1、Designation: E 2069 06Standard Test Method forTemperature Calibration on Cooling of Differential ScanningCalorimeters1This standard is issued under the fixed designation E 2069; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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 temperature calibration ofdifferential scanning calorimeters on cooling using the
3、differ-ence between transition temperatures upon heating and coolingin the temperature range of 50 to 185 C. An offset in theindicated temperature between heating and cooling experi-ments, within this temperature range, may be used to providetemperature calibration on cooling at other temperature ra
4、nges.1.2 SI units are the standard.1.3 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 limit
5、ations prior to use. Specific precau-tionary statements are given in Section 6.2. Referenced Documents2.1 ASTM Standards:2D 3418 Test Method for Transition Temperatures of Poly-mers By Differential Scanning CalorimetryE 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 794 Test Method for
6、Melting And Crystallization Tem-peratures By Thermal AnalysisE 928 Test Method for Purity by Differential ScanningCalorimetryE 967 Test Method for Temperature Calibration of Differ-ential Scanning Calorimeters and Differential ThermalAnalyzersE 1970 Practice for Statistical Treatment of Thermoanalyt
7、i-cal Data3. Terminology3.1 Specific technical terms used in this test method aredefined in Terminology E 473.4. Summary of Test Method4.1 The temperature sensor of the DSC, used to determinethe temperature of a transition, is located close to but externalto the test specimen. This arrangement cause
8、s the indicatedtemperature to lead or lag the actual specimen temperature onheating/cooling causing the reported temperature to be higheron heating and lower on cooling than the actual specimentransition temperature. A DSC apparatus temperature, that hasbeen calibrated for heating experiments, needs
9、 to be re-calibrated for cooling experiments. Such a calibration oncooling is performed using a liquid crystal material, thetransition(s) for which are not subject to super-heating orsuper-cooling.4.2 The transition temperature of a rapid, non-superheatingand non-supercooling transition is determine
10、d upon heatingand upon cooling. The difference between these two indicatedtemperatures provides an offset temperature value betweenheating and cooling experiments at the indicated rate. Thisoffset temperature value, when used with a precise temperaturecalibration upon heating, may serve as an instru
11、ment calibra-tion function upon cooling.5. Significance and Use5.1 This test method is useful in calibrating the temperaturesignal of a differential scanning calorimeter for cooling experi-ments such as the determination of crystallization temperaturesin Test Method D 3418 and Test Method E 794.1Thi
12、s test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on TestMethods and Recommended Practices.Current edition approved Aug. 15, 2006. Published October 2006. Originallyapproved in 2000. Last previous edition appro
13、ved in 2000 as E 206900.2For 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.1Copyright ASTM International, 100 Ba
14、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 This test method may be used for research, develop-ment, analytical, specification acceptance, quality assuranceand control purposes.6. Precautions6.1 Toxic or corrosive effluents, or both, may be releasedwhen heating
15、the material of this test method and may beharmful to personnel and to the apparatus.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The essen-tial instrumentation required providing the minimum differen-tial scanning calorimeter capability for this test method in-cludes:7.1.1 A DSC Test Cham
16、ber, composed of:7.1.1.1 A Furnace(s), to provide uniform controlled heatingand cooling of a specimen and reference material to a constanttemperature or at a constant rate within the applicable tempera-ture range of this method.7.1.1.2 A Temperature Sensor, that indicates specimen orfurnace temperat
17、ure to 60.01 C.7.1.1.3 A Differential Sensor, to detect a heat flow difference(DSC) between the specimen and reference with a range of atleast 100 mW readable to 6 1 W (DSC).7.1.1.4 A means of sustaining a purge gas rate of 10 to 1006 5 mL/min in the test chamber.NOTE 1Typically inert purge gases th
18、at inhibit specimen oxidation are99 + % pure nitrogen, argon or helium. Subambient operation requires drypurge gases. Dry gases are recommended for all experiments unless theeffect of moisture is part of the study.7.1.2 A Temperature Controller, capable of executing aspecific temperature program by
