Designation:D696−16StandardTestMethodforCoefficientofLinearThermalExpansionofPlasticsBetween−30°Cand30°CwithaVitreousSilicaDilatometer1ThisstandardisissuedunderthefixeddesignationD696;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoversdeterminationofthecoefficientoflinearthermalexpansionforplasticmaterialshavingcoef-ficientsofexpansiongreaterthan1µm⁄(m.°C)byuseofavitreoussilicadilatometer.Atthetesttemperaturesandunderthestressesimposed,theplasticmaterialsshallhaveanegli-giblecreeporelasticstrainrateorboth,insofarasthesepropertieswouldsignificantlyaffecttheaccuracyofthemea-surements.1.1.1TestMethodE228shallbeusedfortemperaturesotherthan−30°Cto30°C.1.1.2Thistestmethodshallnotbeusedformeasurementsonmaterialshavingaverylowcoefficientofexpansion(lessthan1µm/(m.°C).Formaterialshavingverylowcoefficientofexpansion,interferometerorcapacitancetechniquesarerec-ommended.1.1.3AlternativetechniquecommonlyusedformeasuringthispropertyisthermomechanicalanalysisasdescribedinTestMethodE831,whichpermitsmeasurementofthispropertyoverascannedtemperaturerange.1.2Thethermalexpansionofaplasticiscomposedofareversiblecomponentonwhicharesuperimposedchangesinlengthduetochangesinmoisturecontent,curing,lossofplasticizerorsolvents,releaseofstresses,phasechangesandotherfactors.Thistestmethodisintendedfordeterminingthecoefficientoflinearthermalexpansionundertheexclusionofthesefactorsasfaraspossible.Ingeneral,itwillnotbepossibletoexcludetheeffectofthesefactorscompletely.Forthisreason,thetestmethodcanbeexpectedtogiveonlyanapproximationtothetruethermalexpansion.1.3ThevaluesstatedinSIunitsaretoberegardedasstandard.Thevaluesinparenthesesareforinformationonly.1.4Thisstandarddoesnotpurport...
