1、Designation: D 3418 03Standard Test Method forTransition Temperatures and Enthalpies of Fusion andCrystallization of Polymers by Differential ScanningCalorimetry1This standard is issued under the fixed designation D 3418; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defen
3、se.1. Scope*1.1 This test method covers determination of transitiontemperatures and enthalpies of fusion and crystallization ofpolymers by differential scanning calorimetry.NOTE 1True heats of fusion are to be determined in conjunction withstructure investigation, and frequently, specialized crystal
4、lization tech-niques are needed.1.2 This test method is applicable to polymers in granularform or to any fabricated shape from which it is possible to cutappropriate specimens.1.3 The normal operating temperature range is from thecryogenic region to 600C. Certain equipment allows thetemperature rang
5、e to be extended.1.4 The values stated in SI units are the standard.NOTE 2This test method does not apply to all types of polymers aswritten (see 6.8).1.5 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
6、 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 3This standard is similar but not equivalent to ISO 11357-1, -2,-3. The ISO procedures provide additional information not supplied bythis test method.2. Refere
7、nced Documents2.1 ASTM Standards:2E 473 Terminology Relating to Thermal AnalysisE 793 Test Method for Enthalpies of Productivity andCrystallization by Differential Scanning CalorimetryE 794 Test Method for Melting and Crystallization Tem-perature by Thermal AnalysisE 967 Practice for Temperature Cal
8、ibration of DifferentialScanning Calorimeters and Differential Thermal AnalyzersE 968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE 1142 Terminology Relating to Thermophysical PropertiesE 1356 Test Method for Glass Transition Temperatures byDifferential Scanning Calorimetr
9、y or Differential ThermalAnalysisE 1953 Practice for Description of Thermal Analysis Appa-ratus2.2 ISO Standards:3ISO 11357-1 PlasticsDifferential Scanning Calorimetry(DSC)Part 1: General PrinciplesISO 11357-2 PlasticsDifferential Scanning Calorimetry(DSC)Part 2: Determination of Glass Transition Te
10、m-peratureISO 11357-3 PlasticsDifferential Scanning Calorimetry(DSC)Part 3: Determination of Temperature and En-thalpy of Melting and Crystallization3. Terminology3.1 Specialized terms used in this test method are defined inTerminologies E 473 and E 1142.4. Summary of Test Method4.1 This test method
11、 consists of heating or cooling the testmaterial at a controlled rate under a specified purge gas at acontrolled flow rate and continuously monitoring with asuitable sensing device the difference in heat input between areference material and a test material due to energy changes inthe material. A tr
12、ansition is marked by absorption or release ofenergy by the specimen resulting in a corresponding endother-mic or exothermic peak or baseline shift in the heating orcooling curve. Areas under the crystallization exotherm orfusion endotherm of the test materials are compared against the1This test met
13、hod is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties(Section D20.30.07).Current edition approved Dec. 1, 2003. Published January 2004. Originallyapproved in 1975. Last previous edition approved in 1999 as D 3418
14、- 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (A
15、NSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*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.respective areas obtained by the treatment of a well-characterized s
16、tandard.5. Significance and Use5.1 Thermal analysis provides a rapid method for measuringtransitions due to morphological or chemical changes, in apolymer as it is heated/cooled through a specified temperaturerange. Change in specific heat capacity, heat flow and tempera-ture values are determined f
17、or these transitions. Differentialscanning calorimetry is used to assist in identifying specificpolymers, polymer alloys, and certain polymer additives,which exhibit thermal transitions. Chemical reactions thatcause or affect certain transitions have been measured with theaid of this technique; such
18、 reactions include oxidation, curingof thermosetting resins, and thermal decomposition.5.2 This test method is useful for specification acceptance,process control, and research.6. Interferences6.1 Differences in heating or cooling rate as well as the finalheating and cooling temperature have an effe
19、ct on the mea-sured results, especially on the enthalpy of fusion or crystalli-zation. Therefore, departure from conditions specified for agiven polymer is not permitted.6.2 The presence of impurities is known to affect thetransition temperature, particularly if an impurity tends to formsolid soluti
20、ons, or to be miscible in the melt phase.6.3 Uncertain radiation losses at temperatures higher than400C have been known to affect the accuracy of results attimes.6.4 Since particle size has an effect upon detected transitiontemperatures, the specimens to be compared shall be approxi-mately the same
