1、Designation: E3142 18Standard Test Method forThermal Lag of Thermal Analysis Apparatus1This standard is issued under the fixed designation E3142; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONIn thermal analysis, the temperature of a test specimen is changed while a physical property ismeasured. The measured physical property is the
3、dependent variable and temperature (also measured)is the independent variable. In the majority of thermal analysis apparatus, temperature sensors cannotbe attached directly to the specimen but can only touch the surface or be placed adjacent or close tothe specimen such that the indicated temperatur
4、e will be different to that of the specimen itself. Inconsequence the specimen temperature will lag the indicated temperature upon heating and coolingdue to thermal resistance between sensor and specimen. The larger the test specimen, the greater thethermal lag is likely to be. To obtain the correct
5、 specimen temperature, thermal analysis apparatus istemperature calibrated so that the recorded temperature correctly indicates the specimen temperature.Such temperature calibration compensates for the temperature offset () between the specimentemperature and that of the temperature sensor. This tem
6、perature offset changes linearly withtemperature rate-of-change () (heating or cooling). The slope of this linear relationship is known as“thermal lag” (T/). The thermal lag for an apparatus permits temperature calibration determinedat one temperature rate-of-change to be adjusted to that at other r
7、ates. It is the purpose of this standardto aid the user to determine the thermal lag for an apparatus and to apply that thermal lag tomeasurements made at temperature rates-of-change different from that at which the temperaturecalibration is performed.1. Scope1.1 This test method addresses the depen
8、dence of tempera-ture calibration on the temperature rate-of-change. This testmethod describes the determination of the thermal lag ofthermal analysis apparatus and its application to the modifica-tion of the temperature calibration for that apparatus obtainedat alternative linear temperature rates-
9、of-change.1.2 This test method is applicable, but not limited to, thetemperature calibration of differential thermal analyzers(DTAs), differential scanning calorimeters (DSCs), thermogra-vimetric analyzers (TGAs), thermomechanical analyzers(TMAs), and dynamic mechanical analyzers (DMAs).1.3 The valu
10、es stated in SI units are to be regarded as thestandard. No other units of measurement are included in thisstandard.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
11、 safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopmen
12、t of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE698 Test Method for Kinetic Parameters for ThermallyUnsta
13、ble Materials Using Differential Scanning Calorim-etry and the Flynn/Wall/Ozawa MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzers1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is
14、the direct responsibility of Subcommittee E37.10 onFundamental, Statistical and Mechanical Properties.Current edition approved Jan. 15, 2018. Published February 2018. DOI:10.1520/E3142-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service
15、astm.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 StatesThis international standard was developed in accordance with
16、 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.1E1142 Terminology Relating to Thermophysic
17、al PropertiesE1363 Test Method for Temperature Calibration of Thermo-mechanical AnalyzersE1582 Test Method for Temperature Calibration of Thermo-gravimetric AnalyzersE1867 Test Methods for Temperature Calibration of Dy-namic Mechanical AnalyzersE1970 Practice for Statistical Treatment of Thermoanaly
18、ticalData3. Terminology3.1 Definitions:3.1.1 Terms applicable to this test method and can be foundin Terminologies E473 and E1142 and include the termscalorimeter, differential, differential scanning calorimeter, dif-ferential thermal analysis, dynamic mechanical analysis,temperature, thermal analys
19、is, thermogravimetric analysis,and thermomechanical analysis.3.2 Definitions of Terms Specific to This Standard:3.2.1 temperature offset, nthe difference between the ac-tual specimen temperature and that reported by a temperaturesensor.3.2.2 thermal lag, nthe change in indicated temperatureoffset wi
20、th temperature rate-of-change.4. Summary of Test Method4.1 Following apparatus temperature calibration with areference material at an identified temperature rate-of-change,the temperature offset of the apparatus is measured with thatsample reference material as a function of additional tempera-ture
21、rates-of-change. A display of temperature (T) versustemperature rate-of-change () produces a linear relationshipfrom which the slope (T/) may be obtained. This slopevalue is known as thermal lag.NOTE 1This test method is applicable only to apparatus demonstrat-ing a linear relationship between indic
22、ated temperature and temperaturerate-of-change.4.1.1 The thermal lag may be used to modify the tempera-ture calibration of an apparatus at temperature rates-of-changeother than at which it is calibrated.4.1.2 The thermal lag of an apparatus may change withexperimental conditions such as temperature,
23、 purge gaspressure, purge gas thermal conductivity, or other experimentalconditions.4.1.3 Thermal lag calculations are rarely used for tempera-ture rate-of-change values greater than 10 K/min.5. Significance and Use5.1 Differing temperature rates-of-change may be requiredfor different measurements (
24、for example, Test Method E698).Temperature calibration changes as a function of temperaturerate-of-change. The use of the known thermal lag of anapparatus may be used to adjust the temperature calibration ofthe apparatus obtained at one temperature rate-of-change withthat at another required for a g
25、iven applications. This adjust-ment procedure for temperature calibration is described in 8.1.5.2 This test method may be used in research, qualityassurance, and specification acceptance.6. Interferences6.1 Thermal lag varies with experimental conditions such ascalibration temperature, purge gas pre
