1、Designation: D4591 07 (Reapproved 2012)D4591 17Standard Test Method forDetermining Temperatures and Heats of Transitions ofFluoropolymers by Differential Scanning Calorimetry1This standard is issued under the fixed designation D4591; the number immediately following the designation indicates the yea
2、r oforiginal adoption or, in 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.This standard has been approved for use by agencies of the U.S. Dep
3、artment of Defense.1. Scope Scope*1.1 This test method defines conditions for the use of differential scanning calorimetry (DSC) with fluoropolymers. It coversthe use of DSC analyses with the fluoropolymers, PTFE, PVDF, PCTFE, and PVF and their copolymers PFA, MFA, FEP, ECTFE,EFEP, VDF/HFP, VDF/TFE/
4、HFP, VDF/CTFE. The test method is applicable to the analysis of powders as well as samples takenfrom semi-finished or finished products. The nature of fluoropolymers is such that special procedures are needed for running DSCanalysis and interpreting the results.1.2 The values stated in SI units as d
5、etailed in IEEE/ASTM SI-10 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 responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practi
6、ces and determine theapplicability of regulatory limitations prior to use.NOTE 1There is currently no ISO standard that duplicates this test method. ISO 12086-1 and ISO 12086-2 cover similar testing and reference thistest method for testing conditions.1.4 This international standard was developed in
7、 accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 A
8、STM Standards:2D1600 Terminology for Abbreviated Terms Relating to PlasticsD3418 Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by DifferentialScanning CalorimetryD4894 Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusi
9、on MaterialsD4895 Specification for Polytetrafluoroethylene (PTFE) Resin Produced From DispersionE473 Terminology Relating to Thermal Analysis and RheologyE793 Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning CalorimetryIEEE/ASTM SI-10 Standard for Use of the Interna
10、tional System of Units (SI) (the Modern Metric System)2.2 ISO Standards:3ISO 12086-1 PlasticsFluoropolymer Dispersion and Molding and Extrusion MaterialsPart 1: Designation and SpecificationISO 12086-2 PlasticsFluoropolymer Dispersion and Molding and Extrusion MaterialsPart 2: Preparation of Test Sp
11、ecimenand Determination of Properties3. Terminology3.1 Definitions:1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved April 1, 2012Dec. 1, 2017. Published June 2012
12、January 2018. Originally approved in 1987. Last previous edition approved in 20072012 asD4591 - 07.D4591 - 07(2012). DOI: 10.1520/D4591-07R12.10.1520/D4591-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of A
13、STM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the
14、 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 cases only the current versionof the standar
15、d as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 differential scanning calorimetry (DSC)a technique
16、 in which the difference in energy inputs into a substance and areference material is measured as a function of temperature, while the substance and reference material are subjected to a controlledincrease or decrease in temperature.3.1.2 Refer to Terminology E473 for general terminology used in thi
17、s test method.3.2 Abbreviated Terms:3.2.1 Abbreviations used in this test method are in accordance with Terminology D1600.3.2.2 PTFEpolytetrafluoroethylene.3.2.3 PFAperfluoro(alkoxy alkane) resin.3.2.4 FEPperfluoro(ethylene-propene) copolymer.3.2.5 ETFEethylene-tetrafluoroethylene copolymer.3.2.6 PV
18、DFpoly(vinylidene fluoride).3.2.7 PCTFEpolymonochlorotrifluoroethylene.3.2.8 ECTFEethylene-monochlorotrifluoroethylene copolymer.3.2.9 EFEPethylene-perfluoroethylene-propene copolymer.3.2.10 VDF/HFPvinylidene fluoride-hexafluoropropene copolymer.3.2.11 VDF/TFEvinylidene fluoride-tetrafluoroethylene
19、copolymer.3.2.12 VDF/TFE/HFPvinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer.3.2.13 VDF/CTFEvinylidene fluoride-chlorotrifluoroethylene copolymer.3.2.14 PVFpoly(vinyl fluoride).3.2.15 MFAperfluoromethylvinylether-tetrafluoroethylene copolymer.3.2.16 SSGstandard specific gravity.4.
