Designation:D6048−07(Reapproved2018)StandardPracticeforStressRelaxationTestingofRawRubber,UnvulcanizedRubberCompounds,andThermoplasticElastomers1ThisstandardisissuedunderthefixeddesignationD6048;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONThereareanumberoftechniquesusedtoidentifytheprocessabilityofrawrubber,unvulcanizedrubbercompounds,andthermoplasticelastomers(rubberandrubberlikematerials).Mostmeasureasingleaveragedvalueofnon-Newtonianviscositywithsomedoingsoafteraperiodofsteadyshear.Thesetechniquesmaynotprovidesufficientinformationwithregardstotheprocessabilityofaselectedmaterial,asthey:(1)failtoprovideameasureoftheviscoelasticbehavior,and(2)destroystructureoftheselectedmaterialthroughthesteadyshearing.Stressrelaxationtestingprovidesameasureoftheviscoelasticresponseofamaterialoveraperiodoftimewithoutdestroyingthestructureofthesample.Insuchtestingboththeinstantaneousandtime-dependentresponsetoanapplieddeformationaremeasured.Theinformationfromthissingleexperimentcanthenbeusedtoexamineamaterial’sreactiontovariousdifferentprocessconditions.Thereareseveraldifferenttechniquesformeasuringstressrelaxationpropertiesofrubberandrubberlikematerials.Thispracticeservestoprovidethereaderwithsomebackgroundinformationaboutthosetechniquesintermsofthetheoryoftestingandtheinterpretationofresults.Manyconceptsareputforwardthatarenotdiscussedindepth,fortodosowouldrequireatextbook,notapractice.Thereaderisthereforeencouragedtoconsulttheidentifiedreferences.1.Scope1.1Thispracticecoversseveraldifferenttechniquesfordeterminingthestressrelaxationcharacteristicsofrubberandrubberlikematerialsandforthepossibleinterconversionofthisstressrelaxationinformationintodynamicmechanicalproper-ties.1.2Thetechniquesareintendedformaterialshavingstressrelaxationmoduliintherangeof103...
