ASTM_D_5604_-_96_2012.pdf

Designation:D560496(Reapproved 2012)Standard Test Methods forPrecipitated SilicaSurface Area by Single Point B.E.T.Nitrogen Adsorption1This standard is issued under the fixed designation D5604;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 These test methods cover a procedure to measure thesurface area of precipitated hydrated silicas by,a single pointapproximation of the Brunauer,Emmett,and Teller(B.E.T.)2theory of multilayer gas adsorption.These test methods specifythe sample preparation and treatment,instrument calibrations,required accuracy and precision of experimental data,andcalculations of the surface area results from the obtained data.1.2 These test methods are used to determine the singlepoint nitrogen surface areas in the range of 10 to 50 hm2kg(10to 500 m2/g).1.3 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information only.1.4 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.The minimumsafety equipment should include protective gloves,sturdy eyeand face protection.2.Referenced Documents2.1 ASTM Standards:3D1799 Practice for Carbon BlackSampling PackagedShipmentsD1900 Practice for Carbon BlackSampling Bulk Ship-mentsD1993 Test Method for Precipitated Silica-Surface Area byMultipoint BET Nitrogen Adsorption3.Summary of Test Methods3.1 Solids adsorb nitrogen and,under specific conditions,the adsorbed molecules approach a monomolecular layer.Thequantity of gas in this hypothetical monomolecular layer iscalculated using an approximation of the B.E.T.equation.Combining this with the area occupied by the nitrogen mol-ecule yields an approximation of the total surface area of thesolid.3.2 These test methods measure the estimated quantity ofnitrogen in the monomolecular layer formed by adsorption atliquid nitrogen temperature and at a fractional saturationpressure of 0.30 6 0.01.3.3 Before a surface area determination can be made it isnecessary that any material which may already be adsorbed onthe surface of the silica be removed.Removal of adsorbedforeign material(by heating under vacuum or in a steam ofnon-adsorbing gas)eliminates two potential errors.The firsterror is due to the mass of the foreign material.The seconderror is due to interference by the foreign material to access bynitrogen the silica surface.4.Significance and Use4.1 These test methods measure the approximate surfacearea of precipitated hydrated silicas that is available to thenitrogen molecule using an approximation of the B.E.T.method.While the multi-point version of the B.E.T.method isgenerally accepted as being less prone to errors arising fromthe varying surface properties of individual samples,thesingle-point approximation is often adequate due to the shortertime per test and relative simplicity of the instrumentationneeded.Quality control applications and comparative tests on1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.20 on CompoundingMaterials and Procedures.Current edition approved May 1,2012.Published July 2012.Originally approvedin 1994.Last previous edition approved in 2006 as D5604 96(2006).DOI:10.1520/D5604-96R12.2Brunauer,Emmett,and Teller,Journal of the American Chemical Society,Vol60,1938,p.309.3For 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 near-identical samples of close chemical and micro-structuralcomposition are likely to be the applications of greatest value.5.ASTM D11 Standard Reference Silicas5.1 None RequiredThis test method is used to determinesurface area of candidate silicas.Reference silicas are avail-able4for determining agreement with data obtained in theinterlaboratory test used for multi-point procedure Test MethodD1993.TEST METHOD A SURFACE AREA BY STATICVOLUMETRIC APPARATUS6.Apparatus6.1 Static-Volumetric Gas Adsorption Apparatus,with de-war flasks and all other accessories required for operation.6.2 Oven,vacuum-type,capable of temperature-regulationto 65C at 110C.Pressure should be less than 13.5 Pa(0.1mmHg).6.3 Sample Cells,which,when attached to the adsorptionapparatus,will maintain isolation of the sample from theatmospheric pressure equivalent to a helium leak rate of 105standard cubic c