ASTM E794-06(2012)
(Test Method)Standard Test Method for Melting And Crystallization Temperatures By Thermal Analysis
Standard Test Method for Melting And Crystallization Temperatures By Thermal Analysis
SIGNIFICANCE AND USE
5.1 Differential scanning calorimetry and differential thermal analysis provide a rapid method for determining the fusion and crystallization temperatures of crystalline materials.
5.2 This test is useful for quality control, specification acceptance, and research.
SCOPE
1.1 This test method describes the determination of melting (and crystallization) temperatures of pure materials by differential scanning calorimetry (DSC) and differential thermal analysis (DTA).
1.2 This test method is generally applicable to thermally stable materials with well-defined melting temperatures.
1.3 The normal operating range is from −120 to 600°C for DSC and 25 to 1500°C for DTA. The temperature range can be extended depending upon the instrumentation used.
1.4 Computer or electronic based instruments, techniques, or data treatment equivalent to those in this test method may be used.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E794 − 06 (Reapproved 2012)
Standard Test Method for
Melting And Crystallization Temperatures By Thermal
Analysis
This standard is issued under the fixed designation E794; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E1142Terminology Relating to Thermophysical Properties
1.1 This test method describes the determination of melting
3. Terminology
(and crystallization) temperatures of pure materials by differ-
3.1 Definitions—Specialized terms used in this test method
ential scanning calorimetry (DSC) and differential thermal
are defined in Terminologies E473 and E1142.
analysis (DTA).
1.2 This test method is generally applicable to thermally
4. Summary of Test Method
stable materials with well-defined melting temperatures.
4.1 The test method involves heating (or cooling) a test
1.3 The normal operating range is from −120 to 600°C for
specimen at a controlled rate in a controlled environment
DSCand25to1500°CforDTA.Thetemperaturerangecanbe throughtheregionoffusion(orcrystallization).Thedifference
extended depending upon the instrumentation used.
in heat flow (for DSC) or temperature (for DTA) between the
test material and a reference material due to energy changes is
1.4 Computer or electronic based instruments, techniques,
continuously monitored and recorded. A transition is marked
ordatatreatmentequivalenttothoseinthistestmethodmaybe
by absorption (or release) of energy by the specimen resulting
used.
in a corresponding endothermic (or exothermic) peak in the
1.5 The values stated in SI units are to be regarded as
heating (or cooling) curve.
standard. No other units of measurement are included in this
NOTE 1—Enthalpies of fusion and crystallization are sometimes deter-
standard.
minedinconjunctionwithmeltingorcrystallizationtemperaturemeasure-
1.6 This standard does not purport to address all of the
ments. These enthalpy values may be obtained by Test Method E793.
safety problems, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5.1 Differential scanning calorimetry and differential ther-
bility of regulatory limitations prior to use.
malanalysisprovidearapidmethodfordeterminingthefusion
and crystallization temperatures of crystalline materials.
2. Referenced Documents
5.2 This test is useful for quality control, specification
2.1 ASTM Standards:
acceptance, and research.
E473Terminology Relating to Thermal Analysis and Rhe-
ology 6. Interferences
E793Test Method for Enthalpies of Fusion and Crystalliza-
6.1 Test specimens need to be homogeneous, since milli-
tion by Differential Scanning Calorimetry
gram quantities are used.
E967Test Method for Temperature Calibration of Differen-
6.2 Toxic or corrosive effluents, or both, may be released
tial Scanning Calorimeters and Differential ThermalAna-
when heating the material and could be harmful to personnel
lyzers
and to apparatus.
7. Apparatus
ThistestmethodisunderthejurisdictionofASTMCommitteeE37onThermal
Measurements and is the direct responsibility of Subcommittee E37.01 on Calo-
7.1 Apparatus shall be of either type listed below:
rimetry and Mass Loss.
7.1.1 Differential Scanning Calorimeter (DSC) or Differen-
Current edition approved Sept. 1, 2012. Published September 2012. Originally
tial Thermal Analyzer (DTA)—The essential instrumentation
approved in 1981. Last previous edition approved in 2006 as E794–06. DOI:
10.1520/E0794-06R12.
required to provide the minimum differential scanning calori-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
metric or differential thermal analyzer capability for this
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
method includes:
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E794 − 06 (2012)
7.1.1.1 Test Chamber composed of: benotedinthereport.Ifsomeheattreatmentisapplied,record
(1)A furnace or furnaces to provide uniform controlled any mass loss as a result of this treatment.
heating (cooling) of a specimen and reference to a constant
temperatureorataconstantratewithintheapplicabletempera- 9. Calibration
ture range of this method.
