ASTM_C_734_-_15.pdf

Designation:C73415Standard Test Method forLow-Temperature Flexibility of Latex Sealants After ArtificialWeathering1This standard is issued under the fixed designation C734;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year 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 laboratory procedure for thedetermination of low-temperature flexibility of latex sealantsafter 500 h artificial weathering.1.2 The values stated in metric(SI)units are to be regardedas the standard.The values given in parentheses are forinformation 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1Currently there is no ISO standard similar to this test method.2.Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC1442 Practice for Conducting Tests on Sealants UsingArtificial Weathering Apparatus3.Terminology3.1 DefinitionsRefer to Terminology C717 for definitionsof the following terms used in this test method:adhesivefailure,latex sealant,sealant,substrate,and standard condi-tions.4.Summary of Test Method4.1 A slab of the sealant is exposed,after drying,for aminimum of 500 h in an artificial weathering unit,after whichit is conditioned and flexed at 17 6 1C(0 6 2F).5.Significance and Use5.1 This test evaluates the flexibility of artificially weath-ered latex sealants in a low-temperature environment.6.Apparatus6.1 T3 Temper Alclad Aluminum Panels,three,each 76 by153-mm(3 by 6-in.)of 16 to 24 gage(1.29 to 0.511 mm).6.2 Accelerated Weathering DeviceOne of the units asdescribed in Practice C1442.Because of differences in spectralpower distributions of the exposure sources and exposureparameters used in the different types of devices described inPractice C1442,test results may differ with the type ofaccelerated weathering device.Choice of type of device shallbe by mutual agreement among the interested parties.6.3 Cold Box or Freezer.6.4 Mandrel,Wood or Metal,25 mm(1 in.)in diameter.6.5 Template,consisting of a 3.2-mm(18-in.)thick brassplate with a rectangular opening 38 by 127 mm(112by 5 in.).6.6 Spatula,metal.7.Sampling7.1 Take the sealant to be tested directly from the containeras commercially supplied by the manufacturer.8.Test Specimens8.1 Prepare three test specimens as follows:8.1.1 Center the template on an aluminum panel,fill it toexcess with the sealant,and strike the excess off flush with thesurface of the template with the metal spatula.8.1.2 Cut around the perimeter of the sealant,next to thetemplate,with the spatula,and carefully remove template.9.Conditioning9.1 Condition the three specimens for 2 days at standardconditions.10.Procedure10.1 Place the conditioned specimens in the artificial weath-ering unit and cycle them for a minimum of 500 h,beginningwith the start of the light cycle.Refer to Practice C1442 for the1This 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 June 1,2015.Published July 2015.Originally approvedin 1972.Last previous edition approved in 2012 as C732 06(2012).DOI:10.1520/C0734-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 artificial weathering unit operating conditions.Expose speci-mens in the xenon arc device for a minimum of 500 h at anirradiance level of 0.51 W(m2 nm)at 340 nm.The radiantexposure for this is 918 kJ/(m2 nm)at 340 nm.To determinethe exposure time required to obtain the same radiant exposureat other irradiance levels specified in Practice C1442,seeAnnex A1 in C1442.10.2 Following artificial weathering exposure,place thespecimens and the mandrel in a cold box maintained at 17 61C(0 6 2F)for 4 h.10.3 While still in the cold box,place each specimen in turnon the mandrel,with the aluminum plate next to the mandrel,and,without holding the sealant,bend the specimen 90 aroundthe mandrel within 1 s.10.4 Visually examine the specimens after bending,forcracking of the sealant or adhesive failure to the aluminum,orboth.11.Report11.1 Report the type and description of the laboratoryaccelerated weathering device,the length of time the testspecimens were exposed in the artificial weathering device andwhether the sealant cracks through to the substrate,or failsadhesively to the al