ASTM_D_3733_-_93_1998.pdf

Designation:D 3733 93(Reapproved 1998)Standard Test Method forSilicon Content of Silicone Polymers and Silicone-ModifiedAlkyds by Atomic Absorption1This standard is issued under the fixed designation D 3733;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the siliconcontent of silicone polymers and silicone modified alkydswhen present in the nonvolatile portion of polymers,resins,orliquid coatings to the extent of 1%or more.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 1153 Specification for Methyl Isobutyl Ketone2D 1193 Specification for Reagent Water3D 2372 Practice for Separation of Vehicle from Solvent-Reducible Paints4D 2698 Test Method for Determination of the PigmentContent of Solvent-Reducible Paints by High-Speed Cen-trifuging4D 2832 Guide for Determining Volatile and NonvolatileContent of Paint and Related Coatings43.Significance and Use3.1 The silicon content of silicone modified alkyds has adirect relationship to the cost and performance characteristics,especially heat resistance of coatings prepared from them.4.Summary of Test Method4.1 The polymer solution or separated coating vehicle isdiluted with methyl isobutyl ketone,and the silicon content isdetermined by atomic absorption spectroscopy.5.Apparatus5.1 Atomic Absorption Spectrophotometer,consisting of anatomizer and a single-slot burner;gas pressure-regulating and-metering devices for nitrous oxide(N2O)and acetylene;asilicon hollow-cathode lamp with a regulated constant currentsupply;a monochromator and associated optics;a photosensi-tive detector connected to an electronic amplifier;and aread-out device.5.2 Centrifuge.5.3 Pipets,5,10,15,and 20-mL capacity.5.4 Volumetric Flasks,25,50,100,and 1000-mL.6.Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water conformingto Type II of Specification D 1193.6.3 Octaphenylcyclotetrasiloxane.66.4 Methyl Isobutyl Ketone(MIBK),complying withSpecification D 1153.6.5 Silicon,Standard Stock Solution(100 g/mL)Weighexactly 0.709 g of octaphenylcyclotetrasiloxane and quantita-tively transfer to a 1-L flask.Dilute to volume with MIBK.1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Material,and Applications and is the direct responsibility ofSubcommittee D 01.33 on Polymers and Resins.Current edition approved April 15,1993.Published June 1993.Originallypublished as D 3733 78.Last previous edition D 3733 78(1984)e1.2Annual Book of ASTM Standards,Vol 06.04.3Annual Book of ASTM Standards,Vol 11.01.4Annual Book of ASTM Standards,Vol 06.01.5Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.6Available as Standard Reference Material No.1066a from Office of StandardReference Materials,Room B-314,Chemistry Building,National Institute ofStandards and Technology,Washington,DC 20234.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.7.Calibration and Standardization7.1 Prepare the following standard solutions from the 100g/mL silicon standard stock solution,diluting to the indicatedvolumes with MIBK:Stock Solution,mLDilute to,mLConcentration,g/mL2025801525601025405252055010510057.2 Operational instructions for atomic absorption spectro-photometers vary with different models.Consult the manufac-turers literature for establishing optimum conditions for thespecific instrument used.7.3 Turn the instrument on and set the wavelength to the251.6-nm silicon line.Apply the recommended current to thesilicon hollow-cathode lamp.Allow the instrument to warm upfor about 15 min and set the slit width.Adjust the nitrous oxideand acetylen