1、Designation: C 1681 09Standard Test Method forEvaluating the Tear Resistance of a Sealant Under ConstantStrain1This standard is issued under the fixed designation C 1681; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method evaluates the impact of an induced tearon a sealant specimen that is dimensioned, cured according tot
3、he guidelines in Test Method C 719 and then subjected to aconstant strain. It is effective in differentiating between seal-ants that are used in dynamic joints subject to abrasion,punctures, tears, or combination thereof.1.2 Since this test method is for the evaluation of tearpropagation, an adhesiv
4、e failure to the substrates provides nousable data regarding tear propagation. This would be consid-ered a failed test and that data would be discarded, or at leastseparated from the other data from specimens that did notexperience an adhesive failure.1.3 This standard does not purport to address al
5、l 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.1.4 The committee with jurisdiction over this standard is notaw
6、are of any comparable standards published by other orga-nizations.2. Referenced Documents2.1 ASTM Standards:2C 719 Test Method for Adhesion and Cohesion of Elasto-meric Joint Sealants Under Cyclic Movement (HockmanCycle)3. Terminology3.1 Definitions:3.1.1 casting spacersrigid spacers made of an anti
7、-adherent material used in the fabrication of joints to maintainthe joint dimension during the extrusion, tooling and curing ofthe sealant material.3.1.2 separatorsrigid spacers used to maintain a constantstrain on the joint specimens during the testing period whilemaintaining parallel bond surfaces
8、.4. Summary of Test Method4.1 Test specimens are fabricated and cured in accordancewith Test Method C 719. At the end of the 21-day cure period,an induced tear is created in the specimens by making a cutwith a sharp blade in the midpoint of the joint. The specimensare then extended to a specified st
9、rain at both standardconditions and at 26 6 2C (15 6 3F). Propagation of theinduced tear is measured at 0, 24 and 168 h.5. Significance and Use5.1 This test method is intended to determine if a joint thatis subjected to a mechanically induced cut will resist tearpropagation during normal joint movem
10、ent. A sealant with ahigh resistance to tear propagation will typically perform betterthan a sealant with a low resistance to tear propagation.6. Apparatus6.1 A device capable of extending the test specimens to thespecified strain.6.2 Freezer, to maintain a constant temperature of 26C.6.3 A suitable
11、 measuring device such as calipers able tomeasure the induced tears to 0.01 mm.6.4 #17 Knife Blade,9mm(38 in.) wide.7. Reagents and Materials7.1 Spatulas, for use in applying the sealant.7.2 Caulking Gun, for extruding sealant from cartridgeswhen applicable.7.3 Glass Substratestwelve substrates, wit
12、h minimumdimensions of 25 by 75 mm (1 by 3 in.) of the same finish arerequired for each test specimen. Glass is the default substrate,however as mentioned in the scope, this is not an adhesion test,therefore the sealant must exhibit excellent adhesion to thesubstrate. Other rigid substrates in the a
13、bove noted dimensionare indeed acceptable.7.4 Casting SpacersMade from polytetrafluoroethylene(PTFE) or a suitable rigid material shall be used with each testspecimen to which the test sealant will not bond and will1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and
14、 Sealants and is the direct responsibility of Subcommittee C24.20 onGeneral Test Methods.Current edition approved Jan. 1, 2009. Published February 2009.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
15、ndards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.provide the appropriate joint dimensions and configurations.These spacers are machined to prov
16、ide exact joint dimensionsof 12.7 by 12.7 by 50.8 mm (12 by12 by 2 in.). See Fig. 5 inTest Method C 719.7.5 Separators, to provide a constant strain on the specimenwhile maintaining parallel bond surfaces.7.6 Substrate Cleaning Material.7.7 Primer, if required on the substrates.7.8 Asuitable measuri
17、ng device, such as calipers, capable ofmeasuring the induced cut in the sealant and additional changesin the cut to 0.01 mm.7.9 Marker, to identify the exact placement of the inducedcut.7.10 A device which holds a #17 knife blade 9 mm (38 in.)wide to induce the cut into the test specimens. See Fig.
