1、Designation: D865 11 (Reapproved 2018)Standard Test Method forRubberDeterioration by Heating in Air (Test TubeEnclosure)1This standard is issued under the fixed designation D865; 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers
3、a procedure to determine thedeterioration induced by heating rubber specimens in indi-vidual test tube enclosures with circulating air. This isolationprevents cross contamination of compounds due to loss ofvolatile materials (for example, antioxidants) and their subse-quent migration into other rubb
4、er compounds (specimens). Theabsorption of such volatile materials may influence the degra-dation rate of rubber compounds.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
5、 thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in ac
6、cor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 A
7、STM Standards:2D412 Test Methods for Vulcanized Rubber and Thermoplas-tic ElastomersTensionD573 Test Method for RubberDeterioration in an AirOvenD1349 Practice for RubberStandard Conditions for Test-ingD2240 Test Method for Rubber PropertyDurometer Hard-nessD3182 Practice for RubberMaterials, Equipm
8、ent, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3. Summary of
9、Test Methods3.1 Specimens of vulcanized rubber are exposed to thedeteriorating influence of air at specified elevated temperaturefor known periods of time, after which their physical propertiesare determined. These are compared with the properties deter-mined on the original unexposed specimens and
10、the changesnoted.3.2 Unless otherwise specified, the determination of thephysical properties shall be carried out in accordance with testmethods in Test Methods D412.3.3 Except as may be otherwise specified in this testmethod, the requirements of Practices D3182 and D3183 shallbe complied with and a
11、re made part of this test method.3.4 In case of conflict between the provisions of this testmethod and those of detailed specifications or test methods fora particular material, the latter shall take precedence or ifotherwise agreed upon between customer and supplier orbetween laboratories.4. Signif
12、icance and Use4.1 Rubber and rubber products must resist the deteriorationof physical properties with time caused by oxidative andthermal ageing. This test method determines these character-istics in a way that is free of some of the complications inherentin community-type ageing devices, that is wh
13、ere numerouscompounds (specimens) are aged in the same enclosure.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand Rubber-like Materials and is the direct responsibility of Subcommittee D11.15on Degradation Tests.Current edition approved July 1, 2018. Published August 20
14、18. Originallyapproved in 1946. Last previous edition approved in 2011 as D865 11. DOI:10.1520/D0865-11R18.2For 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 stand
15、ards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Deci
16、sion on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2 The isolation of compounds (specimens) by the use ofindividual circulating air test tube enclosures prevents crossconta
17、mination from volatile products and permits a morerepresentative assessment of ageing performance.4.3 Please refer to the Annex in Test Method D573 forimportant information on standard compounds used for preci-sion testing for accelerated test ageing evaluation.5. Apparatus5.1 The apparatus for heat
18、 ageing shall consist of borosili-cate glass test tubes 38 mm (1.52 in.) in diameter and 300 mm(12 in.) in length heated uniformly in suitable equipment suchas an oil or water bath or metal block (see Fig. 1) so arrangedas to comply with the following requirements:5.1.1 No more than three specimens
19、shall be exposed ineach test tube, and all specimens in a single tube shall be froma single compound.5.1.2 Provisions shall be made for vertical suspension of thespecimens as near the bottom of the test tube as possiblewithout touching each other or the sides of the test tube duringthe test.Asuggest
20、ed means for holding the specimens is shownin Fig. 2.5.1.3 The test tubes shall be provided with a tight-fittingcork or nonreactive composition stopper through which an inletand an outlet tube shall be placed as shown in Fig. 2.5.1.4 The heating equipment shall be provided with athermostatic control
21、 that will maintain the temperature at thelocation of the specimens in the test tube within 61C(61.8F) of the prescribed temperature. If a liquid medium isused, suitable stirring or circulation shall be provided to assureuniformity of temperature.5.1.5 The temperature should be automatically recorde
22、dover the entire test period using a temperature-measuringdevice capable of measuring at the specified temperaturewithin 61C (61.8F). Apparatus that is not equipped withautomatic recording capabilities, the temperature shall bemeasured with sufficient frequency to assure compliance withthe temperatu
23、re limits specified in 10.1.5.1.6 Prior to commencing a test, or series of tests, a checkof the actual temperature within the test tube shall be made byplacing a thermometer in the tube with the bulb in the locationordinarily occupied by the specimens. Alternatively, a digitaltemperature measuring d
24、evice may be used in place of aliquid-in-glass thermometer, wherein the probe is placed in aposition ordinarily occupied by the specimens. The thermom-eter or probe shall be inserted through either the tubes orthrough a third hole in the stopper which shall be securelyclosed during the test.5.1.7 Th
25、e lip of the test tube shall be within 50 mm (2 in.)of the heating medium during the test.5.1.8 When an oil bath is used, a means shall be provided toremove oil fumes from the oil bath, typically using a refluxcondenser, so that they will not enter the inlet tube.FIG. 1 A Typical Metal Block Type Ag
26、eing OvenABCDEFGmmin.30012115412150626510123811220341.5116FIG. 2 Arrangement of Vent Tubes and Test SpecimensD865 11 (2018)26. Sampling6.1 The sample size shall be sufficient to allow for thedetermination of the original properties on three unexposedspecimens and also on three or more specimens for
27、eachexposure period of the test. At least 24 h must elapse betweencompletion of the vulcanization of the samples and the start ofthe ageing test.6.2 When minimum requirements are specified, one test onthree dumbbells shall be considered sufficient. If the results arebelow the specified requirements,
28、 two additional specimensshall be prepared from the original sample and tested. Shouldthe results of either of these tests be below the specifiedrequirements, the sample shall be considered to have failed tomeet the specifications.7. Test Specimens7.1 Prepare dumbbell-shaped specimens as described i
