 2.Type T measures tear propagation in a direction parallel to thelength of both legs.4.2.5 Type CP, a test piece described in Fig. 3, which is amodified trouser tear

22、 test piece with a constrained path for thetear. Type CP also measures tear propagation in a directionparallel to the length of both legs, but the constrained pathprevents the tear from propagating away from this path, and thethicker legs eliminate the influence of leg extension which mayoccur with

23、Type T test pieces. See (1) for more information onCP tear testing.4.3 No Correlation of results from one test type to anothershould be expected, as each test type measures tear strength fora different tear specimen geometry.5. Significance and Use5.1 Vulcanized rubber and thermoplastic elastomers (

24、TPE)often fail in service due to the generation and propagation of aspecial type of rupture called a tear. This test method measuresthe resistance to tearing action.5.2 Tear strength may be influenced to a large degree bystress-induced anisotropy (mechanical fibering), stress distri-bution, strain r

25、ate, and test piece size. The results obtained ina tear strength test can only be regarded as a measure under theconditions of that particular test and may not have any directrelation to service performance. The significance of tear testingmust be determined on an individual application or productpe

26、rformance basis.6. Apparatus6.1 Testing MachineThe testing machine shall conform tothe requirements as specified in Test Methods D412. It shall becapable of registering the applied forces within 6 2 % of thetotal force range or capacity during the test while maintainingthe specified rate of jaw sepa

27、ration:6.1.1 For Type A, B or C test pieces, the rate of jawseparation shall be 500 6 50 mm/min. (20 6 2.0 in./min.).6.1.2 For Type T and Type CP test pieces, the rate of jawseparation shall be 50 6 5 mm/min. (2 6 0.2 in./min.).6.1.2.1 A low inertia machine having a continuous record-ing of force is

28、 essential when using the Type T or Type CPtrouser tests.NOTE 1Inertia (pendulum) type dynamometers may give resultsFIG. 2 Trouser Tear Test SpecimenCross Section DetailA = 125 mmB=28.5mmC=5.33mmD=1.77mmE=0.75mmFIG. 3 Schematic diagram of “Constrained Path” tear test piece(1)D624 00 (2012)3which dif

29、fer from one another because of frictional and inertial effects. Alow inertia (electronic or optical transducer) dynamometer gives resultswhich are free from these effects and is preferred.6.1.3 Calibration of the testing machine shall be routinelyverified according to the manufacturers recommendati

30、ons.Verification of calibration shall be evidenced by a writtenrecord which shows the date of verification and the testingmachines accuracy at that time.6.2 The test may be conducted at elevated or lower tem-peratures listed in Practice D1349 using equipment describedin Test Methods D412.6.3 GripsTh

31、e testing machine shall be equipped withgrips that tighten automatically and exert a uniform pressureacross the gripping surfaces. Grips shall provide adequatepressure as tension increases to prevent specimen slippage.Constant pressure pneumatic grips are satisfactory for mostspecimens. Test pieces

32、shall be inserted in the grips symmetri-cally positioned and in axial alignment with the direction ofpull. The depth of insertion of the test piece in the grips mustbe consistent and sufficient to prevent slipping. Type T andType CP specimens shall be inserted in the grips as shown inFig. 2.6.4 Test

33、 Piece Cutting DiesTest pieces for tear strengthshall be cut from a test specimen using cutting dies conformingto one of the shapes described in Figs. 1 and 2, or moldedaccording to Fig. 3 for Type CP tests.6.4.1 The inside faces of the cutting dies shall be perpen-dicular to the plane formed by the

34、 cutting edges and polishedfor a distance of at least 5 mm (0.2 in.) from the cutting edge.The die shall at all times be sharp and free from nicks.6.4.2 It is important that the apex of the 90 angle in Die Cbe sharpened to provide a sharp corner. If a segmented Die Cis used, the segment incorporatin

35、g the apex shall extend aminimum of 25 mm from the apex in both directions.6.4.3 Test piece cutting dies shall be routinely examined andverified for accuracy. One method may be by preparing a testpiece and measuring it for conformance to the dimensionslisted in Figs. 1 and 2. Another method may be b

