ASTM_D_4974_-_04_2011.pdf

Designation:D497404(Reapproved 2011)Standard Test Method forHot Air Thermal Shrinkage of Yarn and Cord Using aThermal Shrinkage Oven1This standard is issued under the fixed designation D4974;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 measurement of shrinkageof yarns and cords when exposed in a thermal shrinkage oven.1.2 This test method is applicable to yarns and cords madeof nylon,polyester,and other polymers not detrimentallyaffected by the temperature used and with linear densities in therange from 20 to 700 tex(180 to 6300 denier).1.2.1 Yarns or cords for testing may be taken from yarn orcord packages or from fabrics.1.3 This test method shows values in both SI and inch-pound units.SI is the technically correct name for the systemof units known as the International System of Units.Inch-pound units is the technically correct name for the customaryunits used in the United States.The values stated in eitheracceptable metric units or other units shall be regardedseparately as standard.The values expressed in each systemmay not be exact equivalents;therefore,each system must beused independently of each other,without combining values inany way.Referee decisions are to use SI units.1.4 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.Specific hazardstatements are given in Section 8.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD885 Test Methods for Tire Cords,Tire Cord Fabrics,andIndustrial Filament Yarns Made from ManufacturedOrganic-Base FibersD1776 Practice for Conditioning and Testing TextilesD6477 Terminology Relating to Tire Cord,Bead Wire,HoseReinforcing Wire,and Fabrics3.Terminology3.1 Definitions:3.2 For definitions of terms relating to tire cord,bead wire,hose wire,and tire cord fabrics,refer to Terminology D6477.3.2.1 The following terms are relevant to this standard:greige cord,in tire cords,standard atmosphere for testingtextiles,thermal shrinkage,tire cord.3.3 For definitions of other terms related to textiles,refer toTerminology D123.3.3.1 The following terms are relevant to this standard:yarn.4.Summary of Test Method4.1 A relaxed,conditioned specimen of yarn or cord issubjected to dry heat for a specified time while under aspecified tension.The percent shrinkage is read directly from ascale or display on the instrument while the specimen is stillunder tension and exposed to heat.5.Significance and Use5.1 This test method may be used for the acceptance testingof commercial shipments of yarns and cords.Caution isadvised because yarn and cord may contract in length over aperiod of time due to room temperature retraction.Thermalshrinkage values are reduced proportionately by the amount ofroom temperature retraction.NOTE1Experience,especially with nylon,shows that yarn retraction,which may be observed directly as shortening of length(or indirectly asdenier increase),will occur in unrestrained yarn or cord that is not atequilibrium(equilibrium in this case being defined as essentially zerothermal shrinkage yarn or fully relaxed yarn).Normally,retractive forcesare present in most wound packages of yarn and cord;thus,unrestrainedyarn near the surface is likely,with time,to undergo some retraction.Afterretraction,such yarns exhibit lower thermal shrinkage values than yarn orcord deeper within the package.The opposite condition of yarn on thesurface exists with yarn or cord wound against or near a rigid packagecore,such as a metal or hardwood wind-up spool.Such core yarn or cordcannot move against this restraint,and thus,will exhibit thermal shrinkagevalues even several weeks later near to those which were measured1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.19 on Industrial Fibers andMetallic Reinforcements.Current edition approved Jan.1,2011.Published March 2011.Originallyapproved in 1999.Last previous edition approved in 2004 as D497404.DOI:10.1520/D4974-04R11.2For 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 immediately from the surface of the freshly wound package.Elevatedhumidity will accelerate retraction of unrestrained yarn,but moisturecontent in itself will have little influence on