1、Designation: D 1149 07Standard Test Methods forRubber DeteriorationCracking in an Ozone ControlledEnvironment1This standard is issued under the fixed designation D 1149; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 These test methods are used to estima
3、te the effect ofexposure, under surface tensile strain conditions, either dy-namic or static, in an atmosphere containing specified levels ofozone concentration, expressed as partial pressure (refer toNote 1), on vulcanized rubber, rubber compounds, molded orextruded soft rubber, and other specified
4、 materials, or as maybe determined empirically. The effect of naturally occurringsunlight or light from artificial sources is excluded.1.2 Previously published ASTM documents Test MethodD 518 and Test Methods D 3395 have been included in thesetest methods, D 1149, in 2007. Please refer to Note 2.1.2
5、.1 Test Method D 518 and Test Methods D 3395 havehenceforth been withdrawn and superseded by Test MethodsD 1149. When Test Methods D 1149 is cited, or otherwisereferenced, a notation shall be included to this effect. Pleaserefer to section 3.2 for the appropriate references.1.3 The specified conditi
6、ons of exposure to ozone in thecontrolled environments are accelerated in comparison tooutdoor exposure. These accelerated ozone test methods maynot give results which correlate with outdoor exposure tests orservice performance.1.4 All materials, instruments, or equipment used for thedetermination o
7、f mass, force, dimension, ozone concentration,partial pressure, temperature, velocity, and gas exchange rateshall have direct traceability to the National Institute forStandards and Technology, or other internationally recognizedorganization parallel in nature.1.5 The values stated in SI units are t
8、o be regarded asstandard. The values given in parentheses are for informationonly. Many of the stated SI units are direct conversions fromthe U.S. Customary System to accommodate the instrumenta-tion, practices, and procedures that existed prior to the MetricConversion Act of 1975.1.6 This standard
9、involves hazardous materials, specificallyozone. It may also involve hazardous operations and equip-ment. 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 he
10、alth practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1A discussion and explanation regarding the measurement ofozone concentrations based upon parts of ozone per unit of air versuspartial pressure is provided in Test Methods D 4575, specifically Appen-dices X1
11、and X2. Test Methods D 4575 is also recommended as a sourceof background information regarding standards involving materials ex-posed to ozone.2. Referenced Documents2.1 ASTM Standards:2D 518 Test Method for Rubber DeteriorationSurfaceCrackingD 1171 Test Method for Rubber DeteriorationSurfaceOzone C
12、racking Outdoors or Chamber (Triangular Speci-mens)D 1349 Practice for RubberStandard Temperatures forTestingD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 3395 Test Methods for Rubber DeteriorationDynamicOzone C
13、racking in a ChamberD 4575 Test Methods for Rubber DeteriorationReferenceandAlternative Method(s) for Determining Ozone Level inLaboratory Test ChambersNOTE 2Test Method D 518 and Test Methods D 3395 have beenincorporated into these test methods. They remain technically unchangedand will be supersed
14、ed by Test Methods D 1149. Please refer to TestMethod D 1171 for Test Method D 518 tests which are to be performedoutdoors.3. Summary of Test Methods3.1 There are two methods described:1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and is the direct responsibility of S
15、ubcommittee D11.15 on DegradationTests.Current edition approved Aug. 15, 2007. Published September 2007. Originallyapproved in 1951. Last previous edition approved in 1999 as D 1149 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceast
16、m.org. For 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.3.1.1 Method ADynamic Strain (formerly Test MethodsD 3395):3.
17、1.1.1 Method A, Procedure A1 Dynamic Tensile Elonga-tion (formerly Test Methods D 3395 Method A)rectangulartest specimens are subjected to dynamic maximum amplitudetensile strain of 25 6 3 % at a fixed frequency of 0.5 Hz (30cpm).3.1.1.2 Method A, Procedure A2 Dynamic Belt Flex Test(formerly Test Me
18、thods D 3395 Method B)rectangular testspecimens are affixed to a fabric belt which is continuouslyrotated over two vertically opposed pulleys that induce acyclical surface strain (due to flexing) during the moments ofpassage over the pulleys.3.1.2 Method BStatic Strain (formerly Test MethodD 518):3.
