ASTM F2466-2010(2018) Standard Practice for Determining Silicone Volatiles in Silicone Rubber for Transportation Applications.pdf

1、Designation: F2466 10 (Reapproved 2018)Standard Practice forDetermining Silicone Volatiles in Silicone Rubber forTransportation Applications1This standard is issued under the fixed designation F2466; the number immediately following the designation indicates the year oforiginal adoption or, in the c

2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a means to determine the percentsilicone-producing volatiles present

3、 in heat-cured siliconerubber and room temperature-cured silicones (RTV).1.2 Silicone-producing volatiles contribute to fouling ofoxygen sensor systems used in the control of vehicle emis-sions.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use.

4、It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles o

5、n standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3182 Practice for RubberMaterials, Equ

6、ipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Practice3.1 This practic

7、e consists of four (4) basic steps: (1) thesilicone is cured to its elastomeric form, (2) the volatiles areextracted from the cured material, (3) the extract is separatedand measured by gas chromatography (GC), and (4) the GCresults are quantified using a siloxane calibration.4. Significance and Use

8、4.1 Use of this practice in conjunction with realistic maxi-mum volatility tolerance level can help minimize the risk ofoxygen sensor dysfunction from formed-in-place-sealants intransportation applications. This practice provides a method fordetermination of percentage volatiles in silicone elastome

9、rs.The volatile silicones from a commercial silicone are primarilycyclo dimethyl-siloxane. Other species present having GCretention times similar to those of the cyclics are assumed to besilicone as well.5. Apparatus5.1 Gas Chromatograph, fused silica capillary column sys-tem equipped with a flame i

10、onization detector, split-typecapillary column injector, temperature programming capabilityand an appropriate data recording system. An alternative unitmay be an equivalent instrument equipped with a thermalconductivity detector, or as agreed upon between producer anduser. Specific column and operat

11、ing conditions should beselected to optimize instrument response and chromatographicresolution, particularly separation of the internal standard fromextracted sample components.5.2 Column, suggested to be used is 30 to 60 m by 0.25 mmwith 0.25 to 1.5 m DB-1 or DB-5 fused silica capillarycolumn or eq

12、uivalent.5.3 Operating conditions are:5.3.1 Column50 to 320C at 10C/min (a post-analysisperiod may be required to elute higher boiling componentsprior to subsequent analyses).5.3.2 Injector290C.5.3.3 Detector325C.5.3.4 Sample Size1 L.5.3.5 Injector Split Ratio2:1 to 50:1 (adjusted as needed).5.3.6 H

13、elium or Nitrogen, for the carrier gas.5.3.7 Carrier Gas Flow Velocity1 to 2 mL/min (adjustedas needed for column dimensions).5.4 Humidity Chamber, or controlled lab environment.5.5 Wrist-Action Mechanical Shaker.1This practice is under the jurisdiction ofASTM Committee F03 on Gaskets andis the dire

14、ct responsibility of Subcommittee F03.50 on Analytical Test Methods.Current edition approved Aug. 1, 2018. Published September 2018. Originallyapproved in 2005. Last previous edition approved in 2010 as F2466 10. DOI:10.1520/F2466-10R18.2For referenced ASTM standards, visit the ASTM website, www.ast

15、m.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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis intern

16、ational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Comm

17、ittee.15.6 Analytical Balance, with glass draft shield capable of0.0001 g accuracy.5.7 30-mL Vials, flint glass, with screw cap (polyethylenelined).5.8 Syringe, capable of accurately delivering 20 6 0.1 L(no plastic elements used due to solvents used).5.9 Solvents and standards used are pentane (99

18、%) anddodecane (99 %), both spectral grade.5.10 Rigid Plates (Glass or Aluminum), 0.90 mm thick, forcutting the wet formed-in-place sealant.5.11 Automated devices shall be used for measuring andcalculating peaks.6. Test Specimens6.1 Heat-cured silicone rubber samples shall be procuredfrom either act

19、ual production parts, or shall be compression-molded ASTM tensile plaques (Practice D3182, 2.0 6 0.2 mmthick). Cure conditions of the tensile plaques shall mirror cureconditions used on the production parts. If actual productionparts are used to obtain test samples, best practice would be tocut samp

