ASTM_D_2731_-_21.pdf

Designation:D273121Standard Test Method forElastic Properties of Elastomeric Yarns(CRE Type TensileTesting Machines)1This standard is issued under the fixed designation D2731;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 covers the determination of elasticproperties of“as produced”elastomeric yarns made fromrubber,spandex or other elastomers.Elastic properties includeforce at specified elongations,permanent deformation andstress decay.Other hysteresis related properties can be calcu-lated.NOTE1For a method designed specifically for testing rubber threads,refer to Test Method D2433.1.2 This test method is not applicable to covered,wrapped,or core-spun yarns or yarns spun from elastomeric staple.1.3 This test method is applicable to elastomeric yarnshaving a range of 40 to 3200 dtex(36 to 2900 denier).1.4 The values stated in either SI units or U.S.Customaryunits are to be regarded separately as standard.Within the text,the U.S.Customary units are in parentheses.The values statedin each system are not exact equivalents;therefore,eachsystem shall be used independently of the other.1.5 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.1.6 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:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2258 Practice for Sampling Yarn for TestingD2433 Test Methods for Rubber Thread(Withdrawn 2012)3D2591 Test Method for Linear Density of Elastomeric Yarns(Short Length Specimens)D2653 Test Method for Tensile Properties of ElastomericYarns(CRE Type Tensile Testing Machines)D4848 Terminology Related to Force,Deformation andRelated Properties of TextilesD4849 Terminology Related to Yarns and FibersD6717 Test Method for Linear Density of Elastomeric Yarns(Skein Specimens)3.Terminology3.1 For all terminology relating to D13.58,Yarns andFibers,refer to Terminology D4849.3.1.1 The following terms are relevant to this standard:deformation,elastomeric yarn,elongation,force at specifiedelongation,linear density,permanent deformation,stress,stressdecay.3.2 For definitions of other terms related to force anddeformation,refer to Terminology D4848.For all other termsrelated to textiles,refer to Terminology D123.4.Summary of Test Method4.1 A specimen,mounted in a CRE-type tensile machine,isinitially subjected to a series of five loading/unloading cyclesin which the specimen is extended and relaxed between zeroand 75%of the elongation at first filament break(FFB).During the fifth cycle,the specimen is held at the maximumextension point for 30 s,then unloaded to allow a return to itsoriginal gauge length position.The specimen is then subjectedto a sixth load/unload cycle.4.2 Force at specified elongations are calculated from theforce-elongation curve for the first and fifth loadings and forthe fifth unloading.Stress decay is calculated on the fifth cycle.Extension at a specified force is determined on the sixthloading and is used to calculate the permanent deformation.1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.Current edition approved July 1,2021.Published August 2021.Originallyapproved in 1968.Last previous edition approved in 2015 as D273115.DOI:10.1520/D2731-21.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.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.15.Significance and Use5.1 This test method is considered satisfactory for accep-tance testing