1、Designation: G 114 07Standard Practices forEvaluating the Age Resistance of Polymeric Materials Usedin Oxygen Service1This standard is issued under the fixed designation G 114; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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.1. Scope1.1 These practices describe several procedures that areused to determine the age resistance of plastic, thermosett
3、ing,and elastomeric materials exposed to oxygen-containing me-dia.1.2 While this practice focuses on evaluating the age resis-tance of polymeric materials in oxygen-containing media priorto ignition and combustion testing, it also has relevance forevaluating the age resistance of metals.1.3 These pr
4、actices address both established procedures thathave a foundation of experience and new procedures that haveyet to be validated. The latter are included to promote researchand later elaboration in this practice as methods of the formertype.1.4 The results of these practices may not give exactcorrela
5、tion with service performance since service conditionsvary widely and may involve multiple factors.1.5 Three procedures are described for evaluating the ageresistance of polymeric materials depending on application andinformation sought.1.5.1 Procedure A: Natural AgingThis procedure is usedto simula
6、te the effect(s) of one or more service stressors on amaterials oxygen resistance, and is suitable for evaluatingmaterials that experience continuous or intermittent exposureto elevated temperature during service.1.5.2 Procedure B: Accelerated Aging Comparative OxygenResistanceThis procedure is suit
7、able for evaluating materialsthat are used in ambient temperature service, or at a tempera-ture that is otherwise lower than the aging temperature, and isuseful for developing oxygen compatibility rankings on alaboratory comparison basis.1.5.3 Procedure C: Accelerated Aging LifetimePredictionThis pr
8、ocedure is used to determine the relation-ship between aging temperature and a fixed level of propertychange, thereby allowing predictions to be made about theeffect of prolonged service on oxidative degradation.1.6 The values stated in SI units are to be regarded as thestandard, however, all numeri
9、cal values must also be cited inthe systems in which they were actually measured.1.7 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 de
10、termine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 10.2. Referenced Documents2.1 ASTM Standards:2D 395 Test Methods for Rubber PropertyCompressionSetD 412 Test Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD
11、638 Test Method for Tensile Properties of PlasticsD 1349 Practice for RubberStandard Temperatures forTestingD 1708 Test Method for Tensile Properties of Plastics byUse of Microtensile SpecimensD 2240 Test Method for Rubber PropertyDurometerHardnessD 2512 Test Method for Compatibility of Materials wi
12、thLiquid Oxygen (Impact Sensitivity Threshold and Pass-Fail Techniques)D 2863 Test Method for Measuring the Minimum OxygenConcentration to Support Candle-Like Combustion ofPlastics (Oxygen Index)D 3045 Practice for Heat Aging of Plastics Without LoadD 4809 Test Method for Heat of Combustion of Liqui
13、dHydrocarbon Fuels by Bomb Calorimeter (PrecisionMethod)D 5510 Practice for Heat Aging of Oxidatively DegradablePlasticsG63 Guide for Evaluating Nonmetallic Materials for Oxy-gen Service1These practices are under the jurisdiction of ASTM Committee G04 onCompatibility and Sensitivity of Materials in
14、Oxygen Enriched Atmospheres and isthe direct responsibility of Subcommittee G04.02 on Recommended Practices.Current edition approved March 15, 2007. Published June 2007. Originallyapproved in 1993. Last previous edition approved in 2006 as G 114 06.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Stat
16、es.G72 Test Method for Autogenous Ignition Temperature ofLiquids and Solids in a High-Pressure Oxygen-EnrichedEnvironmentG74 Test Method for Ignition Sensitivity of Materials toGaseous Fluid ImpactG86 Test Method for Determining Ignition Sensitivity ofMaterials to Mechanical Impact in Ambient Liquid
17、 Oxy-gen and Pressurized Liquid and Gaseous Oxygen Environ-mentsG 125 Test Method for Measuring Liquid and Solid Mate-rial Fire Limits in Gaseous OxidantsG 126 Terminology Relating to the Compatibility and Sen-sitivity of Materials in Oxygen Enriched Atmospheres2.2 Federal Standard:Federal Specifica
18、tion BB-0-925 Oxygen, Technical, Gasand Liquid32.3 Military Standard:MIL-O-27210E Amendment 1Oxygen, Aviators Breath-ing, Liquid and Gas33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 agingsee Terminology G 126.3.1.2 accelerated aginga type of artificial aging wherebythe effe
