1、Designation: D 1229 03Standard Test Method forRubber PropertyCompression Set at Low Temperatures1This standard is issued under the fixed designation D 1229; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers evaluation of the ability
3、ofvulcanized rubbers that have been compressed at room tem-perature and then subjected to low temperature (air or carbondioxide atmosphere), to recover from deformation when takenfrom the clamping device while still at the low temperature.1.2 The values stated in SI units are to be regarded as thest
4、andard. 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 appli
5、ca-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 395 Test Methods for Rubber PropertyCompressionSet2D 832 Practice for Rubber Conditioning for Low-Temperature Testing2D 3767 Practice for RubberMeasurement of Dimensions2D 4483 Practice for Determining Preci
6、sion for Test MethodStandards in the Rubber and Carbon Black Industries23. Summary of Test Method3.1 At room temperature, a test specimen is compressed to25 % of its original thickness and exposed for a specified timeat a specified low temperature.3.2 Upon release from compression, the specimen is a
7、l-lowed to recover while remaining at the test temperature.3.3 The residual deformation of the specimen is measured10 s and 30 min after removal from the compressive device.3.4 Compression set of the specimen is calculated accordingto the equations in 9.1.4. Significance and Use4.1 Rubber products,
8、such as hydraulic seals on aircraft,submarine hatch gaskets, and hydraulic brake cups, may beexposed to varying temperature extremes. This test methodprovides a means of determining the extent to which recoveryfrom compression at normal ambient temperatures is inhibitedupon release of the compressiv
9、e force during subsequentexposure at low temperatures.5. Compression Set5.1 For the purpose of this test method, compression set ofvulcanizates shall be the loss in thickness of the specimenexpressed as a percentage of the original deflection. This set,unlike conventional compression set at elevated
10、 temperatures,is temporary since the specimen will regain its originaldimensions when brought back to room temperature or slightlyabove.6. Apparatus6.1 Compression Set Jigs, with suitable steel spacer bars inaccordance with Method B of Test Methods D 395.6.2 Dial Micrometer, as described in Practice
11、 D 3767.6.3 Cold Box, cooled by solid carbon dioxide (Dry Ice),liquid carbon dioxide, liquid nitrogen, or mechanically refrig-erated, preferably by the top-opening type, and capable oftemperature control within 61C (1.8F) of the specifiedtesting temperature as prescribed in Practice D 832. The testc
12、hamber shall be equipped with a vise, “C” clamp, or othersuitable device for holding the compression set jig.7. Test Specimen7.1 The standard test specimen shall be a cylindrical disk29.0 6 0.5 mm (1.14 6 0.02 in.) in diameter and 12.5 6 0.5mm (0.49 6 0.02 in.) in thickness, as specified in Test Met
13、hodsD 395.8. Procedure8.1 Original Thickness MeasurementMeasure the originalthickness, to, at the center of the specimen to the nearest 0.02mm (0.001 in.).1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.14 on Time and Te
14、mperature-Dependent Physical Properties.Current edition approved Feb. 10, 2003. Published March 2003. Originallyapproved in 1952. Last previous edition approved in 1997 as D 1229 87 (1997).2Annual Book of ASTM Standards, Vol 09.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, We
15、st Conshohocken, PA 19428-2959, United States.8.2 Application of LoadPlace a test specimen betweenclean, unlubricated plates of the compression device with thespacers on each side of it. Use only one specimen with eachpair of steel plates, and place in the center between the plates.Tighten the bolts
16、 so as to draw the plates together uniformlyuntil they are in contact with the spacers. The compressionemployed shall be 25 % for all hardnesses.8.3 Within 30 min after the jigs are loaded, place them in thelow-temperature cabinet, and maintain at the service tempera-ture for which the vulcanizates
17、are being evaluated. In theevent the service temperature is unknown, the followingtemperatures are suggested: 40C (40F) and 55C(67F). The conditioning period shall be either 22 or 94 h. Atleast 1 h before the conditioning period is over, place the dialmicrometer in the test chamber and clamp one of
18、the set jigs inthe vise or “C” clamp provided in the low-temperature cham-ber. Use suitable gloves for all operations in the test chamber.At the end of the conditioning period, remove the nuts from thejig, after which release the vise or “C” clamp, and start the stopwatch simultaneously. Measure the
19、 thickness of the specimens10 s and again 30 min after release from the vise or “C” clampand record as t10and t30, respectively. Since the test isconducted at a specific temperature, within 61C (1.8F), theschedule of opening the jigs shall be such that the test chamberwill stay within the permissibl
20、e variations in temperature.NOTE 1It is convenient when conducting many tests to have the dialmicrometer outside the chamber and have an extended insulated stem passthrough the cover or the top to measure the thickness of specimens afterrelease from compression.NOTE 2Slowly crystallizing rubbers may
