1、Designation: E 2550 07Standard Test Method forThermal Stability by Thermogravimetry1This standard is issued under the fixed designation E 2550; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the assessment of materialthermal stability through the determination of the temperatureat which the materials start to
3、decompose or react and theextent of the mass change using thermogravimetry. The testmethod uses minimum quantities of material and is applicableover the temperature range from ambient to 800C.1.2 The absence of reaction or decomposition is used as anindication of thermal stability in this test metho
4、d under theexperimental conditions used.1.3 This test method may be performed on solids or liquids,which do not sublime or vaporize in the temperature range ofinterest.1.4 This test method shall not be used by itself to establisha safe operating or storage temperature. It may be used inconjunction w
5、ith other test methods (for example, E 487, E 537and E 1981) as part of a hazard analysis of a material.1.5 This test method is normally applicable to reaction ordecomposition occurring in the range from room temperatureto 800 C. The temperature range may be extended dependingon the instrumentation
6、used.1.6 This test method may be performed in an inert, areactive or self-generated atmosphere.1.7 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 There is no ISO standard equivalent to this test method.1.9 This standard doe
7、s 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 practices and determine the applica-bility of regulatory limitations prior to use. This standard mayinvolve hazardous
8、materials, operations, and equipment.2. Referenced Documents2.1 ASTM Standards:2E 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 487 Test Method for Constant-Temperature Stability OfChemical MaterialsE 537 Test Method for The Thermal Stability Of ChemicalsBy Differential Scanning Calori
9、metryE 1142 Terminology Relating to Thermophysical PropertiesE 1445 Terminology Relating to Hazard Potential ofChemicalsE 1582 Practice for Calibration of Temperature Scale forThermogravimetryE 1981 Guide for Assessing Thermal Stability of Materialsby Methods of Accelerating Rate CalorimetryE 2040 T
10、est Method for Mass Scale Calibration of Thermo-gravimetric Analyzers3. Terminology3.1 Definition:3.1.1 Specific technical terms used in this test method aredefined in Terminologies E 473, E 1142 and E 1445. Theseterms include thermogravimetry (TG), thermogravimetricanalysis (TGA), thermal stability
11、, onset temperature (To),derivative, and TG curve.3.2 Definitions of Terms Specific to This Standard:3.2.1 DTG curve, na plot of the first derivative of TG datawith respect to temperature or time.3.2.2 mass change plateau, na region of the TG curvewith a relatively constant mass; it is accompanied b
12、y aminimum in the DTG curve for a mass loss, or a maximum fora mass gain.4. Summary of Test Method4.1 A sample of the material to be examined is placed in aninert container and then heated at a controlled rate of 1 to 20Cmin-1under a controlled atmosphere. The sample mass isrecorded continuously as
13、a function of time and temperature.4.2 When the sample undergoes a reaction or thermaldecomposition involving a mass change, that change is indi-cated by a departure from the initially established baseline ofthe mass record (see Fig. 1).4.3 The onset temperature and mass changes are determinedand re
14、ported.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on ThermalTest Methods and Practices.Current edition approved March 1, 2007. Published April 2007.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Stat
16、es.5. Significance and Use5.1 TG provides a rapid method for determining the thermaldecomposition and reaction mass change of a material.5.2 This test method is useful in detecting potentiallyhazardous reactions and in estimating the temperatures atwhich these reactions occur. This test method is re
17、commendedas a screening test for detecting the thermal hazards of anuncharacterized material or mixture (see Section 8).5.3 Energetic materials, pharmaceuticals and polymers areexamples of materials for which this test might be useful. Thistest is especially useful for materials having melting point
18、s thatoverlap with the onset of reaction or decomposition.NOTE 1In Differential Scanning Calorimetry (DSC), the meltingendotherm may interfere with the determination of the onset temperaturefor reaction or decomposition.5.4 This test is not suitable for materials that sublime orvaporize in the tempe
19、rature range of interest. A sample withvolatile impurities needs to be purified prior to the TGAtesting. Alternatively, the sample can be tested as is, however,special caution is required during the data analysis. The massloss due to the loss of impurity should not interfere with thedetermination of