19、ct of prolonged exposure during service is simulated byaging at elevated temperature.3.1.3 artificial agingsee Terminology G 126.3.1.4 oxidative degradationphysical or mechanical prop-erty changes occurring as a result of exposure to oxygen-containing media.3.1.5 oxygen-containing mediaair media con
20、taininggreater than 21 mole % oxygen, or oxygen-enriched mediacontaining greater than 25 mole % oxygen.3.1.6 oxygen resistanceresistance of a material to ignitespontaneously, propagate by sustained combustion, or undergooxidative degradation.3.1.7 oxygen serviceapplications involving the produc-tion
21、, storage, transportation, distribution, of use of oxygen-containing media.3.1.8 natural agingsee Terminology G 126.3.1.9 physical agingaging that occurs during normal stor-age which is a function of time after production.4. Summary of Practice4.1 These practices can be used to evaluate systematical
22、lythe effect of natural aging (Procedure A) or accelerated aging(Procedures B and C) on oxygen resistance. To apply itsprinciple, the user first characterizes the material, then subjectsthe material to an aging stressor or stressors, followed byre-characterizing the material. Caution must be taken i
23、n inter-preting results because interactions occurring in service may bedifferent than those simulated during aging.4.2 It is always more accurate, although not always practi-cal, to determine the effect of natural aging (Procedure A)without resorting to accelerated aging (Procedures B and C).Accele
24、rated aging procedures are more useful for determiningmaterial rankings (Procedure B) or for making lifetime predic-tions (Procedure C).4.3 Summary of Practice for Evaluating the Effect of Agingin Incident Studies:4.3.1 In incident studies, in which initial characterizationdata are not available, hi
25、storical or average property data maybe used to draw coarser conclusions about the effect of agingon oxygen resistance.4.4 Practices for Natural Aging (Procedure A) and Accel-erated Aging for Comparative Oxygen Resistance (ProcedureB):4.4.1 The effect of aging is reported as positive or negativedepe
26、nding upon whether the property used to evaluate oxygenresistance increases or decreases, and the magnitude of theeffect is reported as the degree to which the measured propertychanges relative to that of the unaged material.4.5 Practice for Accelerated Aging for Lifetime Prediction(Procedure C):4.5
27、.1 The time necessary to produce a fixed level ofproperty change is determined at a series of elevated agingtemperatures, and the time necessary to produce the same levelof property change at some lower temperature is then deter-mined by linear extrapolation.4.5.2 A practice for evaluating the effec
28、t of acceleratedaging on physical and mechanical properties under conditionsof variable time and temperature has been validated forsignificance and is described in detail. This practice is similarto those given in Practices D 3045 and D 5510, but is specificto aging in oxygen-containing media.4.5.3
29、A practice for evaluating the effect of acceleratedaging on ignition and combustion properties under conditionsof variable time and temperature has not been validated forsignificance, but may yield meaningful results. The practicedescribed is included to promote research and possible devel-opment in
30、to an established method.4.5.4 There can be very large errors when accelerated agingArrhenius approaches are used to estimate the time necessaryto produce a fixed amount of property change at some lowertemperature. This estimated time to produce a fixed level ofproperty change or “failure” at the lo
31、wer temperature is oftencalled the “service life.” Because of the errors associated withthese calculations, this time should be considered to be the“maximum expected” rather than “typical.”5. Significance and Use5.1 This practice allows the user to evaluate the effect ofservice or accelerating aging
32、 on the oxygen resistance ofpolymeric materials used in oxygen service.5.2 The use of this practice presupposes that the propertiesused to evaluate the effect of aging can be shown to relate tothe intended use of the material, and are also sensitive to theeffect of aging.5.3 Polymeric materials will
33、, in general, be more suscep-tible than metals to aging effects as evidenced by irreversibleproperty loss. Such property loss may lead to catastrophiccomponent failure, including a secondary fire, before primaryignition or combustion of the polymeric material occurs.3Available from Standardization D
34、ocuments Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.G1140725.4 Polymers aged in the presence of oxygen-containingmedia may undergo many types of reversible and irreversiblephysical and chemical property change. The severity of thea