20、 Significance and Use4.1 DSC analysis may be used with fluoropolymers to achieve at least four different objectives as follows:4.1.1 To measure transition temperatures to aid in the identification of the various fluoropolymers, individually or in mixtures;4.1.2 To compare the relative levels of crys
21、talline content of two or more specimens of a sample of a fluoropolymer relativeto another sample by measuring the heat of fusion;NOTE 2Absolute values of crystalline content cannot be determined until values for heats of fusion of the completely crystalline polymers areavailable.4.1.3 The heat of c
22、rystallization of pure PTFE homopolymer is depending on the relative molecular weight of the specimen.Some PTFE resins are modified with small amounts of comonomers. These modifications have profound effects on crystallizationbehavior and shall be considered when evaluating the results.4.1.4 To char
23、acterize PTFE (DSC thermal curves determined on powders or products of PTFE that have never been meltedconvey appreciable information about details of morphology and molecular structure);44.1.5 To supplement the test for standard specific gravity (SSG) described in Specifications D4894 and D4895 by
24、using the heatof crystallization of pure PTFE homopolymer, depending on the relative molecular weight of the specimen. The scopes of thesespecifications, however, include PTFE resins modified with small amounts of comonomers, and many commercial PTFE resins aremodified in this manner. These modifica
25、tions can have profound effects on crystallization behavior. Published relationships4between heat of crystallization and molecular weight refer to pure PTFE homopolymers and, therefore, cannot be applied to themodified resins.5. Apparatus5.1 Differential Scanning Calorimeter, capable of heating and
26、cooling rates of at least 10.0 C/min and of recordingautomatically the differential heat flow between a specimen and a reference material as a function of time, both to the requiredsensitivity and precision. For comparison purposes, the same heating rate shall be used for all calibrations and test r
27、uns. Thermalcurves are recorded using a computerized data collection system or on a time-based recorder. The resulting curves are used for themeasurement of peak areas either by computer integration or an alternative area measuring procedure. The instrument should havea sensitivity for heat flow suf
28、ficient to provide a precision of 61 % when run using a suitable standard for calibration, such asindium. The instrument must have a precision of 61 % for either the computerized data collections or over a time-base range of0.1 to 2.0 min/cm of chart.NOTE 3Most DSC systems report data with a tempera
29、ture ordinate. The temperature values are directly related to time based on the heating or coolingrate. Integrated areas measured from the DSC curves will be directly proportional to the differential caloric input.NOTE 4Noncomputerized area measurement shall be done with a precision of 61 % or bette
30、r.4 Sperati, C. A., “Polytetrafluoroethylene: History of Its Development and Some Recent Advances” (67 references), High Performance Polymers: Their Origin andDevelopment, Seymour and Kirshenbaume (eds), Marcel Deckker, New York, 1986, p. 274.D4591 1725.2 Specimen Holders and Covers, made from alumi
31、num or other materials of high thermal conductivity that do not react withthe specimen. It is preferable to use holders designed for the particular DSC instrument being used. For holders for which the coverhas the shape of a small cup, the top should be inserted with the open side of the cup up.5.3
32、Nitrogen, or other inert gas supply for purging purposes.5.4 Balance, with capacity greater than 15 mg, capable of weighing to the nearest 0.01 mg.6. Procedure6.1 General RequirementsIn general, Test Method D3418 shall be used whenever possible. There are instances, however,when following Test Metho
33、d D3418 will not give the desired results, will not provide information needed for proper interpretationof the resultant thermal curve, or will require more time for the analysis than need be spent for results having suitable precision.Examples of these instances include the following:6.1.1 The requ
34、irement that scans be started at room temperature, a provision usually not required with all fluoropolymers;6.1.2 At times the thermal curve that results from the analysis provides information that cannot be interpreted in a useful mannerby Test Method D3418, but can be interpreted following the pro