36、y testing of acontrol compound and comparing the test results with thoseobtained with a compound of the same formulation using diesknown to be accurate. Verification shall be documented by adated written record.6.5 Nicking devices are used to make an initial cut in testpieces for Type A or B tests.6

37、.5.1 The nicking device shall secure the test piece in amanner that prevents movement, so that the cutting mechanismintroduces a razor blade on a plane perpendicular to the majoraxis of the test piece. The blade shall be positioned to producea precisely controlled and cleanly separated cut in the sp

38、eci-men. Alternatively, a nicking die may also provide acceptableresults so long as the die is routinely examined and verified foraccuracy as specified in 6.4.3.7. Test Piece Preparation7.1 Cut test pieces shall be obtained from molded testspecimen sheets. Compression molded test specimen sheetsshal

39、l use molds conforming to Practice D3182. Molded testspecimen sheets may also be prepared by injection moldinginto plaques. For test pieces cut from products, Practice D3183shall be followed.7.1.1 Molded test specimen sheets shall be 2.3 6 1.0 mm(0.09 6 0.04 in.) thick with the milling grain or flow

40、 directionclearly marked.7.1.2 Injection molded test specimen sheets may not havethe same degree of anisotropy as compression molded sheets,and this may affect the tear test results. In injection moldedsheets, the grain direction is parallel to the flow direction.7.1.3 Anisotropy may also affect res

41、ults for test pieces cutfrom products. A record of the orientation of cut test piecesshall also be made in these cases.7.2 Molded test pieces are molded in shapes defined by thespecifications in Fig. 1, Fig. 2 or Fig. 3. Molded test pieces mayproduce different results from cut test pieces.7.3 The us

42、ual practice is to test with the grain running thelength of the test piece. For Type A, B and C test pieces, thetear would thus be recorded as across the grain. It is to beassumed, unless otherwise specified, that all Type A, B or Ctest pieces are prepared in this manner. Type T and CP testpieces ar

43、e also prepared with the grain running parallel to thelength. This means that for Type T and CP tests the tear will beparallel to the grain. Where grain effects are significant and areto be evaluated, an additional set of test pieces shall beprepared with the grain running across the length. Results

44、 soobtained shall be recorded as with the grain for Type A, B orC tests and across the grain for Type T and CP tests.7.4 Using the cutting die for the desired test type, cut the testpieces from the sheet with a single impact stroke (by hand ormachine) to ensure smooth cut surfaces.7.5 For Type A and

45、 B test pieces, nick the test piece usingthe nicking device described in 6.5.1. Wet the blade with wateror soap solution prior to nicking the test piece. Nick the testpiece to a depth of 0.50 6 0.05 mm (0.020 6 0.002 in.) witha single stroke of the blade. If a nicking die is used, the nick isformed

46、when the test piece is cut from the sheet.7.5.1 To assure a proper cut with the nicking device, one ortwo preliminary nicks shall be made on extra test pieces andthe depth of the cut checked using a microscope with aminimum of 103 magnification.7.6 For Type T and CP test pieces, an initial cut shoul

47、d bemade with a razor blade or sharp knife. The last 1 mm(approximately) of the cut shall be made with a single stroke.7.6.1 Type T test pieces shall have an initial cut of 40 6 5mm as shown in Fig. 2.7.6.2 Type CP test pieces shall have an initial cut of 60 6 5mm made down the groove between the tw

48、o legs.7.7 Three test pieces per sample shall be tested for tearstrength, and the median value of the test pieces reported as atest result. If an individual test piece tear strength valuedeviates by more than 20% from the median of all three testpieces, two additional test pieces shall be tested and

49、 the medianof all five values reported.7.7.1 Tear testing is inherently a highly variable measure-ment since it has many characteristics similar to fatigue testingand is known to give widely dispersed test results, frequentlyD624 00 (2012)4with a non-normal distribution. For referee tear testing, aminimum of five test pieces is recommended.7.8 Measure the thickness of each test piece.7.8.1 For Type A, B, and C test pieces, measure thethickness at three places across the width, near the center, usinga micrometer conforming to Practice D3767. One of them