ASTM_D_2918_-_99_2012.pdf

Designation:D291899(Reapproved 2012)Standard Test Method forDurability Assessment of Adhesive Joints Stressed in Peel1This standard is issued under the fixed designation D2918;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.INTRODUCTIONThe combination of stress and moisture decreases the durability of most adhesive joints.Stresses inthe presence of water or water vapor may cause some adhesive joints to fail at some fraction of thestress required to break the dry joint.The time to failure for a given adhesive joint tested under moistconditions generally decreases with increasing stress,temperature,and relative humidity.1.Scope1.1 This test method provides data for assessing the dura-bilities of adhesive joints by means of T-peel type specimensstressed in contact with air,air in equilibrium with certainsolutions,water,aqueous solutions,or other environments atvarious temperatures.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 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.2.Referenced Documents2.1 ASTM Standards:2B209 Specification for Aluminum and Aluminum-AlloySheet and PlateD907 Terminology of AdhesivesD1828 Practice for Atmospheric Exposure of Adhesive-Bonded Joints and StructuresD1876 Test Method for Peel Resistance of Adhesives(T-Peel Test)D2651 Guide for Preparation of Metal Surfaces forAdhesiveBondingE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions3.Terminology3.1 DefinitionsMany terms in this practice are defined inTerminology D907.4.Significance and Use4.1 The combination of stress and moisture decreases thedurability of most adhesive joints.Stresses in the presence ofwater or water vapor may cause some adhesive joints to fail atsome small fraction of the stress required to break the dry joint.The time to failure for a given adhesive joint generallydecreases with increasing stress,temperature,and relativehumidity.4.2 This test method may be used as an accelerated screen-ing test for assessing the durability of adhesive joints.It may beused to measure durability of adhesive joints exposed outdoorsor to environmental conditions experienced by adhesive jointsin service.It may also be used to determine the effects ofvarious surface preparations or substrates on durabilities ofadhesive joints.4.3 The durability performance of various adhesives may becompared by using this test method under uniform sets ofconditions.To assess the overall durability of a given adhesive,T-peel joints should be tested under a range of stress,relativehumidity,and temperature.For a specific end use it may bepossible to obtain the needed durability data using only one setof test conditions.5.Apparatus5.1 For outdoor exposure the test location should be in anarea free of or protected from high winds.Standard outdoorweathering racks are suggested(Practice D1828),but anystable frame may be used(for example galvanized pipe orpainted steel channel).No other special apparatus is requiredfor outdoor tests.1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.80 on MetalBonding Adhesives.Current edition approved Oct.1,2012.Published October 2012.Originallyapproved in 1971.Last previous edition approved in 2005 as D2918 99(2005).DOI:10.1520/D2918-99R12.2For 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 5.2 For exposure in environmental cabinets or chambers noadditional special apparatus is necessary.Constant-temperaturebaths may also be used.5.3 For exposure to distilled or deionized water in thelaboratory it may be convenient to use the apparatus shown inFig.1.5.4 For exposure to constant relative humidities,the speci-men may be placed in a apparatus similar to that shown in Fig.1.A saturated salt solution may be placed in the bottom of theglass tube to provide a constant relative humidity(see PracticeE104);a stopper having a small glass tube packed with greasemay be used to seal the upper end of the large glass tube.6.Test Specimens6.1 The successful use of the following test method dependson preparing good quality T-peel joint specimens.Prepare thetest panels carefully according to the ad