ASTM_D_8363_-_20.pdf

Designation:D836320Standard Test Method forRubberStress Relaxation in Tension Under Non-Isothermal Conditions1This standard is issued under the fixed designation D8363;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method is used to determine the non-isothermalstress relaxation,also known as temperature scanning stressrelaxation(TSSR).Stress relaxation is a characteristic behaviorof rubber materials.1.2 UnitsThe values stated in SI units are to be regardedas the standard.No other units of measurement are included inthis standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D3182 Practice for RubberMaterials,Equipment,and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD412 Test Methods for Vulcanized Rubber and Thermoplas-tic ElastomersTensionD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3.Terminology3.1 Definitions:3.1.1 standard laboratory temperature,ntemperature of23 6 2C(73.4 6 3.6F).3.1.2 stress relaxation,ndecrease in stress after a giventime at constant strain.4.Summary of Test Method4.1 This test method provides a procedure for non-isothermal stress relaxation as a function of temperature atconstant elongation and at a specific heating rate.4.2 This test method is useful for the accelerated determi-nation of the thermal mechanical behavior of a rubber,forexample,its ageing behavior or the parameters describing thelimits for a thermal application of the material.5.Significance and Use5.1 Non-isothermal stress relaxation,also known as tem-perature scanning stress relaxation,performed at a specificheating rate,delivers a set of parameters useful to specify theproperties of thermo-plastic elastomers.It can also characterizethe deterioration of the cross-linked rubber network in areasonable testing time of a few hours.5.2 Stress relaxation tests are typically performed as time-dependent experiments at constant strain and temperature.It isknown that temperature has a strong influence on the relaxationtime of rubber.When evaluating ageing behavior such asdeterioration of the network,a reliable test using isothermalstress relaxation requires extremely long testing times,forexample,days or weeks depending on the application.6.Apparatus6.1 Tensile tester equipped with an oven according to TestMethods D412 consisting of an electrically driven linearextension actuator equipped with two grips and capable ofholding the test piece without slipping at a fixed extendedlength within 61%accuracy.It shall be able to measure andrecord the force acting on the test piece with an accuracy of 61%.6.2 The grips shall be positioned inside the oven for testingof a single test piece.The oven shall maintain a stable heating1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand Rubber-like Materials and is the direct responsibility of Subcommittee D11.10on Physical Testing.Current edition approved Nov.1,2020.Published December 2020.DOI:10.1520/D8363-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1rate of at least 2 6 0.05 K/min(C/min)at the narrow positionof the dumbbell during the test.The oven is equipped with atemperature sensor placed close to the surface of the testspecimen.7.Test Specimen7.1 The test specimens shall be dumbbells with a standardthickness of 2.0 6 0.2 mm and a length of 75 6 0.5 mm.Thedimension of the narrow portion of dumbbells shall be 2.0