ASTM D4591-07(2012)
(Test Method)Standard Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning Calorimetry
Standard Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning Calorimetry
SIGNIFICANCE AND USE
DSC analysis may be used with fluoropolymers to achieve at least four different objectives as follows:
To measure transition temperatures to aid in the identification of the various fluoropolymers, individually or in mixtures;
To compare the relative levels of crystalline content of two or more specimens of a sample of a fluoropolymer relative to another sample by measuring the heat of fusion;
Note 2—Absolute values of crystalline content cannot be determined until values for heats of fusion of the completely crystalline polymers are available.
To characterize PTFE (DSC thermal curves determined on powders or products of PTFE that have never been melted convey appreciable information about details of morphology and molecular structure);
To supplement the test for standard specific gravity (SSG) described in Specifications D4894 and D4895 by using the heat of crystallization of pure PTFE homopolymer, depending on the relative molecular weight of the specimen. The scopes of these specifications, however, include PTFE resins modified with small amounts of comonomers, and many commercial PTFE resins are modified in this manner. These modifications can have profound effects on crystallization behavior. Published relationships between heat of crystallization and molecular weight refer to pure PTFE homopolymers and, therefore, cannot be applied to the modified resins.
SCOPE
1.1 This test method defines conditions for the use of differential scanning calorimetry (DSC) with fluoropolymers. It covers the use of DSC analyses with the fluoropolymers, PTFE, PVDF, PCTFE, and PVF and their copolymers PFA, MFA, FEP, ECTFE, EFEP, VDF/HFP, VDF/TFE/HFP, VDF/CTFE. The test method is applicable to the analysis of powders as well as samples taken from semi-finished or finished products. The nature of fluoropolymers is such that special procedures are needed for running DSC analysis and interpreting the results.
1.2 The values stated in SI units as detailed in are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, 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.
Note 1—There is currently no ISO standard that duplicates this test method. ISO 12086-1 and ISO 12086-2 cover similar testing and reference this test method for testing conditions.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4591 − 07 (Reapproved 2012)
Standard Test Method for
Determining Temperatures and Heats of Transitions of
Fluoropolymers by Differential Scanning Calorimetry
This standard is issued under the fixed designation D4591; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope D4895 Specification for Polytetrafluoroethylene (PTFE)
Resin Produced From Dispersion
1.1 This test method defines conditions for the use of
E473Terminology Relating to Thermal Analysis and Rhe-
differential scanning calorimetry (DSC) with fluoropolymers.
ology
It covers the use of DSC analyses with the fluoropolymers,
E793Test Method for Enthalpies of Fusion and Crystalliza-
PTFE, PVDF, PCTFE, and PVF and their copolymers PFA,
tion by Differential Scanning Calorimetry
MFA, FEP, ECTFE, EFEP, VDF/HFP, VDF/TFE/HFP, VDF/
IEEE/ASTM SI-10Standard for Use of the International
CTFE.Thetestmethodisapplicabletotheanalysisofpowders
System of Units (SI) (the Modern Metric System)
as well as samples taken from semi-finished or finished
2.2 ISO Standards:
products. The nature of fluoropolymers is such that special
ISO 12086-1 Plastics—Fluoropolymer Dispersion and
procedures are needed for running DSC analysis and interpret-
Molding and Extrusion Materials—Part 1: Designation
ing the results.
and Specification
1.2 The values stated in SI units as detailed in IEEE/ASTM
ISO 12086-2 Plastics—Fluoropolymer Dispersion and
SI-10 are to be regarded as the standard.
Molding and Extrusion Materials—Part 2: Preparation of
1.3 This standard does not purport to address all of the
Test Specimen and Determination of Properties
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.1 Definitions:
bility of regulatory limitations prior to use.
3.1.1 differential scanning calorimetry (DSC)—a technique
in which the difference in energy inputs into a substance and a
NOTE 1—There is currently no ISO standard that duplicates this test
reference material is measured as a function of temperature,
method.ISO12086-1andISO12086-2coversimilartestingandreference
this test method for testing conditions.
while the substance and reference material are subjected to a
controlled increase or decrease in temperature.
2. Referenced Documents
3.1.2 Refer to Terminology E473 for general terminology
2.1 ASTM Standards:
used in this test method.
D1600TerminologyforAbbreviatedTermsRelatingtoPlas-
3.2 Abbreviated Terms:
tics
3.2.1 Abbreviations used in this test method are in accor-
D3418Test Method for Transition Temperatures and En-
dance with Terminology D1600.
thalpies of Fusion and Crystallization of Polymers by
3.2.2 PTFE—polytetrafluoroethylene.
Differential Scanning Calorimetry
3.2.3 PFA—perfluoro(alkoxy alkane) resin.
D4894 Specification for Polytetrafluoroethylene (PTFE)
3.2.4 FEP—perfluoro(ethylene-propene) copolymer.
Granular Molding and Ram Extrusion Materials
3.2.5 ETFE—ethylene-tetrafluoroethylene copolymer.
3.2.6 PVDF—poly(vinylidene fluoride).
3.2.7 PCTFE—polymonochlorotrifluoroethylene.
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-
3.2.8 ECTFE—ethylene-monochlorotrifluoroethylene co-
als.
polymer.
