Designation:D5669–95StandardTestMethodforRubber—EvaluationofResidualUnsaturationinHydrogenatedNitrileRubber(HNBR)byCuremeterTesting1ThisstandardisissuedunderthefixeddesignationD5669;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversatechniqueforevaluatingaparameter,derivedfromcuremetertestingofastandardhydro-genatednitrilerubber(HNBR)formulation,thatisrelatedtothepercentresidualunsaturationoftheHNBR.Thestandardmaterials,testformulation,andmixingprocedurearefullydescribed.ThistestmethodisapplicabletoallgradesofHNBRintherawunvulcanizedstate.1.2Theevaluationoftheunsaturationparameter,desig-natedbyUP,isbasedonspecialregressionequationsdevel-opedfromthemeasuredvaluesfortwocuremeterparametersversusthepercentunsaturationmeasuredbyinfraredspectro-photometryasdefinedbyTestMethodD5670.ThedatausedforthisarecontainedinAppendixX1.1.2.1TheuseofacuremeterandastandardformulationtoevaluatetheresidualunsaturationinHNBRhastheadvantageofbeingarelativelysimpletest,availabletomostrubbertestinglaboratories.ThedisadvantageliesinthenonlinearrelationshipbetweenHNBRunsaturationandthemeasuredcuremeterparametersofscorchtime,tS1andmaximumcuremetertorque,MH.1.2.2TheuseofUP,whichiscalculatedfromascorchtimeparameterandamaximumtorqueparameter,bothofwhichareobtainedfromTableA1.1permitsthedevelopmentofamorerealisticrelationshipoftheunsaturationlevelsamongagroupofHNBRsamplesthanthelessdefinitivetechniqueofsimpleranking.Therankingtechniqueisnotdefinitivebecausetherelationshipbetweenthecuremeterparametersandtheunsat-urationishighlynonlinear.CuremeterrankingofaseriesofHNBRsamplesatlowtrueunsaturationcomparedtotherankingofaseriesofsamplesathightrueunsaturation,maygivemisleadingindicationsofunsaturationdifferencesamongthegroupofrubbers.1.2.3If,U,theunsaturationinpercento...
