ASTM E2008-17 Standard Test Methods for Volatility Rate by Thermogravimetry.pdf

1、Designation: E2008 17Standard Test Methods forVolatility Rate by Thermogravimetry1This standard is issued under the fixed designation E2008; 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 par

2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover procedures for assessing thevolatility of solids and liquids at given temperatures usingthermogravimetry under prescribed e

3、xperimental conditions.Results of these test methods are obtained as volatility ratesexpressed as mass per unit time. Rates 5 g/min are achiev-able with these test methods.1.2 Temperatures typical for these test methods are withinthe range from 25C to 500C. This temperature range maydiffer depending

4、 upon the instrumentation used.1.3 These test methods are intended to provide a value forthe volatility rate of a sample using a thermogravimetricanalysis measurement on a single representative specimen. It isthe responsibility of the user of these test methods to determinethe need for and the numbe

5、r of repetitive measurements onfresh specimens necessary to satisfy end use requirements.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associ

6、ated with its use. It is theresponsibility of the user of these test methods to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principl

7、es on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms

8、Precision and Bias inASTM Test MethodsE473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1142 Terminology Relating to Thermophysical PropertiesE1582 Practice for Calibration of Temperature Scale

9、forThermogravimetryE1860 Test Method for Elapsed Time Calibration of Ther-mal AnalyzersE2040 Test Method for Mass Scale Calibration of Thermo-gravimetric Analyzers3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to these testmethods and can be found in Terminologies E473 and E1

10、142:3.1.1.1 thermogravimetric analysis (TGA),3.1.1.2 thermogravimetry (TG), and3.1.1.3 volatility.3.2 Definitions of Terms Specific to This Standard:3.2.1 volatility ratethe rate of conversion of a solid orliquid substance into the vapor state at a given temperature;mass per unit time.4. Summary of

11、Test Method4.1 A solid or liquid specimen is confined in an appropriatecontainer with a pinhole opening between 0.33 mm and 0.38mm. The confined specimen is heated within a thermogravi-metric analyzer either to a temperature and held constant at thattemperature for a fixed interval of time (Test Met

12、hodA, Fig. 1)or at a slow constant heating rate between temperature limits(Test Method B, Fig. 2). The mass of the specimen is measuredcontinuously and it or its rate of change is displayed as afunction of time or temperature. The volatility rate at anytemperature is reported either as the average r

13、ate of mass lossper unit time from Test Method A or as the instantaneous rateof mass loss (first derivative) per unit time from Test MethodB.5. Significance and Use5.1 Volatility of a material is not an equilibrium thermody-namic property but is a characteristic of a material related to a1These test

14、 methods are under the jurisdiction of ASTM Committee E37 onThermal Measurements and are the direct responsibility of Subcommittee E37.01 onCalorimetry and Mass Loss.Current edition approved April 1, 2017. Published April 2017. Originallyapproved in 1999. Last previous edition approved in 2014 as E2

15、008 08 (2014)1.DOI: 10.1520/E2008-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM Internatio

16、nal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guide

17、s and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1thermodynamic property that is vapor pressure. It is influencedFIG. 1 Test Method A: Rv= Average Volatility RateFIG. 2 Test Method B: Rv= Instantaneous Volatility RateE2008 172by such factors as

18、 surface area, temperature, particle size, andpurge gas flow rate; that is, it is diffusion controlled.5.2 The extent of containment achieved for specimens inthese test methods by means of a pinhole opening between 0.33mm to 0.38 mm allows for measurement circumstances that arerelatively insensitive

19、 to experimental variables other thantemperature. Decreasing the extent of containment by use ofpinholes larger than 0.38 mm will increase the magnitude ofthe observed rate of mass loss but will also reduce themeasurement precision by increasing the sensitivity to varia-tions in other experimental v

20、ariables.5.3 Results obtained by these test methods are not strictlyequivalent to those experienced in processing or handlingconditions but may be used to rank materials for their volatilityin such circumstances. Therefore, the volatility rates deter-mined by these test methods should be considered

21、as indexvalues only.5.4 The volatility rate may be used to estimate such quan-tifiable values as drying interval or the extent of volatile releasefrom a process.6. Interferences6.1 Specimens that consist of a mixture of two or morevolatile components or that undergo decomposition during thistest may

