1、Designation: D572 04 (Reapproved 2010)Standard Test Method forRubberDeterioration by Heat and Oxygen1This standard is issued under the fixed designation D572; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 determine
3、therelative deterioration 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 labor
4、atorycompound or product comparisons.NOTE 1For evaluating rubber vulcanizates under less severe condi-tions more nearly approaching natural aging, the use of Test MethodsD573 and D865 is recommended.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses
5、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 applica-bility of regulatory limitations prio
6、r to use. (For specificprecautionary statement, see Note 2.)2. Referenced Documents2.1 ASTM Standards:2D15 Methods of Compound and Sample Preparation forPhysical Testing of Rubber Products3D412 Test Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD454 Test Method for Rubber Deterio
7、ration by Heat andAir PressureD573 Test Method for RubberDeterioration in an AirOvenD865 Test Method for RubberDeterioration by Heating inAir (Test Tube Enclosure)D3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD3183
8、 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 Method3.1 Specimens of vulcanized rubber are exposed to a dete-riorating influence at a sp
9、ecified 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
10、shall be carried out in accordance with TestMethods 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 the provisions of this testmethod and those
11、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. This test method provides a way to assess th
12、eseperformance characteristics of rubber, under certain acceler-ated conditions as specified.4.2 Please refer to the Annex in Test Method D573 forimportant information on standard compounds used for preci-sion testing for accelerated test aging evaluation.5. Oxygen-Pressure VesselNOTE 2Caution: Adeq
13、uate 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 same1This test method is under the jurisdiction of AST
14、M Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.15 on Degradation Tests.Current edition approved May 1, 2010. Published November 2010. Originallyapproved in 1940. Last previous edition approved in 2009 as D572 04 (2009).DOI: 10.1520/D0572-04R10.2For referenced ASTM stan
15、dards, 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. The last approved version of this historical standard is referencedon www.
16、astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.equipment is used for the oxygen-pressure test and the air-pressure heattest, Test Method D454, care must be exercised to see that the thermostaticcontrols are properly set, si
17、nce the specimens may react very rapidly withoxygen at the temperature of the air-pressure heat test. Liquids acceptableas heating media for one test may be hazardous when used for the othertest.5.1 The oxygen-pressure chamber shall consist of a metalvessel designed to retain an internal atmosphere
18、of oxygen gasunder pressure, with provisions for placing rubber specimenswithin it and subjecting the whole to controlled uniformtemperature. Because of the superior temperature control andheat transfer, metal vessels completely immersed in a liquidmedium are recommended for purposes of referee test
19、s. Theapparatus shall conform to the following requirements:5.1.1 The size of the chamber shall be optional but shall 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 bu
20、t shall be locatedoutside of the aging chamber proper.5.1.3 The heating medium is optional. Water, air, or otherfluids 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 betho
21、roughly circulated by means of mechanical agitation, andbaffles shall be used as required to prevent local overheatingand 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 con
22、trol of the heating mediumby means of thermostatic regulation shall be used. The regu-lation system shall be provided 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
23、period using a temperature-measuringdevice capable of measuring at the specific temperature towithin 61C. For apparatus not equipped with automaticrecording capabilities, temperature shall be measured withsufficient frequency to ascertain that the temperature limitsspecified in 10.2 are adhered to.
24、If the pressure chamber iscompletely immersed, the temperature may be taken as that ofthe heating medium. The sensitive 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, th
25、e sensing element may beplaced in a thermometer well extending into the pressurechamber. The thermometer well should 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 with
26、in the chamber is the sameas that of the heating medium, the temperature may be taken inthe heating medium instead of 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 ov
27、en to verify the uniformity ofheating. In any case, it is desirable to verify the recordedtemperature by checking with 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 heatingm
28、edium shall be maintained so as to assure accurate, uniformheating.5.1.7 The pressure chamber shall be equipped with 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 pressu
29、re chamber and tubing orvalves leading to it.6. Sampling6.1 The sample size shall be sufficient 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 thevulca
30、nization of the samples and the start of the aging test.6.2 When minimum requirements are 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. Shoul
31、dthe 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 Dumbbell-shaped specimens prepared as described inTest Methods D412 shall be considered standard. Their formshall be such that no mec
32、hanical, chemical, or heat treatmentwill be required after exposure in the pressure chamber. If anyadjustments (for 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 mea
33、sured prior toexposure in the aging chamber. Gage lines used for measuringelongations shall be applied after the specimens 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 tes
34、t specimens shall be used 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, one testshall be made for tensile strength and elongation. If the resultsare bel
35、ow 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 samples shall be considered to have failed tomeet the specifications.9. Tests of Unaged Specimens9.1 Determ
36、ine the stress-strain properties or tensile strengthand ultimate elongation and any other required properties ofD572 04 (2010)2the original unaged specimens within 96 h of the start of theaging period. Discard results on specimens that are found to beimperfect and retest.9.2 When rubber compounds ar
37、e to be tested for the purposeof determining compliance with specifications, it shall bepermissible to determine the original 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 Accelera
38、ted Aging10.1 Place the specimens for aging in the aging chamberafter it has been preheated to the operating temperature. It 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 differe
39、ntcompounds if possible. For instance, high-sulfur should not beaged with lower-sulfur compounds, and those containingantioxidants 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 releasi
40、ngthe oxygen pressure and refilling, and check the chamber tomake certain the apparatus does not leak.10.2 The operating temperature 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 mea
41、sured by acalibrated pressure gage.10.4 Start the aging interval at the time the specimens areplaced in the heated chamber 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 inte
42、rvals frequently used are 24, 48, 72, and96 h.10.5 The aging intervals used shall be such that the dete-rioration will not 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 knownmaterial
43、s, fewer intervals may be employed.10.6 At the termination of the aging interval, remove thespecimens from the aging chamber, 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 fr
44、om the oxygen-pressure chamberpreparatory to removing the aged specimens, it is essential thatthe release be slow and uniform, 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: F
45、or the evaluation of rubber compounds intendedfor service at elevated temperatures, the above test methods may be usedwith 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 tempe
46、rature to 80C (176F) from70C (158F) the rate of oxidation may be expected to be approximatelydouble, and if the rubber compound 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 man
47、ganese,the rate of oxidation may be catalyzed to such extent as to become violent.11. Test of Aged Specimens11.1 Determine the tensile strength and ultimate elongationor the stress-strain properties of the specimens, aged fordifferent intervals, as the intervals terminate, disregarding thefact that
48、more specimens may still be aging. In determining thephysical properties after aging, consider as the final values themedian 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.
49、1 If one or more values do not meet the specifiedrequirements when testing for compliance with specifications,or11.1.2 If referee 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 Increas