29、n thetest methods in Test Methods D412. These shall be consideredstandard. Their form shall be such that no mechanical,chemical, or heat treatment will be required after exposure.Make any adjustments that are necessary, for example, tothickness, prior to exposure.7.2 Measure the cross-sectional dime
30、nsions of test speci-mens for calculating the physical properties prior to exposurein the ageing chamber. Apply gage lines used for measuringelongations after the specimens have been aged. Only speci-mens of similar dimensions having approximately the sameexposed areas may be compared with each othe
31、r.8. Number of Test Specimens8.1 Use at least three unexposed test specimens to determinethe original physical properties of each sample and also threeor more specimens of the same material for each exposureperiod of the test.8.2 When minimum requirements are specified, make onetest for tensile stre
32、ngth, elongation, and durometer hardness. Ifthe results are below the specified requirements, prepare twoadditional specimens from the original sample and test. If theresults of either of these tests are below the specifiedrequirements, the samples shall be considered to have failed tomeet the speci
33、fications.9. Tests of Unexposed Specimens9.1 Determine the stress-strain properties or tensile strength,ultimate elongation, durometer hardness (Test Method D2240),and any other desired properties of the original unexposedspecimens within 96 h of the start of the ageing period.Disregard the results
34、of specimens that are found to beunsatisfactory or statistical outliers and retest.9.2 When rubber compounds are to be tested for the purposeof determining compliance with a specification, it shall bepermissible to determine the original properties required in 9.1simultaneously with the determinatio
35、n of the values after thefirst ageing period even though the elapsed time exceeds 96 h.10. Procedure10.1 Bring the heating medium to the temperature selectedfor the ageing test. When the temperature-measuring deviceindicates that this temperature is being maintained, immersethe test tube assembly co
36、ntaining the specimens in the fluidbath or metal block, as specified in 5.1.6 and 5.1.7, and allowto heat for the desired period.10.1.1 The selected temperature may be in the range from70 to 250C (158 to 482F), and it is suggested that one of thestandard temperatures shown in Practice D1349 be used.
37、10.2 Start the ageing period at the time the specimens areplaced in the heating medium. The selection of suitable periodsof ageing will depend on the rate of deterioration of theparticular material being tested.10.2.1 Periods frequently used are 10, 22, 48, 70, and 168 h.Use ageing periods such that
38、 the deterioration will not be sogreat as to prevent determination of the final physical proper-ties. In experimental work it is desirable to use a range ofageing periods, while for routine tests of known materialsfewer intervals may be employed.10.3 At the termination of the ageing interval, remove
39、 thespecimens from the test tubes, cool to the standard laboratorytemperature on a flat, thermally non-conductive surface, andallow to equilibrate not less than 16 nor more than 96 h beforedetermination of the physical properties. Apply gage lines usedfor measuring elongations to the specimens.10.4
40、Clean the test tube and the circulation tubes carefullyfollowing each test or prior to each new test to remove anydeposits of volatile material that may have condensed on thesides of the test tube or in the circulation tubes.11. Physical Tests of Aged Specimens11.1 Determine the stress-strain proper
41、ties or tensilestrength and ultimate elongation and other desired propertiessuch as durometer hardness of the specimens aged for differentperiods as the intervals terminate in the progress of ageing,disregarding the fact that more specimens may still be ageing.In determining the physical properties
42、after ageing, the finalvalues shall be the median of results from three specimensexcept that under the following conditions two additionalspecimens shall be exposed and tested and the median of thevalues for the five specimens shall be used:11.1.1 If one or more values do not meet the specifiedrequi
43、rements when testing for compliance with specifications.11.1.2 If referee tests are being made. After completion ofthe tests, the broken specimens shall be examined visually andmanually and their condition noted.12. Calculations12.1 Express the results of the ageing test (for each ageingperiod) as a
44、 percent change in each physical property (tensilestrength, ultimate elongation, tensile stress, durometerhardness, or others), calculated as follows:P 5A 2 OO3100 (1)where:P = change in property, %,O = original value, andA = value after ageing.D865 11 (2018)313. Report13.1 The report shall include
45、the results calculated inaccordance with 12.1 as follows:13.1.1 All observed and recorded data on which the calcu-lations are based,13.1.2 Type of ageing test,13.1.3 Ageing interval,13.1.4 Ageing temperature,13.1.5 Duration, temperature, and date of vulcanization ofthe rubber, if known,13.1.6 Dates
46、of original and final determinations of physicalproperties,13.1.7 Dimensions of test specimens, and13.1.8 Methods of determining hardness.14. Precision and Bias314.1 This precision and bias section has been prepared inaccordance with Practice D4483. Refer to this practice forterminology and other st
47、atistical calculation details.14.2 A Type 2 (interlaboratory) precision was evaluated in1974. Both repeatability and reproducibility are short term; aperiod of a few days separates replicate test results.Atest resultis expressed on the basis of a median value, as specified by TestMethods D412 obtain
48、ed on 3 determinations or measurementsof the property or parameter in question.14.3 Six different materials were used in the interlaboratoryprogram, these were tested in 3 laboratories on 2 different days.These precision results were obtained for a variety of com-pounds prepared in accordance with M
49、ethod D15 prior to itsremoval from the Annual Book of ASTM Standards. Please seeannex of Test Method D573 for more details on this work.14.4 The results of the precision calculations for repeatabil-ity and reproducibility for both percent tensile strength changeand percent elongation change are given in Table 1,inascending order of material average or level, for each of thematerials evaluated.14.4.1 The precision of this test method may be expressed inthe format of the following statements that use an appropriatevalue of r, R, (r),or(R), that is, that value to be