35、cedures of Section 7.6.2 CalibrationThe procedures for calibration provided in Test Method E793 shall be used. The comments in Test MethodD3418 are helpful when reviewed. The calibration is carried out by using an appropriate amount of at least two selected standardsweighed to the nearest 0.01 mg. S
36、elect the standard materials so that their range includes the first-order transition temperature(s)of the fluoropolymer being tested. It has been found that only one standard is needed to validate the instrument betweencalibrations.6.3 A standard specimen mass shall be in the range of 9 to 10 mg wei
37、ghed to an accuracy of 0.01 mg. For routine analysis, anonstandard specimen size may be used in cases where equivalence to the standard mass has been established for particularproperties. A specimen mass different from the standard shall be reported.NOTE 5Thermal curves from such analyses not using
38、the standard specimen mass range may not compare with curves obtained using the standardmass range. Due to the sensitivity of the peak, Tm, to the specimen size, the results may be outside the expected precision and bias.6.4 Place the test specimen in the DSC sample pan, cover with pan cover, and cr
39、imp. Place the pan with specimen in the DSCsample holder or cell at the heating cycle starting temperature.6.5 Heating and cooling rates of 10C/min shall be standard (except as noted in Table 1). Other heating rates may be useful forTABLE 1 Recommended Temperature Limits for DSCMeasurements and for
40、Integrating DSC Thermal Curves with forVarious FluoropolymersA, BFluoropolymerHeating Curve DwellTime,minCooling Curve Rate,C/minTypicalValues,C CStart,C End,C Start,C End,C(homopolymers)PTFEPCTFE2701303802505 38025019527019513010100.2315360200225PVDF(copolymers)25 210 10 210 25 10 160175PVDF(copoly
41、mers)25 210 10 210 25 10 155180PFA 200 350 350 200 10 280330MFA 200 350 350 200 10 260290FEP 200 320 320 200 10 240290ETFE 140 320 320 140 10 210270ECTFE 200 300 300 200 10 230250VDF/HFP 25 210 10 210 25 10 130165VDF/CTFE 25 210 10 210 25 10 130165VDF/CTFE 25 210 10 210 25 10 90170VDF/TFE 25 200 10
42、200 25 10 100150VDF/TFE/HFP 25 150 10 150 25 10 130AReport peaks (and shoulders) from lowest to highest (for example, Tm1 Tm2 Tm3 . ).BThe integration range should be 10 to 20C above the starting and below the finaltemperature. A smaller integration range would be Tf 20 or 30C and Te + 10 or20C. The
43、 calculated heat value should not be sensitive to small changes (5C inthe integration range).CTypical values cited represent an expected range of peak values for this test.These values shall not be used for specifications. Copolymer peak values (andintensities) will vary with comonomer ratios and ma
44、y not be within the cited ranges.D4591 173some routine analyses. Any rates different from the standard must be reported and thermal curves from such analyses must not beused in comparison with curves obtained using the standard rate.NOTE 6Other heating rates will change the observed melting and cool
45、ing temperature values.6.6 Before starting the scan at the controlled rate, heat the specimen at the highest rate possible with the instrument being usedto the temperature shown in Table 1 for the fluoropolymer being tested. The time required to reach thermal equilibrium at thestarting temperature w
46、ill depend on the particular instrument being used. If heats of crystallization are being determined, stop theheating at the end temperature given in Table 1. Use a dwell time long enough to remove (or normalize) any homogenous crystalnucleation effects of the polymer before starting the cooling. Fo
47、r PVDF a dwell time of ten minutes at 210C is required. DSCanalysis used to determine the presence of other components in the specimens should usually be started at room temperature.NOTE 7Residual homogeneous crystal nuclei can affect the values of Tm, Tc, and heats of transition.7. Calculation7.1 D
48、etermining Transition TemperaturesAs illustrated in both Fig. 1 and in Test Method D3418, the temperature of a meltingpeak on a DSC thermal curve shall be designated Tm1, Tm2, etc., numbered in order of increasing temperature. The temperatureat which a tangent to the curve intercepts an extension of
49、 the base line on the low-temperature side shall be designated T f, andthe temperature at which a tangent to the curve intercepts an extension of the base line on the high-temperature side shall bedesignated Te.NOTE 8Fluoropolymers can have various crystal forms. forms or undergo reorganization. Therefore, the resulting DSC curve can have two or morepeaks or peaks with pronounced shoulders. The Tm1 value of one sample with one peak may be the same as the Tm2 value of another sample with twopeaks.7.1.1 Fig. 1 was selected
