1、Designation: E 2046 08Standard Test Method forReaction Induction Time by Thermal Analysis1This standard is issued under the fixed designation E 2046; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the measurement of ReactionInduction Time (RIT) of chemical materials that undergoexothermic reactions with an i
3、nduction period. The techniquesand apparatus described may be used for solids, liquids, orslurries of chemical substances. The temperature range coveredby this test method is typically from ambient to 400C. Thisrange may be extended depending upon the apparatus used.1.2 The RIT is a relative index v
4、alue, not an absolutethermodynamic property.As an index value, the RIT value maychange depending upon experimental conditions. A compari-son of RIT values may be made only for materials tested undersimilar conditions of apparatus, specimen size, and so forth.Furthermore, the RIT value may not predic
5、t behavior of largequantities of material.1.3 The RIT shall not be used by itself to establish a safeoperating temperature. It may be used in conjunction withother test methods (for example, E 487, E 537, and E 1981) aspart of a hazard analysis of a particular operation.1.4 This test method may be u
6、sed for RIT values greaterthan 15 min (as relative imprecision increases at shorterperiods).1.5 This test method is used to study catalytic and autocata-lytic reactions. These reactions depend upon time as well astemperature. Such reactions are often studied by fixing oneexperimental parameter (that
7、 is, time or temperature) and thenmeasuring the other parameter (that is, temperature or time).This test method measures time to reaction onset detectionunder isothermal conditions. It is related to Test Method E 487that measures detected reaction onset temperature under con-stant time conditions1.6
8、 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 There is no ISO standard equivalent to this test method.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp
9、onsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3350 Specification for Polyethylene Plastics Pipe andFittings MaterialsD 3895 T
10、est Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning CalorimetryD 4565 Test Methods for Physical and Environmental Per-formance Properties of Insulations and Jackets for Tele-communications Wire and CableD 5483 Test Method for Oxidation Induction Time of Lu-bricating Grea
11、ses by Pressure Differential Scanning Calo-rimetryD 6186 Test Method for Oxidation Induction Time of Lu-bricating Oils by Pressure Differential Scanning Calorim-etry (PDSC)E 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 487 Test Method for Constant-Temperature Stability OfChemical Mate
12、rialsE 537 Test Method for The Thermal Stability Of ChemicalsBy Differential Scanning CalorimetryE 967 Test Method for Temperature Calibration of Differ-ential Scanning Calorimeters and Differential ThermalAnalyzersE 968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE 1445 T
13、erminology Relating to Hazard Potential ofChemicalsE 1858 Test Method for Determining Oxidation InductionTime of Hydrocarbons by Differential Scanning Calorim-etryE 1860 Test Method for Elapsed Time Calibration of Ther-mal AnalyzersE 1981 Guide for Assessing Thermal Stability of Materialsby Methods
14、of Accelerating Rate CalorimetryE 2070 Test Method for Kinetic Parameters by Differential1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential of Chemicals and is the direct responsibility of Subcommittee E27.02 onThermal Stability and Condensed Phases.Current edition
15、approved April 1, 2008. Published May 2008. Originallyapproved in 1999. Last previous edition approved in 2003 as E 2046 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, r
16、efer 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.Scanning Calorimetry Using Isothermal Methods3. Terminology3.1 The specialized terms used in this test method aredescribed
17、 in Terminologies E 473 and E 1445.3.2 Definitions of Terms Specific to This Standard:3.2.1 constant temperature stability (CTS) value, nthemaximum temperature at which a chemical compound ormixture may be held for a minimum of two hours withoutexhibiting a measurable exothermic reaction. (See Test
18、MethodE 487.)3.2.2 reaction induction time (RIT) value, nthe time achemical compound or mixture may be held under isothermalconditions until it exhibits a specified exothermic reaction.4. Summary of Test Method4.1 A specimen of the chemical compound or mixture isplaced in an inert container that is
19、then heated to an operator-selected test temperature of interest. The specimen temperatureand the difference in heat flow or temperature between the testspecimen and an inert reference are monitored until an exo-thermic reaction is recorded. The time from the attainment ofthe isothermal test tempera
