ASTM_D_6556_-_14.pdf

Designation:D655614Standard Test Method forCarbon BlackTotal and External Surface Area by NitrogenAdsorption1This standard is issued under the fixed designation D6556;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 test method covers the determination of the totalsurface area by the Brunauer,Emmett,and Teller(B.E.T.NSA)theory of multilayer gas adsorption behavior using multipointdeterminations and the external surface area based on thestatistical thickness surface area method.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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.(The minimumsafety equipment should include protective gloves,sturdy eyeand face protection).2.Referenced Documents2.1 ASTM Standards:2D1799 Practice for Carbon BlackSampling PackagedShipmentsD1900 Practice for Carbon BlackSampling Bulk Ship-mentsD3765 Test Method for Carbon BlackCTAB(Cetyltrim-ethylammonium Bromide)Surface Area(Withdrawn2007)3D4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3.Summary of Test Method3.1 The total and external surface areas are measured byevaluating the amount of nitrogen adsorbed,at liquid nitrogentemperature,by a carbon black at several partial pressures ofnitrogen.The adsorption data is used to calculate the NSA andSTSA values.4.Significance and Use4.1 This test method is used to measure the total andexternal surface area of carbon blacks based on multipointnitrogen adsorption.The NSA measurement is based on theB.E.T.theory and it includes the total surface area,inclusive ofmicropores,pore diameters less than 2 nm(20).The externalsurface area,based on the statistical thickness method(STSA),is defined as the specific surface area that is accessible torubber.4.2 CTAB Surface Area(formerly Test Method D3765)hasbeen withdrawn.The CTAB value may be estimated from theSTSA value using Eq 1.The equation is based on a linearregression of the STSAand CTAB measured values of the SRB5 standards.CTAB5 STSA*1.017012.6434(1)5.Apparatus5.1 Multipoint Static-Volumetric Gas Adsorption Apparatus,with Dewar flasks and all other accessories required foroperation.5.2 Sample Cells,that when attached to the adsorptionapparatus,will maintain isolation of the sample from theatmosphere equivalent to a helium leak rate of 105cm3/min,per atmosphere of pressure difference.5.3 Balance,Analytical,with 0.1 mg sensitivity.5.4 Heating Mantle or Equivalent,capable of maintaining atemperature of 300 6 10C.5.5 Oven,Gravity Convection,capable of maintaining atemperature of 125 6 10C.6.Reagents6.1 Liquid Nitrogen,98%or higher purity.1This test method is under the jurisdiction of ASTM Committee D24 on CarbonBlack and is the direct responsibility of Subcommittee D24.21 on Carbon BlackSurface Area and Related Properties.Current edition approved June 1,2014.Published July 2014.Originally approvedin 2000.Last previous edition approved in 2010 as D6556 10.DOI:10.1520/D6556-14.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 Ultra-High Purity Nitrogen Gas,cylinder or othersource of prepurified nitrogen gas.6.3 Ultra-High Purity Helium Gas,cylinder or other sourceof prepurified helium gas.7.Sampling7.1 Samples may be taken in accordance with PracticesD1799 and D1900.8.Sample Preparation Procedure8.1 Dry a portion of carbon black at 125C for 1 h.If thecarbon black is known to be substantially free of moisture,orsubsequent preparation steps are known to be adequate formoisture removal,then this step may be omitted.8.2 Condition an empty sample cell for a minimum of 10min at the same conditions intended for degassing the sample.Weigh the empty sample cell to the nearest 0.1 mg and recordthe mass.8.3 Weigh approximately 0.4 g of the carbon black into thesample cell.NOTE1For carbon black powder samples,add enough carbon blackto give a depth of approximately 2 in.in straight wall sample tubes,orapproximately 0.4 g for bulb-type sample cells.8.4 Flow Degassing:8.4.1 Open the gas control valve and insert the delivery tubeinto the sample tube,and allow purgin