Designation:D5944–96StandardGuideforDescribingtheGeneralPrinciplesforDeterminingtheTemperatureofDeflectionofPlasticsUnderLoad1ThisstandardisissuedunderthefixeddesignationD5944;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidecoversproceduresfordeterminationofthetemperatureofdeflectionunderload(bendingstressunderthree-pointloading)ofdifferenttypesofmaterial.1.2ThisguideisidenticaltoISO75-1.ThisguideiscomparabletoTestMethodD648,butneitherstandardshouldbesubstitutedfortheother.Thetwostandardsmaydifferwithrespecttotestspecimendimensions,testspecimencondition-ing,testequipment,testingconditions,etc.Thetwoproceduresmaynotgivethesameresults.1.3Theproceduresspecifiedaresuitableforassessingthebehaviorofdifferenttypesofmaterialatelevatedtemperatureunderloadataspecifiedrateoftemperatureincrease.Theresultsobtaineddonotnecessarilyrepresentmaximumusetemperaturesbecause,inpractice,essentialfactorssuchastime,loadingconditions,andnominalsurfacestressmaydifferfromthetestconditions.1.4ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D648TestMethodforDeflectionTemperatureofPlasticsUnderFlexuralLoad22.2ISOStandards:3ISO75-1DeterminationofTemperatureofDeflectionUn-derLoad—Part1:GeneralTestMethodISO291:1977Plastics—StandardAtmospheresforCondi-tioningandTesting3.Terminology3.1Definitions:3.1.1deflection—thedistance,atmid-span,overwhichthetoporbottomsurfaceofatestspecimendeviates,duringflexure,fromitsoriginalposition.Itisexpressedinmil...
