1、Designation: E1824 091E1824 13Standard 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
2、the case 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 NOTEAdded research report information to Section 13 editorially in September 2010.1. Scope1.1
3、This test method covers a procedure for the assignment of a glass transition temperature (Tg) of materials on heating usingthermomechanical measurements.measurements in tension.1.2 This test method may be used as a complement to Test Method E1545 and is applicable to amorphous or to partiallycrystal
4、line materials in the form of films, fibers, wires, etc.etc., that are sufficiently rigid to inhibit extension during loading atambient temperature.1.3 The generally applicable temperature range for this test method is 100 to 600C. This temperature range may be altereddepending upon the instrumentat
5、ion used.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 There is no ISO method equivalent to this method.standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its u
6、se. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and RheologyE1142 Terminology R
7、elating to Thermophysical PropertiesE1545 Test Method for Assignment of the Glass Transition Temperature by Thermomechanical AnalysisE1970 Practice for Statistical Treatment of Thermoanalytical DataE2602 Test Method for the Assignment of the Glass Transition Temperature by Modulated Temperature Diff
8、erential ScanningCalorimetry3. Terminology3.1 Definitions:3.1.1 The following terms are applicable to this test method and can be found in Terminology E473 and Terminology E1142:thermomechanical analysis (TMA), thermodilatometry, glass transition, and glass transition temperature.4. Summary of Test
9、Method4.1 This test method uses thermomechanical analysis equipment (thermomechanical analyzer, dilatometer, or similar device)with the test specimen in tension to determine the change in dimension of a thin specimen observed when the material is subjectedto a constant heating rate through the glass
10、 transition region. This change in dimension associated with the change from vitreoussolid to amorphous liquid is observed as movement of a sensing probe in direct contact with the specimen and is recorded as a1 This test method is under the jurisdiction ofASTM Committee E37 on Thermal Measurements
11、and is the direct responsibility of Subcommittee E37.10 on Fundamental,Statistical and Mechanical Properties.Current edition approved Sept. 1, 2009Aug. 1, 2013. Published February 2010August 2013. Originally approved in 1996. Last previous edition approved in 20082009 asE1824 08.E1824 091. DOI: 10.1
12、520/E1824-09E01.10.1520/E1824-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM
13、 standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all
14、 cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1function of temperature. The intersection of the extrapolation of the slope
15、of the probe displacement curve before and after thetransition is used to determine a temperature 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. Fora
16、morphous and semicrystalline materials the assignment of a glass transition temperature may lead to important information aboutthermal history, processing conditions, stability, progress of chemical reactions, and mechanical and electrical behavior.5.2 Thermomechanical analysis provides a rapid mean
17、s of detecting changes in hardness or linear dimensional changeassociated with the glass transition. Dimensional changes measured as a specimen is heated over the Tglassg transition region mayinclude the interaction of several effects: an increase in the coefficient of expansion, a decrease in the m
18、odulus, which under aconstant stress leads to increased extension, stress relief leading to irreversible dimensional change (shrinkage in one dimension,expansion in another dimension), and physical aging effects which change the kinetics of the dimensional change.5.3 This test method is useful for r
19、esearch and development, quality control, and specification acceptance testing; particularlyof films and fibers.6. Interferences6.1 This test method may be used for materials having a glass transition at or below ambient temperature providing care is takento avoid exposing the specimen to a tensile
20、force prior to cooling the specimen below its glass transition. Applying a tensile loadon a specimen that is above its glass transition will result in elongation of the specimen which may introduce orientation andresidual stresses that will alter the specimen thermal history and may yield erroneous
21、results during the heating cycle.6.2 Specimens of thickness less than 0.2 mm may be difficult to handle.6.3 Specimens of thickness greater than 5 mm may develop temperature nonuniformities of sufficient extent as to yielderroneously high values for an assigned glass transition temperature using this
22、 test method.7. Apparatus7.1 The essential equipment required to provide the minimum instrument capability for this test method includes:7.1.1 A Thermomechanical Analyzer (TMA) or Thermodilatometer, consisting of:7.1.1.1 Rigid Specimen Holder, of inert, low expansivity material (20 m/m-C), usually q
23、uartz, to center the specimen in thefurnace and to fix the specimen to mechanical ground.NOTE 1Use of rigid specimen holders and tension probes constructed of lower thermal expansivity (5 m/m-C)(20 m/m-C) materials orcorrections for hardware expansivity may be necessary if very small changes in spec
24、imen dimensions are encountered with this test method.7.1.1.2 Rigid Tension Probe, of inert, low expansivity material ( 5 m/m-C), usually quartz, which contacts the specimen withan applied in-plane tensile force.7.1.1.3 Sensing Element, with a dynamic range of at least 5 mm, a linearity of 1 % or be
25、tter, and sufficient sensitivity to measurethe displacement of the rigid tension probe within 61 m resulting from changes in length of the specimen.7.1.1.4 Weight or Force Transducer, to generate a constant force between 0 and 50 mN 6 2 % that is applied through the rigidtension probe to the specime
26、n.7.1.1.5 Furnace and Temperature Controller, capable of executing a temperature program of uniform controlled heating of aspecimen at a constant rate of 5 6 0.2C/min between required temperature limits to 60.5C.7.1.1.6 Temperature Sensor, that can be positioned reproducibly in close proximity to th
27、e specimen to measure its temperaturebetween 100 and 600C with a resolution of 60.1C.7.1.1.7 Means of Providing a Specimen Environment, of an inert 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 % pure nit
