1、Designation: E 1824 02Standard Test Method forAssignment of a Glass Transition Temperature UsingThermomechanical Analysis Under Tension1This standard is issued under the fixed designation E 1824; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, 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 a procedure for the assignmentof a glass transition temperature of m
3、aterials on heating usingthermomechanical measurements under tension under pre-scribed experimental conditions.1.2 This test method may be used as a complement to TestMethod E 1545 and is applicable to amorphous or to partiallycrystalline materials in the form of films, fibers, wires, etc. thatare s
4、ufficiently rigid to inhibit extension during loading atambient temperature.1.3 The generally applicable temperature range for this testmethod is 100 to 600C. This temperature range may bealtered depending upon the instrumentation used.1.4 Computer or electronic-based instruments, techniques,or data
5、 treatment equivalent to this test method may also 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 to determine the necessary equivalency priorto use.1.5 There is no ISO
6、 method equivalent to this method.1.6 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 limita
7、tions prior to use.2. Referenced Documents2.1 ASTM Standards:E 473 Terminology Relating to Thermal Analysis2E 1142 Terminology Relating to Thermophysical Proper-ties2E 1545 Test Method for Glass Transition Temperatures byThermomechanical Analysis23. Terminology3.1 Definitions:3.1.1 The following ter
8、ms are applicable to this test methodand can be found in Terminology E 473 and TerminologyE 1142: thermomechanical analysis (TMA), thermodilatom-etry, glass transition, glass transition temperature.4. Summary of Test Method4.1 This test method uses thermomechanical analysis equip-ment (thermomechani
9、cal analyzer, dilatometer, or similar de-vice) in the tensile mode to determine the change in dimensionof a thin specimen observed when the material is subjected toa constant heating rate through the glass transition regime. Thischange in dimension associated with the change from vitreoussolid to am
10、orphous liquid is observed as movement of asensing probe in direct contact with the specimen and isrecorded as a function of temperature. The intersection of theextrapolation of the slope of the probe displacement curvebefore and after the transition is used to determine a tempera-ture that is assig
11、ned as the glass transition temperature.5. Significance and Use5.1 The glass transition is dependent on the thermal history,softening agents or additives of the material to be tested. Foramorphous and semicrystalline materials the assignment of aglass transition temperature may lead to important inf
12、ormationabout thermal history, processing conditions, stability, progressof chemical reactions, and mechanical and electrical behavior.5.2 Thermomechanical analysis provides a rapid means ofdetecting changes in hardness or linear dimensional changeassociated with the glass transition. Dimensional ch
13、angesmeasured as a specimen is heated over the Tgregion mayinclude the interaction of several effects: an increase in thecoefficient of expansion, a decrease in the modulus, whichunder a constant stress leads to increased extension, stressrelief leading to irreversible dimensional change (shrinkage
14、inone dimension, expansion in another dimension), and physicalaging effects which change the kinetics of the dimensionalchange.5.3 This test method is useful for research and development,quality control, and specification acceptance testing; particu-larly of films and fibers.6. Interferences6.1 This
15、 test method may be used for materials having a1This test method is under the jurisdiction of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on TestMethods and Recommended Practices.Current edition approved May 10, 2002. Published July 2002. Origina
16、llypublished as E 182496. Last previous edition E 182496.2Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.glass transition at or below ambient temperature providing careis taken to avoid expos
17、ing the specimen to a tensile force priorto cooling the specimen below its glass transition. Applying atensile load on a specimen that is above its glass transition willresult in elongation of the specimen which may introduceorientation and residual stresses that will alter the specimenthermal histo
