1、Designation: E1231 10E1231 15Standard Practice forCalculation of Hazard Potential Figures-of-Merit Figures ofMerit for Thermally Unstable Materials1This standard is issued under the fixed designation E1231; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the 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 the calculation of hazard potential figures-of-merit figures
3、of merit for exothermic reactions, including:(1) Time-to-thermal-runaway,(2) Time-to-maximum-rate,(3) Critical half thickness,(4) Critical temperature,(5) Adiabatic decomposition temperature rise,(6) Explosion potential,(7) Shock sensitivity,(8) Instantaneous power density, and(9) NFPA instability r
4、ating.1.2 The kinetic parameters needed in this calculation may be obtained from differential scanning calorimetry (DSC) curves bymethods described in other documents.1.3 This technique is the best applicable to simple, single reactions whose behavior can be described by theArrhenius equationand the
5、 general rate law. For reactions which do not meet these conditions, this technique may, with caution, serve as anapproximation.1.4 The calculations and results of this practice might be used to estimate the relative degree of hazard for experimental andresearch quantities of thermally unstable mate
6、rials for which little experience and few data are available. Comparable calculationsand results performed with data developed for well characterized materials in identical equipment, environment, and geometry arekey to the ability to estimate relative hazard.1.5 The figures-of-merit figures of meri
7、t calculated as described in this practice are intended to be used only as a guide for theestimation of the relative thermal hazard potential of a system (materials, container, and surroundings). They are not intended topredict actual thermokinetic performance. The calculated errors for these parame
8、ters are an intimate part of this practice and mustbe provided to stress this. It is strongly recommended that those using the data provided by this practice seek the consultation ofqualified personnel for proper interpretation.1.6 The values stated in SI units are to be regarded as standard. No oth
9、er units of measurement are included in this standard.1.7 There is no ISO standard equivalent to this practice.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safe
10、ty and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C177 Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate Apparatus1 This practice is under the
11、 jurisdiction of ASTM Committee E27 on Hazard Potential of Chemicals and is the direct responsibility of Subcommittee E27.02 on ThermalStability and Condensed Phases.Current edition approved April 15, 2010Nov. 1, 2015. Published May 2010January 2016. Originally approved in 1988. Last previous editio
12、n approved in 20062010 asE1231 01E1231 10. (2006). DOI: 10.1520/E1231-10.10.1520/E1231-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summ
13、ary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends
14、 that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1C518 Test Method fo
15、r Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter ApparatusE473 Terminology Relating to Thermal Analysis and RheologyE537 Test Method for The Thermal Stability of Chemicals by Differential Scanning CalorimetryE698 Test Method for Arrhenius Kinetic Constants for Thermally
16、 Unstable Materials Using Differential Scanning Calorimetryand the Flynn/Wall/Ozawa MethodE793 Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning CalorimetryE1269 Test Method for Determining Specific Heat Capacity by Differential Scanning CalorimetryE1952 Test Method f
17、or Thermal Conductivity and Thermal Diffusivity by Modulated Temperature Differential ScanningCalorimetryE2041 Test Method for Estimating Kinetic Parameters by Differential Scanning Calorimeter Using the Borchardt and DanielsMethodE2070 Test Method for Kinetic Parameters by Differential Scanning Cal
18、orimetry Using Isothermal MethodsE2716 Test Method for Determining Specific Heat Capacity by Sinusoidal Modulated Temperature Differential ScanningCalorimetryE2890 Test Method for Kinetic Parameters for Thermally Unstable Materials by Differential Scanning Calorimetry Using theKissinger Method2.2 Ot
19、her Standards:NFPA 704 Identification of the Hazards of Materials for Emergency Response, 1996201233. Terminology3.1 Definitions:3.1.1 The definitions relating to thermal analysis appearing in Terminology E473 shall be considered applicable to this practice.3.2 Definitions of Terms Specific to This