20、 reaction or decomposition temperature.5.5 The four significant criteria of this test method are: thedetection of a sample mass change; the extent of the masschange; the approximate temperature at which the eventoccurs; the observance of effects due to the atmosphere.6. Limitations6.1 Many environme
21、ntal factors affect the existence, mag-nitude and onset temperature of a particular reaction ordecomposition. Some of these, including heating rate, instru-mental sensitivity, and atmosphere reactivity, will affect thedetectability of a reaction or decomposition using this proce-dure. Therefore, it
22、is imperative that the results obtained fromthe application of this test method be viewed only as anindication of the thermal stability of a material.6.2 This test method can only be used to detect reaction ordecomposition that involves a mass change, such as a produc-tion of gaseous species or a ma
23、ss gain in reactive atmosphere.This test method is not suitable for materials that sublime orvaporize in the temperature of interest.6.3 This test method may not be reliable for heterogeneoussamples.NOTE 2For heterogeneous samples, it is recommended to performreplicate measurements to determine the
24、variability of the results. Ifinconsistent results are obtained, the study should be carried out usinglarger-scale apparatus, such as accelerating rate calorimetry.7. Apparatus7.1 Thermogravimetric Analyzer (TGA)The essential in-strumentation required to provide the minimum thermogravi-metric analyt
25、ical capability for this practice includes:7.1.1 A thermobalance composed of:7.1.1.1 A furnace to provide uniform controlled heating of aspecimen to a constant temperature or at a constant rate withinthe applicable temperature range of this test method.7.1.1.2 A temperature sensor to provide an indi
26、cation of thespecimen/furnace temperature to 60.1C.7.1.1.3 A continuously recording balance to measure thespecimen mass with a minimum capacity of 10 mg and asensitivity of 610 g.NOTE 3An apparatus with a larger capacity can also be used. Thesensitivity must be at least 60.1 mass %.7.1.1.4 A means o
27、f maintaining the specimen/containerunder atmospheric control of an inert or reactive gas of 99.9+% purity at a purge rate of 20 to 100 65 mL min-1.NOTE 4Purge rate may vary depending on the instrument used.Excessive purge rates should be avoided as this may introduce interfer-ences due to turbulenc
28、e effects and temperature gradients.NOTE 5Experiments can also be performed in a self generatedatmosphere. DSC sealed containers with a pinhole of 0.025 to 0.38 mmdiameter have been shown to establish saturation of a gaseous selfgenerated atmosphere.33Kwok, Q. and Seyler, R. J., Journal of Thermal A
29、nalysis and Calorimetry ,831, 2006, p. 117.FIG. 1 Typical TG and DTG CurvesE25500727.1.2 A temperature controller capable of executing a spe-cific temperature program by operating the furnace betweenselected temperature limits at a rate of temperature changebetween 1 and 20C min-1to within 60.1C min
30、-1.7.1.3 A recording device capable of recording and display-ing on the Y-axis any fraction of the specimen mass signal(TGA curve) including the signal noise as a function of anyfraction of the temperature (or time) signal on the X-axisincluding the signal noise.7.1.4 Containers (pans, crucibles, et
31、c.) that are inert to thespecimen and that will remain gravimetrically stable within thetemperature limits of this test method.NOTE 6For experiments in a self generated atmosphere, DSC sealedcontainers with pinhole of 0.025 to 0.38 mm diameter can be used.7.2 Auxiliary equipment necessary or useful
32、in conductingthis test method includes:7.2.1 A balance with a capacity of 100 mg or more to weighspecimens or containers, or both, to 60.1 mg.7.2.2 Device to encapsulate the specimen in DSC sealablecontainers for self-generated atmosphere studies.8. Safety Precautions8.1 The use of this test method
33、as an initial test for materialwhose potential hazards are unknown requires that precautionsbe taken during the sample preparation and testing.8.2 Larger specimens (5 mg) should be used only afterconsideration is given to the potential for hazardous reac-tion(s). For energetic material or materials
34、whose characteris-tics are unknown, it is safest to start with a specimen mass ofno more than 1 mg and a lower heating rate (1 to 10C min-1).8.3 When particle size reduction by grinding is necessary,the user of the test method shall presume that the material issensitive to stimuli such as friction a