18、1.8. Conditioning8.1 Multicomponent SealantsPrepare six test specimensfor each type of substrate that is to be used in the test. Aftermaintaining the unopened sample for at least 24 h at standardconditions, mix thoroughly for 5 min at least 250 g of basecompound with the appropriate amount of curing
19、 agent.Extrude the sealant 12.7 by 12.7 by 50.8 mm (12 by12 by 2 in.)between parallel 25.4 by 76.2 mm (1 by 3 in.) faces of similarblocks or plates. Use appropriate casting spacer blocks to formthe proper size of the bead. Apply polyethylene adhesive tapeor any other suitable inert release agent to
20、the inside surfacesof the spacers to prevent adhesion of the spacers to the sealantafter cure. Use adhesive tape, rubber bands, or clamps to holdthe test assembly together before and after filling it with thecompound. In the case of a pourable-type compound, usemasking or any other suitable tape to
21、retain the compound.8.2 Clean the test substrates using the methods suggested inTest Method C 719. Fabricate the joints using the castingspacers. Mask off the top of the substrate edges, extrude the testsealant into the cavity taking care to fill in the all of the corners,tool the top surface flat,
22、and remove the masking tape.8.3 Single-Component SealantsPrepare six test specimensas described in 8.1 except that no mixing of components isrequired. Condition the sealed cartridge or bulk container atstandard conditions at least 24 h before use.8.4 Cure specimens made with multicomponent sealants
23、for14 days at standard conditions. During the second week of thecuring period, free the compound from the spacer blocks at theends and bottom without damaging the sealant bead.8.5 Cure specimens made with single-component sealantsfor a total of 21 days at standard conditions. See 8.6.1.8.6 Separate
24、the casting spacers from the sealant as soon aspractical during the curing period without damaging thesealant. Fourteen days is typically necessary.8.6.1 The producer may request conditions other than thosespecified in 8.5 for the curing period of single-componentsealants provided they meet the foll
25、owing requirements: (1)The curing period shall extend for 21 days; and (2) Thetemperature during the curing period shall not exceed 50C(122F).9. Procedure9.1 Within 8 h after the cure period (14 days for multicom-ponent or 21 days for single component products), mark theexact location for the induce
26、d cut with a permanent marker andthen induce a cut, 9 mm (38 in.) in length, and 12.7 mm (12 in.)deep with the #17 knife blade. See Fig. 2. Make the cut asparallel as possible to the long direction of the sample, locateddirectly on the midpoint and go perpendicularly throughthickness of the sealant.
27、9.2 Extend all specimens until the separation between thesubstrates provides the desired/specified extension (in theabsence of a specified strain, the sealant shall be strained to itsTest Method C 719 movement capability). Apply this strain ata minimum rate of 3 mm per hour (18 in. per hour). SeeApp
28、endix X2.9.3 When the specimens have reached their specified exten-sion, block the specimens with the appropriate separator andremove from the extension device/machine. Do not removeseparators for the duration of test.9.4 Measure and record the length and width of the inducedcut, immediately after t
29、he joints have been blocked at thespecified strain. This is the 0 hour data.9.5 Place three specimens in the freezer at 26 6 2C.9.6 Place three specimens at room temperature laboratoryconditions.9.7 After 24 and 168 h, measure and record the length andwidth of the induced cut on the top of the joint
30、 and record theobserved character of the tearing on the X and Y axis as notedin Fig. 3 (i.e., clean versus jagged, direction of the tearpropagation, propagation of the tear at one or both ends of theinduced cut, etc.).10. Calculation or Interpretation of Results10.1 Report the change in length and w
31、idth of the inducedcut on the top of the joint in the sealant for each specimenalong the X and Y axis noted below to the nearest 0.1 mm.10.2 Report the average change in dimension for length andwidth for the room temperature and 26C conditions at 24 and168 h.FIG. 1 #17 BladeC168109210.2.1 (DL1 + DL2
32、 + DL3)/3 = Average change in Length.10.2.1.1 L24 h L0h = DL24 h= Change in Length at 24 h.10.2.1.2 L168 h L0h = DL168 h = Change in Length at168 h.10.2.2 (DW1 + DW2 + DW3)/3 = Average change in Width.10.2.2.1 W24 h W0h = DW24 h = Change in Width at 24h.10.2.2.2 W168 h W0h = DW168 h = Change in Widt
33、h at168 h.10.3 See Table 1 for a suggested table for taking data.11. Report11.1 Report the following information:11.1.1 Sealant used, color, manufacturers lot, type (singlecomponent or multicomponent) and rated movement capabilityper Test Method C 719 as designated by the manufacturer,11.1.2 Actual
