1、Designation: D 572 04Standard Test Method forRubberDeterioration by Heat and Oxygen1This standard is issued under the fixed designation D 572; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses 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 procedure to determine therelative det
3、erioration resistance of vulcanized rubber in a hightemperature and high pressure oxygen environment. There maybe no exact correlation between this accelerated test andnatural aging of rubber because of the varied conditions ofnatural aging. This accelerated test is suitable for laboratorycompound o
4、r product comparisons.NOTE 1For evaluating rubber vulcanizates under less severe condi-tions more nearly approaching natural aging, the use of Test MethodsD 573 and D 865 is recommended.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for infor
5、mationonly.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 regulatory limitations prior to use. (Fo
6、r specificprecautionary statement, see Note 2.)2. Referenced Documents2.1 ASTM Standards:2D 15 Methods of Compound and Sample Preparation forPhysical Testing of Rubber Products3D 412 Test Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD 454 Test Method for Rubber Deterioration by
7、Heat andAir PressureD 573 Test Method for RubberDeterioration in an AirOvenD 865 Test Method for RubberDeterioration by Heatingin Air (Test Tube Enclosure)D 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 3183 Pract
8、ice 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 Method3.1 Specimens of vulcanized rubber are exposed to a dete-riorating influence at a specifi
9、ed elevated temperature andoxygen pressure for known periods of time, after which theirphysical properties are determined. These are compared withthe properties determined on the original specimens and thechanges noted.3.2 Unless otherwise specified, the determination of thephysical properties shall
10、 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 testmethod and those of
11、 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. This test method provides a way to assess thes
12、eperformance characteristics of rubber, under certain acceler-ated conditions as specified.4.2 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. Oxygen-Pressure VesselNOTE 2Caution: Adequ
13、ate safety provisions are important whenheating oxidizable organic materials in oxygen since the rate of reactionmay become very rapid in some cases, particularly if large surface area isexposed, and very high pressures may be developed. If the sameequipment is used for the oxygen-pressure test and
14、the air-pressure heat1This 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 July 1, 2004. Published July 2004. Originally approvedin 1940. Last previous edition approved in 1999
15、as D 572 99.2For 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 website.3Withdrawn.1Copyright ASTM International, 100 Bar
16、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.test, Test Method D 454, care must be exercised to see that the thermo-static controls are properly set, since the specimens may react very rapidlywith oxygen at the temperature of the air-pressure heat test. Liquidsaccepta
17、ble as heating media for one test may be hazardous when used forthe other test.5.1 The oxygen-pressure chamber shall consist of a metalvessel designed to retain an internal atmosphere of oxygen gasunder pressure, with provisions for placing rubber specimenswithin it and subjecting the whole to contr
18、olled uniformtemperature. Because of the superior temperature control andheat transfer, metal vessels completely immersed in a liquidmedium are recommended for purposes of referee tests. Theapparatus shall conform to the following requirements:5.1.1 The size of the chamber shall be optional but shal
19、l besuch that the specimens may be suspended therein verticallywithout undue crowding and without touching each other or thesides of the chamber.5.1.2 The source of heat is optional but shall be locatedoutside of the aging chamber proper.5.1.3 The heating medium is optional. Water, air, or otherflui
20、ds known to be safe in the presence of oxygen may be used.Water has an advantage because of its rapid heat transfer andnoncombustible nature. If air is used, the heated air shall bethoroughly circulated by means of mechanical agitation, andbaffles shall be used as required to prevent local overheati
21、ngand dead spots. Oils or other combustible fluids are extremelyhazardous in the presence of oxygen and should not be used asheating media for this test.5.1.4 Automatic temperature control of the heating mediumby means of thermostatic regulation shall be used. The regu-lation system shall be provide
22、d with power failure protectionand over-shoot protection to prevent accidental runaway tem-perature increase.5.1.5 The temperature should be automatically recordedover the entire test period using a temperature-measuringdevice capable of measuring at the specific temperature towithin 61C. For appara
23、tus not equipped with automaticrecording capabilities, temperature shall be measured withsufficient frequency to ascertain that the temperature limitsspecified in 10.2 are adhered to. If the pressure chamber iscompletely immersed, the temperature may be taken as that ofthe heating medium. The sensit
24、ive element of the temperature-measuring device shall be close to the pressure chamber but nottouching it. If the pressure chamber is not completely im-mersed in the heating medium, the sensing element may beplaced in a thermometer well extending into the pressurechamber. The thermometer well should
25、 be filled with water, oroil, to a depth sufficient to cover the element, in order tofacilitate heat transfer. If it is confirmed by actual check thatthe temperature of the oxygen within the chamber is the sameas that of the heating medium, the temperature may be taken inthe heating medium instead o
26、f in the thermometer well. If airis used as the heating medium, a check of the oven temperatureshall be made by means of temperature-indicating devicesplaced in various parts of the oven to verify the uniformity ofheating. In any case, it is desirable to verify the recordedtemperature by checking wi
27、th a temperature-indicating devicehaving its sensitive element directly exposed to the oxygenwithin the pressure chamber.5.1.6 Positive, rapid, and complete circulation of the heatingmedium shall be maintained so as to assure accurate, uniformheating.5.1.7 The pressure chamber shall be equipped with
