ASTM E2008-2017 Standard Test Methods for Volatility Rate by Thermogravimetry《用热重法测定波动率的标准试验方法》.pdf

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1、Designation: E2008 08 (Reapproved 2014)1E2008 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 las

2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEWarning notes were editorially updated throughout in March 2014.1. Scope1.1 These test methods cover procedures for assessing t

3、he volatility of solids and liquids at given temperatures usingthermogravimetry under prescribed experimental conditions. Results of these test methods are obtained as volatility rates expressedas mass per unit time. Rates 5 5 g/min are achievable with these test methods.1.2 Temperatures typical for

4、 these test methods are within the range from 25C to 500C. This temperature range may differdepending upon the instrumentation used.1.3 These test methods are intended to provide a value for the volatility rate of a sample using a thermogravimetric analysismeasurement on a single representative spec

5、imen. It is the responsibility of the user of these test methods to determine the needfor and the number of repetitive measurements on fresh specimens necessary to satisfy end use requirements.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are include

6、d in this standard.1.5 There is no ISO method equivalent to this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of these test methods to establish appropriate safety and health practices and dete

7、rmine the applicability of regulatorylimitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations

8、issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE473 Terminology Relating to Thermal Analysis and RheologyE691 Practice for Conducting an Interlabora

9、tory Study to Determine the Precision of a Test MethodE1142 Terminology Relating to Thermophysical PropertiesE1582 Practice for Calibration of Temperature Scale for ThermogravimetryE1860 Test Method for Elapsed Time Calibration of Thermal AnalyzersE2040 Test Method for Mass Scale Calibration of Ther

10、mogravimetric Analyzers3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to these test methods and can be found in Terminologies E473 and E1142:3.1.1.1 thermogravimetric analysis (TGA),3.1.1.2 thermogravimetry (TG), and3.1.1.3 volatility.3.2 Definitions of Terms Specific to This

11、 Standard:1 These test methods are under the jurisdiction of ASTM Committee E37 on Thermal Measurements and are the direct responsibility of Subcommittee E37.01 onCalorimetry and Mass Loss.Current edition approved March 15, 2014April 1, 2017. Published April 2014April 2017. Originally approved in 19

12、99. Last previous edition approved in 20082014 asE2008 08.E2008 08 (2014)1. DOI: 10.1520/E2008-08R14E01.10.1520/E2008-17.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, ref

13、er to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all ch

14、anges accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

15、United States13.2.1 volatility ratethe rate of conversion of a solid or liquid substance into the vapor state at a given temperature; mass perunit time.4. Summary of Test Method4.1 A solid or liquid specimen is confined in an appropriate container with a pinhole opening between 0.33 mm and 0.38 mm.T

16、he confined specimen is heated within a thermogravimetric analyzer either to a temperature and held constant at that temperaturefor a fixed interval of time (Method (Test MethodA, Fig. 1) or at a slow constant heating rate between temperature limits (Method(Test Method B, Fig. 2). The mass of the sp

17、ecimen is measured continuously and it or its rate of change is displayed as a functionof time or temperature. The volatility rate at any temperature is reported either as the average rate of mass loss per unit time fromTest Method A or as the instantaneous rate of mass loss (first derivative) per u

18、nit time from Test Method B.5. Significance and Use5.1 Volatility of a material is not an equilibrium thermodynamic property but is a characteristic of a material related to athermodynamic property that is vapor pressure. It is influenced by such factors as surface area, temperature, particle size,

19、and purgegas flow rate; that is, it is diffusion controlled.FIG. 1 Test Method A: Rv = Average Volatility RateE2008 1725.2 The extent of containment achieved for specimens in these test methods by means of a pinhole opening between 0.33 mmto 0.38 mm allows for measurement circumstances that are rela

20、tively insensitive to experimental variables other than temperature.Decreasing the extent of containment by use of pinholes larger than 0.38 mm will increase the magnitude of the observed rate ofmass loss but will also reduce the measurement precision by increasing the sensitivity to variations in o