22、 exhibit curvature in the mass loss versus time plot ofTest Method A (see Fig. 3). In such cases the volatility rate isnot constant and shall not be reported as a singular value.7. Apparatus7.1 The essential instrumentation required to provide theminimum thermogravimetric analytical capability for t

23、hese testmethods includes:7.1.1 A Thermobalance, composed of:7.1.1.1 A Furnace, to provide uniform controlled heating ofa specimen at a constant temperature or at a constant ratewithin the applicable temperature range of these test methods;7.1.1.2 A Temperature Sensor, to provide an indication ofthe

24、 specimen/furnace temperature to 61K;7.1.1.3 A continuously recording Balance, to measure thespecimen mass with a minimum capacity of 100 mg and asensitivity of 610 g;7.1.1.4 A means of sustaining the specimen/container underatmospheric control of inert gas (nitrogen, helium, and soforth) of 99.9 %

25、purity at a purge rate of 50 mL/min to 100mL/min 6 5%.7.1.2 A Temperature Controller, capable of executing aspecific temperature program by operating the furnace betweenselected temperature limits at a rate of temperature change of1 K/min to 2 K/min constant to within 60.1 K/min or torapidly heat a

26、specimen at a minimum of 50 K/min to anisothermal temperature that is maintained constant to 61 K fora minimum of 30 min.7.1.3 A Data Collection Device, to provide a means ofacquiring, storing, and displaying measured or calculatedsignals, or both. The minimum output signals required forthermogravim

27、etry are mass, temperature, and time.7.1.4 Sealable Containers, (pans, crucibles, and so forth),that are inert to the specimen, that will remain gravimetricallystable within the temperature limits of these test methods, andthat contain a pinhole in the lid of diameter between 0.33 mmand 0.38 mm.3NOT

28、E 1The most critical parameters for containers suitable for use3See Appendix X1.FIG. 3 Test Method ATwo Component MixtureE2008 173with these test methods are the pinhole diameter and the lid thickness.Sealable containers of volumes (25 L to 50 L) and wall thicknesses (80m to 150 m) commercially avai

29、lable from Mettler-Toledo, Perkin ElmerCorporation, and TA Instruments, Inc., have been found suitable for thispurpose.7.2 Auxiliary equipment necessary or useful in conductingthese test methods includes:7.2.1 While not required, it is convenient to have a dataanalysis device that will continuously

30、calculate and display thefirst derivative of mass with respect to time (in mass/min)capable of detecting 0.05 g/min.7.2.2 Device to encapsulate the specimen in sealable con-tainers.7.2.3 Micropipette or syringe to deliver liquid specimens of1 L to 30 L into the containers.8. Sampling8.1 Samples are

31、ordinarily measured as received. If apretreatment is applied to any specimen, this treatment shall benoted in the report.8.2 Since the applicable samples may be mixtures or blends,care shall be taken to ensure that the analyzed specimen isrepresentative of the sample from which it is taken. If thesa

32、mple is liquid, mixing prior to taking the specimen issufficient to ensure this consideration. If the sample is solid,take several samplings from different areas and either combineinto a single specimen or run as a separate specimen with thefinal analysis representing an average of these determinati

33、ons.Include the number of determinations in the report.9. Calibration9.1 Perform temperature calibration in accordance withPractice E1582 using the same purge gas conditions andcontainer type to be used for the subsequent measurements ata heating rate of 2 K/min. Do not disturb the temperaturesensor

34、 position after this calibration.9.2 Perform mass calibration in accordance with TestMethod E2040.9.3 Perform time scale calibration in accordance with TestMethod E1860.10. Procedure10.1 Test Method AIsothermal Test:10.1.1 Initiate a purge gas flow through the thermobalancebetween 50 mL/min to 100 m

35、L/min 6 5%.10.1.2 Equilibrate the furnace, gas purge, and so forth atroom temperature, and tare the balance.NOTE 2If the balance is tarred tared with the empty crucible and lidin place, then the mass of the test specimen may be recorded directly10.1.3 Encapsulate a specimen in an appropriate contain

