1、Designation: E 595 07Standard Test Method forTotal Mass Loss and Collected Volatile CondensableMaterials from Outgassing in a Vacuum Environment1This standard is issued under the fixed designation E 595; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the 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 Thi
3、s test method covers a screening technique to deter-mine volatile content of materials when exposed to a vacuumenvironment. Two parameters are measured: total mass loss(TML) and collected volatile condensable materials (CVCM).An additional parameter, the amount of water vapor regained(WVR), can also
4、 be obtained after completion of exposuresand measurements required for TML and CVCM.1.2 This test method describes the test apparatus and relatedoperating procedures for evaluating the mass loss of materialsbeing subjected to 125C at less than 7 3 103Pa (5 3 105torr) for 24 h. The overall mass loss
5、 can be classified intononcondensables and condensables. The latter are character-ized herein as being capable of condensing on a collector at atemperature of 25C.NOTE 1Unless otherwise noted, the tolerance on 25 and 125C is61C and on 23C is 62C. The tolerance on relative humidity is 65%.1.3 Many ty
6、pes of organic, polymeric, and inorganic mate-rials can be tested. These include polymer potting compounds,foams, elastomers, films, tapes, insulations, shrink tubings,adhesives, coatings, fabrics, tie cords, and lubricants. Thematerials may be tested in the “as-received” condition orprepared for te
7、st by various curing specifications.1.4 This test method is primarily a screening technique formaterials and is not necessarily valid for computing actualcontamination on a system or component because of differ-ences in configuration, temperatures, and material processing.1.5 The criteria used for t
8、he acceptance and rejection ofmaterials shall be determined by the user and based uponspecific component and system requirements. Historically,TML of 1.00 % and CVCM of 0.10 % have been used asscreening levels for rejection of spacecraft materials.1.6 The use of materials that are deemed acceptable
9、inaccordance with this test method does not ensure that thesystem or component will remain uncontaminated. Therefore,subsequent functional, developmental, and qualification testsshould be used, as necessary, to ensure that the materialsperformance is satisfactory.1.7 This standard does not purport t
10、o address all of thesafety concerns associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 177 Practice for Us
11、e of the Terms Precision and Bias inASTM Test Methods2.2 ASTM Adjuncts:Micro VCM Detailed Drawings33. Terminology3.1 Definitions:3.1.1 collected volatile condensable material, CVCMthequantity of outgassed matter from a test specimen that con-denses on a collector maintained at a specific constant te
12、m-perature for a specified time. CVCM is expressed as apercentage of the initial specimen mass and is calculated fromthe condensate mass determined from the difference in mass ofthe collector plate before and after the test.3.1.2 total mass loss, TMLtotal mass of material out-gassed from a specimen
13、that is maintained at a specifiedconstant temperature and operating pressure for a specifiedtime. TML is calculated from the mass of the specimen asmeasured before and after the test and is expressed as apercentage of the initial specimen mass.3.1.3 water vapor regained, WVRthe mass of the watervapo
14、r regained by the specimen after the optional recondition-ing step. WVR is calculated from the differences in thespecimen mass determined after the test for TML and CVCM1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology and is th
15、e direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Dec. 1, 2007. Published December 2007. Originallyapproved in 1977. Last previous edition approved in 2006 as E 595 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
16、Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International, 100 Barr Harbor Dr., PO Box C700, WestConshohocken, PA 194282959. Order Adjunct ADJE0595.1Copyright ASTM International,
17、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and again after exposure to a 50 % relative humidity atmo-sphere at 23C for 24 h. WVR is expressed as a percentage ofthe initial specimen mass.4. Summary of Test Method4.1 This microvolatile condensable system4was d
18、evelopedfrom an earlier system for determination of macrovolatilecondensables that required much larger samples and a longertest.4.2 The test specimen is exposed to 23C and 50 % relativehumidity for 24 h in a preformed, degreased container (boat)that has been weighed. After this exposure, the boat a
19、ndspecimen are weighed and put in one of the specimen com-partments in a copper heating bar that is part of the testapparatus. The copper heating bar can accommodate a numberof specimens for simultaneous testing. The vacuum chamber inwhich the heating bar and other parts of the test apparatus arepla
20、ced is then sealed and evacuated to a vacuum of at least7 3 103Pa (5 3 105torr).The heating bar is used to raise thespecimen compartment temperature to 125C. This causesvapor from the heated specimen to stream from the hole in thespecimen compartment. A portion of the vapor passes into acollector ch
21、amber in which some vapor condenses on apreviously-weighed and independently temperature-controlled,chromium-plated collector plate that is maintained at 25C.Each specimen compartment has a corresponding collectorchamber that is isolated from the others by a compartmentedseparator plate to prevent c
22、ross contamination. After 24 h, thetest apparatus is cooled and the vacuum chamber is repressur-ized with a dry, inert gas. The specimen and the collector platesare weighed. From these results and the specimen massdetermined before the vacuum exposure, the percentage TMLand percentage CVCM are obtai
23、ned. Normally, the reportedvalues are an average of the percentages obtained from threesamples of the same material.NOTE 2It is also possible to conduct infrared and other analytical testson the condensates in conjunction with mass-loss tests. Sodium chlorideflats may be used for infrared analysis.
