1、Designation: C1735 17Standard Test Method forMeasuring the Time Dependent Modulus of Sealants UsingStress Relaxation1This standard is issued under the fixed designation C1735; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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.1. Scope1.1 This test method covers a procedure for measuring thetime dependence of modulus in elastomeric joint sealants in
3、atest specimen configuration described in Test Method C719.These sealant materials are typified by highly filled rubbermaterials. Any Mullins effect is first assessed and mitigated intwo loading-unloading cycles. Time dependence of modulus inmaterials is then determined using a stress relaxation pro
4、ce-dure.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.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
5、appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC719 Test Method for Adhesion and Cohesion of Elasto-meric Joint Sealants Under Cyclic Movement (
6、HockmanCycle)E4 Practices for Force Verification of Testing MachinesE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE631 Terminology of Building ConstructionsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Def
7、initions:3.1.1 For definitions of terms used in this test method, referto Terminologies E631 and C717.4. Summary of Test Method4.1 This test method consists of two loading cycles wherestrain is increased froma0%toauser-defined maximumstrain and one stress relaxation procedure at a strain no greatert
8、han23 of the user-defined maximum strain. A schematicdiagram of this test strain history is shown in Fig. 1.4.2 The motivation for the two loading-unloading cycles isto assess if any Mullins effect is present and to mitigate any ofthis effect in the subsequent stress relaxation test. As long asthe m
9、aximum strain achieved during the first deformation isnot exceeded, however, all subsequent loadings follow thesame stress-strain curve.4.3 Stress relaxation procedure is based on a sudden impo-sition of either a tensile or compressive strain on the testspecimen at a value of no more than23 of the m
10、aximum strainand the measurement of the load required to maintain thistensile or compressive strain as a function of time.4.4 The conversion of load relaxation values to apparentmodulus and fractional change in apparent modulus is accom-plished by inputting information about the specimen geometryand
11、 the amount of deformation into an equation that is based onthe statistical theory of rubber-like elasticity.5. Significance and Use5.1 The intent of this test method is to determine the timedependence of modulus in building joint sealants using twoloading-unloading cycles to identify and mitigate a
12、ny Mullinseffect, and followed by a stress relaxation procedure todetermine the time dependent modulus.5.2 This test method has found applications in screening theperformance of building joint sealants since the modulus is oneindicator of the ability of elastomeric building sealant towithstand envir
13、onmental induced movements.6. Apparatus6.1 Testing MachineAny testing machine in compliancewith Practices E4, capable of producing a constant crosshead1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.2
14、0 onGeneral Test Methods.Current edition approved Jan. 1, 2017. Published February 2017. Originallyapproved in 2011 as C1735-11. Last previous edition C1735-11. DOI: 10.1520/C1735-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.
15、org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with inte
16、rnationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1displacement rate in displacement control and e
17、quipped withmeans for recording complete load versus displacement curvesduring the test.6.2 Load CellThe load cell of the testing machine shall becapable of recording the load with an accuracy of 61%ofthemaximum indicated value.6.3 Loading FixturesUsed to mount specimens to thetesting machine so tha
18、t the surface of the substrate is perpen-dicular to the direction of the applied load and to minimize anyeccentric loading in the test specimen.6.4 Air-circulating OvenTo condition specimens at thespecific temperature and relative humidity.6.5 Mechanical Fastener or Rubber BandsTo hold aspecimen ass
19、embly together before and after filling it withsealant compound.6.6 Geometry Measuring ToolTo measure the dimensionsof aluminum substrate and sealant to an accuracy of at least 65mm (0.2 in.). Because stress is the load per area exerted on thetest specimen, an accurate measurement of the geometry is
