Designation:D7997−15StandardPracticeforPolyurethaneRawMaterials:GelTestsforPolyurethaneNon-FoamFormulations1ThisstandardisissuedunderthefixeddesignationD7997;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversproceduresfordeterminingthegeltimesofpolyurethanenon-foamformulationsusingcommer-ciallyavailablegeltestequipment.1.2Definitions,terms,andtechniquesaredescribedalongwithproceduresforcalculatingsampleweights.1.3ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.NOTE1—ThereisnoknownISOequivalenttothisstandard.2.ReferencedDocuments2.1ASTMStandards:2D883TerminologyRelatingtoPlastics3.Terminology3.1Definitions—ForgeneraldefinitionsoftermsusedinthispracticeseeTerminologyD883.3.2DefinitionsofTermsSpecifictoThisStandard:3.2.1gelpoint—theextentofpolymerizationatwhichtheupperlimit,asdefinedbytheprocedurebeingrun,isreached.3.2.2geltime—thetimefromtheinitiationofthereactiontothegelpoint.3.2.3resinblend(formulatedpolyol)—completeingredientformulationwithouttheisocyanatecomponent.3.2.4index—theratiooftheequivalentsoftheisocyanatecomponenttotheequivalentsoftheresinblendofapolyure-thaneformulation.4.SummaryofPractice4.1Thegeltimeofapolyurethanenon-foamformulationisdeterminedbymeasuringthetimerequiredfortheviscosityofthepolymerizingsystemtoincreasetoasetlevelusingagelmeter.ItisrecommendedthatthetorqueofthegelmeterbeverifiedwithagaugecertifiedtoNISTstandards.5.SignificanceandUse5.1GeneralUtility:5.1.1Thispracticeissuitableforresearch,qualitycontrol,speci...
