1、Designation: E3007 15Standard Practice forKinetic Values Used to Evaluate the Study of DecompositionReactions by Thermogravimetry1This standard is issued under the fixed designation E3007; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 It is the purpose of this practice to provide kineticparameters for reference material(s) to be used
3、 for evaluationof thermogravimetry methods, apparatus, and software wheredecomposition mass loss and associated temperature are mea-sured. This practice addresses nth order reactions.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisst
4、andard.1.3 There is no International Organization of Standards(ISO) equivalent to this standard.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 p
5、ractices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE1142 Terminology Relating to Thermophysical PropertiesE1641 Test Method for Decomposition Kinetics by Thermo-gravime
6、try Using the Ozawa/Flynn/Wall MethodE2958 Test Methods for Kinetic Parameters by Factor Jump/Modulated ThermogravimetryNOTE 1Test Methods E1641 and E2958 determine the pre-exponential factor A in units of min-1. These results shall be converted tounits of s-1for comparison to values quoted in this
7、practice using:lnA, s21# 5 lnA, min21#1ln60 s min# 5 lnA, min21#14.0943. Terminology3.1 DefinitionsSpecific technical terms used in this prac-tice are defined in Terminologies E473 and E1142, includingArrhenius equation, derivative, reaction, and thermogravimet-ric analysis.3.1.1 decomposition, nthe
8、 process by which a substance isbroken up into constituent parts, elements or simpler com-pounds.3.1.2 kinetics, chemical, nthe study of the dependence ofthe chemical reaction rate on temperature and time.4. Summary of Practice4.1 Kinetics is the measurement and study of the rate of achemical reacti
9、on to the independent parameters of time andtemperature. This relationship is often described using theArrhenius expression, where:ddt 5 Af! exp 2E/RT# (1)and: = fraction reacted (dimensionless),f() = some function of ,E = activation energy (J mol-1),R = gas constant (= 8.314 J mol-1K-1),T = absolut
10、e temperature (K),t = time (s),exp = natural logarithm base,d/dt = fraction reaction rate (s-1),A = pre-exponential factor (s-1), andn = reaction order.4.2 The function f! is commonly in the form:f! 5 1 2 !n(2)and is known as an nth order reaction model.4.3 Eq 1 may be evaluated in either its expone
11、ntial orlogarithmic form:lnd/dt# 5 lnA#1lnf()# 2 ERT (3)4.4 The study of kinetics involves the determination ofvalues of E, A, and n for a given chemical reaction.NOTE 2Activation energy and pre-exponential factor are not indepen-dent parameters.NOTE 3The descriptions provided in Eq 1-3 are only mat
12、hematical1This practice is under the jurisdiction of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.10 onFundamental, Statistical and Mechanical Properties.Current edition approved June 1, 2015. Published July 2015. DOI: 10.1520/E3007-15.2For reference
13、d 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 Cons
14、hohocken, PA 19428-2959. United States1models. That is, they represent the fitting of mathematical equations tooften “noisy” experimental data. In practice, no such model will faithfullydescribe the complete reaction(s) under all conditions for the materialsdescribed in this practice.4.5 Values for
15、the kinetic parameters are typically in theranges of:20,E,350 kJ/mol,5,lnA#,50 with A in s21, and0.0,n,2.04.6 Some, thermally reactive materials may change withtime. For this reason, certified reference materials may not beavailable for use in the evaluation of kinetic parameters. Forany purchased r
16、eference material(s) of high purity from acommercial laboratory supply house or national metrologyinstitute, the source, storage conditions and storage time of thematerial(s) shall be reported.4.7 The recommended kinetic values for the thermallyreactive materials identified in Table 1 are derived fr