24、These flats are nominally 24 mm(1 in.) in diameter by 3.2 mm (0.125 in.) thick and are supported edgewisein a metal holder that fits into the collector plate receptacle. On completionof the test, the flats are placed into an infrared salt flat holder forexamination by an infrared spectrophotometer.
25、As an alternative method,the condensate may be dissolved from the metallic collector, the solventevaporated, and the residue deposited on a salt flat for infrared tests.Sodium chloride flats shall not be used for CVCM determinations.4.3 After the specimen has been weighed to determine theTML, the WV
26、R can be determined, if desired, as follows: thespecimen is stored for 24 h at 23C and 50 % relative humidityto permit sorption of water vapor. The specimen mass after thisexposure is determined. From these results and the specimenmass determined after vacuum exposure, the percentage WVRis obtained.
27、4.4 Two or three empty specimen chambers in the heater barand collector plates on the cold bar, selected for each test atrandom, can be used as controls to ensure that uniformcleaning procedures have been followed after each test.4.5 Atypical test apparatus can have 24 specimen chamberswith 24 assoc
28、iated collector plates so that a number ofspecimens of different types can be tested each time theforegoing operations are conducted. Three specimen compart-ments can serve as controls and three can be used for each typeof material being tested. The total time required for specimensrequiring no prio
29、r preparation is approximately 4 days. Theequipment should be calibrated at least once a year by usingpreviously tested materials as test specimens.4.6 The apparatus may be oriented in any direction as longas the configuration shown in Fig. 1 is maintained and bulkmaterial does not fall from the sam
30、ple holder nor obstruct thegas-exit hole. The dimensions for critical components given inFig. 2 and Table 1 are provided so that apparatus constructedfor the purpose of this test may provide uniform and compa-rable results.5. Significance and Use5.1 This test method evaluates, under carefully contro
31、lledconditions, the changes in the mass of a test specimen onexposure under vacuum to a temperature of 125C and themass of those products that leave the specimen and condenseon a collector at a temperature of 25C.5.2 The 24 h test time does not represent actual outgassingfrom years of operation, so
32、a higher test temperature shortertime was selected to allow material comparisons with no intentto predict actual outgassing in service. The test temperature of125C was assumed to be significantly above the expectedoperating temperature in service. If expected operating tem-peratures exceed 65 to 70C
33、 the test temperature should beincreased. It is suggested that test temperature be at least 30Chigher than expected maximum service temperature in order toprovide material comparisons for TML and CVCM.5.3 Comparisons of material outgassing properties are validat 125C sample temperature and 25C colle
34、ctor temperature4Muraca, R. F., and Whittick, J. S., “Polymers for SpacecraftApplications.” SRIProject ASD-5046, NASA CR-89557, N67-40270, Stanford Research Institute,September 1967.FIG. 1 Schematic of Critical Portion of Test Apparatus (SectionA-A of Fig. 2)E595072only. Samples tested at other temp
35、eratures may be comparedonly with other materials which were tested at that sametemperature.5.4 The measurements of the collected volatile condensablematerial are also comparable and valid only for similarcollector geometry and surfaces at 25C. Samples have beentested at sample temperatures from 50
36、to 400C and at collectortemperatures from 1 to 30C by this test technique. Data takenat nonstandard conditions must be clearly identified and shouldnot be compared with samples tested at 125C sample tem-perature and 25C collector temperature.5.5 The simulation of the vacuum of space in this testmeth
