1、Designation: E2550 11Standard Test Method forThermal Stability by Thermogravimetry1This standard is issued under the fixed designation E2550; 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 pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () 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 dec
3、ompose 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 method u
4、nder 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 with
5、 other test methods (for example, E487, E537and E1981) 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 used.1
6、.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 does not
7、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 materi
8、als, operations, and equipment.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE487 Test Method for Constant-Temperature Stability ofChemical MaterialsE537 Test Method for The Thermal Stability of Chemicalsby Differential Scanning CalorimetryE691
9、 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1142 Terminology Relating to Thermophysical PropertiesE1445 Terminology Relating to Hazard Potential of Chemi-calsE1582 Practice for Calibration of Temperature Scale forThermogravimetryE1981 Guide for Assess
10、ing Thermal Stability of Materialsby Methods of Accelerating Rate CalorimetryE2040 Test 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 E473, E1142 and E1445. These terms
11、include thermogravimetry (TG), thermogravimetric analysis(TGA), thermal stability, 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 plate
12、au, na region of the TG curvewith a relatively constant mass; it is accompanied by aminimum in the DTG curve for a mass loss, or a maximum fora mass gain.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on
13、 Calo-rimetry and Mass Loss.Current edition approved April 1, 2011. Published May 2011. Originallyapproved in 2007. Last previous edition approved in 2007 as E2550 2007. DOI:10.1520/E2550-11.2For 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 A sample of the material t
15、o be examined is placed in aninert container and then heated at a controlled rate of 1 to 20Cmin1under a controlled atmosphere. The sample mass isrecorded continuously as a function of time and temperature.4.2 When the sample undergoes a reaction or thermaldecomposition involving a mass change, that
16、 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 reported.5. Significance and Use5.1 TG provides a rapid method for determining the thermaldecomposition and reaction mass change of
17、 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 recommendedas a screening test for detecting the thermal hazards of anuncharacterized material or mixture (see Section 8).5.3 E
18、nergetic materials, pharmaceuticals and polymers areexamples of materials for which this test might be useful. Thistest is especially useful for materials having melting points thatoverlap with the onset of reaction or decomposition.NOTE 1In Differential Scanning Calorimetry (DSC), the meltingendoth
19、erm 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 temperature range of interest. A sample withvolatile impurities needs to be purified prior to the TGAtesting. Alternatively, the s
20、ample 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 reaction or decomposition temperature.5.5 The four significant criteria of this test method are: thedetection of a sample ma
21、ss 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 environmental factors affect the existence, mag-nitude and onset temperature of a particular reaction ordecomposition. Some of these,
22、including heating rate, instru-mental sensitivity, and atmosphere reactivity, will affect thedetectability of a reaction or decomposition using this proce-dure. Therefore, it is imperative that the results obtained fromthe application of this test method be viewed only as anindication of the thermal
23、 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 mass gain in reactive atmosphere.This test method is not suitable for materials that sublime orvaporize in the temperature of i
24、nterest.6.3 This test method may not be reliable for heterogeneoussamples.NOTE 2For heterogeneous samples, it is recommended to performreplicate measurements to determine the variability of the results. Ifinconsistent results are obtained, the study should be carried out usinglarger-scale apparatus,
25、 such as accelerating rate calorimetry.7. Apparatus7.1 Thermogravimetric Analyzer (TGA)The essential in-strumentation required to provide the minimum thermogravi-metric analytical capability for this practice includes:7.1.1 A thermobalance composed of:7.1.1.1 A furnace to provide uniform controlled
26、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 indication of thespecimen/furnace temperature to 60.1C.7.1.1.3 A continuously recording balance to measure thespecimen mass with
27、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 %.FIG. 1 Typical TG and DTG CurvesE2550 1127.1.1.4 A means of maintaining the specimen/containerunder atmospheric control of an inert or reactiv
28、e gas of99.9+ % purity at a purge rate of 20 to 100 65mLmin1.NOTE 4Purge rate may vary depending on the instrument used.Excessive purge rates should be avoided as this may introduce interfer-ences due to turbulence effects and temperature gradients.NOTE 5Experiments can also be performed in a self g
29、eneratedatmosphere. DSC sealed containers with a pinhole of 0.025 to 0.38 mmdiameter have been shown to establish saturation of a gaseous selfgenerated atmosphere.37.1.2 A temperature controller capable of executing a spe-cific temperature program by operating the furnace betweenselected temperature
30、 limits at a rate of temperature changebetween 1 and 20C min1to within 60.1C min1.7.1.3 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) signa
31、l on the X-axisincluding the signal noise.7.1.4 Containers (pans, crucibles, etc.) 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 0.0
32、25 to 0.38 mm diameter can be used.7.2 Auxiliary equipment necessary or useful 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-gen
33、erated atmosphere studies.8. Safety Precautions8.1 The use of this test method 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
34、 the potential for hazardous reac-tion(s). For energetic material or materials 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 min1).8.3 When particle size reduction by grinding is necessary,the user of the test me
35、thod shall presume that the material issensitive to stimuli such as friction and 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
36、Material Safety Data Sheet is available,it shall be acquired and studied prior 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 h
37、ighly recommended.9. Sampling9.1 Samples shall be representative of the material 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
38、 treatmentand any resulting mass change must be noted in the report.9.3 The selection 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
39、 of a quantity of material as possible, while specimens arestill large enough 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 broa
40、dening due to the thermalconductivity lag into the specimen cores.10. Preparation 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 8
41、Care must be taken to ensure that the specimen container isnot in contact in any 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
42、.3 Maintain a constant flow of purge gas for the furnace inthe range from 20 to 100 mL min1throughout the experiment.11. Calibration11.1 Calibrate the mass signal using Practice E2040 orinstrument manufacturers guidelines and record details.11.2 Calibrate the furnace temperature in accordance withPr
43、actice E1582 using the same heating rate, purge gas, flowrate and temperature 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 m
44、aterials are unknown.NOTE 9For energetic material, it is recommended to use a specimenmass of no more than 1.0 mg.12.2 Heating RateA rate of 10 to 20C min1is consid-ered normal.NOTE 10The onset temperature is affected by heating rate. Therefore,only results obtained at the same heating rate shall be
45、 compared.NOTE 11A lower heating rate (1 to 10C min1) should be used whena complex change of mass is encountered.NOTE 12For energetic material, it is recommended to use a lowerheating rate (1 to 10C min1). For primary explosives, it is suggested tostart with a heating rate of no more than 3C min1.12
46、.3 Temperature RangeThe temperature typically rangesfrom room temperature to 600C.3Kwok, Q., and Seyler, R.J., Journal of Thermal Analysis and Calorimetry,Vol83, No. 1, 2006, p. 117.E2550 11313. Procedure13.1 Tare an empty and clean specimen container.13.2 Weigh the specimen with a mass within 10 ma
47、ss % 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 the specimen and container into the TGA atambient temperature.13.4 Heat the specimen at a constant rate of 10C min1andre
48、cord 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.NOTE 14Other heating rates may be used but shall be reported.13.5 Once the experiment is complete, cool the instrumentto room temperature, remove
49、, 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 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 dete
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