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

1、Designation: E1269 11Standard 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 revision, the year

2、 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 calorimetry.1.2 This t

3、est method is generally applicable to thermallystable solids and liquids.1.3 The normal operating range of the test is from 100 to600 C. 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 thestand

4、ard.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 t

5、o 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 method

6、ology 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 limitatio

7、ns prior to use. Specific precau-tionary statements are given in Section 9.2. Referenced Documents2.1 ASTM 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

8、 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE1142 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 7123 Testing Methods

9、 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 This test method consists of heating the test material ata controlled rate in a controlled atmosphere through the reg

10、ionof 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 method for determining sp

11、ecific 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 homogeneous and representat

12、ive.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 interference. The largeheat of evaporation causes the

13、 specific heat capacity to be too1This test method 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, 2011. Published May 2011. Originallyapproved in 1990. Last

14、previous edition approved in 2005 as E1269 05. DOI:10.1520/E1269-11.2For 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 w

15、ebsite.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.large if there is too much head space in the sealed

16、 crucible.Completely fill the crucible for most accurate results.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The essen-tial instrumentation required to provide the minimum differen-tial scanning calorimetric capability for this method includes:7.1.1 DSC Test Chamber, composed of the follo

17、wing: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 provide an indication of thespecimen temperature t

18、o 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 mL/min.NOTE 2Typically, 99+ % pure nitrogen, argon,

19、 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 Temperature Controller, capable of executing a spe-cific temperature program by operating the furnace(s) betweenselected temperature limits

20、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 Data Collection Device, to provide a means of acquir-ing, storing, and displaying measured and calculated signals.The minimum output signals required for the DSC are heat

21、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 (pans, crucibles, vials, etc., and lids) thatare inert to the specimen and reference materials and which areof suitable structura

22、l 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 cooling rates of up to 10C/min, to achieve subambient operation, or to sustain anis

23、othermal 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: synthetic sapphire disk,10 to 100 mg.NOTE 3Interlaboratory studies indicate tha

24、t 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 released.9.2 Technical Precautions:9.2.1 The same heating rate should be used f

25、or 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 beadjusted once a specific heat capacity calibration has beenperformed.10. Sampli

26、ng10.1 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 representative specimen forthe determinations.10.2 Liquid specimens may be sampled dir

27、ectly 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 be sampled by cutting or slicingwith a clean knife or razor blade. Sample uniformity should beascertained, since segregatio

28、n 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 received. If some heator mechanical treatment is applied to the specimen prior toanalysis, this treatment should be noted in th

29、e 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 calibrated in both thetemperature and heat flow modes. Since specific heat capacityis not a rapidly changing function of t

30、emperature, the instru-ments temperature mode is ordinarily 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 proc

31、edures described by themanufacturer in the operations manual.11.3 Perform a temperature calibration for the apparatususing Practice E967.11.4 Perform a heat flow calibration for the apparatus usingPractice E968.11.5 Heat Flow Calibration:11.5.1 Synthetic sapphire disk (a-aluminum oxide; alu-mina) is

32、 recommended as a heat flow calibration standard forspecific heat capacity measurements for both heating andcooling experiments. Specific heat capacity values for syn-thetic sapphire are given in Table 1.NOTE 5It is possible to use other standard materials or other physicalforms of synthetic sapphir

33、e, but their use should be noted in the report.The potential adverse impact of increased interfacial 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 o

34、f the standard. Synthetic sapphireis usually available from your DSC supplier.E1269 11211.5.2 The heat flow calibration may be performed at someregular interval or prior to every specific heat capacity deter-mination or test specimens.NOTE 6A frequency of calibration of at least once a day is recom-

35、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 regularinterval, the calorimetric sensitivity, E, may be calculated usingthe specific heat capacity values for synthetic sapphire given inTabl

36、e 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 the heat flow calibration is performed prior toevery specific heat capacity determination, it is unnecessary tocalculate the calorimetric sensiti

37、vity, E. Refer to Section 13 forthe procedure.412. Conditioning12.1 Specimens and specimen holders for specific heatcapacity determinations may be handled in ordinary laboratoryenvironments for screening or qualitative measurements. How-ever, if quantitative data are needed over a wide temperature4T

38、he boldface numbers in parentheses refer to the list of references at the end ofthis standard.TABLE 1 Sapphire (a Al2O3) Specific Heat CapacityATemperatureSpecific HeatCapacity(C) (K) J/(g*K)123.15 150 0.3133113.15 160 0.3525103.15 170 0.391293.15 180 0.429083.15 190 0.465973.15 200 0.501463.15 210

39、0.535653.15 220 0.568443.15 230 0.599633.15 240 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

40、 400 0.9429136.85 410 0.9550146.85 420 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 1.0877

41、306.85 580 1.0934316.85 590 1.0988326.85 600 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

42、1.1784546.85 820 1.1839566.85 840 1.1890586.85 860 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/(g*K)-123.

43、15 150 0.684-113.15 160 0.710-103.15 170 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.

44、85 500 0.997276.85 550 1.016326.85 600 1.034376.85 650 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, 7

45、79786 (1980) and Ditmars, D.A.; Plint,C.A.; Shukla, R.C. Int. J. Thermophys, 6, 499515 (1985). These results are to beused for crucibles made of pure aluminum. Crucibles made from an alloy ofaluminum may be different.E1269 113range, specimen conditioning may be required. Specimenswhich will be expos

46、ed to low temperatures should be protectedfrom moisture. Specimens that will be exposed 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

47、. All materials which will come in contactwith 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 accomplished in the DSC a

48、pparatus,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 initiation of the tempe

49、ratureprogram. 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 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-matche