1、Designation: D 865 99 (Reapproved 2005)Standard Test Method forRubberDeterioration by Heating in Air (Test TubeEnclosure)1This standard is issued under the fixed designation D 865; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. 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 a
3、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 rubber
4、 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 t
5、hesafety 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 412 Test Methods for Vul
6、canized Rubber and Thermo-plastic Rubbers and Thermoplastic ElastomersTensionD 573 Test Method for RubberDeterioration in an AirOvenD 1349 Practice for RubberStandard Temperatures forTestingD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Sta
7、ndard Vulcanized SheetsD 3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD 4483 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 the
8、deteriorating 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 specimens and the changes noted.3.2 Unless otherwise specified, the determination of thep
9、hysical properties shall be carried out in accordance with TestMethods D 412.3.3 Except as may be otherwise specified in this testmethod, the requirements of Practices D 3182 and D 3183 shallbe complied with and are made part of this test method.3.4 In case of conflict between the provisions of this
10、 testmethod and those of detailed specifications or test methods fora particular material, the latter shall take precedence.4. Significance and Use4.1 Rubber and rubber products must resist the deteriorationof physical properties with time caused by oxidative andthermal aging. With this test method,
11、 these characteristics maybe determined in a way that is free of some of the complica-tions inherent in community-type aging devices, that is wherenumerous compounds (specimens) are aged in the sameenclosure.4.2 The isolation of compound (specimens) by the use ofindividual circulating air test tube
12、enclosures prevents anycross contamination from volatile products and permits a morerepresentative assessment of aging performance.4.3 Please refer to the Annex in Test Method D 573 forimportant information on standard compounds used for preci-sion testing for accelerated test aging evaluation.5. Ap
13、paratus5.1 The apparatus for the heat aging shall consist of boro-silicate glass test tubes 38 mm (1.52 in.) in diameter and 300mm (12 in.) in length heated uniformly in suitable equipment1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of S
14、ubcommittee D11.15 on Degradation Tests.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 1946. Last previous edition approved in 1999 as D 865 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. F
15、or Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.such as an oil or water bath or metal block so arranged as tocomply w
16、ith the following requirements:5.1.1 No more than three specimens shall be used in eachtest tube, and all specimens in a single tube shall be from asingle compound.5.1.2 Provision shall be made for vertical suspension of thespecimens as near the bottom of the test tube as possiblewithout touching ea
17、ch other or the sides of the test tube duringthe test.Asuggested means for holding the specimens is shownin Fig. 1.5.1.3 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. 1.5.1.4 The
18、heating equipment shall be provided with athermostatic control that will maintain the temperature at thelocation of the specimens in the test tube within 1C (1.8F) ofthe prescribed temperature. If a liquid medium is used, suitablestirring or circulation shall be provided to assure uniformity oftempe
19、rature.5.1.5 The temperature should be automatically recordedover the entire test period using a temperature-measuringdevice capable of measuring at the specified temperaturewithin 61C. For apparatus not equipped with automaticrecording capabilities, temperature shall be measured withsufficient freq
20、uency to ascertain that the temperature limitsspecified in 10.1 are adhered to. A check of the actualtemperature within the test tube should be made by placing athermometer in the tube with the bulb in the location ordinarilyoccupied by the specimens and the stem extending through athird hole drille
21、d in the cork stopper.5.1.6 The lip of the test tube shall be within 50 mm (2 in.)of the heating medium during the test.5.1.7 When an oil bath is used, means shall be provided toremove oil fumes from the oil bath so that they will not enterthe inlet tube.6. Sampling6.1 The sample size shall be suffi
22、cient to allow for thedetermination of the original properties on three specimens andalso on three or more specimens for each exposure period ofthe test. At least 24 h must elapse between completion of thevulcanization of the samples and the start of the aging test.6.2 When minimum requirements are
23、specified, one test onthree dumbbells shall be considered sufficient. But if the resultsare below the specified requirements, 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
24、 be considered to have failed tomeet the specifications.7. Test Specimens7.1 Prepare dumbbell-shaped specimens as described in theTest Methods D 412. These shall be considered standard. Theirform shall be such that no mechanical, chemical, or heattreatment will be required after exposure in the pres
25、surechamber. Make any adjustments that are necessary, for ex-ample, to thickness, prior to exposure.7.2 Measure the cross-sectional dimensions of test speci-mens for calculating the physical properties prior to exposurein the aging chamber. Apply gage lines used for measuringelongations after the sp