35、nd electrostatic discharge.Accordingly, appropriate tests shall be conducted on thosematerials prior to grinding. Use of suitable protective equip-ment is always recommended when preparing materials ofunknown hazard. If a Material Safety Data Sheet is available,it shall be acquired and studied prior
36、 to handling unknownmaterials.8.4 Toxic or corrosive effluents, or both, may be releasedwhen heating the material and could be harmful to thepersonnel or the apparatus. Use of an exhaust system to removesuch effluents is highly recommended.9. Sampling9.1 Samples shall be representative of the materi
37、al beingstudied including particle size and purity.9.2 In the absence of other information, the samples areassumed to be analyzed as received. If a treatment, such asdrying, is applied to the sample prior to analysis, this treatmentand any resulting mass change must be noted in the report.9.3 The se
38、lection of specimen mass depends upon themagnitude of hazard associated with the material, the sensitiv-ity of the instrument, the heating rate and the specimenhomogeneity. This test method should be carried out on assmall of a quantity of material as possible, while specimens arestill large enough
39、to be representative of the material and toexhibit adequate signals. Typical specimen mass is between 1and 10 mg.NOTE 7The particle size of the specimen should be considered, sincethicker specimens may show transition broadening due to the thermalconductivity lag into the specimen cores.10. Preparat
40、ion of Apparatus10.1 Prepare the TGAusing any procedures described in themanufacturers operations manual.10.2 Place the temperature sensor in the proper position inaccordance with the manufacturers operations manual.NOTE 8Care must be taken to ensure that the specimen container isnot in contact in a
41、ny way with the sensor, unless the TGA was designedwith the temperature sensor fixed to the crucible holder. It is alsoimportant that the temperature sensor is not moved after temperaturecalibration has been carried out.10.3 Maintain a constant flow of purge gas for the furnace inthe range from 20 t
42、o 100 mL min-1throughout the experiment.11. Calibration11.1 Calibrate the mass signal using Practice E 2040 orinstrument manufacturers guidelines and record details.11.2 Calibrate the furnace temperature in accordance withPractice E 1582 using the same heating rate, purge gas, flowrate and temperatu
43、re sensor position to be used for subsequentspecimens tests.12. Recommended Condition of Tests12.1 Specimen Mass5 mg of specimen is generally con-sidered adequate. Decrease the specimen mass to 1 mg if thecharacteristics of materials are unknown.NOTE 9For energetic material, it is recommended to use
44、 a specimenmass of no more than 1.0 mg.12.2 Heating RateA rate of 10 to 20C min-1is consid-ered normal.NOTE 10The onset temperature is affected by heating rate. Therefore,only results obtained at the same heating rate shall be compared.NOTE 11A lower heating rate (1 to 10C min-1) should be used when
45、a complex change of mass is encountered.NOTE 12For energetic material, it is recommended to use a lowerheating rate (1 to 10C min-1). For primary explosives, it is suggested tostart with a heating rate of no more than 3C min-1.12.3 Temperature RangeThe temperature typically rangesfrom room temperatu
46、re to 600C.13. Procedure13.1 Tare an empty and clean specimen container.13.2 Weigh the specimen with a mass within 10 mass % ofthe target size into the tared container.NOTE 13Powder and granular samples should be distributed evenlyover the sample container to maximize the exposed surface.13.3 Place
47、the specimen and container into the TGA atambient temperature.13.4 Heat the specimen at a constant rate of 10C min-1andrecord the TG curve. Continue heating until a constant mass isobtained or the temperature is well above the useful tempera-ture range of the material tested.E2550073NOTE 14Other hea
48、ting rates may be used but shall be reported.13.5 Once the experiment is complete, cool the instrumentto room temperature, remove, and clean or replace the speci-men container.13.6 Display the TG and DTG curves.13.7 Using the TG curve, construct a baseline from theinitial mass extrapolated upward in
49、 temperature.13.8 For any reaction(s) observed, determine the onsettemperature by selecting a point on the TG curve where adeflection is first observed from the established baseline priorto the thermal event.NOTE 15The TG curve should be zoomed to a scale of 1 to 2 mass %for the onset temperature selection (see Fig. 2).NOTE 16The onset temperature can also be determined from the DTGcurve where a deflection from the DTG established baseline is firstobserved. However, only results obtained from the same method should becompared.13.9 Calculate the m
