1、Designation: E2716 09Standard Test Method forDetermining Specific Heat Capacity by SinusoidalModulated Temperature Differential Scanning Calorimetry1This standard is issued under the fixed designation E2716; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A 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 determination of specificheat capacity by sinusoid
3、al modulated temperature differentialscanning calorimetry. For the determination of specific heatcapacity by a step-isothermal or multiple step-isothermaltemperature program, the reader is referred to Test MethodE1269.1.2 This test method is generally applicable to thermallystable solids and liquids
4、.1.3 The normal operating range of the test is from 100 to600 C. The temperature range may be extended dependingupon the instrumentation and specimen holders used.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 stan
5、dard does 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.2. Referenced Documents2.1 A
6、STM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE1142 Terminology Relating to T
7、hermophysical PropertiesE1269 Test Method for Determining Specific Heat Capacityby Differential Scanning Calorimetry3. Terminology3.1 Specific technical terms found in this test method aredefined in Terminologies E473 and E1142 including modulatedtemperature, isothermal, differential scanning calori
8、metry, fre-quency, heat capacity and specific heat capacity.3.2 Definitions of Terms Specific to This Standard:3.2.1 modulated Temperature Differential Scanning Calo-rimetry (MTDSC), na version of differential scanning calo-rimetry that provides a sinusoidally varying temperature pro-gram to the tes
9、t specimen in addition to the traditionaltemperature ramp program.3.2.2 Quasi-isothermal modulated temperature differentialscanning calorimetry, na variation of modulated temperaturedifferential scanning calorimetry in which a sinusoidally vary-ing temperature program is applied to a test specimen a
10、roundan underlying isothermal temperature4. Summary of Test Method4.1 The specific heat capacity of a test specimen may bedetermined using the modulated temperature approach inwhich an oscillatory or periodically repeating temperatureprogram is imposed upon a test specimen producing anoscillatory (p
11、eriodic) heat flow into or out of the specimen.4.1.1 Test methodAconsists of heating the test specimen ina controlled atmosphere through the temperature region ofinterest, using temperature modulation conditions that areappropriate for the measurement.4.1.2 Test method B consists of equilibrating an
12、d holdingthe test specimen at an isothermal temperature in a controlledatmosphere and then applying appropriate temperature modu-lation conditions for the measurement. This procedure can berepeated using as many isothermal temperature holds as aredesired.4.2 The accuracy of the heat capacity thus ob
13、tained dependsupon the experimental conditions. For example, when a thintest specimen encapsulated in a specimen pan of high thermalconductivity is treated with temperature oscillations of longperiod (low frequency), the test specimen achieves a uniform1This test method is under the jurisdiction ofA
14、STM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved Sept. 1, 2009. Published December 2009. DOI:10.1520/E2716-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu
15、stomer 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 States.temperature distribution and the
16、resultant heat capacity infor-mation will be comparable with those of other non-oscillatorytest methods.5. Significance and Use5.1 Modulated temperature differential scanning calorimet-ric measurements provide a rapid, simple method for determin-ing specific heat capacities of materials, even under
17、quasi-isothermal conditions.5.2 Specific heat capacities are important for design pur-poses, quality control, and research and development.5.3 The use of a stepped quasi-isothermal program may beused to follow structure changes in materials.6. Interferences6.1 Since milligram quantities of specimen
18、are used, it isessential that specimens are homogeneous and representative.6.2 The occurrence of chemical changes, or mass loss orgain, on heating during the measurement may invalidate thetest. Therefore, the temperature range and specimen holdershould be chosen so as to avoid these processes.7. App
19、aratus7.1 Modulated Differential Scanning CalorimeterThe es-sential instrumentation required to provide the minimummodulated differential scanning calorimetric capability for thismethod includes:7.1.1 A Modulated Temperature Differential Scanning Calo-rimeter (MTDSC) Test Chamber, composed of (1) a
