Designation:D5523−21StandardTestMethodforPolyurethaneRawMaterials:AciditybyArgentometricDeterminationofHydrolyzableChlorineinMonomeric,AromaticIsocyanates1ThisstandardisissuedunderthefixeddesignationD5523;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodmeasuresthehydrolyzablechlorinecontentofmonomeric,aromaticisocyanatesusedaspolyure-thanerawmaterialsandexpressesitasHClacidity.Thetestmethodisapplicabletotoluenediisocyanate(TDI)andmono-mericmethylenedi(phenylisocyanate),knownasMDI.Themainsourcesofhydrolyzablechlorineand,therefore,acidityinmonomericaromaticisocyanatesarecarbamylchlorides,acidchlorides,anddissolvedphosgene.Allofthesecompoundsreactwithalcoholsandwatertoformhydrochloricacid.1.2ThistestmethodappliesonlytomonomericisocyanatesinwhichalloftheacidityisderivedfromspeciesthatgenerateHClonsolvolysis.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.NOTE1—ThereisnoknownISOequivalenttothisstandard.1.5Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D883TerminologyRelatingtoPlasticsE456TerminologyRelatingtoQualityandStatisticsE2935PracticeforConductingEquivalenceTestsforCom-paringTestingProcesses3.Terminology3.1Definitions—TermsusedinthisstandardaredefinedinaccordancewithTerminologyD883,unlessotherwisespe...