20、le so that it is not thicker than the above stated tensileplaque thickness.6.2 Room temperature-vulcanized (RTV) samples shall beprepared by spreading the liquid using a suitable device, intoconsistent 0.90 6 0.20 mm plaques. Avoid entrapped air andknit lines when preparing the sample.6.3 Three 1-g

21、samples shall be cut from the plaque. Thesesamples shall be taken from near one corner, at the center of theplaque, and near the corner at a diagonal from the first.7. Standard Solutions37.1 Add 0.1 g (weighed to the nearest 0.1 mg) of each purecyclic (98 %) to 1.0 g of dodecane (99 %) (weighed to t

22、henearest 0.1 mg). Ten millilitres 6 0.1 mL pentane is added andthe container is sealed to prevent leakage/evaporation. Newstandard mixtures should be prepared if existing one is morethan seven (7) days old.7.2 Calibration of the standard solution is achieved byinjecting 1 L (need verify use with SE

23、 30 column will needto attenuate response or dilute solution) standard solutionsample. Response factors for the individual cyclics are calcu-lated using the following equation:RfDn 5Wt DnADn*ADoDWtDoD(1)where:Rf = response factorDn = the cyclic siloxane species from a 4 member to a10 member ringRfDn

24、 = the response factor for each siloxane species from4to10WtDn = the weight of each siloxane species from 4 to 10used in the standard solutionADn = the area under the curve for each siloxane speciesfrom4to10DoD = the dodecane standard, which is arbitrarily given aresponse factor of “1” (one), and is

25、 used as thebasis for calculating the response factors of thevarious know and unknow siloxane speciesADoD = the area under the curve for the dodecane standardWtDoD = the weight of the dodecane used in the standardsolutions7.3 Response factors for cyclic species vary in a relativelylinear manner from

26、 D5through D10, so that response factors forcyclics not in the standard solution can be calculated from theknown response factors of the cyclics in the standard solution.A sample calculation for response factors of standardsavailable, and a Linear Least Squares Analysis to determineresponse factors

27、of cyclics that are unavailable can be found inAppendix X1.7.4 All of the unknowns that appear in the analysis (betweenD4and D10) are assumed to be dimethyl siloxanes. Allunknowns are given, as response factors, the average responsefactor calculated for the difunctional cyclosiloxane monomersD4throu

28、gh D10.8. Conditioning8.1 Allow RTV samples to cure for 24 h, but not to exceed72 h at 25C and 50 6 10 % relative humidity.9. Procedure9.1 ExtractionPre-weigh each cured sample to 1.0 6 0.2g (record weight to the nearest 0.0001 g) and set aside.9.2 Weigh 0.010 6 0.005 g of dodecane (record weight to

29、the nearest 0.0001 g) and place sample into the 30-mL vial. Tothis add 10 mL of pentane. Immediately place the pre-weighedsample into the vial, and seal the container to prevent leakage/evaporation. Weight precision of the dodecane and test sampleare extremely important for reproducible results. The

30、 samplevial is placed on a wrist shaker for 16 h.NOTE 1The sequence is important due to the volatility of the solvents.used.NOTE 2See 10.1.1 regarding dodecane measurement.9.3 Inject 1 to 5 L into the GC injection port. (Injectionvolume is dependant on the injector split ratio).9.4 After the elution

31、 is complete (about 35 min) identify thepeaks and quantify them by integration using the followingequations (sample calculations are shown in Appendix X2):%Dn 5RfDn*ADnADoD*WtDoDSaWt*100 (2)whereSaWt = the weight of the silicone part9.4.1 Perform Eq 2 for D4through D10.3The sole source of supply of

32、the standards solutions known to the committee atthis time is Ohio Valley Specialty Chemicals, 115 Industrial Road, Marietta, OH,45750, 1-800-729-6972, Catalog number 34569/Cyclic Standard Kit D3 throughD10. If you are aware of alternative suppliers, please provide this information toASTM Internatio