37、od does not require that the pressure be as low as thatencountered in interplanetary flight (for example, 1012PaFIG. 2 Critical Portion of Test Apparatus (See Table 1 for Dimensions)E595073(1014torr). It is sufficient that the pressure be low enough thatthe mean free path of gas molecules be long in
38、 comparison tochamber dimensions.5.6 This method of screening materials is considered aconservative one because maximum operating temperatures inservice are assumed not to exceed 50 to 60C for mostapplications. It is possible that a few materials will haveacceptable properties at the intended use te
39、mperature but willbe eliminated because their properties are not satisfactory at thetest temperature of 125C. Also, materials that condense onlybelow 25C are not detected. The user may designate addi-tional tests to qualify materials for a specific application.5.7 The determinations of TML and WVR a
40、re affected bythe capacity of the material to gain or lose water vapor.Therefore, the weighings must be accomplished under con-trolled conditions of 23C and 50 % relative humidity.5.8 Alternatively, all specimens may be put into open glassvials during the 24-h temperature and humidity conditioning.T
41、he vials must be capped before removal from the conditioningchamber. Each specimen must be weighed within 2 min afteropening the vial to minimize the loss or absorption of watervapor while exposed to an uncontrolled humidity environment.While control of humidity is not necessary at this point, thete
42、mperature for the weighing should be controlled at 23C, thesame temperature prescribed for the 24-h storage test.6. Apparatus6.1 The apparatus used in the determination of TML andCVCM typically contains two resistance-heated copper bars.Generally, each bar is 650 mm (25.5 in.) in length with a25-mm
43、(1-in.) square cross section and contains twelve speci-men chambers. The open section of each specimen chamberallows vapors from the specimen to pass through a hole into acollector chamber where it impinges on a removablechromium-plated collector plate maintained at 25C through-out the test. (See Fi
44、gs. 1 and 2.) Variations in test apparatusconfigurations are acceptable if critical dimensions are main-tained as prescribed in Table 1.6.2 Typically, a total of 24 specimen chambers is used fortesting during a 24-h vacuum operation; 3 of the chambers aremaintained as controls. The test apparatus ca
45、n be mounted onthe base plate of a vacuum system within a narrow vacuumbell, 260 mm (1014 in.) in diameter, that rests on a speciallyadapted feed-through collar, also supported by the base plate.6.3 The operation of the vacuum chamber system and anydevice for raising the vacuum bell can be automatic
46、allycontrolled. Power to the heating element mounted in the copperbars is generally controlled by variable transformers throughtemperature controllers. Recorders with an electronic icepointreference junction feedback may be used to monitor the heaterbar temperatures. A heat exchanger using a suitabl
47、e fluid maybe used to maintain the collector plate at 25C during the test.46.4 It is recommended that the vacuum chamber systeminclude automatic controls to prevent damage in the event ofpower failure or cooling fluid supply failure when in unat-tended operation. Care must be taken to prevent backst
48、reamingof oil from vacuum or diffusion pumps into the vacuumchamber.6.5 The controller thermocouple should be mechanicallyattached to the heater bar or ring to prevent the thermocouplefrom loosening over time. It is essential that the orifice of thesample heater and collector plate be aligned and ch
49、eckedregularly. A good test of alignment and stability is to run theTABLE 1 Test Apparatus Dimensions (See Fig. 2)Letter mm Tolerance in. Tolerance NotesAA6.3 60.1 0.250 60.005 diameterBBA11.1 60.1 0.438 60.005 diameterBCA33.0 60.1 1.300 60.005 diameterBDAC13.45 60.10 0.531 60.005EAC12.7 60.10 0.500 60.005FAC0.65 60.10 0.026 60.005GC9.65 60.3 0.380 60.01HA0.75 60.10 0.030 60.05 stock sizeJA12.7 60.3 0.500 60.010K1.660.8116 6132L8060.8716 6132M 16.0 60.1 0.625 60.005 cover plate must fit snuglyN 16.0 60.858 6132P 32.0 60.8 114 6132Q
