ASTM E1877-2000(2010) Standard Practice for Calculating Thermal Endurance of Materials from Thermogravimetric Decomposition Data《从热解重量分解数据计算材料的耐热性的标准实施规程》.pdf

1、Designation: E1877 00 (Reapproved 2010)Standard Practice forCalculating Thermal Endurance of Materials fromThermogravimetric Decomposition Data1This standard is issued under the fixed designation E1877; the number immediately following the designation indicates the year oforiginal adoption or, in th

2、e 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 practice covers additional treatment of the Arrhe-nius activation energy data det

3、ermined by Test Method E1641to develop a thermal endurance curve and derive a relativethermal index for materials.1.2 This practice is generally applicable to materials with awell-defined decomposition profile, namely a smooth, continu-ous mass change with a single maximum rate.1.3 The values stated

4、 in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 There is no ISO standard equivalent to this practice.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use

5、r 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:2E1641 Test Method for Decomposition Kinetics by Ther-mogravimetry3. Terminology3.1 Definitions of Terms Specific

6、 to This Standard:3.1.1 failure, nchange in some chemical, physical, me-chanical, electrical or other property of sufficient magnitude tomake it unsuitable for a particular use.3.1.2 failure temperature (Tf), nthe temperature at whicha material fails after a selected time.3.1.3 relative thermal inde

7、x (RTI), na measure of thethermal endurance of a material when compared with that of acontrol with proven thermal endurance characteristics.3.1.3.1 DiscussionThe RTI is also considered to be themaximum temperature below which the material resistschanges in its properties over a defined period of tim

8、e. In theabsence of comparison data for a control material, a time-to-failure of 60 000 h has been arbitrarily selected for measuringRTI. The RTI is therefore, the failure temperature, Tf, obtainedfrom the thermal endurance curve.4. Summary of Practice4.1 The Arrhenius activation energy obtained fro

9、m TestMethod E1641 is used to construct the thermal endurancecurve of a material from which an estimate of lifetime atcertain temperatures may be obtained.5. Significance and Use5.1 Thermogravimetry provides a rapid method for thedetermination of the temperature-decomposition profile of amaterial.5.

10、2 This practice is useful for quality control, specificationacceptance, and research.5.3 This practice shall not be used for product lifetimepredications unless a correlation between test results and actuallifetime has been demonstrated. In many cases, multiplemechanisms occur during the decompositi

11、on of a material,with one mechanism dominating over one temperature range,and a different mechanism dominating in a different tempera-ture range. Users of this practice are cautioned to demonstratefor their system that any temperature extrapolations are tech-nically sound.6. Calculation6.1 The follo

12、wing values obtained by Test Method E1641are used to calculate thermal endurance, estimated thermal lifeand failure temperature.6.1.1 The following definitions apply to 6.1 and 6.3:6.1.1.1 E = Arrhenius activation energy (J/mol),6.1.1.2 R = Universal gas constant (= 8.314 510 J/(mol K),6.1.1.3 b = H

13、eating rate (K/min),6.1.1.4 b8 = Heating rate nearest the mid-point of theexperimental heating rates (K/min),6.1.1.5 a = Approximation integral taken from Table 1,6.1.1.6 a = Constant conversion value,1This practice is under the jurisdiction of Committee E37 on Thermal Measure-ments and is the direc

14、t responsibility of Subcommittee E37.10 on Fundamental,Statistical and Mechanical Properties.Current edition approved July 1, 2010. Published August 2010. Originallyapproved in 1997. Last previous edition approved in 2005 as E1877 00 (2005).DOI: 10.1520/E1877-00R10.2For referenced ASTM standards, vi

15、sit 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-

16、2959, United States.6.1.1.7 tf= Estimated thermal life for a given value of a(min),6.1.1.8 Tc= Temperature for the point of constant conver-sion for b (K), and6.1.1.9 Tf= Failure Temperature for a give value of a (K).NOTE 1The precision of the calculation in this practice are exponen-tially dependen

