Designation:D5051−06(Reapproved2021)´1StandardTestMethodforRubberCompoundingMaterials—BenzothiazylDisulfide(MBTS)—Assay1ThisstandardisissuedunderthefixeddesignationD5051;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—Corrected3.2,6.2,9.2,and12.2editoriallyinNovember2021.1.Scope1.1Thistestmethodcoversthedeterminationofassayofbenzothiazyldisulfide(MBTS).ItisbasedonatitrationoffreeiodineliberateduponreductionofMBTS,withpotassiumiodide(KI)inacidmedium.1.2Theassayisdeterminedasmasspercent.1.3Free2-mercaptobenzothiazole(MBT)contentisnotdetermined.1.4ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.6Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D1193SpecificationforReagentWaterD4483PracticeforEvaluatingPrecisionforTestMethodStandardsintheRubberandCarbonBlackManufacturingIndustries3.SummaryofTestMethod3.1Inanacidmedium,MBTSisreducedwithKItoMBTandfreeiodine.Thefreeiodineistitratedwithstandardsodiumthiosulfatesolution.3.2MBTSissparinglysolubleinanyorganicsolvent,whileMBT,formedduringthereactionofMBTSwithKI,isverysoluble.Therefore,afterreagentsareaddedasindicatedintheprocedure,continuetostiruntilallMBTShasreacted.4.SignificanceandUse4.1ThetestmethodisdesignedtoassessthepurityofMBT...
