Designation:D4876–98StandardTestMethodforPolyurethaneRawMaterials:DeterminationofAcidityofCrudeorModifiedIsocyanates1ThisstandardisissuedunderthefixeddesignationD4876;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethoddeterminesthetotalacidity,expressedasHCl,ofcrudeormodifiedisocyanates.Thetestmethodisapplicabletoproductsderivedfromtoluenediisocyanate,methylene-bis-(4-phenylisocyanate),andpolymethylenepolyphenylisocyanates.(SeeNote1.)1.2ThevaluesstatedinSIunitsaretoberegardedasthestandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.Forspecifichazardsstatementssee7.1andNote2.NOTE1—ThereisnoequivalentISOstandard.2.ReferencedDocuments2.1ASTMStandards:D841SpecificationforNitrationGradeToluene2D883TerminologyRelatingtoPlastics3D1193SpecificationforReagentWater4E180PracticeforDeterminingthePrecisionofASTMMethodsforAnalysisandTestingofIndustrialChemicals5E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod63.Terminology3.1Definitions—FordefinitionsoftermsusedinthistestmethodseeTerminologyD883.4.SummaryofTestMethod4.1Labilechlorinecompoundsreactwithmethanoltoliberatehydrogenchloride.Thehydrogenchlorideistitratedpotentiometricallywithalcoholicpotassiumhydroxide.5.SignificanceandUse5.1Thesetestmethodscanbeusedforresearchorforqualitycontroltocharacterizeisocyanatesusedinpolyurethaneproducts.6.Apparatus6.1PotentiometricTitratororpHMeter.6.2CalomelElectrode.6.3GlassElectrode.6.4LungePipet,oranyweighingdevicesuitableforweigh-ingaliquidsamplebydifferencetothenearest0.001g.6.5MagneticStirrer.6.6Thermometer,−10to100°Crange.7...