20、critical.7. Preparation of Test Specimen7.1 Test conditions of temperature and relative humidityused throughout this test method are defined in TerminologyC717.7.2 The standard substrate used in the test shall be alumi-num alloy (76.2 by 12.7 by 12.7 mm) (3 by 0.5 in. by 0.5 in.),6063-T5, or 6061-T6
21、 with anodizing process AA-M10C22A31. Prior to use, the aluminum alloy shall be cleanedaccording to a procedure described in the Test Method C719,which involves cleaning the substrate by wiping the surfacewith methyl ethyl ketone or similar solvent. Then dip thesurface in a detergent solution.An alt
22、ernative would be a 0.1 %solution of a clear hand dishwashing detergent. These solutionsshould be made up in distilled or deionized water. Rinse thesurface (without touching it) in distilled or deionized water andallow it to air dry.7.3 Where use of primer is recommended by the sealantmanufacturer,
23、substrate materials shall be primed with therecommended primer or primers.7.4 Mix thoroughly for 5 min at least 250 g of basecompound with the appropriate amount of curing agent beingcareful not to generate excess heat. For single-componentsealants, no mixing of components is required. Dispense thec
24、ompound from a cartridge into a specimen cavity (50.8 by12.7 by 12.7 mm) (2 by 0.5 by 0.5 in.) formed by two parallelsubstrate faces (50.8 by 12.7 mm) (2 by 0.5 in.) with apolytetrafluoroethylene (PTFE) film on the back and PTFEspacers (12.7 by 12.7 by 12.7 mm) (0.5 by 0.5 by 0.5 in.) oneach end, as
25、 shown in Fig. 2.7.5 Use appropriate mechanical fasteners or rubber bands tohold the specimen cavity together before and after filling itwith the compound.7.6 Condition the specimen in the fixture at the standardconditions of temperature and relative humidity for a minimumof 5 h. Then remove the mec
26、hanical fasteners or rubber bandsand the PTFE backing film. Keep the PTFE spacers and thealuminum substrate intact.7.7 Allow specimen to cure according to the Test MethodC719 specifications.7.8 Test specimens surfaces should be smooth and free fromnicks and scratches.The value of t0is 20 s and t1is
27、typically 2000 s.FIG. 1 Strain History Used for Two Loading-Unloading Cycles and a Stress Relaxation MeasurementFIG. 2 Illustration of Specimen Preparation Before Filling it withthe Sealant CompoundC1735 1727.9 The finished test specimen is shown in Fig. 3.8. Number of Test Specimens8.1 Test at leas
28、t three specimens of each sealant.9. Procedure9.1 Perform the test at the standard conditions of tempera-ture and relative humidity stated in 7.1. Tests at other ambienttemperature and relative humidity may be run if desired.9.2 Mount the specimen (as prepared in Section 7)inthefixture of the testin
29、g machine. Exercise precautions to mini-mize axial misalignment.9.3 Set the testing machine at a crosshead displacement rateof 20 mm/min (0.787 in./min). Set the direction of appliedstrain, either tensile or compressive.9.4 Apply load to the specimen until the strain reaches themaximum strain, after
30、 which the specimen is completelyunloaded at the same crosshead displacement rate.9.5 The specimen is allowed to rest for 200 s. This is doneto ensure the viscoelastic recovery from one loading is com-plete before the next loading is initiated.9.6 Repeat 9.4 and 9.5 for the second loading-unloadingc
31、ycle.9.7 Set the testing machine at a crosshead displacement rateof 1000 mm/min (39.37 in./min).9.8 Apply load to the specimen until the strain reaches thedesired test strain, no greater than23 of the maximum strainand hold that value while load is monitored as a function oftime. The time required t
32、o load the specimen is less than1ssothe first data point is not taken until after 10 s to avoid transienteffects associated with loading.9.9 Inspect the sample to note the locus of joint failure, ifany failure occurs.10. Calculation and Analysis10.1 Calculate an apparent modulus, Ea, using a relatio
33、nshipbased on the statistical theory of rubber-like elasticity:Ea t,! 53Lt!WB 2 22!(1)where:L = load, N (lb),W = length of the specimen, m (in.),B = depth of the specimen, m (in.),t = time, s, = extension ratio, which is given by: 5 11H(2)where: = crosshead displacement of testing machine, andH = wi