19、operating the furnace orfurnaces between selected temperature limits at a rate oftemperature change of 10 C/min constant to within 6 0.1C/min or at an isothermal temperature constant to 6 0.1 C.7.1.3 A Recording Device, capable of recording and display-ing fractions of the heat flow signal (DSC curv
20、e), including thesignal noise, on the Y-axis versus fractions of temperaturesignal, including the signal noise, on the X-axis.7.1.4 Containers, (pans, crucibles, vials, lids, closures,seals, etc.) that are inert to the specimen and referencematerials and that are of suitable structural shape and int
21、egrityto contain the specimen and reference in accordance with therequirements of this test method.NOTE 2DSC containers are commonly composed of aluminum orother inert material of high thermal conductivity. Aluminum has beentested and found compatible with the materials used in this standard.7.1.5 C
22、ooling Capability, at constant cooling rates of up to10 C/min in the temperature range of 185 to 50 C, to hastencool down from elevated temperatures, or to sustain anisothermal subambient temperature, or both.7.2 A Balance, to weigh specimen and/or containers to 6 10g with a capacity of 100 mg or gr
23、eater.8. Calibration Materials8.1 For the temperature range covered by many applica-tions, the liquid crystal transitions of 99.8 to 99.9 % purematerials in Table 1 may be used for calibration. The calibrat-ing liquid crystal materials3are known as M-24, BP-53 andBCH-52.NOTE 3The purity of these liq
24、uid crystal materials may be determinedby Test Method E 928 using the first liquid crystal transition prior to use(see Table 2).8.2 The approximate heat of transitions for these samples isshown in Table 2. The enthalpy of transition for M-24 is sosmall that it is detectable only on the most sensitiv
25、e DSCinstrument.8.3 The actual specimen used for this test should be pre-melted in the crucible for the lowest variance.9. Calibration9.1 Perform any temperature calibration procedures recom-mended by the manufacturer of the differential scanningcalorimeter as described in the operations manual.9.2
26、Perform the temperature calibration of the differentialscanning calorimeter using Practice E 967 and the heating rateof 10 C/min. Indium is recommended as at least one of thecalibration materials.NOTE 4For the purposes of this standard, temperature calibration onheating is performed at 10 C/min and
27、on cooling at 10 C/min. Otherrates for either heating or cooling may be used but shall be reported.10. Procedure10.1 Select a suitable calibrating liquid crystal materialfrom Table 1.10.2 Into a clean, tared specimen container weigh 3.0 to 5.0mg of the liquid crystal calibration material.3The sole s
28、ource of supply of these materials known to the committee at thistime is EMD Chemicals Inc., 480 S. Democrat Road, Gibbstown, NJ 080271296.The part numbers for these chemiclals are as follows: M-24 is pn 1.00008.9005,BP-53 is pn 1.00007.9005 and BCH-52 is pn 1.00006.9005. If you are aware ofalternat
29、ive suppliers, please provide this information to ASTM headquarters. Yourcomments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend.TABLE 1 Transition Temperatures for Selected Liquid CrystalCalibration MaterialsLiquid CrystalMaterialATransit
30、ion TypeBTransition Temperature,CKM-24 Cr SA327.5 54.5SA N 340.2 67.1BP-53 SA N 393.6 120.5BCH-52 N I 437.9 164.8AM-24 = 4-Cyano-4-octyloxybiphenylBP-53 = 4-(4-Pentyl-cyclohexyl)-benzoic acid-4-propyl-phenyl esterBCH-52 = 4-Ethyl-4-(4-propyl-cyclohexyl)-biphenylBCh = CholestericCr = CrystallineI = I
31、sotropic liquidN = NematicSA= Smectic ASC= Smectic CSC*= Chiral smectic CSI*= Smectic I*SJ*= Smectic J*CThe transition temperatures are dependent upon the purity of the liquid crystalmaterial. These transition temperatures are those for 99.9 + mol % pure materials.See Footnotes 5.E2069062NOTE 5Large
32、r specimen masses should not be used, as they willresult in increased thermal lag effects.10.3 Load the specimen into the test chamber, purge withdry nitrogen (or other inert purge gas) at the flow rate to beused for the subsequent application.10.4 Heat the specimen rapidly to the maximum tempera-tu
33、re for the material shown in Table 2 and hold isothermally for1 min.NOTE 6The transition temperature to the isotropic phase dependsupon the calibration material selected and its purity.NOTE 7The samples are not stable above the maximum temperaturelisted in Table 2. Discard the specimen and make a ne
