ASTM_D_5816_-_99.pdf

Designation:D 5816 99Standard Test Methods forCarbon BlackExternal Surface Area by Multipoint NitrogenAdsorption1This standard is issued under the fixed designation D 5816;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 These test methods cover the determination of theexternal surface area of carbon blacks by the statisticalthickness surface area(STSA)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.2.Referenced Documents2.1 ASTM Standards:D 1799 Practice for Carbon BlackSampling PackagedShipments2D 1900 Practice for Carbon BlackSampling Bulk Ship-ments2D 4820 Test Methods for Carbon BlackSurface Area byMultipoint B.E.T.Nitrogen Adsorption23.Significance and Use3.1 These test methods are used to measure the externalsurface area of carbon black.These techniques are based on thestatistical thickness method using a carbon black model.Theexternal surface area is defined as the specific surface area thatis accessible to rubber.The external surface area excludes themicropore area,pore diameters less than 20 A.4.Apparatus4.1 Multipoint Static-Volumetric Gas Adsorption Apparatus,with Dewar flasks and all other accessories required foroperation.4.2 Sample Cellsthat,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.4.3 Analytical Balance,with 0.1 mg sensitivity.4.4 Heating Mantle or Equivalent,capable of maintaining atemperature of 300 6 10C.4.5 Oven,Gravity Convection,capable of maintaining atemperature of 125 6 5C.5.Reagents5.1 Liquid nitrogen,98%or higher purity.5.2 Ultra high-purity nitrogen gas,cylinder,or other sourceof prepurified nitrogen gas.5.3 Ultra high-purity helium gas,cylinder,or other sourceof prepurified helium gas.6.Sampling6.1 Samples shall be taken in accordance with PracticeD 1799 and Practice D 1900.7.Sample Preparation Procedure7.1 Dry a portion of the carbon black to be tested at 125Cfor 1 h.If the carbon black is known to be substantially free ofmoisture,or subsequent preparation steps are known to beadequate for moisture removal,then this step may be omitted.7.2 Weigh a sample cell to the nearest 0.1 mg and record themass.7.3 Weigh into the cell approximately 0.4 g of the carbonblack to be tested.NOTE1For carbon black powder samples,add enough carbon blackto give a depth of approximately 2 in.in straight wall sample tubes,or fillthe sample bulb for bulb-type sample cells.7.4 Flow Degassing:7.4.1 Open the helium control valve and insert the deliverytube into the sample tube,and allow to purge for a minimum of1 min.7.4.2 Place a heating mantle or other source of heat aroundthe sample cell and degas the sample at 300 6 10C for12hor longer to ensure that all traces of moisture condensing in thetop of the tube are absent.7.4.3 Once the typical degassing times have been deter-mined,future samples can be degassed on the basis of timealone,if desired,allowing a reasonable margin of excess time.Some samples will be found to require less than12h,especiallyif moisture exposure has been minimal.In these cases,theminimum time that gives a stable surface area may be used fordegassing.1These test methods are under the jurisdiction of ASTM Committee D-24 onCarbon Black and are the direct responsibility of Subcommittee D24.21 onAdsorptive Properties of Carbon Black.Current edition approved August 10,1999.Published September 1999.Origi-nally published as D 5816 95.Last previous edition D 5816 96.2Annual Book of ASTM Standards,Vol 09.01.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.7.4.4 After degassing,the sample tube may be moveddirectly to the analyzer.Otherwise,remove the sample tubefrom the heat source and continue the flow of purging gas untilit is ready for analysis.7.4.5 Go directly to Section 8 and continue the remainingsteps of the procedure.7.5 Vacuum Degassing:7.5.1 With the apparatus at atmospheric pressure,place thesample cell containing the carbon black onto the degassingapparatus.7.5.2 Begin the degassing procedure as appropriate for theapparatus.7.5.3 Place a heating mantle or other source of heat aroundthe sample cell and degas the sample at 300 6 10C for12h