1、Designation: E 1356 03Standard Test Method for Assignment of theGlass Transition Temperatures by Differential ScanningCalorimetry1This standard is issued under the fixed designation E 1356; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year 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 assignment of the glasstransition temperatures of materials using diff
3、erential scanningcalorimetry or differential thermal analysis.1.2 This test method is applicable to amorphous materials orto partially crystalline materials containing amorphous regions,that are stable and do not undergo decomposition or sublima-tion in the glass transition region.1.3 The normal ope
4、rating temperature range is from 120 to500C. The temperature range may be extended, dependingupon the instrumentation used.1.4 Computer or electronic-based instruments, techniques,or data treatment equivalent to this test method may also beused.NOTE 1Users of this test method are expressly advised t
5、hat all suchinstruments or techniques may not be equivalent. It is the responsibility ofthe user of this standard to determine the necessary equivalency prior touse.1.5 SI units are the standard.1.6 ISO standards 113572 is equivalent to this standard.1.7 This standard does not purport to address all
6、 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 ASTM Standards:E 177 Practice for Use
7、 of the Terms Precision and Bias inASTM Test Methods2E 473 Terminology Relating to Thermal Analysis2E 691 Practice for Conducting an Interlaboratory Test Pro-gram to Determine the Precision of Test Methods2E 967 Practice for Temperature Calibration of DifferentialScanning Calorimeters and Differenti
8、al Thermal Analyz-ers2E 1142 Terminology Relating to Thermophysical Proper-ties22.2 ISO Standard:113572 Differential Scanning Calorimetry (DSC)-Part 2Determination of Glass Transition Temperature33. Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test methodand can be fou
9、nd in Terminology E 473 and TerminologyE 1142: differential scanning calorimetry (DSC); differentialthermal analysis (DTA); glass transition; glass transitiontemperature (Tg); and specific heat capacity.3.2 Definitions of Terms Specific to This Standard:3.2.1 There are commonly used transition point
10、s associatedwith the glass transition region.(See Fig. 1.)3.2.1.1 extrapolated end temperature, (Te), Cthe point ofintersection of the tangent drawn at the point of greatest slopeon the transition curve with the extrapolated baseline followingthe transition.3.2.1.2 extrapolated onset temperature, (T
11、f), Cthe pointof intersection of the tangent drawn at the point of greatestslope on the transition curve with the extrapolated baselineprior to the transition.3.2.1.3 inflection temperature, (Ti), Cthe point on thethermal curve corresponding to the peak of the first derivative(with respect to time)
12、of the parent thermal curve. This pointcorresponds to the inflection point of the parent thermal curve.3.2.1.4 midpoint temperature, (Tm), Cthe point on thethermal curve corresponding to12 the heat flow differencebetween the extrapolated onset and extrapolated end.3.2.1.5 DiscussionMidpoint temperat
13、ure is most com-monly used as the glass transition temperature (see Fig. 1):3.2.2 Two additional transition points are sometimes iden-tified and are defined:1This test method is under the jurisdiction of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.0
14、1 on TestMethods and Recommended Practices.Current edition approved April 10, 2003. Published May 2003. Originallyap-proved in 1991. Last previous edition approved in 1998 as E 1356 98.2Annual Book of ASTM Standards, Vol 09.01.3Available from American National Standards Institute, 11 W. 42nd St., 13
15、thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2.1 temperature of first deviation, (To), Cthe point offirst detectable deviation from the extrapolated baseline prior tothe transition.3.2.2.2 temperatu
