ASTM_F_2466_-_10.pdf

Designation:F246610Standard 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 case 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 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.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 prior to use.2.Referenced Documents2.1 ASTM Standards:2D3182 Practice for RubberMaterials,Equipment,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 practice 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 Use4.1 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 elastomers.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 ionization 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 operating 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 equivalent.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 Helium 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.5.6 Analytical Balance,with glass draft shield capable of0.0001 g accuracy.5.7 30-mL Vials,flint glass,with screw cap(polyethylenelined).1This practice is under the jurisdiction ofASTM Committee F03 on Gaskets andis the direct responsibility of Subcommittee F03.50 on Analytical Test Methods.Current edition approved May 1,2010.Published June 2010.Originallyapproved in 2005.Last previous edition approved in 2005 as F2466 05.DOI:10.1520/F2466-10.2For referenced ASTM standards,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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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%)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 actual 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 sample so that it is not thicker than the above stated tensileplaque