26、ecimens 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 test specimens to determine theoriginal physical properties of each sample and also three ormore specimens of the
27、 same material for each exposure periodof the test.8.2 When minimum requirements are specified, make onetest for tensile strength and elongation. If the results are belowthe specified requirements, prepare two additional specimensfrom the original sample and test. If the results of either ofthese te
28、sts are below the specified requirements, the samplesshall be considered to have failed to meet the specifications.9. Tests of Unaged Specimens9.1 Determine the stress-strain properties or tensile strengthand ultimate elongation and any other required properties ofthe original unaged specimens withi
29、n 96 h of the start of theaging period. Discard results on specimens that are found to beimperfect 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 9.1ABCDEFGmm
30、in.30012115412150626510123811220341.5116FIG. 1 Arrangement of Vent Tubes and Test SpecimensD 865 99 (2005)2simultaneously with the determination of the values after thefirst aging period even though the elapsed time exceeds 96 h.10. Procedure10.1 Bring the heating medium to the temperature selectedf
31、or the aging test. When the temperature-measuring deviceindicates that this temperature is being maintained, immersethe test tube assembly containing the specimens in the oil orwater bath or metal block, as specified in 5.1.6, and allow toheat for the desired period. The selected temperature may be
32、inthe range from 70 to 250C (158 to 482F), and it is suggestedthat one of the standard temperatures shown in Practice D 1349be used. Start the aging period at the time the specimens areplaced in the heating medium. The selection of suitable periodsof aging will depend on the rate of deterioration of
33、 theparticular material being tested. Periods frequently used are 10,20, 40, 70, and 168 h. Use aging periods such that thedeterioration will not be so great as to prevent determination ofthe final physical properties. In experimental work it isdesirable to use a range of aging periods, while for ro
34、utine testsof known materials fewer intervals may be employed.10.2 At the termination of the aging interval, remove thespecimens from the test tubes, cool to room temperature on aflat surface, and allow to rest not less than 16 nor more than 96h before determination of the physical properties. Apply
35、 gagelines used for measuring elongations to the specimens.10.3 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. Physica
36、l Tests of Aged Specimens11.1 Determine the stress-strain properties or tensilestrength and ultimate elongation and durometer hardness of thespecimens aged for different periods as the intervals terminatein the progress of aging, disregarding the fact that morespecimens may still be aging. In determ
37、ining the physicalproperties after aging, the final values shall be the median ofresults from three specimens except that under the followingconditions two additional specimens shall be exposed andtested and the median of the values for the five specimens shallbe used:11.1.1 If one or more values do
38、 not meet the specifiedrequirements 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 aging test (
39、for each agingperiod) as a percent change in each physical property (tensilestrength, ultimate elongation, tensile stress), calculated asfollows:P 5A 2 OO3 100 (1)where:P = change in property, %,O = original value, andA = value after aging.13. Report13.1 The report shall include the results calculat
40、ed 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 aging test,13.1.3 Aging interval,13.1.4 Aging temperature,13.1.5 Duration, temperature, and date of vulcanization ofthe rubber, if known,13.1.6 Dates of original and final d
41、eterminations 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 D 4483. Refer to this practice forterminology and other statistical calculation
42、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 D 412 obtained on 3 determination
43、s 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 Method D 15 prior to i
44、tsremoval from the Annual Book of ASTM Standards. Please seeannex of Test Method D 573 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,inasce
45、nding 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 used indecisions about test results (obtained wit
46、h the test method).The appropriate value is that value of r or R associated with amean 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
47、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.3Supporting data
48、 have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D11-1057.D 865 99 (2005)314.6 ReproducibilityThe reproducibility R, of this testmethod has been established as the appropriate value tabulatedin the precision tables. Two single test results obta
49、ined in twodifferent laboratories, under normal test method procedures,that differ by more than the tabulated R (for any given level)must be considered to have come from different or non-identical sample populations.14.7 The precision results indicate that the repeatability andreproducibility of both percent tensile strength change andpercent elongation change are essentially the same. Also thevalue of r or R, or both does not vary with the magnitude ofpercent elongation or percent tensile strength change. Novalues are given for (r)or(R) because of the near zero a