33、nal Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.F2466 10 (2018)2% Un 5AveRfDn*AUnADoD*WtDoDSaWt*100 (3)where:Un = the unknown cyclic siloxanes in the sampleAveRfDn = the average of the response factors from

34、 D3toD109.4.2 Perform Eq 3 for all unknowns that elute between D4and D10.9.4.3 % Siloxane Volatiles = Sum of % cyclics D4throughD10and sum of % unknowns eluting from D4through D10.NOTE 3Silicone volatiles below D5may not be detected at theircorrect levels due to their loss from the sealant as it cur

35、es for 24 h at 25Cand 50 % relative humidity. Dodecane can mask D5forms and thebeginning of the first unknown. Any D3not lost would be masked byimpurities in pentane. Weight precision is extremely important if theresults are to be reproducible.10. Potential Failure Modes of Test Procedure10.1 Method

36、s/techniques of weighing can be a major sourceof error. Its imperative that the technician be as exacting aspossible when weighing the following materials:(1) Each standard cyclic siloxane species,(2) Dodecane added to standard solutions, and to extractionsample vials, and(3) Each cut test sample to

37、 be added to extraction vial.10.1.1 In order to reduce error associated with weighing thesmall quantity of dodecane directly into the sample vial, it isrecommended to first prepare a standard solution using a largerdodecane weight. This is done by weight out approximately 0.1g dodecane (record weigh

38、t to the nearest 0.0001g) into a10-mL classAvolumetric flask. Dilute to the line with pentane,and calcualte the actual concentration per mL of dodecane,based on the previously recorded weight. One millilitre (1 mL)of this standard solution is added to each sample vial using aHamilton pipette.10.2 Lo

39、ss of Small Amounts of DoD From Extraction VialDue to Incidental SplashIncidental fluid loss due to splashwhen adding dodecane, pentane, and pre-weighed siliconesample to extraction vial will greatly affect results. Care shouldbe taken when adding materials to extraction vial, and until capis tightl

40、y sealed. Any loss of material, no matter how small,must result in discarding that sample and preparing a new one.11. Reporting11.1 Three data points shall be reported for each sample as% total volatiles.11.2 Final results for siloxane should be expressed as0.00 %. Report D4through D10for total vola

41、tiles as cyclicsplus unknowns (Un4through Un10).11.3 All observed and recorded data on which calculationsare based.11.4 Date of the test, cure conditions, and thickness of thesample.12. Precision and Bias412.1 The precision of this test method is based on aninterlaboratory study conducted in 2008. E

42、ach of four labora-tories tested five different materials for silicone volatiles (theresults from these five tested in one of the laboratories wereunusable due to the utilization of improper response factors).Every “test result” represents an individual determination. Alllaboratories were asked to r

43、eport three replicate results for eachsample. Except for the limited number of participatinglaboratories, Practice E691 was followed for the design andanalysis of the data.12.1.1 Repeatability limit (r)Two test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by mor

44、e than the “r” value for that material; “r”istheinterval representing the critical difference between two testresults for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaboratory.12.1.1.1 Repeatability limits are listed in Table 1 below.12.1.2 Re

45、producibility limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representing the criticaldifference between two test results for the same material,obtained by different operators using different equipment indiffere

46、nt laboratories.12.1.2.1 Reproducibility limits are listed in Table 1 below.12.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with statements 12.1.1and 12.1.2 would normally have an approximate 95 % prob-a

47、bility of being correct; however, the precision statisticsobtained in this ILS must not be treated as exact mathematicalquantities which are applicable to all circumstances and uses.The limited number of laboratories reporting results guaranteesthat there will be times when differences greater than

48、predictedby the ILS results will arise, sometimes with considerablygreater or smaller frequency than the 95 % probability limitwould imply. Consider the repeatability limit and the repro-ducibility limit as general guides, and the associated probabil-ity of 95 % as only a rough indicator of what can

49、 be expected.12.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testmethod, therefore no statement on bias is being made.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:F03-1017.TABLE 1 Silicone Volatiles (%)Material AverageARepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SrSRrR1 0.286 0.038 0.099 0.107 0.2782 0.236 0.048 0.092 0.133 0.2583 0.216 0.035 0.059 0.098