20、furnace toprovide uniform controlled heating/cooling of a specimen andreference to a constant temperature or at a constant rate withinthe applicable range 100 to 600C (2) a temperature sensor (orother signal source) to provide an indication of the specimentemperature readable to 0.01 C; (3) a differ
21、ential sensor todetect a heat flow difference between the specimen andreference equivalent to 1.0 W; and (4) a means of sustaining anenvironment of an inert purge gas at a rate of 50 6 10 mL/min.(See section 7.1.6 for more information on purge gases.)7.1.2 A Temperature Controller, capable of execut
22、ing aspecific temperature program by (1) operating the furnacebetween selected temperature limits at a rate of temperaturechange of 1 to 10 C/min, (2) holding at an isothermaltemperature to within 0.1 C, and (3) sinusoidally varying thetemperature with an amplitude of up to 1.5 C and a period ofup t
23、o 100 s (frequency down to 10 mHz) superimposed uponthe underlying rate.7.1.3 A Calculating Device, capable of transforming theexperimentally determined modulated temperature and modu-lated specimen heat flow signals into the required continuousoutput form of specific heat capacity (preferably in un
24、its of J/(gC) and average test temperature to the required accuracy andprecision.7.1.4 A Data Collection Device, to provide a means ofacquiring, storing and displaying measured or calculated sig-nals, or both. The minimum output signals required forMTDSC are amplitude of modulated heat flow, tempera
25、ture,amplitude of modulated temperature and time.7.1.5 A Coolant System, to provide oscillatory heating andcooling rates of at least 5 C/min.7.1.6 Inert Nitrogen, or other low conductivity purge gasflowing at a rate of 50 mL/min.NOTE 1Helium, a commonly used purge gas, is unacceptable for thispurpos
26、e, due to its very high thermal conductivity which results in reducedrange, precision and accuracy.7.2 A Balance, with a range of at least 200 mg and aresolution of 0.001 mg to weigh specimens or containers, orboth, (pans, crucibles, etc.) to an accuracy 60.01 mg.7.3 Containers (pans, crucibles, etc
27、.) that are inert to thespecimen and are of suitable structural shape and integrity tocontain the specimen in accordance with the specific require-ments of this test method.NOTE 2The masses of the specimen holders should not differ by morethan 0.05 mg, otherwise the mass difference in the containers
28、 must beconsidered in the calculation of Cp.8. Reagents and Materials8.1 Specific heat capacity reference material: synthetic sap-phire disk, 10 to 100 mg.NOTE 3Interlaboratory studies have indicated that physical forms ofsynthetic sapphire other than disks give lower precision and greater biasin th
29、e results.9. Hazards9.1 Safety PrecautionsIf a specimen is heated to decom-position, toxic or corrosive products may be released.9.2 Technical Precautions:9.2.1 The same modulation conditions of amplitude andperiod should be used for both the heat capacity calibration andspecimen runs.9.2.2 Precisio
30、n of heating rate, placement of the specimenholder, use of specimen holders with a flat base and theestablishment of equilibrium are essential. Instrument settingsshould not be adjusted once a specific heat capacity calibrationhas been performed.10. Sampling, Test Specimens and Test Units10.1 Powder
31、ed or granular specimens should be mixed priorto sampling and should be sampled by removing portions fromvarious parts of the container. These portions, in turn, should becombined and mixed to ensure a representative specimen forthe determinations.10.2 Liquid specimens may be sampled directly after
32、stir-ring.10.3 Solid specimens may be sampled by cutting or slicingwith a clean knife or razor blade. Ascertain sample uniformityas segregation within the solid sample is possible.10.4 Samples are usually analyzed as received. If somepre-conditioning or mechanical treatment is applied to the testspe
33、cimen prior to analysis, this should be noted in the report.11. Preparation of Apparatus11.1 Perform any setup or calibration procedures recom-mended by the apparatus manufacturer in the operationsmanual.E2716 09212. Calibration and Standardization12.1 Calibrate the temperature signal from the appar
34、atus inaccordance with Practice E 967E967 using an indium refer-ence material and a heating rate of 10 C/min.12.2 Calibrate the heat flow signal from the apparatus inaccordance with Practice E968 using an indium referencematerial.NOTE 4For both sections 12.1 and 12.2, another suitable referencemater
35、ial may be used to cover a different temperature range.12.3 Calibrate the apparatus heat capacity signal(s) forspecific heat capacity measurements under temperature modu-lated conditions in accordance with the instructions of themanufacturer as described in the instrument manual.12.4 Select the temp