35、ging conditions determines the extent and type of changes thattake place. Polymers may not necessarily be degraded byaging, but may be unchanged or improved. For example, agingmay drive off volatile materials, thus raising the ignitiontemperature without compromising mechanical properties.However, a
36、ging under prolonged or severe conditions (forexample, elevated oxygen concentration) will usually cause adecrease in mechanical performance, while improving resis-tance to ignition and combustion.5.5 Aging may result in reversible mass increase (phys-isorption), irreversible mass increase (chemisor
37、ption), plastici-zation, discoloration, loss of volatiles, embrittlement, softeningdue to sorption of volatiles, cracking, relief of moldingstresses, increased crystallinity, dimensional change, advanceof cure in thermosets and elastomers, chain scissioning, andcrosslinking.5.6 After a period of ser
38、vice, a materials properties may besignificantly different from those when new.All materials ratedfor oxygen service should remain resistant to ignition andcombustion (primary fire risk). Furthermore, all materials ratedfor oxygen service should be resistant to oxidative degradationand retain releva
39、nt physical and mechanical properties duringservice, because part failure can indirectly lead to an unaccept-able ignition or combustion risk (secondary fire risk).5.7 In cases where aging makes a material more susceptibleto fire or causes significant oxidative degradation, aging testsmay be used to
40、 evaluate whether the material will becomeunacceptable during service. In cases where aging makes amaterial less susceptible to fire, aging tests may be used toevaluate whether a material can be conditioned (artificiallyaged) to prolong its service lifetime.5.8 Oxygen resistance as determined by thi
41、s practice doesnot constitute grounds for material acceptability in oxygenservice. Determination of material acceptability must be per-formed within the broader context of review of system orcomponent design, plausible ignition mechanisms, ignitionprobability, post-ignition material properties, and
42、reactioneffects such as are covered by Guide G63.5.9 The potential for personnel injury, facility damage,product loss, or downtime occurring as a result of ignition,combustion, or catastrophic equipment failure will be least forsystems or components using air and greatest for systems orcomponents us
43、ing pure oxygen.5.10 In terms of physical and mechanical properties, agingis expected to have a greater influence on a polymers ultimateproperties such as strength and elongation, than bulk propertiessuch as modulus.5.11 In terms of fire properties, aging is expected to have agreater influence on a
44、polymers ignition properties (for ex-ample, autogenous ignition temperature (AIT), mechanical andpneumatic impact) than its propagation properties (for ex-ample, upward and downward flame propagation). To date, theonly background on aging influences is that of the Bundesan-stalt Fr Materialforschung
45、 und -Prfung (BAM) which has foryears assessed the effect of aging at elevated pressure andtemperature on a materials AIT. BAM has used the AIT testresults to establish maximum constraints on the use of mate-rials at elevated pressure and temperature.46. Rationale for Aging Tests6.1 The body of info
46、rmation on the effect of natural agingon oxygen resistance under conditions of multiple stressors issmall, and so, this practice is intended to promote testingtowards the goal of developing better practices to evaluate thecompeting effects of multiple stressors.6.2 The body of information on the eff
47、ect of acceleratedaging on ignition and combustion is small, and so, this practiceis intended to promote testing towards the goal of developingpotential practices to evaluate the effect of accelerated aging onignition and combustion.7. Apparatus7.1 General Considerations:7.1.1 The apparatus used for
48、 aging can vary widely. Agingin ambient pressure air, gravity-convection ovens or forced-ventilation ovens may be used. When aging in pressurizedoxygen-enriched media pressure-rated cell-type ovens or oxy-gen pressure chambers that provide a greater margin of safetymust be used because of the increa
49、sed risk of ignition orcombustion.7.1.2 This practice focuses on small-scale aging methodsinvolving only a few specimens at most. The scale of the agingprocedure can be increased in numerous ways, provided care istaken to ensure safety.7.1.3 A provision shall be made for suspending specimensvertically without touching each other or the sides of the agingchamber. If possible, maintain at leasta5cm(2in.) separationbetween specimens and the sides of the aging oven, cell, orchamber.7.1.4 The temperature, and pressure if different than ambi-ent, should be automati
