ASTM E2781-2011 Standard Practice for Evaluation of Methods for Determination of Kinetic Parameters by Thermal Analysis《用热分析测定动力参数方法评估的标准操作规程》.pdf
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1、Designation: E2781 11Standard Practice forEvaluation of Methods for Determination of KineticParameters by Thermal Analysis1This standard is issued under the fixed designation E2781; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 materials used for evaluation
3、 ofthermal analysis methods, apparatus and software where en-thalpy and temperature are measured. This Practice addressesboth exothermic and endothermic, nth order and autocatalyticreactions.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included i
4、n thisstandard.1.3 There is no International Organization for Standardiza-tion (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 sa
5、fety and health practices 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-ologyE698 Test Method for Arrhenius Kinetic Constants forThermally Unstable Materials Using Differential
6、ScanningCalorimetry and the Flynn/Wall/Ozawa MethodE1142 Terminology Relating to Thermophysical PropertiesE1641 Test Method for Decomposition Kinetics by Ther-mogravimetryE1981 Guide for Assessing Thermal Stability of Materialsby Methods of Accelerating Rate CalorimetryE2041 Test Method for Estimati
7、ng Kinetic Parameters byDifferential Scanning Calorimeter Using the Borchardt andDaniels MethodE2070 Test Method for Kinetic Parameters by DifferentialScanning Calorimetry Using Isothermal Methods3. Terminology3.1 DefinitionsSpecific technical terms used in this prac-tice are defined in Terminologie
8、s E473 and E1142, includingdifferential scanning calorimetry.4. Summary of Practice4.1 Kinetics is the study of the relationship of the extent ofa chemical reaction to the independent parameters of time andtemperature. This relationship is often described using theArrhenius expression where:da/dt 5
9、Zfa! exp E/RT! (1)where:a = fraction left to react,f(a) = some function of (a),E = activation energy (J/mol),R = gas constant (=8.314 J mol1K1),T = absolute temperature (K), andZ = pre-exponential factor (1/sec).4.2 For many reactions of interest the description of thefunction of amount left to reac
10、t is of the form:fa! 5am1a!n(2)where m and n are the overall reaction orders. This form ofthe concentration dependence is known as the auto-catalyticform or the Sestak-Berggren reaction (1).3If the value of mequals 0, then f(a) reduces to the form of f(a) =(1a)ncommonly call nth order reaction.4.3 E
11、q 1 may be evaluated in either its exponential orlogarithmic form:ln da/dt! 5 ln Z 1 ln fa! E/RT (3)4.4 The study of kinetics involves the determination ofvalues of E, Z, m, and n for a given reaction.NOTE 1Activation energy and pre-exponential factor are not indepen-dent parameters but are inter-re
12、lated.NOTE 2The descriptions provided in Eq 1-3 are only mathematicalmodels. That is, they represent the fitting of mathematical equations tooften “noisy” experimental data. In practice no such model will faithfully1This practice is under the jurisdiction of ASTM Committee E27 on HazardPotential of
13、Chemicals and is the direct responsibility of Subcommittee E27.02 onThermal Stability and Condensed Phases.Current edition approved March 1, 2011. Published April 2011. DOI: 10.1520/E2781-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
14、iceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
15、hohocken, PA 19428-2959, United States.describe the complete reaction(s) under all conditions for the materialsdescribed in this practice.4.5 Values for the kinetic parameter are typically in theranges indicated below:log Z: 8 to 30 with Z in s1E: 50 to 250 kJ/moln: 0.0 to 2.0m: 0 to 2.04.6 By their
16、 nature, thermally reactive materials maychange with time. For this reason, certified reference materialsare not available for use in the evaluation of kinetic parameters.The user of this standard may synthesize or purchase from acommercial laboratory supply house materials of suitablepurity for use
17、 in this standard.NOTE 3Storage of reference materials in a refrigerator may prolongshelf life. Observe manufacturers recommendations.4.7 The recommended values for the thermal active mate-rials identified in this standard are taken from “best values”found in the open literature as described in the
18、accompanyingtables.5. Significance and Use5.1 The kinetic parameters provided in this standard may beused to evaluate the performance of a standard, apparatus,techniques or software for the determination parameters (suchas Test Methods E698, E1641, E2041,orE2070) using thermalanalysis techniques suc
19、h as differential scanning calorimetry,and accelerating rate calorimetry (Guide E1981). The resultsobtained by these approaches may be compared to the valuesprovided by this practice.NOTE 4Not all reference materials are suitable for each measurementtechnique.6. Hazards6.1 Thermally reactive materia
20、ls evolve heat as part of theindicated reaction. Build up of this heat may lead to adangerous over-pressure condition or to a self acceleratingreaction. Operators shall use caution when working with suchmaterials. Operators shall use as small amount of material as ispractical for the measurement.6.2
21、 The reference materials described in this standard andtheir decomposition products may be explosive, carcinogenic,hazardous, toxic, or corrosive. Handling of these materialsshould be performed by trained workers who are knowledge-able with the Material Safety Data Sheets (MSDS) for eachmaterial. Te
22、tramethyl succinonitrile (TMSN), a decompositionproduct of azobisisobutyronitrile (AIBN), is considered a verytoxic (neurotoxic agent) and hazardous substance.7. Procedure7.1 Experimentally determined kinetic parameters are com-pared to the values described in this Practice as their quotient,express
23、ed as percent. Thus values less than unity or 100 %indicate that the determined value is less than the referencevalue while those greater than unity or 100 % indicate that thedetermined value is greater than the reference value.8. Calculation8.1 Conformance =(Observed Value 3 100 %)(Referenced Value
24、)NOTE 5Generally speaking, experimentally determined kinetic pa-rameters E and log Z are considered to be in agreement if they haveconformance between 80 and 120 % of the values described in Table 1.Experimentally determined values m and n are considered to be inagreement if they have conformance be
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