18、ry and may yield erroneous results during theheating cycle.6.2 Specimens of thickness less than 0.2 mm may bedifficult to handle.6.3 Specimens of thickness greater than 5 mm may developtemperature nonuniformities of sufficient extent as to yielderroneously high values for an assigned glass transitio
19、n tem-perature using this test method.7. Apparatus7.1 The essential equipment required to provide the mini-mum instrument capability for this test method includes:7.1.1 A Thermomechanical Analyzer (TMA) or Ther-modilatometer, consisting of:7.1.1.1 Rigid Specimen Holder, of inert, low expansivitymate
20、rial (# 20 m/m-C), usually quartz, to center the speci-men in the furnace and to fix the specimen to mechanicalground.NOTE 2Use of rigid specimen holders and tension probes constructedof lower thermal expansivity (#5 m/m-C) materials or corrections forhardware expansivity may be necessary if very sm
21、all changes in specimendimensions are encountered with this test method.7.1.1.2 Rigid Tension Probe, of inert, low expansivity ma-terial (# 20 m/m-C), usually quartz, which contacts thespecimen with an applied in-plane tensile force.7.1.1.3 Sensing Element, with a dynamic range of at least 5mm, a li
22、nearity of 1% or better, and sufficient sensitivity tomeasure the displacement of the rigid tension probe within 61m resulting from changes in length of the specimen.7.1.1.4 Weight or Force Transducer, to generate a constantforce between 0 and 50 mN 62 % that is applied through therigid tension prob
23、e to the specimen.7.1.1.5 Furnace and Temperature Controller, capable ofexecuting a temperature program of uniform controlled heatingof a specimen at a constant rate of 5 6 0.2C/min betweenrequired temperature limits to 6 0.5C.7.1.1.6 Temperature Sensor, that can be positioned repro-ducibly in close
24、 proximity to the specimen to measure itstemperature between 100 and 600C with a resolution of 60.1C.7.1.1.7 Means of Providing a Specimen Environment,ofaninert gas at a purge rate of 10 to 50 mL/min6 5 %. The typicalpurge gas rate is usually given by the instrument manufacturer.NOTE 3Typically 99.9
25、9 % pure nitrogen, argon, or helium is em-ployed when oxidation in air is a concern. Unless effects of moisture areto be studied, use of dry purge gas is recommended; especially foroperation at subambient temperatures.7.1.1.8 Recording Device, either digital or analog, to recordand display the chang
26、es in the rigid tension probe position witha Y-sensitivity of 0.1 m and temperature with an X-sensitivityof 0.1C.7.1.2 Rigid Specimen Clamps, (clamps, grips, pins, or splitshot) of inert, low expansivity material (# 20 m/m-C) thatgrip the specimen between the rigid specimen holder and therigid tensi
27、on probe without distortion (1 %) or slippage(1 %).7.2 Auxiliary equipment considered useful in conductingthis test method includes:7.2.1 Coolant System, that can be coupled directly to thefurnace/temperature controller to hasten recovery from el-evated temperatures, to provide controlled cooling ra
28、tes con-stant to 61.0C/min, and to sustain a subambient temperatureto 60.5C.7.2.2 Calipers, or other measuring device to determinespecimen dimensions to 6 0.01 mm.7.2.3 Balance, to determine the specimen mass to 6 0.1 mg.8. Sampling8.1 Analyze samples as received or after a prescribedpretreatment. I
29、f some treatment is applied to a specimen priorto analysis, note this treatment and any resulting changes inmass or appearance in the report. For samples with a glasstransition below ambient, it may be desirable to form the glasswith a known thermal history by using a controlled constantcooling rate
30、 to the starting temperature. Film samples mayundergo stress relief related dimensional change that dependson whether the sample is prepared and measured parallel to themachine direction of manufacture or perpendicular to themachine direction.9. Calibration9.1 Perform temperature calibration in acco
31、rdance with theapparatus manufacturer operators manual using the sameheating rate, purge, and temperature sensor position to be usedwith the test method.10. Procedure10.1 Attach a pair of rigid specimen clamps to a specimenwith a minimum spacing of 5 mm between the contact points.Weigh the specimen
32、and clamps and record this value.NOTE 4Use of between-clamp distances of less than 5 mm mayimpart erroneous results because of end effects introduced by the clamppressure. Refer to the Precautions Section, if a thicknes outside the rangeof 0.2 to 5 mm is to be used.10.2 Suspend the specimen with cla
