1、Designation: D 624 00 (Reapproved 2007)Standard Test Method forTear Strength of Conventional Vulcanized Rubber andThermoplastic Elastomers1This standard is issued under the fixed designation D 624; 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 (e) 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
3、 method 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 a
4、ddress 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:2D 412 Test
5、Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD 1349 Practice for RubberStandard Temperatures forTestingD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 3183 Practice for RubberPreparation of Pr
6、oduct Piecesfor Test Purposes from ProductsD 3767 Practice for RubberMeasurement of DimensionsD 4483 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, Ang
7、le, and Crescent 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,
8、 i.e. the tear strength, 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
9、.2.2 Type B tear 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, divid
10、ed bythe thickness 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 s
11、trengththe meanor 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 betwe
12、en the point at whichthe first peak occurs and the point at which the test isterminated.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved Nov. 1, 2007. Published January 2008
13、. Originallyapproved in 1941. Last previous edition approved in 2000 as D 624 00e1.2For 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 pa
14、ge 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, PA 19428-2959, United States.Copyright by ASTM Intl (all rights reserved); Sun Dec 7 22:21
15、:20 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.3.2.7 peaka point at which the slope of a trace changesfrom positive to negative.3.2.8 rangethe difference between the greatest and thesmallest observed test values.3.2.9 valleya poin
16、t 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 tensile testing machine operated withoutinterruption at a constant rate of crosshead traverse until thespecimen is completely torn.4.
17、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 piece 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 piec
18、eacts in a direction substantially along the major axis (length)and perpendicular to the “nick”, or 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 sh
19、apeand with tab ends, as shown in Fig. 1, Die B. The force in thistest piece acts in a direction substantially 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-
20、nicked test piece with a 90 angle onone side and with tab ends, as shown in Fig. 1, Die C. The forceacts 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 s
21、trength at the stress concentration located at the 90apex. If tear initiation does not occur at the 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 thel
22、ength of both legs.4.2.5 Type CP, a test piece described in Fig. 3, which is amodified trouser tear 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 awa
23、y from this path, and thethicker legs eliminate the influence of leg extension which mayoccur with 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
24、 tear specimen geometry.5. Significance and Use5.1 Vulcanized rubber and thermoplastic elastomers (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
25、to a large degree bystress-induced anisotropy (mechanical fibering), stress distri-bution, strain rate, 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 perfor
26、mance. The significance of tear testingmust be determined on an individual application or productperformance basis.6. Apparatus6.1 Testing MachineThe testing machine shall conform tothe requirements as specified in Test Methods D 412. It shall becapable of registering the applied forces within 6 2 %
27、 of thetotal force range or capacity during the test while maintainingthe specified rate of jaw separation: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
28、 mm/min. (2 6 0.2 in./min.).6.1.2.1 A low inertia machine having a continuous record-ing of force is essential when using the Type T or Type CPtrouser tests.NOTE 1Inertia (pendulum) type dynamometers may give resultswhich differ from one another because of frictional and inertial effects. Alow inert
29、ia (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 recommendations.Verification of calibration shall be evidenced by a writtenrecord which
30、 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 D 1349 using equipment describedin Test Methods D 412.6.3 GripsThe testing machine shall be equipped withgrips that tighten automatically
31、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 shall be inserted in the grips symmetri-cally positioned and in axial ali
32、gnment 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 Piece Cutting DiesTest pieces for tear strengthshall be cut from a test
33、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 cutting edges and polishedfor a distance of at least 5 mm (0.2 in.) from
34、 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 CD 624 00 (2007)2Copyright by ASTM Intl (all rights reserved); Sun Dec 7 22:21:20 EST 2008Downloaded/printe
35、d byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.is used, the segment incorporating 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
36、 preparing a testpiece and measuring it for conformance to the dimensionslisted in Figs. 1 and 2. Another method may be by 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 docu
37、mented by adated written record.6.5 Nicking devices are used to make an initial cut in testpieces for Type A or B tests.FIG. 1 Type A, B and C Tear Test Specimen Cutting DiesD 624 00 (2007)3Copyright by ASTM Intl (all rights reserved); Sun Dec 7 22:21:20 EST 2008Downloaded/printed byGuo Dehua (CNIS)
38、 pursuant to License Agreement. No further reproductions authorized.6.5.1 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
39、 to producea precisely controlled and cleanly separated cut in the speci-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 mo
40、lded testspecimen sheets. Compression molded test specimen sheetsshall use molds conforming to Practice D 3182. Molded testspecimen sheets may also be prepared by injection moldinginto plaques. For test pieces cut from products, Practice D 3183shall be followed.7.1.1 Molded test specimen sheets shal
41、l be 2.3 6 1.0 mm(0.09 6 0.04 in.) thick with the milling grain or flow 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
42、 is parallel to the flow direction.7.1.3 Anisotropy may also affect results 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 t
43、est pieces mayproduce different results from cut test pieces.7.3 The usual 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 o
44、r Ctest pieces are prepared in this manner. Type T and CP testpieces are 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 pi
45、eces shall beprepared with the grain running across the length. Results 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 stro
46、ke (by hand ormachine) to ensure smooth cut surfaces.7.5 For Type A and 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 s
47、ingle stroke of the blade. If a nicking die is used, the nick isformed 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 10
48、3 magnification.7.6 For Type T and CP test pieces, an initial cut should 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 sh
49、all have an initial cut of 60 6 5mm made down the groove between the two legs.FIG. 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)D 624 00 (2007)4Copyright by ASTM Intl (all rights reserved); Sun Dec 7 22:21:20 EST 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.7.7 Three test pieces per sample shall be tested for tearstrength, and the median value of the test pieces reported as ates