16、re of return to baseline, (Tr), Cthepoint of last deviation from the extrapolated baseline beyondthe transition.4. Summary of Test Method4.1 This test method involves continuously monitoring thedifference in heat flow into, or temperature between, a refer-ence material and a test material when they
17、are heated orcooled at a controlled rate through the glass transition region ofthe test material and analyzing the resultant thermal curve toprovide the glass transition temperature.5. Significance and Use5.1 Differential scanning calorimetry provides a rapid testmethod for determining changes in sp
18、ecific heat capacity in ahomogeneous material. The glass transition is manifested as astep change in specific heat capacity. For amorphous andsemicrystalline materials the determination of the glass transi-tion temperature may lead to important information about theirthermal history, processing cond
19、itions, stability, progress ofchemical reactions, and mechanical and electrical behavior.5.2 This test method is useful for research, quality control,and specification acceptance.6. Interferences6.1 A change in heating rates and cooling rates can affect theresults. The presence of impurities will af
20、fect the transition,particularly if an impurity tends to plasticize or form solidsolutions, or is miscible in the post-transition phase. If particlesize has an effect upon the detected transition temperature, thespecimens to be compared should be of the same particle size.6.2 In some cases the speci
21、men may react with air duringthe temperature program causing an incorrect transition to bemeasured. Whenever this effect may be present, the test shallbe run under either vacuum or an inert gas atmosphere. Sincesome materials degrade near the glass transition region, caremust be taken to distinguish
22、 between degradation and glasstransition.6.3 Since milligram quantities of sample are used, it isessential to ensure that specimens are homogeneous andrepresentative, so that appropriate sampling techniques areused.7. Apparatus7.1 Differential Scanning Calorimeter, The essential instru-mentation req
23、uired to provide the minimum differential scan-ning calorimetric capability for this method includes a TestChamber composed of a furnace(s) to provide uniform con-trolled heating (cooling) of a specimen and reference to aconstant temperature or at a constant rate over the temperaturerange from 120 t
24、o 500 C, a temperature sensor to provide anindication of the specimen temperature to 60.1 C, differentialsensors to detect heat flow difference between the specimenand reference with a sensitivity of 6 W, a means of sustaininga test chamber environment of a purge gas of 10 to 100mL/min within 4 mL/m
25、in, a Temperature Controller, capableof executing a specific temperature program by operating theFIG. 1 Glass Transition Region Measured TemperaturesE 1356 032furnace(s) between selected temperature limits at a rate oftemperature change of up to 20 C/min constant to 6 0.5 C/min.7.2 A Recording Devic
26、e, capable of recording and display-ing any fraction of the heat flow signal (including noise) on theY-axis and any fraction of the temperature signal (includingnoise) on the X-axis.7.3 Containers, (pans, crucibles, vials,etc.) that are inert tothe specimen and reference materials and that are of su
27、itablestructural shape and integrity to contain the specimen andreferences.7.4 For ease of interpretation, an inert reference materialwith an heat capacity approximately equivalent to that of thespecimen may be used. The inert reference material may oftenbe an empty specimen capsule or tube.7.5 Nitr
28、ogen, or other inert purge gas supply, of purity equalto or greater than 99.9 %.7.6 Analytical Balance, with a capacity greater than 100 mg,capable of weighing to the nearest 0.01 mg.8. Specimen Preparation8.1 Powders or GranulesAvoid grinding if a preliminarythermal cycle as outlined in 10.2 is not
29、 performed. Grinding orsimilar techniques for size reduction often introduce thermaleffects because of friction or orientation, or both, and therebychange the thermal history of the specimen.8.2 Molded Parts or PelletsCut the samples with amicrotome, razor blade, paper punch, or cork borer (size No.