34、dimensions of the joint and configuration,11.1.3 Cleaning method for each substrate,11.1.4 Description of the test substrate(s),11.1.5 Primer used on specific substrates,11.1.6 Curing method and duration,11.1.7 Time of removal of casting spacers,11.1.8 Movement induced on the sealant during the test
35、 in% of original joint width,11.1.9 Method used to elongate the specimens to the desiredstrain and an estimated strain rate,11.1.10 Length and width of induced cut in each specimenafter 0, 24, and 168 h for the room temperature and coldtemperatures and observations reported,11.1.11 Average change in
36、 length and width of the inducedcut after 24 and 168 h at both the room temperature and 26Cconditioning, and11.1.12 Any other observations worthy of reporting.12. Precision and Bias12.1 A preliminary study was conducted with 7 laboratoriesand 3 different sealants. Problems encountered in measurement
37、resulted in revisions to the standard. Only single sets of testsTop view of joint showing induced cut centered at the midpoint of the joint.FIG. 2 Top View of Joint Showing the Placement of the Induced CutTop view of joint showing induced cut centered at the midpoint of the joint.NOTEMeasurements of
38、 the length of the cut (X axis) and width of cut (Y axis) are taken and reported at 0, 24, and 168 h.FIG. 3 Top View of a Joint that is Held Under a Fixed ExtensionTABLE 1 Suggested Table for Taking DataLength0hWidth0hLength24 hWidth24 hLength168 hWidth168 hSpecimen 1 RTSpecimen 2 RTSpecimen 3 RTAve
39、rage Change RTafter 24 and 168 hNA NASpecimen 1 26CSpecimen 2 26CSpecimen 3 26CAverage Change 26Cafter 24 and 168 hNA NAC1681093were run so repeatability also was not able to be determined. Asummary of the program is included in the Appendix.12.2 An interlaboratory program will be conducted after th
40、etest method is approved and in practice.13. Keywords13.1 constant strain testing; fixed extension; movementinduced tear; sealantAPPENDIXES(Nonmandatory Information)X1. PILOT STUDYX1.1 A pilot study was conducted on the performance ofthe initial draft of the proposed standard. Seven laboratoriespart
41、icipated by testing three different materials. Three samplesof each material were to be prepared by each laboratory andstored at two different temperatures during the test procedure.X1.2 The draft standard did not define the type andresolution of measurement devices. Some laboratories mea-sured to t
42、he nearest mm while others provided readings toeither 0.1 or 0.01 mm. These later data sets showed variation inall sample sets while those measured to the nearest mm (or halfmm) showed virtually no differences in the samples tested tomake up the test results.X1.3 Since the standard has been revised
43、to require greaterresolution in taking all observations, Table X1.1 only showsresults from the laboratories that conducted more detailed tests.All readings are in millimeters and are the average of threesamples.X1.4 The silicone and the urethane materials tested had aclaimed movement capability rati
44、ng of 25 %. The modifiedpolyether had a claimed movement rating of +10050 %. Thisis reflected in the initial width of cut noted in Table X1.1.TABLE X1.1 Results from Four LaboratoriesNOTEAll measurements are in mm.Material LabInitial Lengthof CutChange in Length1 DayChange in Length7 DayInitial Widt
45、hof CutChange in Width1 DayChange in Width7 DaySilicone RT A 7.03 13.20 27.18 3.73 0.18 0.36B 10.95 4.27 13.00 3.55 0.35 0.86C 9.63 6.50 18.27 2.90 0.10D 8.47 1.28 5.27 2.96 0.19 0.08Urethane RT A 7.62 0.76 0.58 3.66 0.33 0.08B 10.45 0.45 0.37 3.93 0.09 0.23C 8.30 0.33 0.07 2.87 0.17D 8.68 0.02 0.51
46、 2.90 0.36 0.23Modified Polyether RT A 7.90 0.99 2.12 10.84 3.02 2.16B 11.27 0.38 0.08 13.34 0.09 0.07C 10.67 0.37 0.27 13.47 0.17D 9.98 0.86 0.76 12.17 0.47 0.20Silicone 29C A 6.63 5.97 6.67 3.50 1.68 1.13B 9.94 0.49 8.23 4.18 0.01 0.54C 9.07 0.77 0.33 3.47 0.20D 8.68 0.48 0.77 3.14 0.14 0.06Uretha
47、ne 29C A 8.08 1.67 1.40 3.92 0.46 0.40B 10.44 0.23 0.17 3.53 0.37 0.10C 8.17 0.03 0.07 3.40 0.37D 8.62 0.18 1.18 3.05 0.06 0.18Modified Polyether 29C A 8.21 1.18 1.64 11.69 0.83 1.52B 10.77 0.07 1.17 12.84 0.75 0.37C 10.40 0.70 0.33 13.57 0.30D 9.85 1.02 1.02 12.24 0.53 0.49C1681094X2. EXTENSION PAR
48、AMETERSX2.1 The extension that should be used to evaluate sealantswith this test method depends on the reason/purpose forperforming the test. A few examples are:X2.1.1 If the test is being performed to compare tearpropagation performance between different sealants, all thesealants should be extended
49、 to the same separation.X2.1.2 If the test is being performed to evaluate a sealant foruse in a specific application, an analysis of the applicationshould be performed to determine the appropriate extensionparameter to use.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of su
