1、Designation: E 1877 00 (Reapproved 2005)Standard Practice forCalculating Thermal Endurance of Materials fromThermogravimetric Decomposition Data1This standard is issued under the fixed designation E 1877; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、determined by Test Method E 1641to 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 There is no I
4、SO standard equivalent to this practice.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 safety and health practices and determine the applica-bility of regulatory
5、limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 1641 Test Method for Decomposition Kinetics by Ther-mogravimetry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 failure, nchange in some chemical, physical, me-chanical, electrical or other property of suffi
6、cient 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 measure of thethermal endurance of a material when compared with that of acontrol with proven thermal endur
7、ance characteristics. The RTIis also considered to be the maximum temperature belowwhich the material resists changes in its properties over adefined period of time. In the absence of comparison data fora control material, a time-to-failure of 60 000 h has beenarbitrarily selected for measuring RTI.
8、 The RTI is therefore, thefailure temperature, Tf, obtained from the thermal endurancecurve.4. Summary of Practice4.1 The Arrhenius activation energy obtained from TestMethod E 1641 is used to construct the thermal endurancecurve of a material from which an estimate of lifetime atcertain temperature
9、s 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 useful for quality control, specificationacceptance and research.5.3 This practice shall not be used for product lifet
10、imepredications unless a correlation between test results and actuallifetime has been demonstrated. In many cases, multiplemechanisms occur during the decomposition of a material,with one mechanism dominating over one temperature range,and a different mechanism dominating in a different tempera-ture
11、 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 obtained by Test Method E 1641are used to calculate thermal endurance, estimated thermal lifeand failure temperature.6.1.1 The
12、 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),6.1.1.4 b8 = Heating rate nearest the mid-point of theexperimental heating rates (K/min),6.1.1.5 a = Approximation in
13、tegral taken from Table 1,6.1.1.6 a = Constant conversion value,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), and1This practice is under the jurisdiction of Committee E37 on Thermal Measure-ments and is the dir
14、ect responsibility of Subcommittee E37.01 on Test Methods.Current edition approved March 1, 2005. Published April 2005. Originallyapproved in 1997. Last previous edition approved in 2000 as E 1877 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e 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 States.6.1.1.9 Tf= Failure Temperature for a give val
16、ue of a (K).NOTE 1The precision of the 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
17、(tf) versus reciprocal of Tfas, by example, 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 expe
18、rimental heating rates. Use this value,along with the Arrhenius activation energy (E) to calculate thequantity E/(RTc) to select the value in Table 14, 5, 6. Arbitrarilyselect a number of temperatures in the region of the chosenpercent mass loss, indicative of failure, in the mass changecurve at the
19、 midpoint heating rate. Calculate the 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 Me
20、thod E 1641.6.3 The thermal endurance of two or more materials may becompared by calculating the relative thermal index (RTI) foreach material. To compute RTI for each material; select somecommon thermal life for comparison, a typical value may be 60000 h (6.8 years), insert that value (in minutes)
21、and theappropriate activation energy for each material into Eq 2 toobtain Tf. This value of temperature is called the “relativethermal index (RTI) at the specified time”. Materials withgreater resistance to thermal decomposition will have a largerRTI.7. Report7.1 Report the following information:7.1
22、.1 If data other than that generated by Test MethodE 1641 is used 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
23、.3 The calculated thermal life (tf) and RTI values.7.1.4 The specific 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, t
24、hermal life wascalculated by the procedure in this practice using data forpoly(tetrafluoroethylene) from the interlaboratory study con-ducted to develop the precision and bias statement for TestMethod E 1641. Extreme values of thermal life were calculatedusing an arbitrarily chosen value for tempera
25、ture of 600 K andthe extreme values of E corresponding to the 95 % confidencelevel from that interlaboratory study. The resulting calculatedextreme values were 9 years and 3700 years for this material.3Krizanovsky, L., and Mentlik, V., J. Therm. Anal., 13, 1978.4Flynn, J.H., and Wall, L.A., Polym. L
26、ett., 4, pp. 323328, 1966.5Flynn, J.H., J. Therm. Anal., 27, pp. 95102, 1983.6Toop, D. J., IEEE Trans. Elec. Insul, EI-6, pp. 212, 1971.7Copies of the references in footnotes 36 are on file at ASTM Headquarters.Request RR:E371024.TABLE 1 Numerical Integration ConstantsE/RT a8 5.36999 5.898010 6.4157
27、11 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 19.684539 20.140840 20.596641 21.0
28、51942 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 29.6281E 1877 00 (2005)2FIG.1ThermalEnduranceCurveE 1877 00 (2005)39. Keywords9.1 Arrhenius activation energy; Arr
29、henius 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 mentionedin this standard
30、. 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 must be reviewed
31、every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible te
32、chnical 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 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 through the ASTM website(www.astm.org).E 1877 00 (2005)4
