1、Designation: E487 09Standard Test Method forConstant-Temperature Stability Of Chemical Materials1This standard is issued under the fixed designation E487; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 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 test method describes the assessment of constant-temperature stability of chemical materials that undergo exo-thermic reactions.
3、The techniques and apparatus described maybe used on solids, liquids, or slurries of chemical substances.1.2 When a series of materials is tested by this test method,the results permit ordering the materials relative to each otherwith respect to their thermal stability.1.3 Limitations of Test:1.3.1
4、This test method is limited to ambient temperaturesand above.1.3.2 This test method determines neither a safe storagetemperature nor a safe processing temperature.NOTE 1A safe storage or processing temperature requires that anyheat produced by a reaction be removed as fast as generated and thatprope
5、r consideration be given to hazards associated with reaction prod-ucts.1.3.3 When this test method is used to order the relativethermal stability of materials, the tests must be run under thesame confinement condition (see 8.3).1.4 The values stated in SI units are to be regarded asstandard. No othe
6、r units of measurement are included in thisstandard.1.5 This standard should be used to measure and describethe properties of materials, products, or assemblies in responseto heat and flame under controlled laboratory conditions andshould not be used to describe or appraise the fire hazard orfire ri
7、sk of materials, products, or assemblies under actual fireconditions. However, results of this test may be used aselements of a fire risk assessment which takes into account allof the factors which are pertinent to an assessment of the firehazard of a particular end use.1.6 This standard may involve
8、 hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety problems associated with its use. It isthe responsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of reg
9、ulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE537 Test Method for The Thermal Stability Of ChemicalsBy Differential Scanning CalorimetryE967 Test Method for Temperature Calibration of Differen-tial Scanning Cal
10、orimeters and Differential Thermal Ana-lyzersE968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE1445 Terminology Relating to Hazard Potential of Chemi-calsE1860 Test Method for Elapsed Time Calibration of Ther-mal Analyzers3. Terminology3.1 Definitions:3.2 constant-temperat
11、ure stability (CTS) valuethe maxi-mum temperature at which a chemical compound or mixturemay be held for a 2h period under the conditions imposed inthis test without exhibiting a measurable exothermic reaction.3.3 The specialized terms in this standard are described inTerminologies E473 and E1445 in
12、cluding differential scanningcalorimetry, differential thermal analysis, exotherm, and first-deviation-from-baseline.4. Summary of Test Method4.1 A sample of the chemical compound or mixture isplaced in a glass or metal tube that is heated to a testtemperature of interest. The sample temperature and
13、 heat flowor the difference between the sample temperature and thetemperature of an inert reference material, are monitored overa 2-h period or until an exothermic reaction is recorded. Testtemperatures are decreased in 10 C intervals until no exother-mic reaction is observed in the 2-h test period.
14、 The ConstantTemperature Stability is determined and reported using eitherMethod A or Method B.1This test method is under the jurisdiction ofASTM Committee E27on and is thedirect responsibility of E27.02 onCurrent edition approved 1, 2009 Published November 2009. Originally ap-proved in 1974. Last p
15、revious edition approved in 2009 as E487 04. DOI:10.1520/E0487-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM web
16、site.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 2Test periods other than two 2 h may be used but shall bereportedNOTE 3The processing times in many industrial scale unit operations(for example, drying, distillations, and th
17、e like) normally significantlyexceed the 2 h time period in this CTS test procedure. Therefore, for theeffective application of the CTS data for industrial scale operations, theCTS time must be extended to be greater than the processing time in theactual operation.5. Significance and Use5.1 This tes
18、t method is a useful adjunct to dynamic thermaltests that are performed under conditions in which the sampletemperature is increased continuously at a programmed rate.Results obtained under dynamic test conditions present diffi-culties in determining the temperature at which an exotherminitiates bec
