1、Designation: D2918 99 (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
2、 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 prese
3、nce 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 Thi
4、s 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 r
5、egarded 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 det
6、ermine 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
7、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 a
8、nd 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
9、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 exper
10、ienced 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
11、 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
12、 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 ju
13、risdiction 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
14、.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
15、C700, West Conshohocken, PA 19428-2959. United States15.2 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 appar
16、atus 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
17、 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 adhesive manufacturersdirections or
18、according to some other specified set of condi-tions agreed upon between the manufacturer and the purchaser.6.2 Use the test-panel construction and the test specimendescribed in Test Method D1876. To adapt to differing testconditions and constraints due to size or configuration ofvarious test enviro
19、nments and apparatus, dimensions of thespecimen may be varied as long as they are identical whenmaking direct comparisons of different adhesives.FIG. 1 Apparatus for Measuring Adhesive Peel Rates in WaterD2918 99 (2012)2NOTE 1For example, test specimens may be cut to 12.7 mm (1 in.)wide to fit more
20、readily into a glass tube as shown in Fig. 1.6.3 The adherend surfaces may be either etched (see GuideD2651), solvent wiped, degreased, or treated by some otherspecified method of surface preparation.7. Conditioning7.1 Condition the peel specimens while either stressed orunstressed in the environmen
21、t of the specific test for aminimum of one day before beginning measurements. Carrythis out by discounting measurements made during the firstday.8. Procedure8.1 Clamp one end of the nonbonded part of the T-peel testspecimen as shown in Fig. 1 and attach to a stationary frame orobject relatively free
22、 of vibrations. Clamp the other end of thepanel and attach the desired weight (if the apparatus shown inFig. 1 is used, the total force on the adhesive joint is equal tothe sum of the weights of the water, the wet-peel apparatus, andthe applied weight. To avoid possible breaking of the glass tubewhe
23、n a joint fails it is useful to attach a light-weight string fromthe hose clamp or wire around the upper part of the glass tubeto the fixed point of support. If this apparatus is not used, thepeel joints may be tested in series by bolting several jointstogether and attaching the weight at the bottom
24、). The forceexerted on the adhesive joint being tested should be a multipleof 450 g (1.0 lb). Expose the stressed specimen to one of thestandard test environments, and then measure the length of theunpeeled portion of the specimen. Record this length hourly,daily, or weekly depending on the rate of
25、peel of the specimenuntil the specimen has peeled to failure. Make at least sixmeasurements for each specimen. Test a minimum of threespecimens under each set of conditions (test environment andstress). Suggested stress levels are 25, 50, and 75 % of thenormal T-peel strength as measured by Test Met
26、hod D1876.9. Calculation9.1 Plot the distance peeled (distance peeled equals initiallength of unpeeled portion minus length of unpeeled portion attime t) versus time. The slope of the curve at any point is thepeel rate at the corresponding time t. Divide the curve into sixequal parts. If the peel ra
27、te varies less than a factor of two overall six parts of the curve, then obtain an average peel rate (slopeof the curve) for the specimen. In order to assess durability,compare the peel rates under different levels of stress andactivities of water (for example, three stresses each for testenvironmen
28、ts 1 and 3) by plotting the log of peel rate versusstress.10. Report10.1 Report the following information:10.1.1 Complete identification of the adhesive tested, in-cluding type, form, source, and manufacturers code number.10.1.2 Complete identification of the adherends used, in-cluding composition,
29、thickness, and the temper for metals.NOTE 2The two adherends need not be identical; for example, a thinadherend may be bonded to a thick adherend with peeling occurring at180.10.1.3 Method of preparing the test panel (both adhesiveand adherends) and conditioning treatment.10.1.4 Method of testing (w
30、eight in grams per millimetre(pounds per inch); test environment number from Table 1,including a complete description of any special test environ-ments; location of outdoor test site and time of year, high, low,average temperatures, and sun exposure; angle of peel).10.1.5 Number of specimens tested,
31、 average bond linethickness, initial peel strength of specimens from the same testpanel, average peel rate (or curves of distance peeled versustime) for each specimen, and plot of log of peel rate versusstress when available.11. Keywords11.1 adhesive; durability; exposure; joint; moisture;stressed;
32、T-peelTABLE 1 Standard Test EnvironmentsTest EnvironmentNumberTemperatureAMoisture ConditionsB1 23C (73.4F) immersed in distilled ordeionized water2 23C (73.4F) 50 % RH (relative humidity)3 23C (73.4F) 15 % RH4 35C (95F) 90 % RH5 35C (95F) 100 % RH6 50C (122F) 90 % RH7 50C (122F) 100 % RH8 35C (95F)
33、 5 % salt fog9 ambient (outdoors) ambient (outdoors)10 other (specify) other, including aqueoussolutions or nonaqueousliquids (specify)AThe tolerance for test temperature shall be 1C (1.8F) for environments 1 to 8.BThe moisture condition may be provided by controlling the relative humidity of abox,
34、room, or other chamber by any convenient means.D2918 99 (2012)3ASTM 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 expressly advised that determination of the validity of any such
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