20、Standard:3.2.1 adiabatic decomposition temperature rise, Tdan estimation of the computed temperature which a specimen would attainif all of the enthalpy (heat) of decomposition reaction were to be absorbed by the sample itself, expressed by Eq 5. High valuesrepresent high hazard potential.3.2.2 crit
21、ical half thickness, aan estimation of the half thickness of a sample in an unstirred container, in which the heat lossesto the environment are less than the retained heat. This buildup of internal temperature leads to a thermal-runaway reaction,expressed by Eq 3.3.2.2.1 DiscussionThis description a
22、ssumes perfect heat removal at the reaction boundary. This condition is not met if the reaction takes place in aninsulated container such as when several containers are stacked together or when a container is boxed for shipment. Thesefigures-of-merit figures of merit underestimate the hazard as a re
23、sult of this underestimation of thermal conductivity.3.2.3 critical temperature, Tcan estimation of the lowest temperature of an unstirred container at which the heat losses to theenvironment are less than the retained heat leading to a buildup of internal temperature expressed by Eq 4. This tempera
24、turebuildup leads to a thermal-runaway reaction. (See Note 3.)3.2.4 explosion potential, EPan index value, the magnitude and sign of which may be used to estimate the potential for a rapidenergy release that may result in an explosion. Positive values indicate likelihood. Negative values indicate un
25、likelihood. Thereliability of this go-no-go indication is provided by the magnitude of the numerical value. The greater the magnitude, the morereliable the go-no-go indication.3.2.5 instantaneous power density, IPDthe amount of energy per unit time per unit volume initially released by an exothermic
26、reaction.3.2.5.1 DiscussionThis practice calculates the IPD at 250 C (482 F, 250C (482F, 523 K).3.2.6 NFPA instability rating, IRan index value for ranking, on a scale of 0 to 4, the instantaneous power density of materials.The greater the value, the more unstable the material.3.2.7 shock sensitivit
27、y, SSan estimation of the sensitivity of a material to shock induced reaction relative to m-dinitrobenzenereference material. A positive value indicates greater sensitivity; a negative value less sensitivity. The reliability of this go-no-goindication is provided by the magnitude of the numerical va
28、lue. The greater the magnitude, the more reliable the go-no-goindication.3 Available from National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA 02169-7471,02269, http:/www.nfpa.org.E1231 1523.2.8 time-to-maximum-rate, TMRan estimate of the time required for an exothermic react
29、ion, in an adiabatic container (thatis, no heat gain or loss to the environment), to reach the maximum rate of reaction, expressed by Eq 2.3.2.9 time-to-thermal-runaway, tcan estimation of the time required for an exothermic reaction, in an adiabatic container (thatis, no heat gain or loss to the en
30、vironment), to reach the point of thermal runaway, expressed by Eq 1.4. Summary of Practice4.1 This practice describes the calculation of nine figures-of-merit figures of merit used to estimate the relative thermal hazardpotential of thermally unstable materials. These figures-of-merit figures of me
31、rit include time-to-thermal-runaway (tc),time-to-maximum-rate (TMR), critical half thickness (a), critical temperature (Tc), adiabatic decomposition temperature rise (Td),explosion potential (EP), shock sensitivity (SS), instantaneous power density (IPD), and instability rating (IR). These calculati
32、onsare based upon the determined or assumed values for activation energy (E), pre-exponential factor (Z), specific heat capacity (Cp),thermal conductivity (), heat of reaction (H), heat flow rate (q) and density or concentration (). The activation energy andpre-exponential factor may be calculated u
33、sing Test Methods E698, E2041, E2070or , or E2070E2890. The specific heat capacitymay be obtained from Test MethodMethods E1269 or E2716. Thermal conductivity may be obtained from Test Methods C177,C518, or E1952. Heat of reaction may be obtained from Test Method E793. Heat flow rate may be obtained
34、 from Test MethodE2070, 13.5, where it is called dH/dt. Values for concentration or density may be estimated from known values of model materialsor through actual measurement. In addition, certain assumptions, such as initial temperature and container geometries, must besupplied.5. Significance and