17、om ameta-analysis of literature values.3These reference values maybe used for the evaluation of methods, apparatus or softwarewhere decomposition mass loss and temperature are measured.NOTE 4Kinetic parameters are known to be affected by specimenparticle size. Large particle size is thought to retar
18、d escaping decompo-sition produced thereby affecting the reaction kinetics. While not specifi-cally addressed by this practice, the user is advised to cryogenically grindsamples for 1 minute prior to use.NOTE 5Kinetic parameters may be affected by specimen atmosphere.Kinetic results obtained in an i
19、nert atmosphere shall be used forcomparison purposes (see Table 1).5. Significance and Use5.1 The kinetic parameters provided in this practice may beused to evaluate the performance of a standard, apparatus,technique or software for the determined mean parameters(such as Test Methods E1641 and E2958
20、). The results obtainedby these approaches may be compared to the values providedby this practice.6. Hazards6.1 Thermally reactive materials evolve decompositionproducts as part of the indicated reaction. These products maybe toxic or corrosive. Operators shall use as small an amount ofmaterial as i
21、s practical for the measurement. Handling of thesematerials shall be performed by trained workers who areknowledgeable with their Safety Data Sheets (SDS) and adoptappropriate safety precautions according to local regulations.7. Procedure7.1 Experimentally determined mean kinetic parameters fora ref
22、erence material are compared to the values described inthis practice as their quotient, expressed as percent. Thecloseness of the conformance quotient to 100 % is an indica-tion of accuracy. Values less than 100% indicate that thedetermined value is less than the reference value while thosegreater t
23、han unity or 100 % indicate that the determined valueis greater than the reference value.NOTE 6The kinetic values for polytetrafluoroethylene are consideredthe standard. Other values presented in Table 1 are provided for userinformation.8. Calculation8.1 Conformance5Observed Value 3 100 %!Referenced
24、 Value!NOTE 7Observed values include E,lnA, s21# and n.8.2 Example CalculationIf the observed experimentalvalue for activation energy of polytetrafluoroethylene decom-position is Eo= 320 kJ/mol and the reference value of Ertakenfrom Table 1 is 319 kJ/mol, then:Conformance 5 320 kJ/mol 3 100 %!319 kJ
25、/mol 5 100 %9. Report9.1 Identification of the kinetic method being examined.9.2 Identification of the reference material being used forthe comparison, its source, physical form (that is, powder, film,etc.), particle size, and purity.9.3 The comparison quotient (conformance) for each kineticparamete
26、r.10. Precision and Bias10.1 This practice is used to determine the bias of kineticvalues determined by other standards, candidate standards,apparatus, or software.10.2 This practice does not generate experimental data andhas no precision.11. Keywords11.1 activation energy; kinetics; pre-exponential
27、 factor; re-action order; thermal analysis; thermogravimetry; thermogra-vimetric analysis3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E37-1044. ContactASTM CustomerService at serviceastm.org.TABLE 1 Kinetic Parameters for Kin
28、etic Reference Materials (see Note 1 in 2.1 and Note 6 in 7.1)NOTE 1Where: E = activation energy, A = pre-exponential factor, and n is reaction order.NOTE 2Derivation of these values is described in supporting data filed at ASTM International Headquarters and may be obtained by requestingResearch Re
29、port RR:E37-1044. Contact ASTM Customer Service at serviceastm.org.Material CAS E, kJ/mol lnA,s-1 n DescriptionCalcium Carbonate 471-34-1 194 17 (8.7 %) 17.3 1.5 (8.7 %) 0.51 0.42 nitrogenCalcium Oxalate Monohydrate 24804-31-70 97 16 (16 %) 19.3 3.1 (16 %) 0.83 0.18 nitrogen and airPolytetrafluoroet
30、hylene 9002-84-0 319 24 (7.5 %) 45.1 3.4 (7.5 %) 1.00 0.01 nitrogenPolyethylene 9002-88-4 255 41 (16 %) 37.5 6.0 (16 %) 0.96 0.12 nitrogenPolypropylene 9003-07-0 232 27 (12 %) 34.3 4.1 (12 %) 0.96 0.12 nitrogenPolystyrene 9003-53-6 211 60 (28 %) 34.0 9.5 (28 %) 0.96 0.15 nitrogenE3007 152ASTM Intern
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