17、t on the uncertainty of activation energy value used. Careshould be taken to use only the most precise values of E.6.2 Use Eq 1 or Eq 23and trial values of Tfto plot thelogarithm of estimated thermal life (tf) versus reciprocal of Tfas, by example, shown in Fig. 1.log tf5 E / 2.303 RTf! 1 log E /R b

18、!# a (1)Tf5 E / 2.303 R log tf log $E / R b! 1 a! (2)6.2.1 To calculate tf, select the value for the temperature atthe constant conversion point (Tc) for a heating rate (b) nearestthe mid-point of the experimental heating rates. Use this value,along with the Arrhenius activation energy (E) to calcul

19、ate thequantity E/(RTc) to select the value in Table 1.4, 5, 6Arbitrarilyselect a number of temperatures in the region of the chosenpercent mass loss, indicative of failure, in the mass changecurve at the midpoint heating rate. Calculate the logarithm ofthe thermal life from Eq 1. Plot the thermal e

20、ndurance curve,as shown in Fig. 1, with thermal life on the ordinate andreciprocal of absolute temperature on the abscissa.NOTE 2The values for E and b may be obtained by the proceduredescribed in Test Method E1641.6.3 The thermal endurance of two or more materials may becompared by calculating the

21、RTI for each material. To computeRTI for each material; select some common thermal life forcomparison, a typical value may be 60 000 h (6.8 years), insertthat value (in minutes) and the appropriate activation energyfor each material into Eq 2 to obtain Tf. This value oftemperature is called the “rel

22、ative thermal index (RTI) at thespecified time”. Materials with greater resistance to thermaldecomposition will have a larger RTI.7. Report7.1 Report the following information:7.1.1 If data other than that generated by Test MethodE1641 is used in these calculations, then include a descriptionof the

23、data source in the report,7.1.2 Designation of the material under test, including thename of the manufacturer, the lot number, and supposedchemical composition when known, and7.1.3 The calculated thermal life (tf) and RTI values.7.1.4 The specific dated version of this practice that is used.8. Preci

24、sion and Bias78.1 The precision and bias of these calculations depend onthe precision and bias of the kinetic data used in them. Toprovide an example of the precision expected, thermal life wascalculated by the procedure in this practice using data forpoly(tetrafluoroethylene) from the interlaborato

25、ry study con-ducted to develop the precision and bias statement for TestMethod E1641. Extreme values of thermal life were calculatedusing an arbitrarily chosen value for temperature of 600 K andthe extreme values of E corresponding to the 95 % confidencelevel from that interlaboratory study. The res

26、ulting calculatedextreme values were 9 years and 3700 years for this material.3Krizanovsky, L., and Mentlik, V., Journal of Thermal Analysis, Vol 13, 1978.4Flynn, J.H., and Wall, L.A., Polymer Letters, Vol 4, 1966 pp. 323328.5Flynn, J.H., Journal of Thermal Analysis, Vol 27, 1983, pp. 95102.6Toop, D

27、.J., IEEE Transactions on Electrical Insulation, Vol EI-6, 1971, pp.212.7Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E37-1024.TABLE 1 Numerical Integration ConstantsE/RT a8 5.36999 5.898010 6.415711 6.927612 7.432713 7.932314

28、 8.427315 8.918216 9.405617 9.890018 10.371619 10.850720 11.327721 11.802622 12.275723 12.747124 13.217025 13.685526 14.152727 14.618728 15.083629 15.547430 16.010331 16.472232 16.933333 17.393634 17.853235 18.312036 18.770137 19.227638 19.684539 20.140840 20.596641 21.051942 21.506643 21.960944 22.

29、414845 22.868246 23.321247 23.773848 24.226049 24.677950 25.129451 25.580652 26.031453 26.482054 26.932355 27.382356 27.831957 28.281458 28.730559 29.179460 29.6281E1877 00 (2010)2FIG. 1 Thermal Endurance CurveE187700(2010)39. Keywords9.1 Arrhenius activation energy; Arrhenius pre-exponentialfactor;

30、 kinetic parameters; relative thermal index; thermaldecomposition; thermal endurance; thermal life; thermogravi-metric analysisASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are

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33、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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United S

34、tates. 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 through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E1877 00 (2010)4