28、rogen, argon, or helium is employed when oxidation in air is a concern. Unless effects of moisture are to be studied,use of dry purge gas is recommended; especially for operation at subambient temperatures.7.1.1.8 Data Collection Device, provide a means of acquiring, storing, and displaying measured
29、 or calculated signals, or both.The minimum output signals required for thermomechanical analysis are dimension change, temperature and time.7.1.2 Rigid Specimen Clamps, (clamps, grips, pins, or split shot) of inert, low expansivity material ( 20 m/m-C) that grip thespecimen between the rigid specim
30、en holder and the rigid tension probe without distortion (1 %) or slippage (1 %).7.2 Auxiliary equipment considered useful in conducting this test method includes:7.2.1 Coolant System, that can be coupled directly to the furnace/temperature controller to hasten recovery from elevatedtemperatures, to
31、 provide controlled cooling rates constant to 61.0C/min, and to sustain a subambient temperature to 60.5C.7.2.2 Calipers, or other measuring device to determine specimen dimensions to 60.01 mm.7.2.3 Balance, to determine the specimen mass to 60.1 mg.E1824 1328. Sampling8.1 Analyze samples as receive
32、d or after a prescribed pretreatment. If some treatment is applied to a specimen prior to analysis,note this treatment and any resulting changes in mass or appearance in the report. For samples with a glass transition belowambient, it may be desirable to form the glass with a known thermal history b
33、y using a controlled constant cooling rate to thestarting temperature. Film samples may undergo stress relief related dimensional change that depends on whether the sample isprepared and measured parallel to the machine direction of manufacture or perpendicular to the machine direction.9. Calibratio
34、n9.1 Perform temperature calibration in accordance with the apparatus manufacturer operators manual using the same heatingrate, purge, and temperature sensor position to be used with the test method.10. Procedure10.1 Attach a pair of rigid specimen clamps to a specimen with a minimum spacing of 5 mm
35、 between the contact points. Weighthe specimen and clamps and record this value.NOTE 3Use of between-clamp distances of less than 5 mm may impart erroneous results because of end effects introduced by the clamp pressure.Refer to the Precautions Section, if a thickness outside the range of 0.2 to 5 m
36、m is to be used.10.2 Suspend the specimen with clamps between the contact points of the specimen holder and the tension probe. BE SURETHE POSITION OF THE TEMPERATURE SENSOR IS UNCHANGED FROM THAT USED IN THE CALIBRATIONPROCEDURE.10.3 Move the furnace to enclose the specimen and clamps. Start the ine
37、rt gas purge and equilibrate the specimen and clampsat the desired starting temperature.NOTE 4Cool or heat the specimen, clamps and furnace to a temperature equivalent to at least 3 min of heating below the first temperature of interestto ensure stable heater control; for example, 15C for a 5C/min r
38、ate. The coolant used to lower the temperature should not come in contact with thespecimen or clamps.10.4 Apply a constant tensile force to the specimen in the range of either 5 to 10 mN (to observe shrinkage) or of 20 to 50 mN(to observe elongation).NOTE 5The observed inflection temperature will be
39、 dependent upon the applied stress. Therefore, the applied force should be adjusted for specimencross-section area to ensure the same stress level is applied to all specimens.10.5 Heat the specimen and clamps at a constant rate of 5C/min over the desired temperature range.NOTE 6Other forces and heat
40、ing rates may be used if applied both in the calibration and throughout the testing. The test conditions shall be notedin the report.FIG. 1 Determination of TgE1824 13310.6 Note the occurrence of an abrupt change in slope (positive for shrinkage and negative for elongation) of the length versustempe
41、rature curve that indicates a transition of the material from one state to another.10.7 Upon reaching the upper temperature limit of the heating program, remove the applied tensile force and restore the furnace,specimen, and clamps to ambient temperature.10.8 Reweigh the specimen and clamps reportin
42、g any change in mass.NOTE 7Weighing of the specimen and clamps is required to determine whether changes such as loss of solvent or plasticizer which may alter theassigned glass transition temperature have occurred.11. Calculation11.1 Derive a glass transition temperature as follows using graphics or
43、 software:11.1.1 Construct a tangent to the lower temperature portion of the thermal curve,11.1.2 Construct a tangent to the steepest portion of the slope beyond the transition, and11.1.3 The temperature at which these tangents intersect is the derived glass transition temperature, Tg.11.2 Apply any
44、 temperature correction determined from the instrument temperature calibration to Tg to obtain the assignedglass transition temperature, Tg. (See Fig. 1.) Note, there are three cases illustrated, namely, a sample that exhibits shrinkage (overthe Tg region under the conditions utilized), a sample tha
45、t exhibits elongational reorientation, and a sample with no apparentstress-relied induced dimensional change. Because Tg is an assigned parameter its value may depend on experimental conditions,namely on the applied stress on the sample, and in the case of a film, the direction of the applied stress
46、 relative to the vector ofthe stress relief.12. Report12.1 Report the following information:12.1.1 Acomplete identification and description of the material tested including specimen dimensions, clamp distance, and anypretreatment,12.1.2 Description of the instrument used for the test including tensi
47、le force,12.1.3 Test conditions including temperature program executed, purge gas composition and flow rate, and cooling medium ifused,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
48、.7 Any change in mass associated with the test.13. Precision and Bias313.1 An interlaboratory test was conducted in 2007 on a polystyrene film. Ten laboratories participated in the test using twoinstrument models from a single manufacturer.13.2 Precision:13.2.1 Within laboratory variability may be d
49、escribe using the repeatability value (r) obtained by multiplying the repeatabilitystandard deviation by 2.8. The repeatability value estimates the 95 % confidence limits. That is, two results from the samelaboratory should be considered suspect (at the 95 % confidence level) if they differ by more than the repeatability value.13.2.1.1 The within laboratory repeatability standard deviation for polystyrene is 0.53C with 28 ( n 1) (p 1) degrees ofexperimental freedom (with 5 replicates (n) and 8 laboratories (p).13.2.2 Between la