34、w one if it has beenexposed to a temperature above the maximum temperature.10.5 Cool the specimen at 10 C/min to 30 C and holdisothermally for 1 min. Record the resultant thermal curveupon cooling (see Note 4).NOTE 8Liquid crystalline transitions are very narrow. Data collectionrates of one data poi
35、nt every 0.05 C (preferably every 0.01 C) shall beused to achieve the precision required.10.6 Heat the specimen at 10 C/min to 30 C above thetemperature of the transition to the isotropic phase as indicatedin Table 1. Record the resulting thermal curve upon heating(see Note 4).10.7 From the resultan
36、t thermal curve upon cooling from10.5, determine the extrapolated onset temperature (Tc)to60.01 C for each transition in Table 2 observed as illustrated inFig. 1.NOTE 9Use only a transition where the signal returns to baselinebefore the transition onset.NOTE 10Retain all available significant figure
37、s for these calculationsand round to the final result to the number of significant figures describedin section 1310.8 From the resultant thermal curve upon heating from10.6, determine the extrapolated onset temperature (Th)to60.01 C for each transition in Table 2 observed as illustrated inFig. 2 (se
38、e Note 9).Fig. 3Fig. 4Fig. 5Fig. 610.9 Calculate the offset temperature (DT) for each liquidcrystal transition to 6 0.01 C according to 11.1.11. Calculation11.1 Calculate the offset temperature (DT)to6 0.01 C foreach transition according to Eq 1:DT 5 Th Tc(1)where:Th= the transition temperature of a
39、 specific liquid crystaltransition observed on heating,Tc= the temperature of the same transition measured oncooling, andDT = the offset temperature for the specific liquid crystaltransition.11.2 In an application cooling experiment, where the differ-ential scanning calorimeter has been calibrated u
40、pon heating,the temperature of a cooling transition within or without the 50to 185 C temperature range may be determined using Eq 2:Tx5 To1DT (2)where:Tx= the temperature of the unknown transition uponcooling,To= the observed temperature upon cooling, andDT = the offset temperature determined for th
41、e specificheating rate-cooling rate combination determined inthis test method.12. Report12.1 Report the following information:12.1.1 Description of the differential scanning calorimeterused for the test including model and serial number,12.1.2 Complete identification and description of the refer-enc
42、e materials and their transitions used including source,method or purification (if any) and purity,12.1.3 Statement of the sample name and mass,12.1.4 Statement of the crucible material,12.1.5 Statement of the temperature program rate on heatingand cooling,12.1.6 Statement of the maximum temperature
43、,12.1.7 Identification of the specimen atmosphere by purgegas composition, purity and flow rate,12.1.8 The value of the offset temperature (DT) term, and12.1.9 The specific dated version of the ASTM standardused.13. Precision and Bias13.1 An interlaboratory test is planned for to determine theprecis
44、ion and bias of this test method. Anyone wishing toTABLE 2 Temperatures of the Crystal to First Liquid Crystal Transition of the Calibrating MaterialsLiquid CrystalMaterialATransition TypeBTemperature,CEnthalpy Maximum TemperatureK C J/g CM-24 SA N 340.2 67.1 0.08 97BP-53 SA N 393.6 120.5 0.6 130BCH
45、-52 N I 437.9 164.8 1.3 184AM-24 = 4-Cyano-4-octyloxybiphenylBP-53 = 4-(4-Pentyl-cyclohexyl)-benzoic acid-4-propyl-phenyl ester BCH-52 = 4-Ethyl-4-(4-propyl-cyclohexyl)-biphenylBCh = CholestericCr = CrystallineI = Isotropic liquidN = NematicSA= Smectic ASC= Smectic CSC*= Chiral smectic CSI*= Smectic
46、 I*SJ*= Smectic J*CThe transition temperatures are dependent upon the purity of the liquid crystal material. These transition temperatures are those for 99.9 + mol % pure materials. SeeFootnotes 5, 6, and 7.E2069063FIG. 1 Cooling Curve for M-24FIG. 2 Heating Curve for M-24E2069064FIG. 3 Cooling Curv
47、e for HP-53FIG. 4 Heating Curve for HP-53E2069065FIG. 5 Cooling Curve for BCH-52FIG. 6 Heating Curve for BCH-52E2069066participate in this interlaboratory test may contact the E 37Staff Manager at ASTM Headquarters.13.2 Precision:13.2.1 Testing in the manufacturers laboratory indicatesthat the stand
48、ard deviation for transition temperature is 6 0.4C for all three materials.13.3 Bias:13.3.1 Testing on DSCs from different manufacturers, in-dicates that the calibration (_T) may differ for differentheating and cooling rates.14. Keywords14.1 calibration; cooling; differential scanning calorimetry;te
49、mperature; thermal analysisASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withd
