1、Designation: D3769 10Standard Test Method forMicrocellular UrethanesHigh-Temperature Sag1This standard is issued under the fixed designation D3769; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 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 the procedure and apparatus formeasuring high-temperature sag of microcellular urethanematerials.1.2 The values state
3、d in SI units are to be regarded asstandard.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 regulat
4、ory limitations prior to use.NOTE 1There is no similar or equivalent ISO standard to this testmethod.2. Referenced Documents2.1 ASTM Standards:2D3040 Practice for Preparing Precision Statements for Stan-dards Related to Rubber and Rubber Testing3E145 Specification for Gravity-Convection and Forced-V
5、entilation OvensE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Significance and Use3.1 This test method is used to indicate the deformationtendency of microcellular materials that may occur duringpaint application in an assembly plant operation. Si
6、nce astandard specimen is used, heat sag measurements cannot beassumed to be exactly those which will occur on a part duringor after the paint application and baking operation of anassembly process.3.2 Before proceeding with this test method, referenceshould be made to the specification of the mater
7、ial being tested.Any test specimen preparation, conditioning, or dimensions, orcombination thereof, and testing parameters covered in thematerials specification shall take precedence over those men-tioned in these test methods. If there are no material specifi-cations, then the default conditions ap
8、ply.NOTE 2This test method is applicable to solid urethanes.4. Apparatus4.1 Test Fixture, capable of holding the specimens in a fixedcantilever position for the duration of the entire test procedure.The test fixture shall be constructed from a material such asaluminum or steel that exhibits a low co
9、efficient of linearthermal expansion and therefore allows the test fixtures heightto be considered constant through the test. See Fig. 1.4.2 Oven, conforming to the specifications for a Type IAlaboratory oven in accordance with Specification E145.4.3 Scaled Rule, accurate to 1 mm.4.4 Thickness Indic
10、ator, accurate to 0.03 mm.1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials -Plastics and Elastomers.Current edition approved Aug. 1, 2010. Published August 2010. Originallyapproved in 1979. Last
11、previous edition approved in 2005 as D3769 - 05. DOI:10.1520/D3769-10.2For 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
12、 website.3Withdrawn.NOTE 1Not to scale.FIG. 1 Fixture for High-Temperature Sag1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.5 Base, a flat, smooth surface free of any surface irregu-larities that would affect the height measureme
13、nts. The basemust be heat-resistant to the maximum temperature that the testfixtures will be exposed.5. Test Specimens5.1 The test specimen shall have a minimum length of 125mm, and be 25 6 1 mm in width by the nominal thickness ofthe plaque or part. The recommended standard test specimen is4 mm in
14、thickness. The minimum specimen thickness shall be3 mm.5.2 Three specimens to each material shall be tested.NOTE 3If test specimens are cut from parts, the specimens must becut from areas that are of constant thickness; that is, no ribs, bosses, holes,or other section changes are allowed.6. Conditio
15、ning6.1 Unless otherwise specified, condition the specimens andfixture a minimum of1hat236 2C and 50 6 10 % relativehumidity before testing.7. Procedure7.1 Measure the thickness in the clamping area of the testspecimen to the nearest 0.03 mm.7.2 Clamp the specimen in the fixture with a 100 6 1mmunsu
16、pported overhang. Primed or painted surfaces are to bemounted facing up.7.3 After 5 min, measure the distance between the base andthe unsupported end of the specimen as shown in Fig. 1 andcall this Ao.7.4 Place the clamped specimen in an air-circulating oven atthe test temperature of 120 6 1C for 60
17、 6 1 min.7.5 After oven aging, remove the fixture with the specimenfrom the oven.7.6 After 5 min, repeat the measurement as in 7.3 for Aoandcall this distance Af.NOTE 4Other combinations of test temperatures, test times, andoverhang lengths are permitted subject to prior agreement between the testre
18、questor and the testing facility.These conditions are to be included in thetest report.8. Calculation8.1 Sag = Ao Af.9. Report9.1 The report shall include the following:9.1.1 Direction of cutting,9.1.2 Conditioning procedures before testing,9.1.3 Time and temperature of the test,9.1.4 Initial value
19、at 23C, average of three,9.1.5 Final sag value at test temperature, average of three,and9.1.6 Specimen thickness.10. Precision and Bias10.1 Table 1 is based on a round robin conducted in 1980 inaccordance with Practice D3040, involving three materialstested by four laboratories. For each material, a
20、ll the sampleswere prepared at one source and the individual specimens werealso prepared at one source. Each test result consisted of oneindividual determination. Each laboratory obtained four testresults for each material. (WarningThe explanation of r(10.2-10.2.2) is only intended to present a mean
21、ingful way ofconsidering the approximate precision of these test methods.The data in Table 1 should not be applied to acceptance orrejection of materials, as these data apply only to the materialstested in the round robin and are unlikely to be rigorouslyrepresentative of other lots, formulations, c
22、onditions, materials,or laboratories. Users of this test method should apply theprinciples outlined in Practice E691 to generate data specific totheir materials and laboratory (or between specific laborato-ries). The principles of 10.2-10.2.2 would then be valid forsuch data.)10.2 Concept of r in Ta
23、ble 1If Srhas been calculated froma large enough body of data, and for test results that wereaverages from testing three specimens for each test result, then:10.2.1 RepeatabilityTwo test results obtained within onelaboratory shall be judged not equivalent if they differ by morethan the r value of th
24、at material. r is the interval representingthe critical difference between two test results for the samematerial, obtained by the same operator using the sameequipment on the same day in the same laboratory.10.2.2 Any judgment in accordance with 10.2.1 would havean approximate 95 % (0.95) probabilit
25、y of being correct.10.3 There are no recognized standards by which to esti-mate bias of this test method.11. Keywords11.1 deformation; heat sag; high-temperature; microcellu-lar; sag; urethaneTABLE 1 Precision for Heat Sag TestMaterialFlexural ModulusMPa (psi)Values expressed in unit of mm (in.)Aver
26、age SrArBUrethane A 700 (100 000) 7.06 (0.278) 1.55 (0.061) 4.34 (0.171)Urethane B 350 (50 000) 0.43 (0.017) 0.66 (0.026) 1.85 (0.073)Urethane C 175 (25 000) 3.40 (0.134) 3.53 (0.139) 9.88 (0.389)ASr= within-laboratory standard deviation for the indicated material. It is obtained by pooling the with
27、in-laboratory standard deviations of the test results from all of theparticipating laboratories:Sr5 s1!21 s2!2 1 sn!2#/n#.Br = within-laboratory critical interval between two test results = 2.8 3 Sr.D3769 102ASTM International takes no position respecting the validity of any patent rights asserted i
28、n 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 the r
29、esponsible 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 receive car
30、eful 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 Internation
31、al, 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D3769 103
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