1、Designation: C 1257 06aStandard Test Method forAccelerated Weathering of Solvent-Release-Type Sealants1This standard is issued under the fixed designation C 1257; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method includes two laboratory acceleratedexposure procedures for predicting the effects of ultraviolet orultraviol
3、et/visible radiation, heat, and moisture on color, chalk-ing, cracking, and adhesion of solvent-release sealants.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 address all of thesafety
4、 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 notaware of any com
5、parable standards published by other orga-nizations.2. Referenced Documents2.1 ASTM Standards:2C 717 Terminology of Building Seals and SealantsC 1442 Practice for Conducting Tests on Sealants UsingArtificial Weathering ApparatusG113 Terminology Relating to Natural and ArtificialWeathering Tests of N
6、onmetallic MaterialsG 151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light SourcesG 154 Practice for Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic MaterialsG 155 Practice for Operating Xenon Arc Light Apparatusfor Exposure of No
7、n-Metallic Materials3. Terminology3.1 Definitions3.1.1 Refer to Terminology C 717 and G113for definitionsof terms used in this test method.4. Summary of Test Method4.1 Four test specimens are prepared in U-shaped aluminumchannels. After curing, three of the specimens are exposed inthe laboratory acc
8、elerated weathering device and the fourthspecimen is stored under standard conditions as an unexposedfile specimen.At the end of the exposure period, the specimensare examined for chalking, color change, center cracking, edgecracking, and loss of adhesion versus the unexposed filespecimen.5. Signifi
9、cance and Use5.1 It is difficult to establish a precise correlation betweenlaboratory accelerated and natural weathering because of (1)geographical climatic variations, local weather variation fromnormal, and local pollutants and (2) the fact that the accelera-tion factor is material dependent, vary
10、ing with the type ofmaterial as well as its formulation. This test method is used todetermine the resistance of a sealant to laboratory acceleratedweathering and, if a control material with known outdoorweathering performance is used, the relative weathering per-formance of the sealant against that
11、of the control material.5.2 This test method is conducted using aluminum channels.Other substrate materials may show different results.6. Apparatus6.1 Exposure Apparatus:6.1.1 Fluorescent UV/Condensation Apparatus, that con-forms to the requirements in Practices G 151 and G 154 withUVA-340 type lamp
12、s.6.1.2 Xenon-Arc Apparatus, that conforms to the require-ments in Practices G 151 and G 155 with daylight type filters.6.2 Four-Mill Finish Aluminum U-Channels, 76 mm longby 19 mm wide by 9.5 mm deep (3 by34 by38 in.) insidedimensions. Additional substrate materials may be specified.6.3 Steel Spatu
13、la.1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.40 onWeathering.Current edition approved Sept. 1, 2006. Published September 2006. Originallyapproved in 1994. Last previous edition approved in 2006
14、as C 1257-06.2For 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 page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor D
15、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Procedure7.1 Condition sufficient compound in an original closedcontainer for at least 24 h at standard conditions. Standardconditions are to be a temperature of 23 6 2C (73 6 3.6F)and relative humidity of 50 6 5%.7.2 Prepare four
16、 sealant test specimens in aluminumU-channels.7.2.1 Thoroughly clean channels using a suitable solventsuch as methyl ethyl ketone (MEK). Allow to dry before fillingwith sealant.7.2.2 Block the ends of the U-channels with masking tapeand overfill the entire channel with conditioned compoundfrom the b
17、ottom up being careful to avoid air entrapment.Strike the channel off flat with a spatula. Do not remove themasking tape. It is to stay in place for the entire test. Removingit may disturb the uncured or cured sealant.7.3 Cure the test specimens at standard conditions for 21days.NOTE 1The producer m
18、ay request conditions other than those speci-fied in 7.3 for the curing period, provided they meet the followingrequirements: the curing period must extend for 21 days, and thetemperature during the curing period shall not exceed 70C (158F).7.4 After the curing period, place three of the specimens i
19、none of the laboratory accelerated exposure devices listedbelow. Choice of the type of apparatus shall be by mutualagreement among the interested parties. Because of differencesin type of light source and test conditions, test results maydiffer with the type of apparatus used. Consult Practices G 15
