Designation:D7444−11StandardPracticeforHeatandHumidityAgingofOxidativelyDegradablePlastics1ThisstandardisissuedunderthefixeddesignationD7444;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticeindicateshowtotesttheoxidativedegra-dationcharacteristicsofplasticsthatdegradeintheenviron-mentunderatmosphericpressureandthermalandhumiditysimulations,only,intheabsenceofanyselecteddisposalenvironmentsuchassoil,landfill,orcompost.Thispracticedoesnotbyanyextensionorextrapolationofdataorresultsgeneratedindicatethatsuchplasticsaresuitablefororwilldegradeondisposalinthesesaidenvironments.Itisparticu-larlynotedthatinrealworldenvironmentssuchassoil,compostandlandfilloxidations,iftheyoccur,willpredomi-nantlybeunderconditionswhereotherinterferingingredientsarepresentand,inthecaseoflandfill,atsub-atmosphericoxygenconcentrations.Thispractice,therefore,canonlyresultinarelativeorderingofthepotentialforoxidationofplasticmaterialsundertheconditionstested,whicharenotalwaysreflectiveoftheirbehaviorinaparticularrealworlddisposalsystems.Predictionoftheoxidationofaplasticunderrealworlddisposalconditionsisanessentialfurthertestinginappropriatemethodologies,suchasTestMethodD5338forcomposting.Noclaimscanbemadeforrealworldbehaviorbasedonthispractice.1.2Thispracticeisonlyintendedtodefinetheexposureconditionsofplasticsatvarioustemperaturesinairatatmo-sphericpressureundercontrolledhumiditylevelsforextendedperiodsoftime.Thehumiditylevelsandtemperaturerangesareselectedtobewithinthevariablerecordedseasonalranges(upperandlowerlevels)generallyobservedindisposalsiteswheresuchplasticsarediscarded.Forexample:soil(15to40percentmoisture);landfill(35to60percentmoisture),andcompost(45to70percentmoisture).Itisoptionaltoexposetheplasticatzerohumidity,ifcomparisonwithspecifiedhumidityrange...
