1、Designation: D 624 00e1Standard 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 case of revision, t
2、he 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.e1NOTEThe table in Fig. 1 on DIE C wa
3、s corrected editorially in March 2001.1. Scope1.1 This test 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
4、for informationonly.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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to
5、 use.2. Referenced Documents2.1 ASTM Standards:D 412 Test Methods for Vulcanized Rubber and Thermo-plastic Rubbers and Thermoplastic Elastomers Tension2D 1349 Practice for Rubber Standard Temperatures forTesting2D 3182 Practice for Rubber Materials, Equipment, andProcedures for Mixing Standard Compo
6、unds and Prepar-ing Standard Vulcanized Sheets2D 3183 Practice for Rubber Preparation of Pieces for TestPurposes from Products2D 3767 Practice for Rubber Measurement of Dimensions2D 4483 Practice for Determining Precision for Test MethodStandards in the Rubber and Carbon Black Industries22.2 ISO Sta
7、ndard:ISO/34 Rubber, Vulcanized Determination of TearStrength (Trouser, Angle, 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 followingdef
8、initions define different techniques for measuring the resis-tance to tear, 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 piec
9、e togrow by tearing the rubber, divided by the thickness of the testpiece.3.2.2 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 f
10、orce required tocause a rupture of a Type C (right angle) test piece, divided 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
11、by the thickness of the test piece.3.2.5 Type CP or constrained path tear strengththe 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 tracet
12、he section of a graphical plot offorce versus jaw separation distance between the point at whichthe 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.3.2.8 rangethe difference between the greatest and thesm
13、allest 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 tensile testing machine operated withoutinterruption at a constant rate of crosshead tr
14、averse until thespecimen is completely torn.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 July 10, 2000. Published September 2000. Originallypublished as D 624 41T. Last
15、previous edition D 624 98.2Annual Book of ASTM Standards, Vol 09.01.3Available from American National Standards Institute, 11 West 42ndSt., 13thFloor, New York, NY 10036.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.4.2 This test method measures the force pe
16、r 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 pieceacts in a direction substantially along
17、 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 shapeand with tab ends, as shown in Fig. 1
18、, 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-nicked test piece with a 90 angle onone
19、side and with tab ends, as shown in Fig. 1, Die C. The forceacts on the test piece in a direction substantially parallel to theFIG. 1 Type A, B and C Tear Test Specimen Cutting DiesD 6242tab ends of the specimen (45 to the 90 center angle) in thedirection of grip separation. Type C measures rupture,
20、 or tearinitiation strength 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 direct
21、ion parallel to thelength 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
22、from propagating away 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 str
23、ength fora different 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 strengt
24、h may be influenced 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 directrelati
25、on to service performance. 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 Method D 412. It shall becapable of registering the applied
26、forces within 6 2 % 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 jawseparat
27、ion 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 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
28、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 recommendations.Verification of calibration shall be evidenced by a
29、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 D 1349 using equipment described in TestMethod D 412.6.3 GripsThe testing machine shall be equipped withgrips that tighten autom
30、atically and exert a uniform pressureFIG. 2 Trouser Tear Test SpecimenCross Section DetailA = 125 mmB = 28.5 mmC = 5.33 mmD = 1.77 mmE = 0.75 mmFIG. 3 Schematic diagram of “Constrained Path” tear test piece(1)D 6243across the gripping surfaces. Grips shall provide adequatepressure as tension increas
31、es 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 alignment with the direction ofpull. The depth of insertion of the test piece in the grips mustbe consistent and suf
32、ficient 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 specimen using cutting dies conformingto one of the shapes described in Figs. 1 and 2, or moldedaccording to Fig.
33、 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 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
34、the 90 angle in Die Cbe sharpened to provide a sharp corner. If a segmented Die Cis 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 prepar
35、ing 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 documented
36、by adated written record.6.5 Nicking devices are used to make an initial cut in testpieces for Type A or B tests.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
37、the test piece. The blade shall be positioned 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 Preparation
38、7.1 Cut test pieces shall be obtained from molded 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 fo
39、llowed.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 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. I
40、n injection moldedsheets, the grain direction 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 thespecifi
41、cations in Fig. 1, Fig. 2 or Fig. 3. Molded test 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, unl
42、ess otherwise specified, that all Type A, B or 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 are
43、to be evaluated, an additional set of test pieces 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 testpi
44、eces from the sheet with a single impact stroke (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
45、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 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 c
46、hecked using a microscope with aminimum of 103 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
47、 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 two 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 va
48、luedeviates by more than 20% from the median of all three testpieces, two additional test pieces shall be tested and 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
49、widely dispersed test results, frequentlywith 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 D 3767. One of themeasurements should be at the slit or apex. Record the medianvalue for calculation of test results.7.8.2 For Type T test pieces, measure the thickness at threeplaces across the length and record the media