21、 need to be tested at 10C(14F) or 25C (13F), with a conditioning period of 166 h.NOTE 3In the event that the dail micrometer gage being used isunacceptable for use at a low temperature, it may be placed outside of thetest chamber. The test specimen is to remain in the cold box until it ismeasured. I
22、mmediately upon removal from the chamber the first measure-ment, t10, is to be taken and the specimen immediately returned to the coldbox. At the 30 min time interval the specimen is again removed from thechamber and immediately measured to obtain the value for t30.8.4 Check TestRun tests in duplica
23、te. The results shouldagree within 5.0 %.9. Calculation9.1 Calculate the compression set, expressed as a percentageof the original deflection, as follows:C 5 t02 t10!/t02 ts! 3 100 (1)orC 5 t02 t30!/t02 ts! 3 100 (2)where:C = compression set expressed as a percentage of theoriginal deflection, andts
24、= thickness of the spacer bar used.10. Report10.1 The report shall include the following:10.1.1 The original thickness of the test specimen,10.1.2 The percentage compression of the specimen actu-ally employed,10.1.3 The thickness of the test specimen 10 s, t10, and 30min, t30, after removal from the
25、 clamp, and10.1.4 The compression set expressed as a percentage of theoriginal deflection.11. Precision and Bias311.1 This precision and bias section was prepared in accor-dance with Practice D 4483. Refer to Practice D 4483 forterminology and other statistical calculation details.11.2 Although prep
26、ared in accordance with PracticeD 4483, the data generated for this test method were obtainedprior to the adoption of Practice D 4483 in 1985. No recordsexist for the original test program. The values of within-and-between laboratory standard deviation have been used toconstruct Table 1. A Type 1 pr
27、ecision was evaluated.11.3 Compression set test specimens were prepared in onelaboratory from three different rubber compounds. Ten labora-tories tested two specimens from each of these compounds on4 different days. The precision statements are based on theaverage of two measurements and are express
28、ed in terms of thecompression set, in percent.11.4 The precision of this test method may be expressed inthe format of the following statements which use what is calledan “appropriate value” or r, R, (rr), or (R), that is, that value tobe used in decisions about test results (obtained with the test3S
29、upporting data are available from ASTM Headquarters. Request RR: D-11-1042.TABLE 1 Type 1 Precision, Compression Set, %NOTE 1Sr= Within laboratory standard deviation.r = Repeatability (in measurement units).(r) = Repeatability (in percent).SR= Between laboratory standard deviation.R = Reproducibilit
30、y (in measurement units).(R) = Reproducibility (in percent).Materials Measured AtRange ofValues, %Within Laboratories Between LaboratoriesSrr (r) SRR (R)Three unknown compounds 10 s 75 to 104 0.60 1.70 1.9A2.60 7.4 8.2AThree unknown compounds 30 min 42 to 93 1.60 4.5 6.6A5.60 15.8 23.2AAAn estimated
31、 value of relative repeatability (r) and reproducibility (R) using the mid-point of the range.D 1229 032method). The appropriate value is that value of r or Rassociated with a mean level in Table 1 closest to the meanlevel under consideration at any given time, for any givenmaterial in routine testi
32、ng operations.11.5 RepeatabilityThe repeatability, r, of this test methodhas been established as the appropriate value tabulated in Table1. Two single test results, obtained under normal test methodprocedures, that differ by more than this tabulated r (for anygiven level) must be considered as deriv
33、ed from different ornonidentical sample populations.11.6 ReproducibilityThe reproducibility, R, of this testmethod has been established as the appropriate value tabulatedin Table 1. Two single test results obtained in two differentlaboratories, under normal test method procedures, that differby more
34、 than the tabulated R (for any given level) must beconsidered to have come from different or nonidentical samplepopulations.11.7 Repeatability and reproducibility expressed as a per-centage of the mean level, (r) and (R), have equivalentapplication statements as above for r and R. For the (r) and (R
35、)statements, the difference in the two single test results isexpressed as a percentage of the arithmetic mean of the two testresults.11.8 BiasIn test method terminology, bias is the differ-ence between an average test value and the reference (or true)test property value. Reference values do not exis
36、t for this testmethod since the value (of the test property) is exclusivelydefined by the test method. Bias, therefore, cannot be deter-mined.12. Keywords12.1 compression set; low temperatureASTM International takes no position respecting the validity of any patent rights asserted in connection with
37、 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 responsible techni
38、cal 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 careful consideratio
39、n 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 International, 100 Barr Harb
40、or 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).D 1229 033
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