1、Designation: E1824 091Standard Test Method forAssignment of a Glass Transition Temperature UsingThermomechanical Analysis: Tension Method1This standard is issued under the fixed designation E1824; 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 () indicates an editorial change since the last revision or reapproval.1NOTEAdded research report information to Section 13 editorially in September 2010.1. Scope1.1 This test
3、 method covers a procedure for the assignmentof a glass transition temperature of materials on heating usingthermomechanical measurements.1.2 This test method may be used as a complement to TestMethod E1545 and is applicable to amorphous or to partiallycrystalline materials in the form of films, fib
4、ers, wires, etc. thatare sufficiently 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 The values stated in SI units are
5、to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 There is no ISO 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
6、 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE1142 Terminology Relating to Thermophysical PropertiesE1545 Test Method f
7、or Assignment of the Glass TransitionTemperature by Thermomechanical AnalysisE1970 Practice for Statistical Treatment of Thermoanalyti-cal DataE2602 Test Method for the Assignment of the Glass Tran-sition Temperature by Modulated Temperature DifferentialScanning Calorimetry3. Terminology3.1 Definiti
8、ons:3.1.1 The following terms are applicable to this test methodand can be found in Terminology E473 and TerminologyE1142: thermomechanical analysis (TMA), thermodilatometry,glass transition, glass transition temperature.4. Summary of Test Method4.1 This test method uses thermomechanical analysis eq
9、uip-ment (thermomechanical analyzer, dilatometer, or similar de-vice) with the test specimen in tension to determine the changein dimension of a thin specimen observed when the material issubjected to a constant heating rate through the glass transitionregion. This change in dimension associated wit
10、h the changefrom vitreous solid to amorphous liquid is observed as move-ment of a sensing probe in direct contact with the specimen andis recorded as a function of temperature. The intersection of theextrapolation of the slope of the probe displacement curvebefore and after the transition is used to
11、 determine a tempera-ture that is assigned 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 transitio
12、n temperature may lead to important informationabout 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 wi
13、th the glass transition. Dimensional changesmeasured 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 irre
14、versible dimensional change (shrinkage in1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.10 on Funda-mental, Statistical and Mechanical Properties.Current edition approved Sept. 1, 2009. Published February 2
15、010. Originallyapproved in 1996. Last previous edition approved in 2008 as E1824 08. DOI:10.1520/E1824-09E01.2For 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 sta
16、ndards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.one dimension, expansion in another dimension), and physicalaging effects which change the kinetics of the dimensionalchange.5.3 This tes
17、t method is useful for research and development,quality control, and specification acceptance testing; particu-larly of films and fibers.6. Interferences6.1 This test method may be used for materials having aglass transition at or below ambient temperature providing careis taken to avoid exposing th
18、e 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 history and
19、 may yield erroneous results during theheating cycle.6.2 Specimens of thickness less than 0.2 mm may be diffi-cult 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 transition te
20、m-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 expansivitymaterial
21、 (#20 m/m-C), usually quartz, to center the speci-men in the furnace and to fix the specimen to mechanicalground.NOTE 1Use 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 small c
22、hanges in specimendimensions are encountered with this test method.7.1.1.2 Rigid Tension Probe, of inert, low expansivity ma-terial (# 5 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 least5 mm, a linearit
23、y 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 6 2 % that is applied through therigid tension probe to
24、 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 60.5C.7.1.1.6 Temperature Sensor, that can be positioned repro-ducibly in close prox
25、imity to the specimen to measure itstemperature between 100 and 600C with a resolution of60.1C.7.1.1.7 Means of Providing a Specimen Environment,ofaninert gas at a purge rate of 10 to 50 mL/min 6 5 %. The typicalpurge gas rate is usually given by the instrument manufacturer.NOTE 2Typically 99.99 % p
26、ure 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 Data Collection Device, provide a means of acquir-ing, storing, and displaying
27、measured or calculated signals, orboth. The minimum output signals required for thermome-chanical analysis are dimension change, temperature and time.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 rigi
28、d specimen holder and therigid tension 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 temperatur
29、es, to provide controlled cooling rates 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 60.01 mm.7.2.3 Balance, to determine the specimen mass to 60.1 mg.8. Sampling8.1 Analyze samples as received or
30、 after a prescribedpretreatment. If 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
31、 a controlled constantcooling rate 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 Perfo
32、rm temperature calibration in accordance 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
33、contact points.Weigh the specimen and clamps and record this value.NOTE 3Use 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 thickness outside the rangeof 0.2 to 5 mm is to be used
34、.10.2 Suspend the specimen with clamps 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
35、 equilibrate the specimen andclamps at the desired starting temperature.E1824 0912NOTE 4Cool 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. T
36、he coolant used to lower the temperature should 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).NOTE 5The observed inflection temperature will be depend
37、ent uponthe applied stress. Therefore, 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 6Other forces and heating rates
38、may be used if applied both inthe calibration 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
39、material from one state to another.10.7 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 7Weighing of the specime
40、n and clamps is required to deter-mine 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
41、temperature portionof the thermal curve,11.1.2 Construct a tangent to the steepest portion of theslope beyond the transition, andFIG. 1 Determination of TgE1824 091311.1.3 The temperature at which these tangents intersect isthe derived glass transition temperature, Tg8.11.2 Apply any temperature cor
42、rection determined from theinstrument temperature calibration to Tg8 to obtain 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 elongati
43、onal reorientation, and a sample with noapparent stress-relied induced dimensional 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 vecto
44、r of the stress relief.12. Report12.1 Report the following information:12.1.1 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
45、 conditions including temperature program ex-ecuted, purge gas composition 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 ma
46、ss associated with the test.13. Precision and Bias313.1 An interlaboratory test was conducted in 2007 on apolystyrene film. Ten laboratories participated in the test usingtwo instrument models from a single manufacturer.13.2 Precision:13.2.1 Within laboratory variability may be describe usingthe rep
47、eatability value (r) obtained by multiplying the repeat-ability standard deviation by 2.8. The repeatability value esti-mates the 95 % confidence limits. That is, two results from thesame laboratory should be considered suspect (at the 95 %confidence level) if they differ by more than the repeatabil
48、ityvalue.13.2.1.1 The within laboratory repeatability standard devia-tion for polystyrene is 0.53C with 28 (n1)(p1)degreesof experimental freedom (with 5 replicates (n) and 8 laborato-ries (p).13.2.2 Between laboratory variability may be describedusing the reproducibility value (R) obtained my multi
49、plying thereproducibility standard deviation by 2.8. The reproducibilityvalue estimates the 95 % confidence limit. That is, two resultsobtained from different laboratories, operators or apparatusshould be considered suspect (at the 95 % confidence level) ifthey differ by more than the reproducibility value.13.2.2.1 The between laboratory reproducibility standarddeviation for polystyrene was 1.2C with 28 degrees of experi-mental freedom.13.2.3 The between laboratory reproducibility standard de-viation for polystyrene was 1.2C with 28 degree
