1、Designation: D 3418 08Standard 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 () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defens
3、e.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 crystall
4、ization 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 range
5、 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. Referen
7、ced Documents2.1 ASTM Standards:2E 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 967 Test Method for Temperature Calibration of Differ-ential Scanning Calorimeters and Differential ThermalA
8、nalyzersE 968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE 1142 Terminology Relating to Thermophysical PropertiesE 1953 Practice for Description of Thermal Analysis andRheology Apparatus2.2 ISO Standards:3ISO 11357-1 PlasticsDifferential Scanning Calorimetry(DSC)Part 1: G
9、eneral PrinciplesISO 11357-2 PlasticsDifferential Scanning Calorimetry(DSC)Part 2: Determination of Glass Transition Tem-peratureISO 11357-3 PlasticsDifferential Scanning Calorimetry(DSC)Part 3: Determination of Temperature and En-thalpy of Melting and Crystallization3. Terminology3.1 Specialized te
10、rms used in this test method are defined inTerminologies E 473 and E 1142.4. Summary of Test Method4.1 This test method 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
11、the difference in heat input between areference material and a test material due to energy changes inthe material. A transition 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. A
12、reas under the crystallization exotherm orfusion endotherm of the test materials are compared against the1This test method 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 appro
13、ved Nov. 1, 2008. Published December 2008. Originallyapproved in 1975. Last previous edition approved in 2003 as D 3418 - 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
14、refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Har
15、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.respective areas obtained by the treatment of a well-characterized standard.5. Significance and Use5.1 Thermal analysis provides a rapid method for measuringtransitions due to morphological or chemical changes, in apolymer as it
16、 is heated/cooled through a specified temperaturerange. Change in specific heat capacity, heat flow and tempera-ture values are determined for these transitions. Differentialscanning calorimetry is used to assist in identifying specificpolymers, polymer alloys, and certain polymer additives,which ex
17、hibit thermal transitions. Chemical reactions thatcause or affect certain transitions have been measured with theaid of this technique; such reactions include oxidation, curingof thermosetting resins, and thermal decomposition.5.2 This test method is useful for specification acceptance,process contr
18、ol, and research.6. Interferences6.1 Differences in heating or cooling rate as well as the finalheating and cooling temperature have an effect on the mea-sured results, especially on the enthalpy of fusion or crystalli-zation. Therefore, departure from conditions specified for agiven polymer is not
19、permitted.6.2 The presence of impurities is known to affect thetransition temperature, particularly if an impurity tends to formsolid solutions, 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 attime
20、s.6.4 Since particle size has an effect upon detected transitiontemperatures, the specimens to be compared shall be approxi-mately the same 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 blan
21、ket to avoid any incorrect measurement.Since some materials degrade near the melting region, caremust be used to distinguish between degradation 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 p
22、ossible that toxic or corrosive effluents are releasedwhen heating the material, and be harmful to the personnel orto the apparatus.6.8 Not all polymers lend themselves to the exact terms ofthis test method. For some polymers such as polyarylamides,crystallization is only possible from solution. For
23、 other poly-mers such as crystallizable polystyrene, annealing is onlypossible above their glass transition temperatures. When thistest method is used for polymers of this type, carefullyannealed samples must be tested without conditioning.7. Apparatus7.1 Differential Scanning Calorimeter (DSC)The e
24、ssen-tial instrumentation required to provide the minimum differen-tial scanning calorimetric capability for this test methodincludes:7.1.1 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 con
25、stant temperatureor at a constant rate within the applicable cryogenic to 600Ctemperature range of this test method.7.1.1.2 Temperature Sensor, 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
26、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 4Typically, 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 ga
27、s is recommended and is essential foroperation at sub-ambient temperatures.7.1.2 Temperature Controller, Temperature Controller, ca-pable of executing a specific temperature program by operatingthe furnace(s) between selected temperature limits at a rate oftemperature change of 0.5 to 20C/min consta
28、nt 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 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 exo
29、thermic peaks, or both.7.1.5 Containers (pans, crucibles, and so forth) that areinert to the specimen and reference materials; and that are ofsuitable structural shape and integrity to contain the specimenand reference in accordance with the specific requirements ofthis test method.7.1.6 Cooling cap
30、ability to hasten cool down from elevatedtemperatures, to provide constant cooling rates of 0.5 - 20C/min to obtain repeatable crystallization temperatures, toachieve sub-ambient operation, or to sustain an isothermalsub-ambient temperature, or combination thereof.7.2 Balance, capable of weighing to
31、 610 g.8. Sample8.1 Powdered or Granular SpecimensAvoid grinding ifthe preliminary thermal cycle as outlined in 10.1.3 is notperformed. Grinding or similar techniques for size reductionoften introduce thermal effects because of friction or orienta-tion, or both, and thereby change the thermal histor
32、y of thespecimen.8.2 Molded or Pelleted SpecimensCut the specimens witha microtome, razor blade, hypodermic punch, paper punch, orcork borer (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
33、will approxi-mately meet the desired weight in the subsequent procedure.4The boldface numbers in parentheses refer to the list of references at the end ofthis test method.D34180828.3 Film or Sheet SpecimensFor films thicker than 40 m,see 8.2. For thinner films, cut slivers to fit in the specimencaps
34、ules 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 tests 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
35、 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 using 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 ca
36、libration to be performed simultaneously. In such cases,use the same heating rate for this method (10C/min) andfollow the manufacturers instruction.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 thi
37、s test method.10. Procedure10.1 For First-Order Transition (melting and crystalliza-tion):10.1.1 The purge gas shall be used during testing. The flowrate of the gas shall be the same as used in the calibration (9.1).10.1.2 Use a specimen mass appropriate for the material tobe tested. In most cases a
38、 5-mg specimen mass is satisfactory.Avoid overloading. Weigh the specimen to an accuracy of 610g.10.1.2.1 Intimate thermal contact between the pan andspecimen is essential for reproducible results. Crimp a metalcover against the pan with the sample sandwiched in betweento ensure good heat transfer.
39、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 least 50Cbelow to 30C above the melting temperature to erase previousthermal history.NOTE 6The selection of temperature and time are critical when theeffect of
40、annealing is studied. Minimize the time of exposure to hightemperature to avoid sublimation or decomposition. In some cases it ispossible that the preliminary thermal cycle will interfere with thetransition of interest, causing an incorrect transition or eliminating atransition. Where it has been sh
41、own 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-temperature 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 c
42、rystallizationtemperature 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 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 ont
43、he curves: Teim,Tpm,Tefm,Teic,Tpc, and Teic(see Fig. 1).Report two Tpms or Tpcs if observed.where:Teim= melting extrapolated onset temperature, C,Tefm= melting extrapolated end temperature, C,Tpm= melting peak temperature, C,Teic= crystallization extrapolated onset temperature, C,Tpc= crystallizatio
44、n peak temperature, C, andTefc= crystallization extrapolated end temperature, C.NOTE 8The actual temperature displayed on the temperature axisdepends upon the instrument type (for example, specimen temperature,program temperature, or specimen-program temperature average). Followany recommended proce
45、dures or guidelines of the instrument manufac-turer to obtain specimen temperature at the point of interest.10.2 For Glass Transition:10.2.1 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 f
46、or 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 Perform 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 prev
47、iousthermal 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 of 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
48、 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 Tgmeasurements. The instrument shall be calibrated at thisheating rate. If both first- and second-order transitions (TmandTg, respectively) are to be determined in the
49、 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 temperature, C, andTefg= extrapolated end temperature, C.A new baseline will likely be established after the transition,rather than a peak (see Note 10). For most ap