34、dth of the specimen, m (in.).10.2 For convenience in comparing the relative change inapparent modulus of materials during environmentalexposures, the fractional change in apparent modulus, F, maybe calculated as a function of time:F 5Eat1!Eat0!(3)where:Ea(t0) = apparent modulus at time, t0, andEa(t1
35、) = apparent modulus at time, t1.10.3 A plot of the fractional change in apparent modulus isuseful for comparison between different exposure times. Forsuch a graph, no change would be represented as a horizontalstraight line at F = 0. A horizontal line above or below F =0indicates that exposure caus
36、es a vertical shift in the stressrelaxation curve but no change in shape (that is, the timedependence does not change. Something other than a horizon-tal straight line indicates a change in time dependence.11. Report11.1 Report the following information:11.1.1 Identification of the sealant tested, i
37、ncluding type,source, manufacturer code number, curing conditionsemployed,11.1.2 Identification of the substrate used,11.1.3 Name and description of primers used, if any,11.1.4 Temperature and relative humidity,11.1.5 Number of specimens tested,11.1.6 Type of strain (compressive or tensile),11.1.7 M
38、aximum strain, test strain.11.1.8 Descriptive of the type of failure, if any:11.1.8.1 Cohesive failure, if separation occurred within thematerial,11.1.8.2 Adhesive failure, if separation occurred at theinterface of the substrate and the sealant,11.1.8.3 Mixed failure, if both adhesive and cohesive f
39、ailureregions are present.11.1.9 Records in terms of apparent modulus or normalizedmodulus as a function of time.12. Precision and Bias12.1 The precision of this test method is based on aninter-laboratory study of C1735 Standard Test Method forMeasuring the Time Dependent Modulus of Sealants UsingH,
40、 B and W are the width, depth and length of the specimen, respectively.FIG. 3 Geometry for the Sealant SpecimenC1735 173Stress Relaxation, conducted in 2016. Seven laboratories testeda single type of sealant. Every “test result” represents anindividual determination, and each laboratory reported tri
41、pli-cate test results. Practice E691 was followed for the design andanalysis of the data; the details are given in ASTM ResearchReport No. C24-1063.312.1.1 Repeatability (r)The difference between repetitiveresults obtained by the same operator in a given laboratoryapplying the same test method with
42、the same apparatus underconstant operating conditions on identical test material withinshort intervals of time would in the long run, in the normal andcorrect operation of the test method, exceed the followingvalues only in one case in 20.12.1.1.1 Repeatability can be interpreted as maximum dif-fere
43、nce between two results, obtained under repeatabilityconditions, that is accepted as plausible due to random causesunder normal and correct operation of the test method.12.1.1.2 Repeatability limits are listed in Table 1.12.1.2 Reproducibility (R)The difference between twosingle and independent resu
44、lts obtained by different operatorsapplying the same test method in different laboratories usingdifferent apparatus on identical test material would, in the longrun, in the normal and correct operation of the test method,exceed the following values only in one case in 20.12.1.2.1 Reproducibility can
45、 be interpreted as maximumdifference between two results, obtained under reproducibilityconditions, that is accepted as plausible due to random causesunder normal and correct operation of the test method.12.1.2.2 Reproducibility limits are listed in Table 1.12.1.3 The above terms (repeatability limi
46、t and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with 12.1.1 and 12.1.2would have an approximate 95 % probability of being correct.12.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for th
47、is testmethod, therefore no statement on bias is being made.12.3 The precision statement was determined through sta-tistical examination of eighteen test results, as reported by sixof the seven participating laboratories, on a single type ofsealant material. The sealant tested was described as a com
48、-mercial silicone sealant formulation prepared according to TestMethod C719.13. Keywords13.1 elastomeric joint sealant; environmental attack; Hock-man cycle; modulus; Mullins effect; stress relaxationASTM International takes no position respecting the validity of any patent rights asserted in connec
49、tion 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 such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Yo