28、 a reli-able safety valve or rupture diaphragm set for release at 3450kPa (500 psi) of pressure.5.1.8 No copper or brass parts shall be exposed to theatmosphere, nor used in the pressure chamber and tubing orvalves leading to it.6. Sampling6.1 The sample size shall be sufficient to allow for thedete
29、rmination 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 specified, one test onthre
30、e 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 be considered to have fai
31、led tomeet the specifications.7. Test Specimens7.1 Dumbbell-shaped specimens prepared as described inTest Methods D 412 shall be considered standard. Their formshall be such that no mechanical, chemical, or heat treatmentwill be required after exposure in the pressure chamber. If anyadjustments (for
32、 example, to thickness) are necessary, theyshould be performed prior to exposure.7.2 The cross-sectional dimensions of test specimens forcalculating the physical properties shall be measured prior toexposure in the aging chamber. Gage lines used for measuringelongations shall be applied after the sp
33、ecimens have beenaged. Only specimens of similar dimensions having approxi-mately the same exposed areas may be compared with eachother.8. Number of Test Specimens8.1 At least three test specimens shall be used to determinethe original physical properties of each sample and also threeor more specime
34、ns of the same material for each exposureperiod of the test.8.2 When minimum requirements are specified, one testshall be made for tensile strength and elongation. If the resultsare below the specified requirements, two additional specimensshall be prepared from the original sample and tested. Shoul
35、dthe results of either of these tests be below the specifiedrequirements, the samples shall be considered to have failed tomeet the specifications.9. Tests of Unaged Specimens9.1 Determine the stress-strain properties or tensile strengthand ultimate elongation and any other required properties ofthe
36、 original unaged specimens within 96 h of the start of theaging period. Discard results on specimens that are found to beimperfect and retest.D5720429.2 When rubber compounds are to be tested for the purposeof determining compliance with specifications, it shall bepermissible to determine the origin
37、al properties required in 9.1simultaneously with the determination of the values after thefirst aging period even though the elapsed time exceeds 96 h.10. Procedure for Accelerated Aging10.1 Place the specimens for aging in the aging chamberafter it has been preheated to the operating temperature. I
38、t isrecommended that not more than 10 % of the volume of thepressure chamber be occupied by rubber or oxidizable sub-stance. Avoid simultaneous aging of a mixed group of differentcompounds if possible. For instance, high-sulfur should not beaged with lower-sulfur compounds, and those containingantio
39、xidants should not be aged with those having no antioxi-dants. Some migration is known to occur. When starting a test,flush the air out of the oxygen-pressure chamber by releasingthe oxygen pressure and refilling, and check the chamber tomake certain the apparatus does not leak.10.2 The operating te
40、mperature shall be 70 6 1C (158 61.8F) determined in accordance with 5.1.5.10.3 The pressure of oxygen supplied to the aging chambershall be 2100 6 100 kPa (300 6 15 psi) as measured by acalibrated pressure gage.10.4 Start the aging interval at the time the specimens areplaced in the heated chamber
41、and continue for a measured timeinterval. The selection of suitable intervals of aging willdepend on the rate of deterioration of the particular materialsbeing tested. Time intervals frequently used are 24, 48, 72, and96 h.10.5 The aging intervals used shall be such that the dete-rioration will not
42、be so great as to prevent determination of thefinal physical properties. In experimental work, it is desirableto use a range of periods, while for routine tests of knownmaterials, fewer intervals may be employed.10.6 At the termination of the aging interval, remove thespecimens from the aging chambe
43、r, cool to room temperatureon a flat surface, and allow to rest not less than 16 h nor morethan 96 h before determination of the physical properties. Inrelieving the pressure from the oxygen-pressure chamberpreparatory to removing the aged specimens, it is essential thatthe release be slow and unifo
44、rm, requiring at least 5 min so asto avoid possible formation of porosity in the specimen. Thenapply to the specimens gage lines used for measuring elonga-tions:NOTE 3Caution: For the evaluation of rubber compounds intendedfor service at elevated temperatures, the above test methods may be usedwith
45、an operating temperature of 80 6 1C (176 6 1.8F), employingtime intervals as suggested in 10.4, or as otherwise agreed upon. It shouldbe noted that by increasing the aging temperature to 80C (176F) from70C (158F) the rate of oxidation may be expected to be approximatelydouble, and if the rubber comp
46、ound property change may be expected tobe approximately double, and if the rubber compound is of a rapid agingtype, or if it is contaminated with such materials as copper or manganese,the rate of oxidation may be catalyzed to such extent as to become violent.11. Test of Aged Specimens11.1 Determine
47、the tensile strength and ultimate elongationor the stress-strain properties of the specimens, aged fordifferent intervals, as the intervals terminate, disregarding thefact that more specimens may still be aging. In determining thephysical properties after aging, consider as the final values themedia
48、n of results from three specimens except that under thefollowing conditions expose and test two additional specimensand use the median of the values for the five specimens:11.1.1 If one or more values do not meet the specifiedrequirements when testing for compliance with specifications,or11.1.2 If r
49、eferee tests are being made. After completion ofthe tests, examine the broken specimens visually and manuallyand note their condition.12. Calculations12.1 Express the results of the aging test as a percent of thechange in each physical property (tensile strength, ultimateelongation, or tensile stress), calculated as follows:P 5 A 2 O!/O 3 100 (1)where:P = percentage change in property,O = original value, andA = value after aging.12.2 Increases will be indicated as positive and decreases asnegative.13. Report13.1 The report shall include the following results calcu