Current edition approved April 1, 2012. Published June 2012. Originally
3.2.9 EFEP—ethylene-perfluoroethylene-propene copoly-
approved in 1987. Last previous edition approved in 2007 as D4591-07. DOI:
mer.
10.1520/D4591-07R12.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4591 − 07 (2012)
3.2.10 VDF/HFP—vinylidene fluoride-hexafluoropropene sufficient to provide a precision of 61% when run using a
copolymer. suitable standard for calibration, such as indium. The instru-
3.2.11 VDF/TFE—vinylidene fluoride-tetrafluoroethylene ment must have a precision of 61% for either the computer-
copolymer. ized data collections or over a time-base range of 0.1 to 2.0
3.2.12 VDF/TFE/HFP—vinylidene fluoride- min/cm of chart.
tetrafluoroethylene-hexafluoropropene copolymer.
NOTE 3—Most DSC systems report data with a temperature ordinate.
3.2.13 VDF/CTFE—vinylidene fluoride-
Thetemperaturevaluesaredirectlyrelatedtotimebasedontheheatingor
chlorotrifluoroethylene copolymer.
cooling rate. Integrated areas measured from the DSC curves will be
3.2.14 PVF—poly(vinyl fluoride). directly proportional to the differential caloric input.
NOTE 4—Noncomputerized area measurement shall be done with a
3.2.15 MFA—perfluoromethylvinylether-tetrafluoroethyl-
precision of 61% or better.
ene copolymer.
3.2.16 SSG—standard specific gravity.
5.2 Specimen Holders and Covers, made from aluminum or
other materials of high thermal conductivity that do not react
4. Significance and Use
with the specimen. It is preferable to use holders designed for
4.1 DSC analysis may be used with fluoropolymers to the particular DSC instrument being used. For holders for
achieve at least four different objectives as follows: whichthecoverhastheshapeofasmallcup,thetopshouldbe
4.1.1 To measure transition temperatures to aid in the inserted with the open side of the cup up.
identification of the various fluoropolymers, individually or in
5.3 Nitrogen,orotherinertgassupplyforpurgingpurposes.
mixtures;
4.1.2 Tocomparetherelativelevelsofcrystallinecontentof 5.4 Balance, with capacity greater than 15 mg, capable of
weighing to the nearest 0.01 mg.
twoormorespecimensofasampleofafluoropolymerrelative
to another sample by measuring the heat of fusion;
6. Procedure
NOTE 2—Absolute values of crystalline content cannot be determined
until values for heats of fusion of the completely crystalline polymers are
6.1 General Requirements—In general,Test Method D3418
available.
shallbeusedwheneverpossible.Thereareinstances,however,
4.1.3 To characterize PTFE (DSC thermal curves deter-
when following Test Method D3418 will not give the desired
mined on powders or products of PTFE that have never been
results, will not provide information needed for proper inter-
melted convey appreciable information about details of mor-
pretation of the resultant thermal curve, or will require more
phology and molecular structure);
time for the analysis than need be spent for results having
4.1.4 To supplement the test for standard specific gravity
suitable precision. Examples of these instances include the
(SSG) described in Specifications D4894 and D4895 by using
following:
theheatofcrystallizationofpurePTFEhomopolymer,depend-
6.1.1 The requirement that scans be started at room
ing on the relative molecular weight of the specimen. The
temperature,aprovisionusuallynotrequiredwithallfluoropo-
scopes of these specifications, however, include PTFE resins
lymers;
modified with small amounts of comonomers, and many
6.1.2 At times the thermal curve that results from the
commercial PTFE resins are modified in this manner. These
analysis provides information that cannot be interpreted in a
modifications can have profound effects on crystallization
useful manner by Test Method D3418, but can be interpreted
behavior. Published relationships between heat of crystalliza-
following the procedures of Section 7.
tion and molecular weight refer to pure PTFE homopolymers
6.2 Calibration—Theproceduresforcalibrationprovidedin
and, therefore, cannot be applied to the modified resins.
TestMethodE793shallbeused.ThecommentsinTestMethod
5. Apparatus D3418 are helpful when reviewed. The calibration is carried
out by using an appropriate amount of at least two selected
5.1 Differential Scanning Calorimeter, capable of heating
standards weighed to the nearest 0.01 mg. Select the standard
and cooling rates of at least 10.0 °C/min and of recording
materials so that their range includes the first-order transition
automatically the differential heat flow between a specimen
temperature(s) of the fluoropolymer being tested. It has been
and a reference material as a function of time, both to the
found that only one standard is needed to validate the instru-
required sensitivity and precision. For comparison purposes,
ment b
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