19、ause onset temperature is dependent on heatingrate. The test method described in the present standard attemptsto determine the onset temperature under isothermal conditionswhere the heating rate is zero.6. Apparatus6.1 The design and complexity of the apparatus required forthis method depends upon t
20、he size of the sample to be used. Ingeneral, observance of an exothermic reaction in small samples(less than 50 mg) is best done using differential thermalanalysis or differential scanning calorimetry equipment andtechniques. Larger samples (up to 2 g) may be tested using aKuhner Micro CTS apparatus
21、.6.2 The following items are required to obtain the appro-priate experimental data:6.2.1 A test chamber composed of:6.2.1.1 Furnace(s), to provide uniform controlled heating ofa specimen and reference to a constant temperature.6.2.1.2 Temperature Sensor, to provide an indication of thespecimen/furna
22、ce temperature to 6 0.1 C.6.2.1.3 Differential Sensor, to detect a difference in heatflow or temperature between specimen and reference specimenequivalent to 1 mW or 40 mK.NOTE 4Sample temperature may be measured either absolutely ordifferentially. When differential temperature measurements are made
23、, anda reference material is used, the reference material should match thephysical state and heat capacity of the sample as closely as practical.Typical reference materials are calcined aluminum oxide, glass beads,silicone oils, and a combination of these.NOTE 5Commercially available differential th
24、ermal analysis or dif-ferential scanning calorimetry apparatus capable of operating in anisothermal mode may be used. Alternatively, the apparatus may beassembled or fabricated from commercially available components (see12.1).6.2.2 A temperature Controller capable of heating fromambient to 400 C at
25、a rate of up to 50 C/min and maintainingan isothermal temperature constant within that range to 6 1Cfor 120 min.6.2.3 A Data Collection Device, to provide a means ofacquiring, storing, and displaying measured or calculatedsignals, or both. The minimum output signals required fordifferential scanning
26、 calorimetry are heat flow, temperature andtime6.2.4 Containers (pans, crucibles, vials, test tubes, etc.)which are inert to the specimen and reference material andwhich are of suitable structure, shape, and integrity to containthe specimen and reference in accordance with the temperatureand specime
27、n mass requirements described in this section.6.3 A Balance with a capacity of 100 mg or more to weighspecimens and/or containers (pans, crucibles, vials, and thelike) to 6 0.1 mg (see Note 6).7. Hazards7.1 Dynamic thermal tests are normally carried out on smallsamples before the present test is und
28、ertaken. Therefore, theexperimenter should have some knowledge of the magnitude ofhazard associated with the material. Larger samples should beused only after due consideration is given to the potential forhazardous reaction. Thermodynamic calculations also can beused to determine the potential haza
29、rd.7.2 Special precautions should be taken to protect personneland equipment when the apparatus in use requires the insertionof samples into a heated block or furnace. These should includeadequate shielding and ventilation of equipment, and face andhand protection.8. Sampling8.1 Specimens should be
30、representative of the materialbeing studied and should be prepared to achieve good thermalcontact between the sample and container.8.2 Specimen size depends upon the sensitivity of theavailable apparatus (see 12.1).NOTE 6Specimen size of 47 mg is typically used in thermal analysisapparatus. The Kuhn
31、er Micro CTS uses up to2gofsample. For testspecimen size greater than 1 g, record mass to 6 0.1 g.8.3 Specimens may be run in an unconfined or in a sealedspecimen container, depending upon which condition has themore relevance for the end use of the data.8.4 In selecting the material of construction
32、 of the specimencontainer, consideration should be given to possible interactionwith the specimen.9. Calibration9.1 Apparatus temperature calibration shall be performedaccording to Practice E967 at a heating rate of 1 C/min.9.2 Apparatus heat flow calibration shall be performedaccording to Practice
33、E968 for differential scanning calorim-eters. Differential thermal and Kuhner Micro CTS apparatusshall be calibrated according to the manufacturers instruc-tions.9.3 Apparatus elapsed time shall be calibrated according toTest Method E1860.10. Procedure10.1 Bring the sample holder of the apparatus to
34、 a tempera-ture 10 C below that approximated as the onset temperature ina previous differential thermal analysis measurement. Maintaincontrol at the set temperature at no more than 61 C.NOTE 7The onset temperature may be determined using PracticeE537E487 09210.2 Place the samples and containers in t
