ASTM_D_7426_-_08_2013.pdf

Designation:D742608(Reapproved 2013)Standard Test Method forAssignment of the DSC Procedure for Determining Tgof aPolymer or an Elastomeric Compound1This standard is issued under the fixed designation D7426;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 assignment of the glasstransition temperatures(Tg)of materials using differentialscanning calorimetry.1.2 This test method is applicable to amorphous materials,including thermosets or semicrystaline materials containingamorphous regions,that are stable and do not undergo decom-position or sublimation in the glass transition region.1.3 The normal operating temperature range is from 120to 500C.The temperature range may be extended,dependingupon the instrumentation used.1.4 Computer or electronic-based instruments,techniques,or data treatment equivalent to this test method may also beused.NOTE1Users of this test method are expressly advised that all suchinstruments or techniques may not be equivalent.It is the responsibility ofthe user of this standard to determine the necessary equivalency prior touse.1.5 ISO 113572 is equivalent to this test method.1.6 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.7 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:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE1142 Terminology Relating to Thermophysical Properties2.2 ISO Standard:3ISO 113572 Differential Scanning Calorimetry(DSC)-Part2 Determination of Glass Transition Temperature3.Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test methodand can be found in Terminology E473 and TerminologyE1142:differential scanning calorimetry(DSC),differentialthermal analysis(DTA),glass transition,glass transitiontemperature(Tg),and specific heat capacity.3.2 Definitions of Terms Specific to This Standard:3.2.1 There are commonly used transition points associatedwith the glass transition region.(See Fig.1.)3.2.2 extrapolated end temperature(Te),C,nthe point ofintersection of the tangent drawn at the point of greatest slopeon the transition curve with the extrapolated baseline followingthe transition.3.2.3 extrapolated onset temperature(Tf),C,nthe pointof intersection of the tangent drawn at the point of greatestslope on the transition curve with the extrapolated baselineprior to the transition.3.2.4 inflection temperature(Ti),C,nthe point on thethermal curve corresponding to the peak of the first derivative(with respect to time)of the parent thermal curve.This pointcorresponds to the inflection point of the parent thermal curve.3.2.5 midpoint temperature(Tm),C,nthe point on thethermal curve corresponding to12the heat flow differencebetween the extrapolated onset and extrapolated end.3.2.5.1 DiscussionThe inflection point temperature(Ti)is1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved Nov.1,2013.Published January 2014.Originallyapproved in 2008.Last previous edition approved in 2008 as D7426 08.DOI:10.1520/D7426-08R13.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 most easily determined from the first derivative curve and willbe used as the glass transition temperature(see Fig.1).3.2.6 Two additional transition points are sometimes iden-tified and are defined as follows:3.2.7 temperature of first deviation(To),C,nthe point offirst detectable deviation from the extrapolated baseline prior tothe transition.3.2.8 temperature of return to baseline(Tr),C,nthe pointof last deviation from the extrapolated baseline beyond thetransition.4.Summary of Test Method4.1 This test method involves continuously monitoring thediffere