Designation:D8016−22StandardTestMethodforSilica,Precipitated,Hydrated—SearsNumber1ThisstandardisissuedunderthefixeddesignationD8016;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThistestmethodisusedtodeterminethenumberofsilanolgroupsonthesurfaceofsilicabytitrationaccordingtoamethodasdevelopedbySears.Thistestmethodissuitableforcharacterizingrubber-gradesilicas.1.2Units—ThevaluesstatedinSIunitsaretoberegardedasthestandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.4Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D4483PracticeforEvaluatingPrecisionforTestMethodStandardsintheRubberandCarbonBlackManufacturingIndustriesD6738TestMethodforPrecipitatedSilica—VolatileCon-tent3.SummaryofTestMethod3.1Anionexchangereactioninsilicaispossiblebasedontheacidiccharacterofthesurfacesilanolgroups.AccordingtoSears,3itispossibletodeterminethesurfaceareaofcolloidalsilicaonthebasisofthisionexchangemechanism,aftercertainpreliminarytreatments,bytitrationwithabasicsolu-tion.Theinitialpreliminarytreatmentstepconsistsofexposureofthesilicatoasufficientlyconcentratedsolutionofsodiumchloride(NaCl).AfterthisthesuspensionofsilicaandNaClisback-titratedwithsodiumhydroxidesolution.3.2A1.5gsampleofsilicaisweighedintoa250cm3beakercontaining150cm3NaCls...