21、ther experimental variables.5.3 Results obtained by these test methods are not strictly equivalent to those experienced in processing or handling conditionsbut may be used to rank materials for their volatility in such circumstances. Therefore, the volatility rates determined by these testmethods sh

22、ould be considered as index values only.5.4 The volatility rate may be used to estimate such quantifiable values as drying interval or the extent of volatile release froma process.6. Interferences6.1 Specimens that consist of a mixture of two or more volatile components or that undergo decomposition

23、 during this test mayexhibit curvature in the mass loss versus time plot of Test Method A (see Fig. 3). In such cases the volatility rate is not constantand shall not be reported as a singular value.7. Apparatus7.1 The essential instrumentation required to provide the minimum thermogravimetric analy

24、tical capability for these testmethods includes:7.1.1 A Thermobalance, A Thermobalance, composed of:7.1.1.1 A Furnace, A Furnace, to provide uniform controlled heating of a specimen at a constant temperature or at a constantrate within the applicable temperature range of these test methods;7.1.1.2 A

25、 Temperature Sensor, A Temperature Sensor, to provide an indication of the specimen/furnace temperature to 61 K;7.1.1.3 Acontinuously recording Balance, to measure the specimen mass with a minimum capacity of 100 mg and a sensitivityof 610 g;7.1.1.4 A means of sustaining the specimen/container under

26、 atmospheric control of inert gas (nitrogen, helium, and so forth)of 99.9 % purity at a purge rate of 50 mL/min to 100 mL/min 6 5 %.FIG. 2 Test Method B: Rv = Instantaneous Volatility RateE2008 1737.1.2 A Temperature Controller, A Temperature Controller, capable of executing a specific temperature p

27、rogram by operatingthe furnace between selected temperature limits at a rate of temperature change of 1 K/min to 2 K/min constant to within 60.1K/min or to rapidly heat a specimen at a minimum of 50 K/min to an isothermal temperature that is maintained constant to 61K for a minimum of 30 min.7.1.3 A

28、 Data Collection Device, A Data Collection Device, to provide a means of acquiring, storing, and displaying measuredor calculated signals, or both. The minimum output signals required for thermogravimetry are mass, temperature, and time.7.1.4 Sealable Containers, Sealable Containers, (pans, crucible

29、s, and so forth), that are inert to the specimen, that will remaingravimetrically stable within the temperature limits of these test methods, and that contain a pinhole in the lid of diameter between0.33 mm and 0.38 mm.3NOTE 1The most critical parameters for containers suitable for use with these te

30、st methods are the pinhole diameter and the lid thickness. Sealablecontainers of volumes (25 L to 50 L) and wall thicknesses (80 m to 150 m) commercially available from Mettler-Toledo, Perkin Elmer Corporation,and TA Instruments, Inc., have been found suitable for this purpose.7.2 Auxiliary equipmen

31、t necessary or useful in conducting these test methods includes:7.2.1 While not required, it is convenient to have a data analysis device that will continuously calculate and display the firstderivative of mass with respect to time (in mass/min) capable of detecting 0.05 g/min.7.2.2 Device to encaps

32、ulate the specimen in sealable containers.7.2.3 Micropipette or syringe to deliver liquid specimens of 1 L to 30 L into the containers.8. Sampling8.1 Samples are ordinarily measured as received. If a pretreatment is applied to any specimen, this treatment shall be noted inthe report.8.2 Since the ap

33、plicable 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 the sample is liquid, mixing prior to taking the specimen is sufficient toensure this consideration. If the sample is solid, take several sam

34、plings from different areas and either combine into a singlespecimen or run as a separate specimen with the final analysis representing an average of these determinations. Include the numberof determinations in the report.9. Calibration9.1 Perform temperature calibration in accordance with Practice

35、E1582 using the same purge gas conditions and container typeto be used for the subsequent measurements at a heating rate of 2 K/min. Do not disturb the temperature sensor position after thiscalibration.3 See Appendix X1.FIG. 3 Test Method ATwo Component MixtureE2008 1749.2 Perform mass calibration i

