1、Designation: E1824 09Standard 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.1. Scope1.1 This test method covers a procedure for the assignmentof a glass transition temperature of ma
3、terials on heating usingthermomechanical measurements.1.2 This test method may be used as a complement to TestMethod E2602 and is applicable to amorphous or to partiallycrystalline materials in the form of films, fibers, wires, etc. thatare sufficiently rigid to inhibit extension during loading atam
4、bient 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 to be regarded asstandard. No other units of measurement are included in thisstandar
5、d.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 establish appro-priate safety and health practices and determine the applica-bility
6、 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 for Assignment of the Glass TransitionTemperature by Thermomechanical AnalysisE1970 P
7、ractice 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 Definitions:3.1.1 The following terms are applicable to this test methodand can be found in
8、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 equip-ment (thermomechanical analyzer, dilatometer, or similar de-vice) with the test
9、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 with the changefrom vitreous solid to amorphous liquid is observed as move-ment of a se
10、nsing 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 determine a tempera-ture that is assigned as the glass transition temperature.5. Si
11、gnificance 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 informationabout thermal history, processing con
12、ditions, 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 changesmeasured as a specimen is heated over th
13、e Tgregion mayinclude the interaction of several effects: an increase in the1This 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
14、Sept. 1, 2009. Published February 2010. Originallyapproved in 1996. Last previous edition approved in 2008 as E182408. DOI:10.1520/E1824-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volum
15、e information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.coefficient of expansion, a decrease in the modulus, whichunder a constant stress leads to increased exten
16、sion, stressrelief leading to irreversible dimensional change (shrinkage 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 accep
17、tance 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 the specimen to a tensile force priorto cooling the specimen below its glass transition. A
18、pplying 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 may yield erroneous results during theheating cycle.6.2 Specimens of thickness less tha
19、n 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 transition tem-perature using this test method.7. Apparatus7.1 The essential equipment required to prov
20、ide 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 (# 20 m/m-C), usually quartz, to center the speci-men in the furnace and to fix the speci
21、men 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 changes in specimendimensions are encountered with this test method.7.1.1.2 Rigid Tension
22、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 least 5mm, a linearity of 1% or better, and sufficient sensitivity tomeasure the displacement of the rigid ten
23、sion 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 probe to the specimen.7.1.1.5 Furnace and Temperature Controller, capable ofexecuting a temperature
24、 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 proximity to the specimen to measure itstemperature between 100 and 600C with a resolution of
25、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 2Typically 99.99 % pure nitrogen, argon, or helium is em-ployed when oxidation in air is a concern. Unless eff
26、ects 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 measured or calculated signals, orboth. The minimum output signals required for thermome-c
27、hanical analyis 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 rigid specimen holder and therigid tension probe without distortion (1 %) or slippage(1 %).7.2
28、 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 rates con-stant to 61.0C/min, and to sustain a subambien
29、t 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. If some treatment is applied to a specimen priorto anal
30、ysis, 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 to the starting temperature. Film samples mayundergo
31、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 accordance with theapparatus manufacturer operators manual
32、 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 and clamps and record this value.NOTE 3Use of between-
33、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 clamps between the contactpoints of the specimen holder a
34、nd the tension probe. BE SURETHE POSITION OF THE TEMPERATURE SENSOR ISE1824 092UNCHANGED 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 at the desired starting temperature.NOTE 4Co
35、ol 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 should not come in contactwith the specimen or cl
36、amps.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 dependent uponthe applied stress. Therefore, the applied force should be adjusted forspecimen cr
37、oss-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 may be used if applied both inthe calibration and throughout the testing. The test conditi
38、ons 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.10.7 Upon reaching the upper temperature limit of thehe
39、ating 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 specimen and clamps is required to deter-mine whether changes such as loss of solvent or plasticiz
40、er 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,11.1.2 Construct a tangent to the steepest portion
41、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 obtain the assignedglass transition temperature, Tg. (S
42、ee 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 dimensional change. Because Tgis an assigned parameter i
43、ts 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:12.1.1 A complete identification and description of them
44、aterial 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 and flow rate, and coolingmedium if used,12.1.4 Desc
45、ription 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 An interlaboratory test was conducted in 2007 on apolystyrene film. Ten
46、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 repeatability value (r) obtained by multiplying the repeat-ability standard deviation by 2.8. The repeatability valueestimates the
47、95 % confidence limits. That is, two results fromthe same laboratory should be considered suspect (at the 95 %confidence level) if they differ by more than the repeatabilityvalue.13.2.1.1 The within laboratory repeatability standard devia-tion for polystyrene is 0.53 C. with 28 (n1)(p1)degrees of ex
48、perimental freedom (with 5 replicates (n) and 8laboratories (p).13.2.2 Between laboratory variability may be describedusing the reproducibility value (R) obtained my multiplying thereproducibility standard deviation by 2.8. The reproducibilityvalue estimates the 95 % confidence limit. That is, two r
49、esultsobtained from different laboratories, operators or apparatusshould be considered suspect (at the 95 % confidence level) ifthey differ by more than the reproducibility value13.2.2.1 The between laboratory reproducibility standarddeviation for polystyrene was 1.2 C with 28 degrees ofexperimental freedom.13.2.3 The between laboratory reproducibility standard de-viation for polystyrene was 1.2 C with 28 degrees of experi-mental freedom.13.3 Bias:13.3.1 Bias is the difference between the mean valueobtained and an acceptable reference value for