36、erature that, for method A, is themid-point of the temperature range over which the measure-ment is to be made, or, for method B, that is the temperature atwhich the measurement is to be made, or the midpoint of all theisothermal temperatures used in the measurement, if multipleisothermal temperatur
37、es are used.12.5 Crimp a clean, empty specimen holder plus lid andrecord the mass to a precision of 6 0.01 mg. Place on thereference side of the DSC.12.6 Weigh a clean, empty specimen holder plus lid to aprecision of 6 0.01 mg. Encapsulate the sapphire materialfrom section 8.1 in this specimen holde
38、r. Record the mass ofthe sapphire standard and specimen holder to a precision of 60.01 mg, and place on the sample side of the instrument. Applythe following temperature modulation conditions: 6 1.0 Camplitude, 100 s period (10 mHz frequency) (if differentmodulation conditions are used, they shall b
39、e reported). Holdthe sample isothermal for at least 10 minat the desiredtemperature and then measure the heat capacity value at theend of the isotherm.12.7 Calculate the specific heat capacity constant (KCp)bytaking the ratio of the theoretical value of sapphire to themeasured value at the test temp
40、erature.NOTE 5 Specific heat capacity values for synthetic sapphire may befound in Table 1 of Practice E1269.13. Procedure13.1 Purge the DSC apparatus with dry nitrogen at a flowrate of 50 6 10 mL/min throughout the experiment.13.2 Crimp a clean, empty specimen holder plus lid andplace on the refere
41、nce of the MTDSC apparatus. Record themass of the specimen holder plus lid to a precision of 6 0.01mg if required for proper operation of the DSC apparatus.13.3 Weigh a clean, empty specimen holder plus lid to aprecision of 6 0.01 mg. Record as the tare weight.13.4 Encapsulate the sample to be studi
42、ed into the speci-men holder plus lid combination and record the mass of thesample plus specimen holder and lid to 6 0.01 mg. Calculatethe sample mass to 6 0.01 mg.13.5 Method A.13.5.1 Beginning 30 C below the lowest temperature ofinterest to 10 C above the highest temperature of interest,execute a
43、ramped modulated DSC experiment over the tem-perature range of interest using the following modulatedparameters: 61.0 C amplitude, 100 s period (10 mHz fre-quency), and 3 C/min heating rate (if different modulationconditions are used, they should be reported).13.5.2 Record the amplitude of the modul
44、ated heat flow andthe amplitude of the modulated temperature continually or atthe temperature of interest.13.5.3 Using the amplitude of the modulated heat flow andamplitude of the modulated temperature from section 13.5.2,calculate and report the specific heat capacity at the tempera-ture of interes
45、t as described in section 14.13.5.4 Re-weigh the specimen holder plus specimen. If amass loss of 0.3% or greater occurred with respect to the initialmass, the measurement is invalid. Any change in mass shall bereported.13.6 Method B:13.6.1 Establish the isothermal test temperature of interest.Initia
46、te a temperature modulation of 61.0 C amplitude, 100 speriod (10 mHz frequency) (if different modulation conditionsare used, they should be reported). After 10 minutes oftemperature modulation, record and report the heat capacity.13.6.2 Record the amplitude of the modulated heat flow andthe amplitud
47、e of the modulated temperature continually or atthe temperature of interest.13.6.3 Using the amplitude of the modulated heat flow andamplitude of the modulated temperature from section 13.5.2,calculate and report the specific heat capacity at the tempera-ture of interest as described in section 14.1
48、3.6.4 Re-weigh the specimen holder plus specimen. If amass loss of 0.3% or greater occurred with respect to the initialmass, the measurement is invalid. Any change in mass shall bereported.14. Calculation or Interpretation of Results14.1 At the temperatures of interest, measure the amplitudeof the m
49、odulated heat flow and record to the nearest 6 0.01mW.14.2 At the same temperatures in section 14.1, measure theamplitude of the modulated heating rate to the nearest 60.01C/min. 14.3 Cal14.3 culate the specific heat capacity as follows:Cps5 60s/min Amhf KCp!/Amhr Ws! (1)where:Cps= Specific heat capacity of the specimen, J/g CAmhf= Amplitude of the modulated heat flow calculated insection 14.1, mWAmhr= Amplitude of the modulated heating rate calcu-lated in section 14.2, C/min.Ws= Mass of the sample specimen, mg.KCp= Calibration constant calculated i
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