21、particle size (1-5).46.5 In cases that specimens react with air during thetemperature cycle, provision shall be made for running the testunder an inert gas blanket to avoid any incorrect measurement.Since some materials degrade near the melting region, caremust be used to distinguish between degrada
22、tion and transition.6.6 Since milligram quantities of a specimen are used, it isessential to ensure that specimens are homogeneous andrepresentative.6.7 It is possible that toxic or corrosive effluents are releasedwhen heating the material, and be harmful to the personnel orto the apparatus.6.8 Not
23、all polymers lend themselves to the exact terms ofthis test method. For some polymers such as polyarylamides,crystallization is only possible from solution. For other poly-mers such as crystallizable polystyrene, annealing is onlypossible above their glass transition temperatures. When thistest meth
24、od is used for polymers of this type, carefullyannealed samples must be tested without conditioning.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The essen-tial instrumentation required to provide the minimum differen-tial scanning calorimetric capability for this test methodincludes:7.1.1
25、DSC Test ChamberThis chamber is composed of thefollowing:7.1.1.1 Furnace(s), to provide uniform controlled heating(cooling) of a specimen and reference to a constant temperatureor at a constant rate within the applicable cryogenic to 600Ctemperature range of this test method.7.1.1.2 Temperature Sens
26、or, to provide an indication of thespecimen temperature to 60.01C.7.1.1.3 Differential Sensor, to detect heat flow differencebetween the specimen and reference equivalent to 1 mW.7.1.1.4 Means of Sustaining a Test Chamber Environ-ment of purge gas at a purge flow rate of 10 to 50 6 5 mL/min.NOTE 4Ty
27、pically, 99+ % pure nitrogen, argon or helium are em-ployed when oxidation in air is a concern. Unless effects of moisture areto be studied, use of dry purge gas is recommended and is essential foroperation at sub-ambient temperatures.7.1.2 Temperature Controller, Temperature Controller, ca-pable of
28、 executing a specific temperature program by operatingthe furnace(s) between selected temperature limits at a rate oftemperature change of 0.5 to 20C/min constant to 60.1C/min or at an isothermal temperature constant to 60.1C.7.1.3 Recording Device, capable of recording and display-ing any fraction
29、of the heat flow signal (DSC curve) includingthe signal noise as a function of temperature.7.1.4 Software, for integrating areas under endothermicvalleys or exothermic peaks, or both.7.1.5 Containers (pans, crucibles, and so forth) that areinert to the specimen and reference materials and which are
30、ofsuitable structural shape and integrity to contain the specimenand reference in accordance with the specific requirements ofthis test method.7.1.6 Cooling capability to hasten cool down from elevatedtemperatures, to provide constant cooling rates of 0.5 - 20C/min to obtain repeatable crystallizati
31、on temperatures, toachieve sub-ambient operation, or to sustain an isothermalsub-ambient temperature, or combination thereof.7.2 Balance, capable of weighing to 610 g.8. Sample8.1 Powdered or Granular SpecimensAvoid grinding ifthe preliminary thermal cycle as outlined in 10.1.3 is notperformed. Grin
32、ding or similar techniques for size reductionoften introduce thermal effects because of friction or orienta-tion, or both, and thereby change the thermal history of thespecimen.8.2 Molded or Pelleted SpecimensCut the specimens witha microtome, razor blade, hypodermic punch, paper punch, orcork borer
33、 (Size No. 2 or 3) or other appropriate means toappropriate size, in thickness or diameter and length that willbest fit the specimen containers as in 7.1.5 and will approxi-mately meet the desired weight in the subsequent procedure.4The boldface numbers in parentheses refer to the list of references
34、 at the end ofthis test method.D34180328.3 Film or Sheet SpecimensFor films thicker than 40 m,see 8.2. For thinner films, cut slivers to fit in the specimencapsules or punch disks, if the circular specimen capsules areused.8.4 Use any shape or form listed in 8.1-8.3 except whenconducting referee tes
35、ts that shall be performed on films asspecified in 8.3.9. Calibration9.1 The purge gas shall be used during calibration.9.2 Calibrate the DSC temperature signal using PracticeE 967 and the same heating rate to be used in this test method(10C/min) (see Note 5).9.3 Calibrate the DSC heat flow signal u
36、sing Practice E 968and the same heating rate to be used in this test method(10C/min) (see Note 5).9.4 Some instruments allow for the temperature and heatflow calibration to be performed simultaneously. In such cases,use the same heating rate for this method (10C/min) andfollow the manufacturers inst
37、ruction.NOTE 5Use of other heating rates is permitted but shall be reported.It is the responsibility of the user of other rates to demonstrate equivalencyto this test method.10. Procedure10.1 For First-Order Transition (melting and crystalliza-tion):10.1.1 The purge gas shall be used during testing.
