1、Designation: E1877 11Standard 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 the case of revision
2、, 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 determined by Test Me
3、thod 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 in SI units are t
4、o 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 user of this standard
5、 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 to This Standard:
6、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 index (RTI), na measur
7、e 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 time. In theabsence o
8、f 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 from TestMethod E1641
9、 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.5.2 This practice is
10、 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 decomposition of a material,w
11、ith 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 following values obtain
12、ed 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 = Heating rate (K/min
13、),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 direct responsibility o
14、f Subcommittee E37.10 on Fundamental,Statistical and Mechanical Properties.Current edition approved Aug. 1, 2011. Published September 2011. Originallyapproved in 1997. Last previous edition approved in 2010 as E1877 00 (2010).DOI: 10.1520/E1877-11.2For referenced ASTM standards, visit the ASTM websi
15、te, 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 19428-2959, United State
16、s.6.1.1.7 tf= Estimated thermal life for a given value ofconversion (a) (min) (see Test Method E1641),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 conver-sion (a) (K) (see Test Method E1641).NOTE 1The precision of the
17、 calculation in this practice are exponen-tially dependent 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 exa
18、mple, shown in Fig. 1.log tf5 E / 2.303 RTf! 1 log E /R b!# 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 val
19、ue,along with the Arrhenius activation energy (E) to calculate 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
20、 logarithm ofthe thermal life from Eq 1. Plot the thermal endurance 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
21、of two or more materials may becompared by calculating the 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
22、2 to obtain Tf. This value oftemperature is called the “relative 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 us
23、ed in these calculations, then include a descriptionof the 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 sp
24、ecific dated version of this practice that is used.8. Precision 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 usi
25、ng data forpoly(tetrafluoroethylene) from the interlaboratory 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
26、 % confidencelevel from that interlaboratory study. The resulting 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., Jo
27、urnal of Thermal Analysis, Vol 27, 1983, pp. 95102.6Toop, D.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
28、/RT a8 5.36999 5.898010 6.415711 6.927612 7.432713 7.932314 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 19.6
29、84539 20.140840 20.596641 21.051942 21.506643 21.960944 22.414845 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 112FIG. 1 Thermal Endurance CurveE18771139. Keywords9.1 Arrhenius activ
30、ation energy; Arrhenius pre-exponentialfactor; 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 mentione
31、din this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and
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33、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 International, 100 Barr Harbor Drive, PO Box C
34、700, 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 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 114
