ASTM_E_2958_-_14.pdf

Designation:E295814Standard Test Methods forKinetic Parameters by Factor Jump/ModulatedThermogravimetry1This standard is issued under the fixed designation E2958;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 These test methods describe the model-free determina-tion of Arrhenius activation energy by thermogravimetry usingthe factor jump(1)2(Method A)or modulated thermogravim-etry(2)(Method B)techniques.With the assumption of afirst-order kinetic model,the pre-exponential factor is addition-ally determined.1.2 These test methods are applicable to materials withwell-defined decomposition profiles,namely,a smooth,con-tinuous mass change.1.3 These test methods are applicable to decompositionoccurring in the range from 400 K to 1200 K(nominally 100Cto 900C).The temperature range may be extended dependingon the instrumentation and material used.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 There is no ISO standard similar to this standard.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:3E473 Terminology Relating to Thermal Analysis and Rhe-ologyE1142 Terminology Relating to Thermophysical PropertiesE1582 Practice for Calibration of Temperature Scale forThermogravimetryE1641 Test Method for Decomposition Kinetics by Thermo-gravimetry Using the Ozawa/Flynn/Wall MethodE1877 Practice for Calculating Thermal Endurance of Ma-terials from Thermogravimetric Decomposition DataE1970 Practice for Statistical Treatment of ThermoanalyticalDataE2040 Test Method for Mass Scale Calibration of Thermo-gravimetric AnalyzersE2550 Test Method for Thermal Stability by Thermogravi-metry3.Terminology3.1 DefinitionsTechnical terms used in this test methoddefined in Terminologies E473 and E1142 include Arrheniusequation,activation energy,Celsius,failure criterion,pre-exponential factor,reaction order,and thermogravimetricanalysis.4.Summary of Test Method4.1 These test methods consist of heating a test specimenweighing a few milligrams at a heating rate of about 1 K/minwith a superimposed step-and-hold(factor jump)or sinusoidal(modulated)temperature program through the decompositiontemperature region.The specimen mass rate-of-change iscontinuously calculated and recorded as a function of tempera-ture.The activation energy is then determined from the massrate-of-change at two(or more)closely spaced temperatureregions.The activation energy thus determined is based on noassumed reaction model or mechanism and thus is model free.4.2 Assuming a first-order reaction model(n=1),theadditionalreactionparameterlogarithm-of-the-pre-exponential-factor(lnZ)is additionally determined.4.3 Activationenergyandlogarithm-of-the-pre-exponential-factor may be displayed as a function of averagetemperature or conversion to provide additional informationabout the constancy of the decomposition reaction relative tothese experimental parameters.5.Significance and Use5.1 The activation energy may be used to calculate thermalendurance and an estimate of the lifetime of the material atspecified temperatures using Test Method E1877.1These test methods are under the jurisdiction of ASTM Committee E37 onThermal Measurements and is the direct responsibility of Subcommittee E37.01 onCalorimetry and Mass Loss.Current edition approved April 1,2014.Published June 2014.DOI:10.1520/E2958-14.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For 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 5.2 The kinetic parameters determine by this test methodmay be used in quality assurance,research and development.5.3 The kinetic parameters of activation energy and loga-rithm of the pre-exponential factor determined by this methodhave little intrinsic value in themselves.Most practical appli-cations of this information,such as lifetime estimation(seeTest Method E1877),also require an estimation of the preci-sion of the respective values.Determination of that precisionby replicated determination is a non-manditory part of thisstandard.6.Apparatus6.1 The essential equipment required to provide minimumthermogravimetric analytical capability of this test methodin