1、Designation: D3418 121Standard Test Method forTransition Temperatures and Enthalpies of Fusion andCrystallization of Polymers by Differential ScanningCalorimetry1This standard is issued under the fixed designation D3418; 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 Defense
3、.1NOTEEditorially corrected Fig. 2 in December 2012.1. 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 i
4、nvestigation, and frequently, specialized crystallization 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 6
5、00C. Certain equipment allows thetemperature range 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
6、 use. It is theresponsibility of the user of this 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 info
7、rmation not supplied bythis test method.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial
8、Scanning Calorimeters and Differential Thermal Ana-lyzersE968 Practice for Heat Flow Calibration of DifferentialScanning CalorimetersE1142 Terminology Relating to Thermophysical PropertiesE1953 Practice for Description of Thermal Analysis andRheology Apparatus2.2 ISO Standards:3ISO 11357-1 PlasticsD
9、ifferential Scanning Calorimetry(DSC)Part 1: General 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 C
10、rystallization3. Terminology3.1 Specialized terms used in this test method are defined inTerminologies E473 and E1142.4. 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 a1This test method is under the juri
11、sdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties(Section D20.30.07).Current edition approved Aug. 1, 2012. Published September 2012. Originallyapproved in 1975. Last previous edition approved in 2008 as D3418 - 08. DOI:10.1520/D3
12、418-12E01.2For 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 Institu
13、te (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*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 States1controlled flow rate and continuously monitor
14、ing with asuitable sensing device 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
15、 in the heating orcooling curve. Areas under the crystallization exotherm orfusion endotherm of the test materials are compared against therespective areas obtained by the treatment of a well-characterized standard.5. Significance and Use5.1 Thermal analysis provides a rapid method for measuringtran
16、sitions 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 for these transitions. Differentialscanning calorimetry is used to assist in identifying speci
17、ficpolymers, 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 reactions include oxidation, curingof thermosetting resins, and thermal decomposition.5.2 Th
18、is 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 effect on the mea-sured results, especially on the enthalpy of fusion or crystalli-zation. Theref
19、ore, 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 solutions, or to be miscible in the melt phase.6.3 Uncertain radiation losses at temperatures highe
20、r 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 particle size (1-5).46.5 In cases that specimens react with air during thetemperature cycle,
21、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 degradation and transition.6.6 Since milligram quantities of a specimen are used, it isessential to
22、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 all polymers lend themselves to the exact terms ofthis test method. For some polymers such as
23、 polyarylamides,4The boldface numbers in parentheses refer to the list of references at the end ofthis test method.FIG. 2 Assignment of Glass Transition of Poly(Methyl Methacrylate) (PMMA)D3418 1212crystallization is only possible from solution. For other poly-mers such as crystallizable polystyrene
24、, 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 essentialinstrumentation required to provide the min
25、imum differentialscanning calorimetric capability for this test method includes: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 constant temperatureor at a constant rate within the appl
26、icable 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 equivalent to 1 mW.7.1.1.4 Means of Sustaining a Test
27、Chamber Environment ofpurge gas at a purge flow rate of 10 to 50 6 5 mL/min.NOTE 4Typically, 99+ % pure nitrogen, argon or helium are employedwhen oxidation in air is a concern. Unless effects of moisture are to bestudied, use of dry purge gas is recommended and is essential foroperation at sub-ambi
28、ent 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 constant to 60.1C/min or at an isothermal temperature constant t
29、o 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 exothermic peaks, or both.7.1.5 Containers (pans, crucibles,
30、and so forth) that are inertto the specimen and reference materials; and that are of suitablestructural shape and integrity to contain the specimen andreference in accordance with the specific requirements of thistest method.7.1.6 Cooling capability to hasten cool down from elevatedtemperatures, to
31、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 60.0001 grams fortransition temperatures and to 60.00001
32、grams for determin-ing enthalpies.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 ororientation, or both, and thereby
33、change the thermal history ofthe specimen.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 co
34、ntainers as in 7.1.5 and will approxi-mately meet the desired weight in the subsequent procedure.8.3 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 o
35、r 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 using PracticeE967 and the same heating rate to be used in this test methodprefer
36、ably 10C/min or 20C/min (see Note 5). (See Section 10for details.)9.3 Calibrate the DSC heat flow signal using Practice E968and the same heating rate as in 9.2 (see Note 5).9.4 Some instruments allow for the temperature and heatflow calibration to be performed simultaneously. In such cases,use the s
37、ame heating rate for this method and follow themanufacturers instruction. Report the heating rate. (See12.1.3.)NOTE 5Use of other heating rates is permitted. However, test resultsare affected by the heating rate. It is the responsibility of the user of otherrates to demonstrate equivalency to this t
38、est 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 5-
39、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. Tak
40、e care to ensure flat panbottoms.10.1.3 Perform and record a preliminary thermal cycle byheating the sample at the same rate used for testing from atleast 50C below to 30C above the melting temperature toerase previous thermal history.10.1.4 When the effect of annealing is studied, selection oftempe
41、rature and time are critical. Minimize the time ofexposure to high temperature to avoid sublimation or decom-position. In some cases it is possible that the preliminarythermal cycle will interfere with the transition of interest,causing an incorrect transition or eliminating a transition.Where it ha
42、s been shown that this effect is present, omit thepreliminary thermal cycle.D3418 121310.1.5 Hold the temperature for 5 min (10.1.3).NOTE 6In cases that high-temperature annealing cause polymerdegradation, the use of shorter annealing times is permitted but shall bereported.10.1.6 Cool to at least 5
43、0C below the peak crystallizationtemperature using the same rate that was used for heating andrecord the cooling curve.10.1.7 Hold the temperature for 5 min.10.1.8 Repeat heating at the same rate used in 10.1.3(10C/min or 20C/min) and record the heating curve. Use thiscurve to calculate the enthalpi
44、es of transition.10.1.9 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.10.1.10 In case of dispute determine Tmand Tcat a heatingrate of 10C/min.where:Teim= melting extrapolated onset temperature, C,Tefm=
45、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 7The actual temperature displayed on the temperature axisdepends up
46、on 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 The purge g
47、as 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-mg specimen mass is satisfactory.Weigh the specimen to an accuracy of 610 g.10.2.3 Perform and record a
48、 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 6.)10.2.5 Quench cool to at least 50C below the transitiontemperature of interest.10.2.6
49、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 the preferredFIG. 1 First-Order Transition of NylonD3418 1214heating rate for Tgmeasurements. The instrument shall becalibrated at the same heating rate used for testing. If both first-and second-order transitions (Tmand Tg, respectively) are to bedetermined in