35、Use5.1 This practice provides nine figures-of-merit figures of merit which may be used to estimate the relative thermal hazardpotential of thermally unstable materials. Since numerous assumptions must be made in order to obtain these figures-of-merit,figures of merit, care must be exercised to avoid
36、 too rigorous interpretation (or even misapplication) of the results.5.2 This practice may be used for comparative purposes, specification acceptance, and research. It should not be used to predictactual performance.6. Interferences6.1 Since the calculations described in this practice are based upon
37、 assumptions and physical measurements which may notalways be precise, care must be used in the interpretation of the results. These results should be taken as relative figures-of-meritfigures of merit and not as absolute values.6.2 The values for time-to-thermal-runaway, critical half thickness, an
38、d critical temperature are exponentially dependent uponthe value of activation energy. This means that small imprecisions in activation energy may produce large imprecisions in thecalculated figures-of-merit. figures of merit. Therefore, activation energy of the highest precision available should be
39、 used (1).46.3 Many energetic materials show complex decompositions with important induction processes. Many materials are used orshipped as an inhibited or stabilized composition, ensuring an induction process. In such cases, time-to-thermal-runaway will bedetermined largely by the induction proces
40、s while critical temperature will be determined by the maximum-rate process. These twoprocesses typically have very different kinetic parameters and follow different rate-law expressions.6.4 It is believed that critical temperature, using the same size and shape container, provides the best estimate
41、 of relative thermalhazard potential for different materials (see Section 10).6.5 Extrapolation of TMR to temperatures below those actually measured shall be done only with caution due to the potentialchanges in kinetics (activation energy), the potential for autocatalysis, and the propagation of er
42、rors.7. Apparatus7.1 No special apparatus is required for this calculation.8. Calculation8.1 Time-to-thermal-runaway from sample initial temperature T is defined by (see Ref (2):tc 5Cp R T2 eE/RTE Z H (1)where:tc = time-to-thermal-runaway, s,Cp = specific heat capacity, J/(g K),4 The boldface number
43、s in parentheses refer to the list of references at the end of this standard.E1231 153R = gas constant = 8.314 J/(K mol),R = gas constant = 8.314 J(K mol),E = activation energy, J/mol,Z = pre-exponential factor, s1,H = enthalpy (heat) of reaction, J/g, andT = initial temperature, K.NOTE 1Time-to-the
44、rmal-runaway is related to time-to-maximum-rate but assumes a first order reaction.8.2 Time-to-maximum-rate, TMR, is defined by (see Refs (1) and (3):Cp R T12Eq (2)TMR 5Cp R T12E q (2)where:T1 = initial temperature, K (that is, the temperature at which TMR is to be estimated), andq = mass normalized
45、 heat flow rate at (T1), W/g.NOTE 2Time-to-maximum-rate is related to time-to-thermal-runaway but assumes a zeroth order reaction.8.3 Critical half thickness at environmental temperature To is defined by (see Ref (4):a 5SR To2 eE/RToH Z E D12 (3)where:a = critical half-thickness, cm; = thermal condu
46、ctivity, W/(cm K);To = environment temperature, K; = density or concentration, g/cm3; and = form factor (dimensionless) (4, 5):0.88 for infinite slab,2.00 for infinite cylinder,2.53 for a cube,2.78 for a square cylinder, and3.32 for sphere.8.4 Critical temperature Tc is defined by (see Refs (1) and
47、(6):Tc 5SRElnSd2 H Z ET 2c R DD21(4)where:Tc = critical temperature, K, andd = shortest semi-thickness, cm.8.5 Adiabatic decomposition temperature rise Td is defined by:Td 5 HCp(5)where:Td = adiabatic decomposition temperature rise, K.8.6 Explosion potential EP is defined by (7, 8):EP5logH# 20.38log
48、Tonset2298 K#22.29 (6)where:EP = explosion potential, andTonset = onset temperature by DSC, K.8.7 Shock sensitivity SS is defined by (7):SS5logH# 20.72logTonset2298 K#21.60 (7)where:SS = shock sensitivity relative to m-dinitrobenzene.E1231 1548.8 Instantaneous power density at 250 C 250C is defined
49、by (NFPA 704):5IPD5H Z exp2E/523 KR# (8)8.9 Instability rating is defined by Table 1 (NFPA 704).8.10 Methods of Obtaining Parameters:8.10.1 The activation energy E and frequency factor Z may be obtained byTest Methods E698, E2041, or E2070. Other methodsmay be used but shall be reported.NOTE 3InTest Methods E698 and E2041, the activation energy and pre-exponential are mathematically related and must be determined from the sameexperimental study.8.10.2 The enthalpy (heat) of reaction H may be obtained by Test Methods E793 or E537
