ASTM_D_6048_-_07_2012.pdf

Designation:D604807(Reapproved 2012)Standard Practice forStress Relaxation Testing of Raw Rubber,UnvulcanizedRubber Compounds,and Thermoplastic Elastomers1This standard is issued under the fixed designation D6048;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.INTRODUCTIONThere are a number of techniques used to identify the processability of raw rubber,unvulcanizedrubber compounds,and thermoplastic elastomers(rubber and rubberlike materials).Most measure asingle averaged value of non-Newtonian viscosity with some doing so after a period of steady shear.These techniques may not provide sufficient information with regards to the processability of aselected material,as they:(1)fail to provide a measure of the viscoelastic behavior,and(2)destroystructure of the selected material through the steady shearing.Stress relaxation testing provides a measure of the viscoelastic response of a material over a periodof time without destroying the structure of the sample.In such testing both the instantaneous andtime-dependent response to an applied deformation are measured.The information from this singleexperiment can then be used to examine a materials reaction to various different process conditions.There are several different techniques for measuring stress relaxation properties of rubber andrubberlike materials.This practice serves to provide the reader with some background informationabout those techniques in terms of the theory of testing and the interpretation of results.Manyconcepts are put forward that are not discussed in depth,for to do so would require a textbook,nota practice.The reader is therefore encouraged to consult the identified references.1.Scope1.1 This practice covers several different techniques fordetermining the stress relaxation characteristics of rubber andrubberlike materials and for the possible interconversion of thisstress relaxation information into dynamic mechanical proper-ties.1.2 The techniques are intended for materials having stressrelaxation moduli in the range of 103to 108Pa(0.1 to 1.5 104psi)and for test temperatures from 23 to 225C(73 to 437F).Not all measuring apparatus may be able to accommodate theentire ranges.These techniques are also intended for measure-ment of materials in their rubbery or molten states,or both.1.3 Differences in results will be found among the tech-niques.Because of these differences,the test report needs toinclude the technique and the conditions of the test.Thisinformation will allow for resolving any issues pertaining tothe test measurements.1.4 The generalized descriptions of apparatus are based onthe measurement of force as a function of time.Mathematicaltreatment of that relationship produces information that can berepresentative of material properties.Mathematical transfor-mation of the force measurements will first yield stressrelaxation moduli with subsequent transformation producingdynamic mechanical properties.1.5 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are provided forinformation only.1.6 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1566 Terminology Relating to Rubber1This practice is under the jurisdiction of Committee D11 on Rubber and is thedirect responsibility of Subcommittee D11.12 on Processability Tests.Current edition approved May 1,2012.Published July 2012.Originally approvedin 1996.Last previous edition approved in 2007 as D6048 07.DOI:10.1520/D6048-07R12.2For 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 States1 D1646 TestMethodsforRubberViscosity,StressRelaxation,andPre-VulcanizationCharacteristics(Mooney Viscometer)D5992 Guide for Dynamic Testing of Vulcanized Rubberand Rubber-Like Materials Using Vibratory MethodsE328 Test Methods for Stress Relaxation for Materials andStructures3.Terminology3.1 Definitions:3.1.1 Each of the following terms applies to linear vis-coelastic behavior.The terms have been arranged logically sothat simple basic terms are defined first and are then used todefine more complex terms that either contain the simple termsor depend upon the simple terms for comprehension.Someterms in this section have been excerpted from TerminologyD1566,Guide D5992,or Test Me