ASTM E1269-2005 Standard Test Method for Determining Specific Heat Capacity by Differential Scanning Calorimetry《用差示扫描热量测定仪测定比热容量的标准试验方法》.pdf

1、Designation: E 1269 05Standard Test Method forDetermining Specific Heat Capacity by Differential ScanningCalorimetry1This standard is issued under the fixed designation E 1269; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye

2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 calorimetry.1.2 Thi

3、s 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 The values stated in SI units are to be regarded as thesta

4、ndard.1.5 Computer or electronic-based instrumentation, tech-niques, or data treatment equivalent to this test method may beused.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

5、 to determine equivalency prior to use.1.6 This method is similar to ISO 113574, but containsadditional methodology not found in that method.Additionally,ISO 113574 contains practices not found in this standard.Thismethod is similar to Japanese Industrial Standard K 7123, butcontains additional meth

6、odology not found in that method.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 safety and health practices and determine the applica-bility of regulatory limitat

7、ions prior to use. Specific precau-tionary statements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:2E 473 Terminology Relating to Thermal AnalysisE 967 Practice for Temperature Calibration of DifferentialScanning Calorimeters and Differential ThermalAnalyzersE 968 Practice for He

8、at Flow Calibration of DifferentialScanning Calorimeters and Differential ThermalAnalyzersE 1142 Terminology Relating to Thermophysical Properties2.2 ISO Standard:ISO 113574 Plastics- Differential Scanning Calorimetry(DSC)- Determination of Specific Heat Capacity32.3 Japanese Industrial Standard:K 7

9、123 Testing Methods for Specific Heat Capacity ofPlastics33. Terminology3.1 DefinitionsTechnical terms used in this test methodare described in Terminologies E 473 and E 1142.4. Summary of Test Method4.1 This test method consists of heating the test material ata controlled rate in a controlled atmos

10、phere 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. Significance and Use5.1 Differential scanning calorimetric measurements pro-vide a rapid, simple meth

11、od for determining specific heatcapacities of materials.5.2 Specific heat capacities are important for reactor andcooling system design purposes, quality control, and researchand development.6. Interferences6.1 Since milligram quantities of specimen are used, it isessential that specimens are homoge

12、neous 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.1This test method is under the jurisdiction ofASTM Committee E37

13、on ThermalMeasurement and is the direct responsibility of Subcommittee E37.01 on TestMethods and Recommended Practices.Current edition approved March 1, 2005. Published April 2005. Originallyapproved in 1990. Last previous edition approved in 2004 as E 126901.2For referenced ASTM standards, visit th

14、e 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 Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.

15、1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The essen-tial instrumentation required to provide the minimum differen-tial scanning calorimetric capability for this method incl

16、udes: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 applicable 100 to 600 Ctemperature range of this test method.7.1.1.2 Temperature Sensor, to

17、provide an indication of thespecimen temperature to 6 10 mK (0.01 C).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 chamber environmentof inert purge gas at a purge flow rate of 10 to 50 mL/min 65 m

18、L/min.NOTE 2Typically, 99+ % pure nitrogen, argon, or helium are em-ployed when oxidation in air is a concern. Unless effects of moisture areto be studied, use of dry purge gas is recommended and is essential foroperation at subambient temperatures.7.1.2 Temperature Controller, capable of executing

19、a spe-cific temperature program by operating the furnace(s) betweenselected temperature limits at a rate of temperature change of10 to 20 C/min constant to 6 0.1 C/min or at an isothermaltemperature constant to 6 0.1 C.7.1.3 Recording Device, either digital or analog, capable ofrecording and display

20、ing any fraction of the heat flow signal(DSC curve) including the signal noise as a function oftemperature.7.1.4 While not required, the user may find useful softwareto perform the mathematical treatments described in this testmethod.7.1.5 Containers (pans, crucibles, vials, etc., and lids) thatare

21、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 elevatedtemperatures, to provide constant coo

22、ling rates of up to 10C/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, to6 10 g.8. Reagents and Materials8.1 Specific heat capacity standard:

23、 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 to decom-position, toxic or corrosive products may be

24、 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 essential. Instrument settings should not b

25、eadjusted 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, should becombined and mixed to ensure a repres

26、entative specimen forthe determinations.10.2 Liquid specimens may be sampled directly after stir-ring.10.3 Solid specimens may 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 specime

27、ns should be so sampled as to maximize contactwith the surface of the specimen holder.10.4 Samples are usually analyzed as received. 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 capacit

28、y is a quantitative measurement ofenergy made as a function of temperature. Thus, the instrumentused in its measurement must be 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 o

29、rdinarily calibrated and checkedonly occasionally. The heat flow information, however, ismuch more critical and becomes an integral part of the specificheat capacity measurement through the use of a referencematerial.11.2 Perform any calibration procedures described by themanufacturer in the operati

30、ons manual.11.3 Perform a temperature calibration for the apparatususing Practice E 967.11.4 Perform a heat flow calibration for the apparatus usingPractice E 968.11.5 Heat Flow Calibration:11.5.1 Synthetic sapphire disk (a-aluminum oxide; alu-mina) is recommended as a heat flow calibration standard