26、ssure, purge gas thermalconductivity, etc.6.2 Thermal lag on heating may differ from that on cooling.7. Procedure7.1 Select the appropriate ASTM standard for temperaturecalibration of the apparatus (Test Method E967 for differentialscanning calorimeters or differential thermal analyzers, TestMethod
27、E1582 for thermogravimetric analyzers, Test MethodE1363 for thermomechanical analyzers, or Test MethodsE1867 for dynamic mechanical analyzers).7.2 Perform the procedure described in the calibrationstandard and record the determined temperature as T1and theobserved temperature rate-of-change as 1.NOT
28、E 2The temperature rate-of-change shall be measured. Use of theprogrammed temperature rate-of-change is not satisfactory.7.3 Perform the procedure described in the calibrationstandard at two additional heating rates other than 1repre-senting the low, medium, and high heating rate capability of theap
29、paratus. Record these additional data pair values as T2and2, and T3and 3.NOTE 3The reliability of the results of this determination areincreased with increased temperature rate-of-change.7.4 Prepare a display of the values for 7.2 and 7.3, withT-values on the Y-axis and the corresponding -values on
30、theX-axis.NOTE 4The display shall approximate a straight line. If not, then thistest method is not applicable.7.5 Using linear regression (see Practice E1970), determineand report the slope (T/) and its standard deviation(T/) of the best-fit straight line for these three points.NOTE 5The appropriate
31、 SI units for this value is seconds. However,it is easier to leave this value in the units of minutes for the purpose of itsapplication. Alternatively, one may use the conversion factor of 1 min =60 s in the calculations.NOTE 6The thermal lag is known to vary with temperature. If amultipoint tempera
32、ture calibration is used, then thermal lag shall bedetermined at each calibration temperature.8. Calculation and Interpretation of Results8.1 The value of the thermal lag (T/) determined in 7.5may be used to determine the off-set value applied to thetransition temperature obtained at temperature rat
33、es-of-changeother than that specified in the corresponding temperaturecalibration standard using Eq 1 and Eq 2. 5 T ! 3 s2 o! (1)Tt5 To1 (2)where:s= the temperature rate-of-change at which the appa-ratus was temperature calibrated, K/min,E3142 182o= the temperature rate-of-change for the observedmea
34、surement, K/min, = temperature offset due to thermal lag, KT/ = thermal lag, min, obtained from linear regression,To= observed transition temperature, K, andTt= true transition temperature, K.NOTE 7The values for have direction. Heating rates are positive andcooling rates are negative. This conventi
35、on gives direction to as well.9. Report9.1 Report thermal lag (T/) and its imprecision(glyph507T/glyph507) or relative imprecision (T/(T/).10. Precision and Bias10.1 This standard is used to determine the bias introducedby the thermal lag effect of a thermal analysis measurementand to correct for th
36、at effect. The precision of temperatureoffset may be estimated by the principal of propagation ofuncertainties by the relative standard deviation of the thermallag. (3) 5 T 3 !21 T 3 !2#12(4)Tt5 To!21 !2#12(5)where:To= the observed transition temperature, K,To= standard deviation of the absolute tem
37、peraturemeasurement, K (obtained from the precisionstate of the respective calibration standard in 7.1),T/ = thermal lag, min,T/ = the thermal lag standard deviation, min, obtainedfrom linear regression, = s o, = standard deviation of glyph507, and = standard deviation of the temperature rate-of-cha
38、nge measurement.10.1.1 The value of is often much smaller than T and sothe imprecision in the corrected temperature Ttis equivalent tothe imprecision of the uncorrected temperature To.10.2 An interlaboratory study is planned from 20182023 toestablish within laboratory repeatability, between laborato
39、ryreproducibility, and bias. Anyone wishing to participate in thisinterlaboratory study should contact the Committee E37 StaffManager at ASTM International Headquarters.10.3 Precision:10.3.1 A limited repeatability study was performed in usingfour calibration materials in a single laboratory. The re
40、sults ofthat study are presented in Table 1 and have been filed atASTM Headquarters.310.3.2 Within laboratory variability may be described usinghe repeatability value (r) obtained by multiplying the standarddeviation by 2.8. The repeatability value estimates the 95 %confidence limit. That is, two re
41、sults obtained in the samelaboratory (using the same apparatus, on the same specimen bythe same operator, closely spaced in time) have a 95 %probability of being within the repeatability value of eachother.10.3.3 Between laboratory variability may be describedusing the reproducibility value (R) obta
42、ined by multiplying thereproducibility standard deviation by 2.8. The reproducibilityvalue estimates the 95 % confidence limit. That is, two resultsobtained in different laboratories, or using different apparatus,or by different operators, or at different times, have a 95 %probability of being withi
43、n the repeatability value of eachother.10.3.4 The reproducibility of this test method has not yetbeen determined (see 10.2).10.4 Bias:10.4.1 Bias is the difference between a mean determinedvalue and an acceptable reference value.10.4.2 The bias of this test method has not been determined(see 10.2).1
44、1. Keywords11.1 calibration; differential scanning calorimetry; differen-tial thermal analysis; dynamic mechanical analysis; tempera-ture calibration; thermal lag; thermogravimetric analysis; ther-momechanical analysisASTM International takes no position respecting the validity of any patent rights
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47、eceive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM I
48、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or th
49、rough the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E37-1051. ContactASTM CustomerService at serviceastm.org.TABLE 1 Single Laboratory Repeatability for Differentia
