ASTM_D_3765_-_04.pdf

Designation:D 3765 04Standard Test Method forCarbon BlackCTAB(Cetyltrimethylammonium Bromide)Surface Area1This standard is issued under the fixed designation D 3765;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 measurement of specificsurface area of carbon black exclusive of area contained inmicropores too small to admit hexadecyltrimethyl ammoniumbromide(cetyltrimethyl ammonium bromide,commonly re-ferred to as CTAB).However,it should be noted that thepreferred method for measuring external surface area is STSA(Test Method D 6556).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:2D 1193 Specification for Reagent WaterD 1799 Practice for Carbon BlackSampling PackagedShipmentsD 1900 Practice for Carbon BlackSampling Bulk Ship-mentsD 4483 Practice for Determining Precision for Test MethodStandards in the Rubber and Carbon Black IndustriesD 6556 Test Method for Carbon BlackTotal and ExternalSurface Area by Nitrogen Adsorption3.Summary of Test Method3.1 The isotherm for adsorption of an aqueous solution ofCTAB on carbon black has a long horizontal plateau corre-sponding to a monolayer coverage of the substrate surface fromwhich the adsorbate is not sterically excluded.The CTABadsorption by carbon black is independent of residual tars andfunctional groups containing hydrogen and oxygen,and thelike.Rapid equilibration is achieved by using mechanicalstirring and ultrasonic vibration.Titration with dioctyl sodiumsulfosuccinate(Aerosol OT3)solution to a turbidity maximumend point is used to determine the unadsorbed CTAB afterremoval of the colloidally dispersed carbon black by ultrafil-tration.All results are scaled by using the Industry TintReference Black(ITRB)as a primary standard and taking itsaccessible surface area to be exactly 83.0 3 103m2/kg(83.0m2/g).3.2 Titration of the unadsorbed CTAB with Aerosol OTsolution is accomplished by the following:3.2.1 Part AAutomatic Titration.3.2.2 Part BManual Turbidity Titration.4.Significance and Use4.1 The CTAB molecule is relatively large;so it is notadsorbed in micropores or on surface roughness.Thus,theCTAB surface area reflects only the surface of the carbon blackthat is available for interaction with rubber molecules.5.Apparatus5.1 Analytical Balance,0.1-mg sensitivity.5.2 Ultrasonic Cleaning Bath,4modified to incorporateintegral magnetic stirring and vial holder to properly positiontwo sample vials.(If desired,a separate ultrasonic cleaningbath and a separate magnetic stirrer may be used.)5.3 Magnetic Spinbars,chemically resistant,covered(poly-chlorotrifluoroethylene or TFE-fluorocarbon),6.4 or 4.8-mm(14or316-in.)diameter,and length nearly equal to the diameterof 50 or 100-cm3Berzelius beakers,glass vials,or other glassvessels.5.4 Microfiltration Membrane Filter Disks,mixed celluloseester or cellulose nitrate,47-mm diameter,0.1-m pore size5.5.5 Filter Holder.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 1,2004.Published June 2004.Originallyapproved in 1979.Last previous edition approved in 2003 as D 3765 03a.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.3Aerosol OT is a registered trademark of the American Cyanamid Co.,ProcessChemicals Dept.,Wayne,NJ 07470.4This equipment is no longer commercially available.As an alternative,thesample vial to be immersed in the ultrasonic bath may be fixed to an automaticshaker in order to assure proper agitation during the ultrasonic treatment.5Membrane filter disks of hydrophilic polysulfone,pore size 0.2 m,also havebeen found to be suitable.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.6 Sampling Cylinder,30-cm3stainless steel,double endwith 6.4-mm(14-in.)NPT female openings,suitable for 0.7-MPa(100-psi)pressure.5.7 Pressure Manifold,connected to air or nitrogen supplyregulated at 0.4 to 0.7 MPa(60 to 100 psi).Fig.1 shows aschematic diagram of a typical assembly.5.8 Glass Funnel,small.5.9 Glass Vials,with plastic screw caps,28 mm in outside