ASTM E1269-2011(2018) Standard Test Method for Determining Specific Heat Capacity by Differential Scanning Calorimetry《用差示扫描量热法测定比热容的标准试验方法》.pdf

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1、Designation: E1269 11 (Reapproved 2018)Standard Test Method forDetermining Specific Heat Capacity by Differential ScanningCalorimetry1This standard is issued under the fixed designation E1269; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、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 covers the determination of specificheat capacity by differential scanning calo

3、rimetry.1.2 This test method is generally applicable to thermallystable solids and liquids.1.3 The normal operating range of the test is from 100 to600C. The temperature range can be extended, dependingupon the instrumentation and specimen holders used.1.4 Computer or electronic-based instrumentatio

4、n,techniques, or data treatment equivalent to this test methodmay be used.NOTE 1Users of this test method are expressly advised that all suchinstruments or techniques may not be equivalent. It is the responsibility ofthe user of this test method to determine equivalency prior to use.1.5 This test me

5、thod is similar to ISO 113574, but containsadditional methodology not found in that method.Additionally,ISO 113574 contains practices not found in this standard.Thistest method is similar to Japanese Industrial Standard K 7123,but contains additional methodology not found in that method.1.6 The valu

6、es stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 This standard 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 saf

7、ety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 9.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization establ

8、ished 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:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE967

9、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 Thermophysical Properties2.2 ISO Standard:3ISO 113574 Plastics: Differential Sca

10、nning Calorimetry(DSC)Determination of Specific Heat Capacity2.3 Japanese Industrial Standard:K 7123 Testing Methods for Specific Heat Capacity ofPlastics33. Terminology3.1 DefinitionsTechnical terms used in this test methodare described in Terminologies E473 and E1142.4. Summary of Test Method4.1 T

11、his test method consists of heating the test material ata controlled rate in a controlled atmosphere through the regionof interest. The difference in heat flow into the test material anda reference material or blank due to energy changes in thematerial is continually monitored and recorded.5. Signif

12、icance and Use5.1 Differential scanning calorimetric measurements pro-vide a rapid, simple method for determining specific heatcapacities of materials.5.2 Specific heat capacities are important for reactor andcooling system design purposes, quality control, and researchand development.1This test met

13、hod is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved April 1, 2018. Published May 2018. Originallyapproved in 1990. Last previous edition approved in 2011 as E1269 11.

14、DOI:10.1520/E1269-11R18.2For referenced ASTM standards, visit the ASTM website, 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.3Available from American National Sta

15、ndards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principle

16、s on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16. Interferences6.1 Since milligram quantities of specimen are used, it isessen

17、tial that specimens are homogeneous and representative.6.2 The occurrence of chemical changes or mass loss onheating during the measurement may invalidate the test.Therefore, the temperature range and specimen holders shouldbe chosen so as to avoid these processes.6.3 Water samples have a special in

18、terference. The largeheat of evaporation causes the specific heat capacity to be toolarge if there is too much head space in the sealed crucible.Completely fill the crucible for most accurate results.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The essentialinstrumentation required to prov

19、ide the minimum differentialscanning calorimetric capability for this test method includes:7.1.1 DSC Test Chamber, composed of the following:7.1.1.1 Furnace(s), to provide uniform controlled heating(cooling) of a specimen and reference to a constant temperatureor at a constant rate within the applic

20、able 100 to 600Ctemperature range of this test method.7.1.1.2 Temperature Sensor, to provide an indication of thespecimen temperature to 610 mK (0.01C).7.1.1.3 Differential Sensor, to detect heat flow differencebetween the specimen and reference equivalent to 1 W.7.1.1.4 A means of sustaining a test

21、 chamber environmentof inert purge gas at a purge flow rate of 10 to 50 mL/min 65 mL/min.NOTE 2Typically, 99+ % pure nitrogen, argon, or helium are em-ployed when oxidation in air is a concern. Use of dry purge gas isrecommended and is essential for operation at subambient temperatures.7.1.2 Tempera