35、he heated sampleholder at the control temperature. Note the starting time as thetime of sample insertion and begin a temperature record versustime immediately.NOTE 8If the test apparatus allows the sample to be brought to the testtemperature in less than 10 min with not more than 1 C overshoot, then
36、place the sample and reference in the heating unit at ambient temperature10.3 Maintain the sample temperature for 2 h or until anexothermic reaction is observed. Reaction is indicated by anexothermic heat flow, departure of the temperature trace fromthe set heater temperature or from the reference t
37、emperaturedepending on the type apparatus used. The reaction is exother-mic if it results in a measurable increase in sample temperature.Record the isothermal test temperature and the time intervalfrom the start of the experiment to occurrence of an exothermas measured by the first-deviation-from ba
38、seline.NOTE 9Other test periods may be used but shall be reported10.4 When an exothermic reaction is observed, decrease theexperimental temperature by 10 C, and repeat the experimentwith a new sample. Follow the procedure until no exothermicreaction is observed in a 2-h period.10.5 Repeat 10.4 using
39、 a sample twice as large as that usedin the initial determinations. If a significant change in time ortemperature is noted repeat by again doubling the sample size.10.6 A rectilinear plot of temperature versus time using thevalues obtained in 10.4 and 10.5 is helpful in minimizing thenumber of tests
40、 required and in predicting the limiting CTSvalue.11. Calculations11.1 Method A:11.1.1 Report the highest temperature at which the first-deviation-from-baseline (taken to be the indication of a exo-thermic reaction) is observed at more than 120 min. Report thisvalue as CTS (Method A) = yy C at 120 m
41、in.NOTE 10The first-deviation-from-baseline is determined on a scalethat permits the peak of the exotherm to be displayed.11.2 Method B:11.2.1 Create a rectilinear plot of the temperature versustime for the first-deviation-from-baseline (taken to be theindication of an exothermic reaction) using the
42、 values obtainedin sections 10.4 and 10.5. Using this plot interpolate the timeaxis to 120 min and determine the corresponding temperature.Report this value as CTS (MethodB=xxCat120min.12. Performance Criteria for Test Apparatus12.1 The apparatus used for this test is considered adequateif a CTS val
43、ue of 120 to 140 C is obtained for 4nitroso-N-phenylbenzeneamine (also known as 4nitrosodiphenylamine)or a value of 210 to 230 C for 3methyl-4nitrophenol.13. Report13.1 The report shall include the following:13.1.1 Description of the sample,13.1.2 Sample weight,13.1.3 Description of apparatus includ
44、ing materials or con-struction of sampler container,13.1.4 Test conditions including atmosphere and degree ofconfinement,13.1.5 Temperatures investigated,13.1.6 Whether an exothermic reaction took place at eachtemperature,13.1.7 Time interval before each exotherm, and13.1.8 The Constant Temperature
45、Stability determined in-cluding Method, temperature and time. For example CTS(Method A) = 140 C.14. Precision and Bias14.1 Precision14.1.1 An interlaboratory test program was conducted in2003 in which 13 laboratories, using 7 instrument modelssupplied by 4 vendors examined the Constant TemperatureSt
46、ability of 1-phenyl-1H-tetrazole-5-thiol, known to decom-posed autocatalytically3.14.1.2 Within laboratory variability may be described usingthe repeatability value (r) obtained by multiplying the repeat-ability standard deviation by 2.8. The repeatability valueestimates the 95 % confidence limits,
47、That is, two resultsobtained in the same laboratory, using the same apparatus bythe same operator should be considered suspect (at the 95 %confidence level) if they differ by more than the repeatabilityvalue r.14.1.3 For method A, within laboratory precision is definedby section 10.4 of this standar
48、d requiring that the test specimenbe tested only at 10 C intervals.14.1.4 For Method B, the within laboratory repeatabilitystandard deviation is 0.95 C.14.1.5 5 Between laboratory variability may be describedusing the reproducibility value (R) obtained by multiplying thereproducibility standard devi
49、ation by 2.8. The reproducibilityvalue estimates the 95 % confidence limits. That is, two resultsobtained in different laboratories, using different apparatus oroperators should be considered suspect (at the 95 % confidencelevel) if they differ by more than he reproducibility value R.14.1.6 6 For Method A, the between laboratory reproduc-ibility standard deviation is 4.8 C.14.1.7 For Method B, the between laboratory reproducibil-ity standard deviation is 4.3 C.14.2 Bias14.2.1 Bias is the difference between the value obtained bythis standard and th