36、n accordance with Test Method E2040.9.3 Perform time scale calibration in accordance with Test Method E1860.10. Procedure10.1 Test Method AIsothermal Test:10.1.1 Initiate a purge gas flow through the thermobalance between 50 mL/min to 100 mL/min 6 5 %.10.1.2 Equilibrate the furnace, gas purge, and s

37、o forth at room temperature, and tare the balance.NOTE 2If the balance is tarred tared with the empty crucible and lid in place, then the mass of the test specimen may be recorded directly10.1.3 Encapsulate a specimen in an appropriate container with the specified pinhole. Specimen sizes between 1 m

38、g and 30 mgare typical for this test method, with the larger mass being used for more volatile specimens. (WarningVolatile materials maypose a respiratory hazard. Avoid unnecessary exposure to vapors.)10.1.4 Place the encapsulated specimen in the thermogravimetric analyzer, close the furnace, and al

39、low the temperature, purge,and so forth, to become stable within 61 % of settings.NOTE 3For highly volatile substances, a significant mass fraction of the specimen could be lost during this period of equilibration. Any largediscrepancy between the specimen mass as delivered and subsequently recorded

40、 by the thermobalance should be noted in the report.10.1.5 Heat the specimen rapidly at 50 K/min to the desired isothermal temperature, and thereafter, maintain the isothermaltemperature to 61 K for 30 min. Record the specimen mass in mg or g continually during this heating program versus time. Thes

41、pecimen temperature should be recorded during the heating programprogram.NOTE 4If the specimen is exhausted before 30 min have elapsed, it is recommended that the test be repeated with a larger specimen mass. Ifexcessively large specimen mass is required to complete a 30-min test time, a shorter tim

42、e interval or a lower isothermal temperature may be used andshall be reported.NOTE 5The initial rapid heating to the desired isothermal temperature may result in a momentary overshoot in the furnace temperature. Overshootin itself does not create a measurement question provided the data in 10.1.7 is

43、 taken only from the region where the isothermal temperature is stable andprovided the entire specimen has not been exhausted.10.1.6 Restore the furnace to ambient temperature, and remove the specimen container.10.1.7 Calculate the volatility rate in accordance with11.2.10.1.8 Repeat 10.1.2 10.1.7 f

44、or 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 6 0.1 K/min between ambient temperature and the desired limittemperature. Record the specimen mass in mg or g continually

45、during this heating program versus temperature, and calculate anddisplay 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 limit temperature, repeat the test using a larger specimen mass. If excessively

46、 largespecimen mass is required to reach the limit temperature, it may be necessary to terminate the test at a lower limit temperature, and this shall be notedin the report.10.2.3 Restore the furnace to ambient temperature, and remove the specimen container.10.2.4 Calculate the volatility rate in ac

47、cordance 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 the calculations. Round the final volatility rate to the nearest 0.1 g/min.11.2 Using Test MethodA, the volatility rate is obtained from the difference in mass at th

48、e initial time and the mass at the finaltime at the isothermal temperature divided by 30 min (or other elapsed time used, see Fig. 1):TABLE 1 Volatility Rate PrecisionMaterial Temperature,KAverageVolatility Rate,g min-1RepeatabilityStandardDeviation, Srg min-1ReproducibilityStandardDeviation,SRg min

49、-1RepeatabilityLimit, r gmin-1ReproducibilityLimit, R gmin-1Material Temperature,KAverageVolatility Rate,g/min-1RepeatabilityStandardDeviation, Srg/min-1ReproducibilityStandardDeviation, SRg/min-1RepeatabilityLimit, r g/min-1ReproducibilityLimit, R g/min-1Camphor 333 2.31 0.194 0.271 0.543 0.760Squalane 573 113 24.2 49.3 67.8 138Water 323 44.4 6.54 8.12 18.3 22.7Water 353 205 23.9 36.6 67.0 102E2008 175volatility rate, rv 5mi 2mf!/tf 2ti! or mi 2mf!/30 (1)where:mi = mass at initial time (ti), andmf = mass at final time (t