1、Designation: D865 11Standard 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 year of last revis
2、ion. 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 Department of Defense.1. Scope1.1 This test method covers a procedure to determin
3、e 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 rubber compounds (specimens
4、). 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 thesafety concerns, if
5、 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:2D412 Test Methods for Vulcanized Rubber and The
6、rmo-plastic ElastomersTensionD573 Test Method for RubberDeterioration in an AirOvenD1349 Practice for RubberStandard Temperatures forTestingD2240 Test Method for Rubber PropertyDurometerHardnessD3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing
7、Standard 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 Test Methods3.1 Specimens of vulcanized rubber are exposed to th
8、edeteriorating 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 the changesnoted.3.2 Unless otherwise specified, the determinati
9、on 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 are made part of this test method.3.4 In case of conflict between
10、 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. Significance and Use4.1 Rubber and rubber products must resist the det
11、eriorationof 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 where numerouscompounds (specimens) are aged in the same enclosure
12、.4.2 The isolation of compounds (specimens) by the use ofindividual circulating air test tube enclosures prevents crosscontamination 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
13、standard compounds used for preci-sion testing for accelerated test ageing evaluation.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.15 on Degradation Tests.Current edition approved Aug. 15, 2011. Published September 20
14、11. Originallyapproved in 1946. Last previous edition approved in 2005 as D865 99 (2005).DOI: 10.1520/D0865-11.2For 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 s
15、tandards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Apparatus5.1 The apparatus for heat ageing shall consist of borosili-cate glass test tubes 38 mm (1.52 in.) in diameter and 300 mm(1
16、2 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 shall be exposed ineach test tube, and all specimens in a single tube shall be froma single compo
17、und.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.Asuggested means for holding the specimens is shownin Fig. 2.5.1.3 The test tubes shall be provided with
18、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 that will maintain the temperature at thelocation of the specimens in the test tube within 61C(6
19、1.8F) 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 recordedover the entire test period using a temperature-measuringdevice capable of measuring at the spec
20、ified temperaturewithin 61C (61.8F). Apparatus that is not equipped withautomatic recording capabilities, the temperature shall bemeasured with sufficient frequency to assure compliance withthe temperature limits specified in 10.1.5.1.6 Prior to commencing a test, or series of tests, a checkof the a
21、ctual 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 device may be used in place of aliquid-in-glass thermometer, wherein the probe is placed in aposit
22、ion 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 The lip of the test tube shall be within 50 mm (2 in.)of the heating medium during the test.5.1.8 W
23、hen 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.6. Sampling6.1 The sample size shall be sufficient to allow for thedetermination of the original properties on three unexposedspecime
24、ns and also on three or more specimens for eachexposure period of the test. At least 24 h must elapse betweencompletion of the vulcanization of the samples and the start ofthe ageing test.FIG. 1 A Typical Metal Block Type Ageing OvenABCDEFGmmin.30012115412150626510123811220341.5116FIG. 2 Arrangement
25、 of Vent Tubes and Test SpecimensD865 1126.2 When minimum requirements are specified, one test onthree dumbbells shall be considered sufficient. If the results arebelow the specified requirements, two additional specimensshall be prepared from the original sample and tested. Shouldthe results of eit
26、her 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 in thetest methods in Test Methods D412. These shall be consideredstandard. Their form shall be such that
27、 no mechanical, chemi-cal, or heat treatment will be required after exposure. Make anyadjustments that are necessary, for example, to thickness, priorto exposure.7.2 Measure the cross-sectional dimensions of test speci-mens for calculating the physical properties prior to exposurein the ageing chamb
28、er. 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 other.8. Number of Test Specimens8.1 Use at least three unexposed test specimens to determinethe original
29、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 strength, elongation, and durometer hardness. Ifthe results are below the specified requirements, prepare
30、twoadditional specimens from the original sample and test. If theresults of either of these tests are below the specified require-ments, the samples shall be considered to have failed to meetthe specifications.9. Tests of Unexposed Specimens9.1 Determine the stress-strain properties or tensile stren
31、gth,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 of specimens that are found to beunsatisfactory or statistical outliers and retest.9.2 When rubber c
32、ompounds 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 determination of the values after thefirst ageing period even though the elapsed time exceeds 96 h.10. Procedure
33、10.1 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 containing the specimens in the fluidbath or metal block, as specified in 5.1.6 and 5.1.7, and allowto
34、 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.10.2 Start the ageing period at the time the specimens areplaced in the heating medium. The selectio
35、n 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 the deterioration will not be sogreat as to prevent determination of the final physical proper-ties
36、. 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 thespecimens from the test tubes, cool to the standard laboratorytemperature on a flat, thermally n
37、on-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 Clean the test tube and the circulation tubes carefullyfollowing each test or prior to each new test
38、 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 properties or tensilestrength and ultimate elongation and other desired propertiessuch as durometer hardne
39、ss 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 after ageing, the finalvalues shall be the median of results from three specimensexcept that under t
40、he 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 specifiedrequirements when testing for compliance with specifications.11.1.2 If referee tests are being made. Afte
41、r 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 percent change in each physical property (tensilestrength, ultimate elongation, tensile stress, dur
42、ometer hard-ness, or others), calculated as follows:P 5A 2 OO3 100 (1)where:P = change in property, %,O = original value, andA = value after ageing.13. Report13.1 The report shall include the results calculated inaccordance with 12.1 as follows:13.1.1 All observed and recorded data on which the calc
43、u-lations are based,13.1.2 Type of ageing test,13.1.3 Ageing interval,13.1.4 Ageing temperature,D865 11313.1.5 Duration, temperature, and date of vulcanization ofthe rubber, if known,13.1.6 Dates of original and final determinations of physicalproperties,13.1.7 Dimensions of test specimens, and13.1.
44、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 statistical calculation details.14.2 A Type 2 (interlaboratory) precision was evaluated in1974. Both repea
45、tability 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 obtained on 3 determinations or measurementsof the property or parameter in question.14.3 Six different materi
46、als 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 Method D15 prior to itsremoval from the Annual Book of ASTM Standards. Please seeannex of Test Method D57
47、3 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 T
48、he 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 used indecisions about test results (obtained with the test method).The appropriate value is that value of r or R associated with amea
49、n level in the precision tables closest to the mean levelunder consideration at any given time, for any given material inroutine testing operations.14.5 RepeatabilityThe repeatability r, of this test methodhas been established as the appropriate value tabulated in theprecision tables. Two single test results, obtained under normaltest method procedures, that differ by more than this tabulatedr (for any given level) must be considered as derived fromdifferent or non-identical sample populations.14.6 ReproducibilityThe reproducibility R, of this testmethod has be