33、mps between the contactpoints of the specimen holder and the tension probe. BE SURETHE POSITION OF THE TEMPERATURE SENSOR ISUNCHANGED FROM THAT USED IN THE CALIBRA-TION PROCEDURE.10.3 Move the furnace to enclose the specimen and clamps.Start the inert gas purge and equilibrate the specimen andclamps
34、 at the desired starting temperature.NOTE 5Cool or heat the specimen, clamps and furnace to a tempera-ture equivalent to at least 3 min of heating below the first temperature ofinterest to ensure stable heater control; for example, 15C for a 5C/minrate. The coolant used to lower the temperature shou
35、ld not come in contactwith the specimen or clamps.10.4 Apply a constant tensile force to the specimen in therange of either 5 to 10 mN (to observe shrinkage) or of 20 to50 mN (to observe elongation).E 18242NOTE 6The observed inflection temperature will be dependent uponthe applied stress. Therefore,
36、 the applied force should be adjusted forspecimen cross-section area to ensure the same stress level is applied to allspecimens.10.5 Heat the specimen and clamps at a constant rate of5C/min over the desired temperature range.NOTE 7Other forces and heating rates may be used if applied both inthe cali
37、bration and throughout the testing. The test conditions shall benoted in the report.10.6 Note the occurrence of an abrupt change in slope(positive for shrinkage and negative for elongation) of thelength versus temperature curve that indicates a transition ofthe material from one state to another.10.
38、7 Upon reaching the upper temperature limit of theheating program, remove the applied tensile force and restorethe furnace, specimen and clamps to ambient temperature.10.8 Reweigh the specimen and clamps reporting anychange in mass.NOTE 8Weighing of the specimen and clamps is required to deter-mine
39、whether changes such as loss of solvent or plasticizer which mayalter the assigned glass transition temperature have occurred.11. Calculation11.1 Derive a glass transition temperature as follows usinggraphics or software:11.1.1 Construct a tangent to the lower temperature portionof the thermal curve
40、,11.1.2 Construct a tangent to the steepest portion of theslope beyond the transition, and11.1.3 The temperature at which these tangents intersect isthe derived glass transition temperature, Tg8.11.2 Apply any temperature correction determined from theinstrument temperature calibration to Tg8 to obt
41、ain the assignedglass transition temperature, Tg. (See Fig. 1.) Note, there arethree cases illustrated, namely, a sample that exhibits shrinkage(over the Tgregion under the conditions utilized), a sample thatexhibits elongational reorientation, and a sample with noapparent stress-relied induced dime
42、nsional change. Because Tgis an assigned parameter its value may depend on experimentalconditions, namely on the applied stress on the sample, and inthe case of a film, the direction of the applied stress relative tothe vector of the stress relief.12. Report12.1 Report the following information:12.1
43、.1 A complete identification and description of thematerial tested including specimen dimensions, clamp dis-tance, and any pretreatment,12.1.2 Description of the instrument used for the testincluding tensile force,12.1.3 Test conditions including temperature program ex-ecuted, purge gas composition
44、and flow rate, and coolingmedium if used,12.1.4 Description of the temperature calibration procedure,12.1.5 The thermomechanical analysis curves,12.1.6 The assigned glass transition temperature, Tg, and12.1.7 Any change in mass associated with the test.13. Precision and Bias13.1 The precision and bi
45、as for this test method have yet tobe determined from an interlaboratory study.14. Keywords14.1 glass transition; glass transition temperature; Tg; ten-sile mode; thermomechanical analysis (TMA); thermodilatom-etryASTM International takes no position respecting the validity of any patent rights asse
46、rted 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
47、 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 this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will recei
48、ve careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Inter
49、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 Determination of TgE 18243