20、ture until the extrapolated onset tothe exothermic reaction is taken as the Reaction InductionTime.4.2 Using fresh specimens measurements at more than oneisothermal test temperature may be made.4.3 The RIT is expressed as time at a specific test tempera-ture. For example:RIT = 120 min at 100 C5. Sig
21、nificance and Use5.1 This test method measures the time to extrapolated onsetof an exothermic reaction under constant temperature (isother-mal) conditions for reactions which have an induction period,for example, those which are catalytic or autocatalytic in natureor which contain reaction inhibitor
22、s.5.2 The RIT determined by this test method is an indexmeasurement that is useful for comparing one material toanother at the test temperature of interest and in the sameapparatus type only.5.3 This test method is a useful adjunct to dynamic thermaltests, such as Test Method E 537, which are perfor
23、med underconditions in which the sample temperature is increasedcontinuously at constant rate. Results obtained under dynamictest conditions may result in higher estimates of temperature atwhich an exothermic reaction initiates because the detectedonset temperature is dependent upon the heating rate
24、 andbecause dynamic methods allow insufficient time for autocata-lytic reactions to measurably affect the onset temperature.5.4 RIT values determined under a series of isothermal testconditions may be plotted as their logarithm versus thereciprocal of the absolute temperature to produce a plot, thes
25、lope of which is proportional to the activation energy of thereaction as described in Test Method E 2070.5.5 This test method may be used in research and develop-ment, manufacturing, process and quality control, and regula-tory compliance.5.6 This test method is similar to that for Oxidation Induc-t
26、ion Time (OIT) (for example, Specification D 3350 and TestMethods D 3895, D 4565, D 5483, D 6186, and E 1858) wherethe time to the oxidation reaction under isothermal testconditions is measured. The OIT test method measures thepresence of antioxidant packages and is a relative measurementof a materi
27、als resistance to oxidation.6. Apparatus6.1 The design and complexity of the apparatus required forthis test method depends upon the size of the specimen to beused. In general, observation of an exothermic reaction in smallspecimens (less than 50 mg) is performed using differentialscanning calorimet
28、ry or differential thermal analysis equipmentand techniques. Large samples (up to 2 g) may be tested usingdevices such as the Kuhner Micro CTS apparatus.6.2 The following items are required to obtain the appro-priate experimental data.NOTE 1Commercially available differential scanning calorimetry ap
29、-paratus may be used. Alternatively, the apparatus may be assembled orfabricated from commercially available components.6.2.1 Test Chamber, composed of the following:6.2.1.1 Furnace(s), to provide uniform controlled heating ofa specimen and reference to a constant temperature.6.2.1.2 Temperature Sen
30、sor, to provide an indication ofspecimen/furnace temperature to 60.1 K.6.2.1.3 Differential Sensor, to detect a difference in heatflow (or temperature) between the specimen and the referencespecimen equivalent to 10 W or 0.01 mK.NOTE 2A reference material is used when differential heat flow ordiffer
31、ential temperature measurements are made. The reference materialshould match the physical state and heat capacity of the specimen asclosely as practical. Typical reference materials include calcined alumi-num oxide, glass beads, silicone oil, or combinations thereof.6.2.1.4 Means of Sustaining a Tes
32、t Chamber Environment,through the use of an air purge gas at a rate of 10 to 100 6 5mL/min.NOTE 3Typically, air or inert 99.9+ % pure nitrogen, argon, or heliumis employed (when oxidation in air is a concern). Unless effects ofmoisture are to be studied, use of dry purge gas is recommended.NOTE 4For
33、 the Kuhner Micro CTS apparatus, the purge gas isprovided by operation in a laboratory hood with the door(s) approximately50 % closed.6.2.2 Temperature Controller, capable of heating from am-bient to 400 C at a rate of up to 20C/min and maintaining anisothermal temperature constant within that range
34、 of 60.4Cfor the duration of the test, or both.6.2.3 Recording Device, to record and display any fractionof the differential heat flow or differential temperatures, testspecimen temperature, and time, including signal noise, to thesensitivities previously described. Typical temperature rangesare fro