19、1.2.1 Method B, Procedure B1 Static Strain (formerly TestMethod D 518, Method A)rectangular specimens are ex-posed to a continuous elongation of 20 %.3.1.2.2 Method B, Procedure B2 Static Strain Looped Speci-men Test (formerly Test Method D 518, Method B)rectangular specimens are mounted, in a loope
20、d fashion,causing a continuous strain to be applied on the looped portion.3.1.2.3 Method B, Procedure B3 Static Percent ElongationTest (formerly Test Method D 518, Method C)tapered speci-mens are exposed to specified percentages of elongation (10,15, and 20 %) during the course of exposure.3.1.2.4 M
21、ethod B, Procedure B4 Static Strain TriangularSpecimen (formerly Test Method D 1171)triangular speci-mens are mounted around a wooden mandrel causing acontinuous strain to be applied to the looped portion.3.2 The Procedures appear as follows:ProcedureDescription SectionsA1Dynamic Tensile Elongation
22、7-10 (formerly D 3395 Method A)A2Dynamic Belt Flex 11-14 (formerly D 3395 Method B)B1Straight Specimens(Static Elongation)15-17/24 (formerly D 518/D 1149 Method A)B2Bent Loop Specimen 18-20/24 (formerly D 518/D 1149 Method B)B3Tapered Specimens(Static Elongation)21-23/24 (formerly D 518/D 1149 Metho
23、d C)B4Triangular Specimens 24 (formerly D 1171)4. Significance and Use4.1 The significance of these test methods lies in the abilityto differentiate between the degrees of ozone resistance underthe limited and specified conditions of the accelerated tests.The degree of resistance being judged by the
24、 appearance andmagnitude of the formation of cracks in the surface of thesubject material.4.2 In service, rubber materials deteriorate when exposed toozone. It is imperative to have test methods in which simple,accelerated time/exposure, comparisons of the materials abil-ity to resist cracking cause
25、d by ozone exposure can beempirically evaluated. Such tests can be used for producer/consumer acceptance, referee purposes, research, and develop-ment.4.3 These methods are not necessarily suited for use inpurchase specifications as there may be no correlation withservice performance as actual servi
26、ce conditions (outdoorexposure) vary widely due to geographic location and, there-fore, may not yield repeatable or reproducible results.5. Apparatus5.1 The apparatus employed to provide a controlled envi-ronment containing specified concentrations of ozone andpartial pressures, at specified tempera
27、tures, is described in 5.2,being common to all test methods enumerated herein. Theancillary equipment required to perform individual proceduresis described in their respective sections.5.2 Ozone Test Apparatus:5.2.1 Test ChamberGeneral requirements for an accept-able ozone test chamber are adequate
28、control and measurementof ozone concentration levels based upon partial pressure (referto Note 1); volume exchange rate; temperature; internal cham-ber circulation of the gas (airozone mixture, refer to Note 3);and internal chamber volume. An acceptable ozone test cham-ber may be individually manufa
29、ctured for a particular applica-tion, or a commercially manufactured chamber. The ozone testchambers shall conform to the following requirements:NOTE 3Daltons Law and the gas equation is used to express ozonecontent as partial pressure. The partial pressure of ozone in a mixture withair, P(O3), is g
30、iven in millipascals (mPa).5.2.1.1 The internal chamber shall be constructed of amaterial with minimal reaction to ozone, preferably stainlesssteel, contained within an integral external structure whichprovide unencumbered access to the mechanical, electrical,display, and control devices.(1) The int
31、ernal chamber shall be accessible through a doorhaving an adequate closure mechanism and seal to prevent lossof partial pressure or adversely affect the ozone concentrationlevels throughout the duration of a test. It is recommended thatthe door have a means by which to prevent inadvertent openingdur
32、ing the intended duration of a test.(2) The access door may be equipped with an observationwindow. This shall be of tempered glass and shall be sealed toprevent loss of partial pressure or adversely affect the ozoneconcentration level throughout the duration of a test.(3) The internal chamber may be
33、 equipped with a source ofillumination. It shall be situated in a manner so that neither thetemperature of the internal chamber, the ozone concentrationlevel, or partial pressure is adversely affected. Illumination is tobe used in a temporary fashion, intended for intermediateviewing of the specimen
34、s. Long term use, in excess of aconsecutive 5-min period, or more than a total of 15 min,during any given 24-h period, invalidates determinations andtherefore requires monitoring and reporting.(4) The internal chamber may be equipped with shelves, orracks, on which to place specimens. They shall be