38、 The flowrate of the gas shall be the same as used in the calibration (9.1).10.1.2 Use a specimen mass appropriate for the material tobe tested. In most cases a 5-mg specimen mass is satisfactory.Avoid overloading. Weigh the specimen to an accuracy of 610g.10.1.2.1 Intimate thermal contact between t
39、he pan andspecimen is essential for reproducible results. Crimp a metalcover against the pan with the sample sandwiched in betweento ensure good heat transfer. Take care to ensure flat panbottoms.10.1.3 Perform and record a preliminary thermal cycle byheating the sample at a rate of 10C/min from at
40、least 50Cbelow to 30C above the melting temperature to erase previousthermal history.NOTE 6The selection of temperature and time are critical when theeffect of annealing is studied. Minimize the time of exposure to hightemperature to avoid sublimation or decomposition. In some cases it ispossible th
41、at the preliminary thermal cycle will interfere with thetransition of interest, causing an incorrect transition or eliminating atransition. Where it has been shown that this effect is present, omit thepreliminary thermal cycle.10.1.4 Hold the temperature for 5 min (10.1.3).NOTE 7In cases that high-t
42、emperature annealing cause polymerdegradation, the use of shorter annealing times is permitted but shall bereported.10.1.5 Cool to at least 50C below the peak crystallizationtemperature at a rate of 10C/min and record the cooling curve.10.1.6 Hold the temperature for 5 min.10.1.7 Repeat heating at a
43、 rate of 10C/min and record theheating curve. Use this curve to calculate the enthalpies oftransition.10.1.8 Measure the temperatures for the desired points onthe curves: Teim,Tpm,Tefm,Teic,Tpc, and Teic(see Fig. 1).Report two Tpms or Tpcs if observed.where:Teim= melting extrapolated onset temperatu
44、re, C,Tefm= melting extrapolated end temperature, C,Tpm= melting peak temperature, C,Teic= crystallization extrapolated onset temperature, C,Tpc= crystallization peak temperature, C, andTefc= crystallization extrapolated end temperature, C.NOTE 8The actual temperature displayed on the temperature ax
45、isdepends upon the instrument type (for example, specimen temperature,program temperature, or specimen-program temperature average). Followany recommended procedures or guidelines of the instrument manufac-turer to obtain specimen temperature at the point of interest.10.2 For Glass Transition:10.2.1
46、 The purge gas shall be used during testing. The flowrate of the gas shall be the same as used in the calibration (9.1).10.2.2 Use a specimen mass appropriate for the material tobe tested. In most cases, a 10 to 20-mg specimen mass issatisfactory. Weigh the specimen to an accuracy of 610 g.10.2.3 Pe
47、rform and record a preliminary thermal cycle byheating the sample at a rate of 20C/min from at least 50Cbelow to 30C above the melting temperature to erase previousthermal history.10.2.4 Hold the temperature for 5 min. (See Note 7.)10.2.5 Quench cool to at least 50C below the transitiontemperature o
48、f interest.10.2.6 Hold the temperature for 5 min.10.2.7 Repeat heating at a rate of 20C/min, and record theheating curve until all desired transitions have been completed.(See Note 5.)10.2.8 The glass transition is more pronounced at fasterheating rates. A heating rate of 20C/min is used for Tgmeasu
49、rements. The instrument shall be calibrated at thisheating rate. If both first- and second-order transitions (TmandTg, respectively) are to be determined in the same run, useprocedure 10.1 and determine results from the second heatingstep (10.1.7).NOTE 9Tgobtained using Procedure 10.1 will be different from Tgmeasured using procedures 10.2.3-10.2.7. The heating rate must bereported as described in 12.1.3.10.2.9 Measure temperatures Teig,Tmg, and Tefg(see Fig. 2):where:Teig= extrapolated onset temperature, C,Tmg= midpoint temperatu