9.1 Using the same heating rate, purge gas, and flow rate as
(2)A temperature sensor to provide an indication of the
that to be used for analyzing the specimen, calibrate the
specimen or furnace temperature to within 60.01°C.
temperature axis of the instrument using the procedure in
(3)Differential sensors to detect a heat flow difference
Practice E967.
(DSC) or temperature difference (DTA) between the specimen
andreferencewitharangeofatleast100mWandasensitivity
10. Procedure
of 61 µW (DSC) or 4°C and a sensitivity of 40 µ°C (DTA).
10.1 Weigh 1 to 15 mg of material to an accuracy of 0.01
(4)Ameansofsustaininga test chamber environmentwith
mg into a clean, dry specimen capsule. The specimen mass to
a purge gas of 10 to 100 6 5 mL/min.
be used depends on the magnitude of the transition enthalpy
NOTE2—Typically99.9+%purenitrogen,argonorheliumisemployed
and the volume of the capsule. For comparing multiple results,
when oxidation in air is a concern. Unless effects of moisture are to be
use similar mass (65%) and encapsulation.
studied, use of dry purge gas is recommended and is essential for
operation at subambient temperatures.
10.2 Load the encapsulated specimen into the instrument
7.1.1.2 A temperature controller, capable of executing a chamber, and purge the chamber with dry nitrogen (or other
inertgas)ataconstantflowrateof10to50mL/minthroughout
specific temperature program by operating the furnace or
furnaces between selected temperature limits at a rate of the experiment. The flow rate should be measured and held
constantforalldatatobecompared.Theuseof99.99%purity
temperature change of 10°C/min constant to within 60.1°C/
purge gas and a drier is recommended.
min or at an isothermal temperature constant to 60.1°C.
7.1.2 A recording device, capable of recording and display-
10.3 When a DSC is used, heat the specimen rapidly to
ing on the Y-axis any fraction of the heat flow signal (DSC
30°C (60°C in a DTA) below the melting temperature, and
curve) or differential temperature Signal (DTA Curve) includ-
allowtoequilibrate.Forsomematerials,itmaybenecessaryto
ing the signal noise as a function of any fraction of the
start the scan substantially lower in temperature, for example,
temperature (or time) signal on the X-axis including the signal
belowtheglasstransitioninordertoestablishabaselinewhere
noise.
there is no evidence of melting or crystallization.
7.2 Containers (pans, crucibles, vials, lids, closures, seals,
10.4 Heat the specimen at 10°C/min through the melting
etc.) that are inert to the specimen and reference materials and
range until the baseline is reestablished above the melting
that are of suitable structural shape and integrity to contain the
endotherm. Other heating rates may be used but shall be noted
specimenandreferenceinaccordancewiththerequirementsof
in the report.To allow the DSC system to achieve steady state,
this test method.
provide at least 3 min of scanning time both before and after
NOTE 3—DSC containers are commonly composed of aluminum or
other inert material of high thermal conductivity. DTA containers are
commonly composed of borosilicate glass (for use below 500°C),
alumina, or quartz (for use below 1200°C).
7.3 Nitrogen, or other inert purge gas supply.
7.4 Auxiliary instrumentation and apparatus considered
necessary or useful for conducting this method includes:
7.4.1 Analytical Balance, with a capacity greater than 100
mg, capable of weighing to the nearest 0.01 mg.
7.4.2 Cooling capacity to hasten cooling down from el-
evated temperatures, to provide constant cooling rates or to
sustain an isothermal subambient temperature.
7.4.3 A means, tool or device, to close, encapsulate or seal
the container of choice.
8. Sampling
8.1 Powdered or granular materials should be mixed thor-
oughly prior to sampling and should be sampled by removing
portions from various parts of the container.These portions, in
turn, should be combined and mixed well to ensure a repre-
sentative specimen for the determination. Liquid samples may
be sampled directly after mixing.
8.2 In the absence of information, samples are assumed to
be analyzed as received. If some heat or mechanical treatment
FIG. 1 Fusion and Crystallization Temperatures for Pure Crys-
is applied to the sample prior to analysis, this treatment should talline Material
E794 − 06 (2012)
FIG. 2 Fusion and Crystallization Temperatures for Polymeric Material
the peak. For DTA instrumentation,
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.