31、 forspecific heat capacity measurements. Specific heat capacityvalues for synthetic sapphire 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 i

32、nterfacial resistance encoun-tered with granular/textured samples may be 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.11.5.2 The heat flow calibration may be performed at someregular interval o

33、r prior 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.E126905211.5.3 If the heat flow calibration is performed a

34、t a regularinterval, 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/60 Dst!# Wst Cpst! 1DW Cpc!# (1)Refer to Section 13 for the procedure and Section 14 for thelist of symbols.11.5.4 If

35、 the heat flow calibration 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

36、 in ordinary laboratoryenvironments for screening or qualitative measurements. How-ever, if quantitative data are needed over a wide temperaturerange, specimen conditioning may be required. Specimenswhich will be exposed to low temperatures should be protectedfrom moisture. Specimens that will be ex

37、posed to very hightemperatures 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 contact4The boldface numbers in parentheses ref

38、er to the list of references at the end ofthis standard.TABLE 1 Sapphire (a Al2O3) Specific Heat CapacityATemperatureSpecific HeatCapacity(C) (K) J(gK)1123.15 150 0.3133113.15 160 0.3525103.15 170 0.391293.15 180 0.429083.15 190 0.465973.15 200 0.501463.15 210 0.535653.15 220 0.568443.15 230 0.59963

39、3.15 240 0.629423.15 250 0.657713.15 260 0.68463.15 270 0.71026.85 280 0.734416.85 290 0.757426.85 300 0.779236.85 310 0.799946.85 320 0.819456.85 330 0.838066.85 340 0.855676.85 350 0.872186.85 360 0.887896.85 370 0.9027106.85 380 0.9168116.85 390 0.9302126.85 400 0.9429136.85 410 0.9550146.85 420

40、0.9666156.85 430 0.9775166.85 440 0.9879176.85 450 0.9975186.85 460 1.0074196.85 470 1.0164206.85 480 1.0250216.85 490 1.0332226.85 500 1.0411236.85 510 1.0486246.85 520 1.0559256.85 530 1.0628266.85 540 1.0694276.85 550 1.0758286.85 560 1.0819296.85 570 1.0877306.85 580 1.0934316.85 590 1.0988326.8

41、5 600 1.1040336.85 610 1.1090346.85 620 1.1138356.85 630 1.1184366.85 640 1.1228376.85 650 1.1272386.85 660 1.1313396.85 670 1.1353406.85 680 1.1393416.85 690 1.1431426.85 700 1.1467446.85 720 1.1538466.85 740 1.1605486.85 760 1.1667506.85 780 1.1727526.85 800 1.1784546.85 820 1.1839566.85 840 1.189

42、0586.85 860 1.1939606.85 880 1.1986626.85 900 1.2031636.85 910 1.2053646.85 920 1.2074666.85 940 1.2116686.85 960 1.2155706.85 980 1.2194726.85 1000 1.2230ASee Ref (1).4TABLE 2 Aluminum Specific Heat CapacityATemperatureSpecific HeatCapacity(C) (K) J(gK)1-123.15 150 0.684-113.15 160 0.710-103.15 170

43、 0.734-93.15 180 0.754-83.15 190 0.773-73.15 200 0.789-63.15 210 0.804-53.15 220 0.818-43.15 230 0.831-33.15 240 0.843-23.15 250 0.853-13.15 260 0.863-3.15 270 0.8736.85 280 0.88216.85 290 0.89026.85 300 0.89776.85 350 0.930126.85 400 0.956176.85 450 0.978226.85 500 0.997276.85 550 1.016326.85 600 1

44、.034376.85 650 1.052426.85 700 1.073476.85 750 1.098526.85 800 1.128ACalculated from a least-square representation of the measured heat capacityand enthalpy increment values from: Downie, D.B.; Martin, J.F., Giauque, W.F.;Meads, P.F.; J Chem. Thermodynam,12, 779786 (1980) and Ditmars, D.A.; Plint,C.

45、A.; Shukla, R.C. Int. J. Thermophys, 6, 499515 (1985)E1269053with the specimen should also be purged in a dry, inertenvironment. 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 accomp

46、lished in the DSC apparatus,using the inert purge stream of the instrument. This condition-ing procedure will not protect specimens that are hermeticallysealed under normal laboratory atmospheric conditions.12.4 The specimen should be held at the starting tempera-ture for several minutes before init

47、iation of the temperatureprogram. An equilibrium time of four minutes is suggested.However, other equilibrium times may be 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

48、6 5 mL per min throughoutthe experiment.13.1.2 Weigh a clean, empty specimen holder plus lid to aprecision of 60.01 mg. Record 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 s

49、ame reference specimen holder + lid should be used forthe sapphire standard run and for the test specimen run.13.1.4 Heat or cool the DSC test chamber to the initialtemperature for the experiment at 20 C/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 finaltemperature at a rate of 20 C/min. Continue to record thethermal curve.NOTE 8The precision of this test method