30、 2or 3) to appropriate size in thickness or diameter, and lengththat will approximate the desired mass in the subsequentprocedure.8.3 Films or SheetsFor films thicker than 40 m, see 8.2.For thinner films, cut slivers to fit in the specimen tubes orpunch disks, if circular specimen pans are used.8.4
31、Report any mechanical or thermal pretreatment.9. Calibration9.1 Using the same heating rate, purge gas, and flow rate asthat to be used for analyzing the specimen, calibrate thetemperature axis of the instrument following the proceduregiven in Practice E 967.10. Procedure10.1 Use a specimen mass app
32、ropriate for the material to betested. In most casesa5to20mgmass is satisfactory. Anamount of reference material with a heat capacity closelymatched to that of the specimen may be used. An emptyspecimen pan may also be adequate.10.2 If appropriate, perform and record an initial thermalprogram in flo
33、wing nitrogen or air environment using a heatingrate of 10C/min to a temperature at least 20C above Tetoremove any previous thermal history. (See Fig. 1.)NOTE 2Other, preferably inert, gases may be used, and other heatingand cooling rates may be used, but must be reported.10.3 Hold temperature until
34、 an equilibrium as indicated bythe instrument response is achieved.10.4 Program cool at a rate of 20C/min to 50C below thetransition temperature of interest.10.5 Hold temperature until an equilibrium as indicated bythe instrument response is achieved.10.6 Repeat heating at same rate as in 10.2, and
35、record theheating curve until all desired transitions have been completed.Other heating rates may be used but must be reported.10.7 Determine temperatures Tm(preferred) Tf,orTi, (SeeFig. 1.)where:Tig= inflection temperature, CTf= extrapolated onset temperature, C, andTm= midpoint temperature, C.Incr
36、easing the heating rate produces greater baseline shiftsthereby improving detectability. In the case of DSC the signalis directly proportional to the heating rate in heat capacitymeasurements.NOTE 3The glass transition takes place over a temperature range andis known to be affected by time dependent
37、 phenomena, such as the rate ofheating (cooling). For these reasons, the establishment of a single numberfor the glass transition needs some explanation. Either Tfor Tmor Timaybe selected to represent the temperature range over which the glasstransition takes place. The particular temperature chosen
38、 must be agreedon by all parties concerned. In selecting which value should be taken asTg, the reader may wish to consider the following:(a)Tmwas found to have higher precision than Tf(see 12.3).(b) The measurement of Tfis often easier for those who construct therespective tangents by hand.(c)Tm(pre
39、ferred) or Tiis more likely to agree with the measurement ofTgby other techniques since it is constructed closer to the middle of thetemperature range over which the glass transition occurs.(d)Tfmay be taken to more closely represent the onset of thetemperature range over which the glass transition
40、occurs. Any comparisonof glass transition temperatures should contain a statement of how the testwas run and how the value was obtained.10.8 Recheck the specimen mass to ensure that no loss ordecomposition has occurred during the measurement.11. Report11.1 Report the following information:11.1.1 A c
41、omplete identification and description of thematerial tested.11.1.2 Description of instrument used for the test.11.1.3 Statement of the dimensions, geometry, and materialof the specimen holder.11.1.4 The scan rate in C/min.11.1.5 Description of temperature calibration procedure.11.1.6 Identification
42、 of the specimen environment by pres-sure, gas flow rate, purity and composition, including humidity,if applicable.11.1.7 Results of the transition measurements using tem-perature parameters (Tg, etc.) cited in Fig. 1, or any combina-tion of parameters that were chosen.11.1.8 Tg(half extrapolated he
43、at capacity temperature) ispreferred.11.1.9 Any side reactions (for example, crosslinking, ther-mal degradation, oxidation) shall also be reported and thereaction identified, if possible.E 1356 03312. Precision and Bias412.1 Interlaboratory Test ProgramAn interlaboratorystudy for the determination o
44、f glass transition temperature asindicated by both the midpoint and the extrapolated onset wasconducted in 1984. Three polymeric materials were tested;polyurethane, polystyrene, and epoxy glass. Each of six par-ticipants tested four specimens of each material. (One did notreport test data on polyure
45、thane.) Practice E 691 was followedfor the design and the analysis of the data.12.2 Test ResultThe precision information given below inCelsius degrees is for the comparison of two test results, eachof which is a single determination.12.3 Precision:DSC Determination of Tg:TfData95 % Limit, CMaterial
46、Tf, C Repeatability ReproducibilityPolyurethane 4.5 4.59 6.53Polystyrene 103.6 2.05 3.18Epoxy Glass 118.4 3.90 6.88DSC Determination of Tg:TmData95 % Limit, CMaterial Tm, C Repeatability ReproducibilityPolyurethane 12.2 2.24 4.15Polystyrene 106.3 1.85 2.02Epoxy Glass 123.0 2.77 5.17The above terms r
47、epeatability and reproducibility limit areused as specified in Practice E 177. The respective standarddeviations among test results may be obtained by dividing thenumbers in the third and fourth columns by 2.8.12.4 The bias for these measurements is undeterminedbecause there are no reference values
48、available for the mate-rials used.NOTE 4A new interlaboratory test program, including Tg(half heatcapacity temperature) value will be performed.13. Keywords13.1 differential scanning calorimetry (DSC); differentialthermal analysis (DTA); glass transition; specific heat capacityASTM International tak
49、es 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 withdrawn. Your comments are invited either for revision of thi
