1、Designation: C1257 15Standard Test Method forAccelerated Weathering of Solvent-Release-Type Sealants1This standard is issued under the fixed designation C1257; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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 includes two laboratory acceleratedexposure procedures for predicting the effects of ultraviolet orultraviolet/v
3、isible radiation, heat, and moisture on color,chalking, 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 conce
4、rns, 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 comparabl
5、e standards published by other orga-nizations.2. Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC1442 Practice for Conducting Tests on Sealants UsingArtificial Weathering ApparatusG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmeta
6、llic MaterialsG151 Practice for Exposing Nonmetallic Materials in Accel-erated Test Devices that Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Ultraviolet (UV)Lamp Apparatus for Exposure of Nonmetallic MaterialsG155 Practice for Operating Xenon Arc Light Apparatus forExposure o
7、f Non-Metallic Materials3. Terminology3.1 Definitions:3.1.1 Refer to Terminology C717 and G113 for definitionsof terms used in this test method: standard conditions.4. Summary of Test Method4.1 Four test specimens are prepared in U-shaped aluminumchannels. After curing, three of the specimens are ex
8、posed inthe laboratory accelerated 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 unexpos
9、ed filespecimen.5. Significance 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 i
10、s material dependent, varying 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
11、 the sealant against that 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 G151 and G1
12、54 withUVA-340 type lamps.6.1.2 Xenon-Arc Apparatus, that conforms to the require-ments in Practices G151 and G155 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 spe
13、cified.6.3 Steel Spatula.7. Procedure7.1 Condition sufficient compound in an original closedcontainer for at least 24 h at standard conditions.1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.40 onWeat
14、hering.Current edition approved March 15, 2015. Published April 2015. Originallyapproved in 1994. Last previous edition approved in 2012 as C1257-06a(2012).DOI: 10.1520/C1257-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
15、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 States17.2 Prepare four sealant test specimens in aluminumU-channels.7.2.1 T
16、horoughly 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 bottom up being careful to avoid air entrapment.Strike
17、 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 may request conditions other than thosespecified in 7.
18、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 inone of the laboratory accelerated exposure devices lis
19、tedbelow. 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 G154and G155 for differences in the spectral power distribu
20、tions ofthe exposure sources and Practice C1442 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 specimens to thesample holder such that the open or top surfac
21、e 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 Fluorescent UV/CondensationApparatusOperate the device in accordance
22、 with the proce-dure in Section 7.3 of Practice C1442. Remove the specimensfrom the apparatus after a minimum of 1000 h of exposure.7.4.2 Procedure for Xenon-Arc ApparatusOperate the de-vice in accordance with the procedure in Section 7.2 ofPractice C1442. When operated at the preferred irradiancele
23、vel 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 C1442 for determining theexposure time required to provide the same radiant exposure atother irradiance levels.7.5 Condition the samples at standard conditions
24、 for 2 h.Inspect the specimens for chalking, color change, centercracking, edge cracking, and loss of adhesion versus theunexposed file specimen. Compare the effect of exposure onthe test specimens with the effect on the control material, ifused, to determine the relative performance of the test mat
25、erial.8. Report8.1 In addition to the items specified in Practice G151,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 visual description of the test specimensafter exposure compared to the unexposed file specimen
26、 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-ence standards shown in Figs. 1-3. Ratings range from 0, nodamage, to 5, severe damage. The
27、 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 test procedure.8.1.6 Total number of hours test specimens were exposed inweathering device.FIG. 1 Edge CrackingC1257 1529. P
28、recision 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 repeatability (within a given labo-ratory) interval is 1.281. In future use of this test method, thediff
29、erence 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) interval is 3.691. Infuture use of this test method, the difference between two testresults
30、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 future use of this test method,the difference between two test results obtained in the samelabor
31、atory on the same material will be expected to exceed0.820 only about 5 % of the time. The center crackingreproducibility (between given laboratories) interval is 3.124.In future use of this test method, the difference between twoFIG. 2 Center CrackingFIG. 3 AdhesionC1257 153test results obtained in
32、 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 this test method, thedifference between two test results obtained in the samelaboratory on the
33、 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 between two test resultsobtained in a different laboratory on the same material will beexpect
34、ed 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 asserted in connection with any item mentionedin this standard. Users of this standard are expressl
35、y 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, e
36、ither 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 receive careful consideration at a meeting of theresponsible technical committee, which you may atte
37、nd. 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. I
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