35、m ambient to 400C. Typical time ranges are from 0 to200 min.6.2.4 Containers (pans, crucibles, vials, test tubes, and soforth, and lids), which are inert to the specimen and referencematerials at the maximum temperature used and which are ofsuitable structure, shape, and integrity to contain the spe
36、cimenE2046082and reference in accordance with the temperature and massrequirements as described in this section.6.3 Balance, with a capacity of 100 mg or more to weighspecimens or containers to 60.1 mg.NOTE 5A balance capacity of 10 g or more with a readability to 60.1g is required for use with the
37、Kuhner Micro CTS device.7. Hazards7.1 Dynamic thermal tests, utilizing milligram quantities ofmaterials, such as Test Method E 537, are normally conductedon specimens before the present test is undertaken. Theexperimenter shall have sufficient knowledge of the magnitudeof hazard associated with the
38、material. Larger specimens shallbe used only after due consideration is given to the potential forhazardous reaction. Thermodynamic calculations also may beused to determine the potential hazard.7.2 Special precautions shall be taken to protect personneland equipment when the apparatus in use requir
39、es the insertionof specimens into a heated block or furnace. These shallinclude adequate shielding and ventilation of equipment, andface and hand protection (see Note 8).8. Sampling8.1 Specimens shall be representative of the material beingstudied and shall be prepared to achieve good thermal contac
40、tbetween the specimen and the container.8.2 Specimen size depends upon the sensitivity of theavailable apparatus.NOTE 6Specimen size of1-7mgistypically used in thermal analysisapparatus. Specimen size of 1 - 2 g is typically used with the KuhnerMicro CTS apparatus.8.3 Specimens may be run in an unco
41、nfined or in a sealedcontainer, depending upon which condition has the morerelevance for the end use of the data.9. Calibration9.1 Apparatus temperature calibration shall be performed inaccordance with Practice E 967 at a heating rate of 1C/min.9.2 Apparatus heat flow calibration may be performed in
42、accordance with Practice E 968.9.3 Apparatus elapsed time shall be verified to be better than61 % by Test Method E 1860.10. Procedure10.1 Weigh 1 to 7 mg with a precision of 6 1 mg of the testspecimen into a clean specimen container. Seal the container, ifdesired.NOTE 7The Kuhner Micro CTS device us
43、es up to 2-g specimens. Forspecimens of a size greater than 1 g, record mass to 60.1 g.10.2 Place the test specimen into the apparatus onto thesample position, at ambient temperature conditions. Place aspecimen container containing 1 to 7 mg of inert referencematerial (1 to 2 g for the Kuhner Micro
44、CTS) in the referenceposition.10.3 Heat the test specimen and reference material fromambient to the isothermal temperature of test at 20 C/min withno more than 1C overshoot. Zero time is recorded when thespecimen test temperature reaches the isothermal test tempera-ture 6 1C. Record the thermal curv
45、e.NOTE 8In some apparatus, it may be possible to load the specimenand reference into the furnace preheated to the isothermal test tempera-ture. Appropriate provisions shall be made to ensure the safety of theoperator.NOTE 9A dynamic test method, such as Test Method E 537 may beused to estimate poten
46、tial isothermal test temperatures.10.4 Record the sample temperature 5 min into the experi-ment.10.5 Terminate the experiment when the peak of the reac-tion exotherm is observed or when no exotherm is observed orafter an operator-selected time. (In the absence of otherinformation, after 200 min). Th
47、e reaction is exothermic if itresults in a measurable increase in specimen temperature orheat flow above baseline.10.6 Display the thermal curve with differential heat flow ordifferential temperature on the Y-axis and time on the X-axis.Extend the recorded baseline beyond the reaction exotherm.Const
48、ruct a tangent at the point of the most rapid rate ofincrease in heat flow and extrapolate it to intersect with theconstructed baseline. The time at the intersection of these twolines is the reaction induction time. (See Fig. 1.)NOTE 10The precision of this test method is a constant value (seeSectio
49、n 12) and does not depend upon the measured value. For this reason,this test method is applicable to RIT values greater than 15 min. If RITvalues of less than 15 min are observed, the test temperature may belowered to obtain longer RIT values.NOTE 11In some cases, where agreed upon by the parties involved,the time at the first deviation from baseline may be taken as the RITvalues. This alternative shall be included in the report.10.7 Report the RIT (from 10.6) and the isothermal testtemperature (from 10.4) as follows:RIT = 120 min at 200 CNOTE 12If no react