22、ture Controller, capable of executing a spe-cific temperature program by operating the furnace(s) betweenselected temperature limits at a rate of temperature change of10 to 20C/min constant to 60.1C/min or at an isothermaltemperature constant to 60.1C.7.1.3 Data Collection Device, to provide a means

23、 ofacquiring, storing, and displaying measured and calculatedsignals. The minimum output signals required for the DSC areheat flow, temperature and time.7.1.4 While not required, the user may find useful softwareto perform the mathematical treatments described in this testmethod.7.1.5 Containers (pa

24、ns, crucibles, vials, etc., and lids) thatare inert to the specimen and reference materials and which areof suitable structural shape and integrity to contain the speci-men and reference in accordance with the specific requirementsof this test method.7.1.6 Cooling capability to hasten cool down from

25、 elevatedtemperatures, to provide constant cooling rates of up to10C/min, to achieve subambient operation, or to sustain anisothermal subambient temperature, or a combination thereof.7.2 Balance, with a capacity of 100 mg or greater to weighspecimens or containers, or both, to 610 g.8. Reagents and

26、Materials8.1 Specific heat capacity standard: synthetic sapphire disk,10 to 100 mg.NOTE 3Interlaboratory studies indicate that physical forms of thesynthetic sapphire other than disks give lower precision and greater biasin the results.9. Hazards9.1 Safety PrecautionsIf a specimen is heated todecomp

27、osition, toxic or corrosive products may be released.9.2 Technical Precautions:9.2.1 The same heating rate should be used for both thecalibration and specimen runs.9.2.2 Precision of heating rate, placement of the specimenholder, use of flat specimen holders, and the establishment ofequilibrium are

28、essential. Instrument settings should not beadjusted once a specific heat capacity calibration has beenperformed.10. Sampling10.1 Powdered or granular specimens should be mixed priorto sampling and should be sampled by removing portions fromvarious parts of the container.These portions, in turn, sho

29、uld becombined and mixed to ensure a representative specimen forthe determinations.10.2 Liquid specimens may be sampled directly after stir-ring. Make sure the crucible is as full as possible if the sampleis water or aqueous. Do not exceed the pressure limit for thecrucible.10.3 Solid specimens may

30、be sampled by cutting or slicingwith a clean knife or razor blade. Sample uniformity should beascertained, since segregation within the solid is possible.NOTE 4Solid specimens should be so sampled as to maximize contactwith the surface of the specimen holder.10.4 Samples are usually analyzed as rece

31、ived. If some heator mechanical treatment is applied to the specimen prior toanalysis, this treatment should be noted in the report.11. Calibration11.1 Specific heat capacity is a quantitative measurement ofenergy made as a function of temperature. Thus, the instrumentused in its measurement must be

32、 calibrated in both thetemperature and heat flow modes. Since specific heat capacityis not a rapidly changing function of temperature, the instru-ments temperature mode is ordinarily calibrated and checkedonly occasionally. The heat flow information, however, ismuch more critical and becomes an inte

33、gral part of the specificheat capacity measurement through the use of a referencematerial.11.2 Perform any calibration procedures described by themanufacturer in the operations manual.11.3 Perform a temperature calibration for the apparatususing Test Method E967.11.4 Perform a heat flow calibration

34、for the apparatus usingPractice E968.E1269 11 (2018)211.5 Heat Flow Calibration:11.5.1 Synthetic sapphire disk (-aluminum oxide; alumina)is recommended as a heat flow calibration standard for specificheat capacity measurements for both heating and coolingexperiments. Specific heat capacity values fo

35、r synthetic sap-phire are given in Table 1.NOTE 5It is possible to use other standard materials or other physicalforms of synthetic sapphire, but their use should be noted in the report.The potential adverse impact of increased interfacial resistance encoun-tered with granular/textured samples may b

36、e minimized with the use of apowdered synthetic sapphire standard. It is preferred that the physicalform of the sample be similar to that of the standard. Synthetic sapphireis usually available from your DSC supplier.11.5.2 The heat flow calibration may be performed at someregular interval or prior