36、erwith the specified pinhole. Specimen sizes between 1 mg and30 mg are typical for this test method, with the larger massbeing used for more volatile specimens. (WarningVolatilematerials may pose a respiratory hazard. Avoid unnecessaryexposure to vapors.)10.1.4 Place the encapsulated specimen in the

37、 thermogravi-metric analyzer, close the furnace, and allow the temperature,purge, and so forth, to become stable within 61 % of settings.NOTE 3For highly volatile substances, a significant mass fraction ofthe specimen could be lost during this period of equilibration. Any largediscrepancy between th

38、e specimen mass as delivered and subsequentlyrecorded by the thermobalance should be noted in the report.10.1.5 Heat the specimen rapidly at 50 K/min to the desiredisothermal temperature, and thereafter, maintain the isothermaltemperature to 61 K for 30 min. Record the specimen mass inmg or g contin

39、ually during this heating program versus time.The specimen temperature should be recorded during theheating program.NOTE 4If the specimen is exhausted before 30 min have elapsed, it isrecommended that the test be repeated with a larger specimen mass. Ifexcessively large specimen mass is required to

40、complete a 30-min testtime, a shorter time interval or a lower isothermal temperature may beused and shall be reported.NOTE 5The initial rapid heating to the desired isothermal temperaturemay result in a momentary overshoot in the furnace temperature.Overshoot in itself does not create a measurement

41、 question provided thedata in 10.1.7 is taken only from the region where the isothermaltemperature is stable and provided the entire specimen has not beenexhausted.10.1.6 Restore the furnace to ambient temperature, andremove the specimen container.10.1.7 Calculate the volatility rate in accordance w

42、ith11.2.10.1.8 Repeat 10.1.2 10.1.7 for additional samples.10.2 Test Method BConstant Heating Rate Test:10.2.1 Follow the instructions given in 10.1.1 10.1.4.10.2.2 Heat the specimen at a constant heating rate of 2 60.1 K/min between ambient temperature and the desired limittemperature. Record the s

43、pecimen mass in mg or g continu-ally during this heating program versus temperature, andcalculate and display the first derivative (with respect to time)of the mass loss in g/min during heating.NOTE 6If the specimen is exhausted before reaching the desired limittemperature, repeat the test using a l

44、arger specimen mass. If excessivelylarge specimen mass is required to reach the limit temperature, it may benecessary to terminate the test at a lower limit temperature, and this shallbe noted in the report.10.2.3 Restore the furnace to ambient temperature, andremove the specimen container.10.2.4 Ca

45、lculate the volatility rate in accordance with 11.3.10.2.5 Repeat 10.2.1 10.2.4 for additional samples.11. Calculation11.1 Use all available decimals for each value in thecalculations. Round the final volatility rate to the nearest 0.1g/min.11.2 Using Test Method A, the volatility rate is obtainedfr

46、om the difference in mass at the initial time and the mass atthe final time at the isothermal temperature divided by 30 min(or other elapsed time used, see Fig. 1):volatility rate, rv5 mi2 mf!/tf2 ti! or mi2 mf!/30 (1)where:mi= mass at initial time (ti), andmf= mass at final time (tf).NOTE 7If the m

47、ass loss rate is not constant with time at the isothermaltemperature, this calculation will result in an average value of volatilityrate. Selecting shorter time segments, such as the first few minutes and thelast few minutes, will result in different values that could demonstrate theE2008 174range o

48、f volatility rate exhibited by the sample (see also Fig. 3).11.3 Using Test Method B, the volatility rate is either thecomputed first derivative of the mass loss curve at any specifictemperature(s) of interest or is the rate obtained by determiningthe slope of the mass loss curve overa4K(2min) inter

49、valcentered about the specific temperature of interest (see Fig. 2).12. Report12.1 Report the following information:12.1.1 A complete identification and description of thematerial tested, including any pretreatment of a specimen.12.1.2 A description of the instrumentation used.12.1.3 Test conditions, including temperature programexecuted, purge gas composition and flow rate, initial specimensize, and pinhole size.12.1.4 The mass loss curve or the first derivative withrespect to time of mass loss, or both.12.1.5 The volati