20、4and G 155 for differences in the spectral power distributions ofthe exposure sources and Practice C 1442 for differences in testparameters in two types of apparatus specified. Place threereplicate specimens of the control material, if used, in thedevice along with the test material. Attach the spec
21、imens to thesample holder such that the open or top surface of the channelis in contact with the sample holder and the sealant surfacefaces the light source. Keep the fourth test specimen as anunexposed file specimen of the test material and store atstandard conditions.7.4.1 Procedure for Fluorescen
22、t UV/CondensationApparatusOperate the device in accordance with the proce-dure in Section 7.3 of Practice C 1442. Remove the specimensfrom the apparatus after a minimum of 1000 h of exposure.7.4.2 Procedure for Xenon-Arc ApparatusOperate thedevice in accordance with the procedure in Section 7.2 ofPr
23、actice C 1442. When operated at the preferred irradiancelevel of 0.51 W(m2 nm) at 340 nm, remove the specimensfrom the apparatus after a minimum of 1000 h (1835 kJ/(m2nm) at 340 nm). See Annex A1 in C 1442 for determining theexposure time required to provide the same radiant exposure atother irradia
24、nce levels.7.5 Condition the samples at 23 6 2C (73 6 4F) and 506 5 % relative humidity for 2 h. Inspect the specimens forchalking, color change, center cracking, edge cracking, andloss of adhesion versus the unexposed file specimen. Comparethe effect of exposure on the test specimens with the effec
25、t onthe control material, if used, to determine the relative perfor-mance of the test material.8. Report8.1 In addition to the items specified in Practice G 151,report the following for each sample tested:8.1.1 Identification of sealant tested.8.1.2 Sealant cure cycle employed.8.1.3 Qualitative visu
26、al description of the test specimensafter exposure compared to the unexposed file specimen andspecimens of the control material, if used, with regard tochalking and color change.8.1.4 Quantitative visual description of edge cracking, cen-ter cracking, and adhesion loss using the photographic refer-e
27、nce standards shown in Figs. 1-3. Ratings range from 0, noFIG. 1 Edge CrackingC 1257 06a2damage, to 5, severe damage. The unexposed file specimen isalso rated so that it can be determined if the cracking oradhesion loss was the sole result of exposure.8.1.5 Variations, if any, from the specified tes
28、t procedure.8.1.6 Total number of hours test specimens were exposed inweathering device.9. Precision and Bias9.1 The precision and bias calculations were based on edgecracking, center cracking, and adhesion loss results from fivelaboratories testing six materials.9.1.1 The edge cracking repeatabilit
29、y (within a given labo-ratory) interval is 1.281. In future use of this test method, thedifference between two test results obtained in the samelaboratory on the same material will be expected to exceed1.281 only about 5 % of the time. The edge cracking repro-ducibility (between given laboratories)
30、interval is 3.691. Infuture use of this test method, the difference between two testresults obtained in a different laboratory on the same materialwill be expected to exceed 3.691 only about 5 % of the time.9.1.2 The center cracking repeatability (within a givenlaboratory) interval is 0.820. In futu
31、re use of this test method,FIG. 2 Center CrackingFIG. 3 AdhesionC 1257 06a3the difference between two test results obtained in the samelaboratory on the same material will be expected to exceed0.820 only about 5 % of the time. The center crackingreproducibility (between given laboratories) interval
32、is 3.124.In future use of this test method, the difference between twotest results obtained in a different laboratory on the samematerial will be expected to exceed 3.124 only about 5 % of thetime.9.1.3 The adhesion loss repeatability (within a given labo-ratory) interval is 1.216. In future use of
33、this test method, thedifference between two test results obtained in the samelaboratory on the same material will be expected to exceed1.216 only about 5 % of the time. The adhesion loss reproduc-ibility (between given laboratories) interval is 3.643. In futureuse of this test method, the difference
34、 between two test resultsobtained in a different laboratory on the same material will beexpected to exceed 3.643 only about 5 % of the time.10. Keywords10.1 accelerated weathering; sealant; solvent-release sealantASTM International takes no position respecting the validity of any patent rights asser
35、ted 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 such rights, are entirely their own responsibility.This standard is subject to revision at any time by
36、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. Your comments will receiv
37、e careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Intern
38、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 1257 06a4