37、to every specific heat capacity deter-mination or test specimens.NOTE 6A frequency of calibration of at least once a day is recom-mended. Other time intervals may be selected for heat flow calibration butshould be noted in the report.11.5.3 If the heat flow calibration is performed at a regularinter

38、val, the calorimetric sensitivity, E, may be calculated usingthe specific heat capacity values for synthetic sapphire given inTable 1 and the following equation:E 5 b/60Dst!#WstCpst!1WCpc!# (1)Refer to Section 13 for the procedure and Section 14 for thelist of symbols.11.5.4 If the heat flow calibra

39、tion is performed prior toevery specific heat capacity determination, it is unnecessary tocalculate the calorimetric sensitivity, E. Refer to Section 13 forthe procedure.412. Conditioning12.1 Specimens and specimen holders for specific heatcapacity determinations may be handled in ordinary laborator

40、yenvironments for screening or qualitative measurements.However, if quantitative data are needed over a wide tempera-ture range, specimen conditioning may be required. Specimenswhich will be exposed to low temperatures should be protectedfrom moisture. Specimens that will be exposed to very hightemp

41、eratures should be protected from the effects of oxidation.12.2 Any volatile specimens suspected of being sensitive tomoisture or oxidation should be hermetically sealed in a dry,inert environment. All materials which will come in contactwith the specimen should also be purged in a dry, inertenviron

42、ment. Vacuum degassing of specimens to be heated toa very high temperature is recommended.12.3 Conditioning of nonvolatile specimens run in crimpedlid or open pans may be accomplished in the DSC apparatus,using the inert purge stream of the instrument. This condition-ing procedure will not protect s

43、pecimens that are hermeticallysealed under normal laboratory atmospheric conditions.12.4 The specimen should be held at the starting tempera-ture for several minutes before initiation of the temperatureprogram. An equilibrium time of four minutes is suggested.However, other equilibrium times may be

44、used but shall bereported.13. Procedure13.1 Reference MaterialSynthetic sapphire.13.1.1 Purge the DSC apparatus with dry nitrogen (or otherinert gas) at a flow rate of 10 to 50 6 5 mL per min throughoutthe experiment.13.1.2 Weigh a clean, empty specimen holder plus lid to aprecision of 60.01 mg. Rec

45、ord as the tare weight.13.1.3 Position the empty specimen holder plus lid and areference specimen holder plus lid (weight-matched, if pos-sible) in the DSC apparatus.NOTE 7The same reference specimen holder + lid should be used forthe sapphire standard run and for the test specimen run.13.1.4 Heat o

46、r cool the DSC test chamber to the initialtemperature for the experiment at 20C/min.13.1.5 Hold the DSC test chamber isothermally at the initialtemperature for at least 4 min to establish equilibrium. Recordthis thermal curve (refer to 12.4).13.1.6 Heat the test specimen from the initial to finaltem

47、perature at a rate of 20C/min. Continue to record thethermal curve.NOTE 8The precision of this test method is enhanced by this highheating rate. Other heating rates may be used but shall be reported.13.1.7 Record a steady-state isothermal baseline at theupper temperature limit. Refer to 12.4.13.1.7.

48、1 Terminate the thermal curve after this period.13.1.7.2 Cool the DSC test chamber to ambient tempera-ture.13.1.8 Place the sapphire standard into the same specimenholder plus lid used in 13.1.2.13.1.9 Weigh sapphire standard and specimen holder pluslid to a precision of 60.01 mg and record the weig

49、ht.13.1.10 Follow 13.1.4 13.1.7.NOTE 9The procedure (13.1.1 13.1.9) may be performed at someregular interval, or prior to every specific heat capacity determination oftest specimens. Refer to 11.5.13.2 Unknown Specimens13.1.1 13.1.7.NOTE 10Calculations are simplified if the same specimen holder isused for the empty specimen holder and the specimen plus specimenholder scans. In cases where two different specimen holders have to beused, a correction for the difference in weights of the two specimenholders can be made. Refer to 14.1.13