35、constructedof a material with minimal reaction to ozone, preferablystainless steel. They shall be of a design that minimizes theeffect on the introduction, circulation, exchange, or exhaust ofthe gas (airozone mixture).5.2.1.2 The internal volume of the chamber shall be no lessthan 0.11 m (4 ft3). T
36、he internal chamber volume may begreater, provided the prescribed levels of ozone concentrationand partial pressure are maintained (refer to 5.2.1.3(1) andNote 1).5.2.1.3 A means for generating, measuring, and controllingozone concentrations levels and partial pressure shall beD1149072provided. The
37、ozone generating source shall be isolated fromthe internal chamber and within the integral external structure.(1) The generation and introduction of ozone shall be by ameans whereby ozone concentration levels in the internal testchamber of between 25 and 200 pphm (parts per hundredmillion) 6 10 % at
38、 100 kPa (atmospheric pressure at mean sealevel, MSL) and the equivalent pressures of between 25 and200 mPa 6 10 % are maintained throughout the duration of thetest (refer to Notes 1 and 2). The preferred method of ozonegeneration being either quartz UV, corona discharge (dielec-tric), or a combinat
39、ion of both.(2) The test chamber ozone concentration levels andpressures shall be either infinitely variable between thoseprescribed or, at minimum, selectable at 25, 50, 100, 200 pphmand mPa, respectively. Broader ranges of ozone concentrationand partial pressure are acceptable, provided the specif
40、iedconcentrations of ozone and partial pressure are maintained asspecified.(3) The means of measurement of the ozone concentrationshall be by any of the methods described in Test MethodsD 4575, with ultraviolet (UV) absorption measurement beingpreferred as it has been shown to be more accurate and p
41、recise.5.2.1.4 The source of air may be ambient, or from acompressed air supply. In either case, adequate filtration ofparticulate matter from the source shall be provided. Themoisture content of the air source shall be minimized, eitherthrough filtration, a desiccant, or by other means.5.2.1.5 The
42、flow of the gases (air and ozone) shall beintroduced into the chamber in a manner that prevents strati-fication or stagnation.5.2.1.6 The gas (airozone mixture) exchange rate shall beof a magnitude such that no appreciable reduction in ozoneconcentration or partial pressure results from the introduc
43、tionof test specimens.(1) The exchange rate will vary with the gas (airozonemixture) level, temperature, number of test specimens intro-duced, and their reaction with ozone.(2) A gas (airozone mixture) exchange rate of 75 % of thetotal volume of the internal chamber per minute has been foundto be an
44、 acceptable and adequate rate, and shall be consideredto be the minimum acceptable rate of gas exchange.(3) As indicated, this exchange rate will vary, dependentupon the enumerated variables, and the minimum exchangerate shall be established locally, as agreed upon betweencustomer and supplier, or b
45、etween laboratories, but shall not beless than that described in 5.2.1.6(2).5.2.1.7 A means of providing internal chamber circulationof the gas (airozone mixture) shall be provided by an electricfan capable of maintaining a constant velocity throughout theduration of a test. The velocity shall be no
46、 less than 0.6 m/s(2 ft/s) as measured at 50 6 1 mm (1.97 6 0.04 in.) from theforward edge of the fan blades on the internal side of thechamber.(1) The fan motor shall not be located within the internalchamber. The fan motor shall employ an extension shaft, ordrive mechanism, that isolates the motor
47、 from the internalchamber with an ozone resistant seal that assures the integrityof separation between the motor and the internal chamber.(2) The fan blades shall be recessed from the chamber andseparated, or enclosed, by a protective mesh or grid-like cage.5.2.1.8 A means of controlling the interna
48、l chamber tem-perature to within 6 1C (6 1.8F) of that established, ordesired, throughout the duration of a test, shall be provided.(1) The standard test temperature shall be 40 6 1C(104 6 1.8 F). Other temperatures may be established locally,agreed upon between customer and supplier, or betweenlabo
49、ratories. It is recommended that the standard temperaturesgiven in Practice D 1349 be followed.(2) Testing at subnormal or elevated temperatures requiresthe use of refrigerated chambers or chambers having additionalheating capability. These shall meet all other requirements asdescribed heretofore.5.2.1.9 Chambers shall be equipped so that concentrationsof ozone are safely exhausted from the internal test chamber soas not to introduce them to the proximal ambient atmosphere(refer to 1.4). This shall be accomplished by properly exhaust-ing the gas (
