1、Designation: D 4473 03Standard Test Method forPlastics: Dynamic Mechanical Properties: Cure Behavior1This standard is issued under the fixed designation D 4473; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 Defense.1. Scope*1.1 This test method covers the use of dynamic-me
3、chanical-oscillation instrumentation for gathering and reporting thethermal advancement of cure behavior of thermosetting resin.It may be used for determining the cure properties of unsup-ported resins and resins supported on substrates and subjectedto various oscillatory deformations. These deforma
4、tions maybe in shear or the dynamic compression of supported resinsusing a dynamic mechanical instrument.1.2 This test method is intended to provide means fordetermining the cure behavior of supported and unsupportedthermosetting resins over a range of temperatures by freevibration and resonant and
5、nonresonant forced-vibration tech-niques, in accordance with Practice D 4065. Plots of modulus,cure behavior, tan delta, and damping index as a function oftime/temperature are indicative of the thermal advancement orcure characteristics of a resin.1.3 This test method is valid for a wide range of fr
6、equencies,typically from 0.01 to 100 Hz. However, it is stronglyrecommended that low-frequency test conditions, generallybelow 1.5 Hz, will generate more definitive cure-behaviorinformation.1.4 This test method is intended for resin/substrate compos-ites that have an uncured effective elastic modulu
7、s in sheargreater than 0.5 MPa.1.5 Apparent discrepancies may arise in results obtainedunder differing experimental conditions. These apparent differ-ences from results observed in another study can usually bereconciled, without changing the observed data, by reporting infull (as described in this t
8、est method) the conditions underwhich the data were obtained.1.6 Due to possible instrumentation compliance, especiallyin the compressive mode, the data generated may indicaterelative and not necessarily absolute property values.1.7 Test data obtained by this test method are relevant andappropriate
9、for use in engineering design.1.8 The values stated in SI units are to be regarded as thestandard.1.9 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 standard to establish appro-priate safety and health
10、 practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Note 5.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 4000 Classification System for Specifying Plastic Mate-rialsD 4
11、065 Practice for Plastics: Dynamic Mechanical Proper-ties: Determination and Report of ProceduresD 4092 Terminology for Plastics: Dynamic MechanicalPropertiesASTM/IEEE SI10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 DefinitionsFor definitions
12、 applicable to this testmethod refer to Terminology D 4092.4. Summary of Test Method4.1 A known amount of thermosetting liquid or resin-impregnated substrate is placed in mechanical oscillation atfixed or natural resonant frequencies at either isothermalconditions, with a linear temperature increase
13、 or a time-temperature relation simulating a processing condition. Theelastic or loss modulus, or both, of the composite specimen aremeasured in shear as a function of time. The point in time whentan delta is maximum, and the elastic modulus levels after anincrease, is calculated as the gel time of
14、the resin under theconditions of the test.NOTE 2The particular method for measuring the elastic and lossmoduli and tan delta depends upon the individual instruments operatingprinciples.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Su
15、bcommittee D20.10 on Mechanical Properties.Current edition approved July 10, 2003. Published September 2003. Originallyapproved in 1985. Last previous edition approved in 2001 as D 4473 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
16、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.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, Unite
17、d States.5. Significance and Use5.1 This test method provides a simple means of character-izing the cure behavior of thermosetting resins using very smallamounts of material (fewer than 3 to 5 g). The data obtainedmay be used for quality control, research and development, andestablishment of optimum
18、 processing conditions.5.2 Dynamic mechanical testing provides a sensitivemethod for determining cure characteristics by measuring theelastic and loss moduli as a function of temperature or time, orboth. Plots of cure behavior and tan delta of a material versustime provide graphical representation i
19、ndicative of cure behav-ior under a specified time-temperature profile.5.3 This test method can be used to assess the following:5.3.1 Cure behavior, including rate of cure, gel, and curetime.5.3.2 Processing behavior, as well as changes as a functionof time/temperature.NOTE 3The presence of the subs
20、trate prevents an absolute measure,but allows relative measures of flow behavior during cure.5.3.3 The effects of processing treatment.5.3.4 Relative resin behavioral properties, including curebehavior and damping.5.3.5 The effects of substrate types on cure.NOTE 4Due to the rigidity of a supporting
21、 braid, the gel time obtainedfrom dynamic mechanical traces will be longer than actual gel time of theunsupported resin measured at the same frequency. This difference will begreater for composites having greater support-to-polymer rigidity ratios.35.3.6 Effects of formulation additives that might a
22、ffectprocessability or performance.5.4 For many materials, there may be a specification thatrequires the use of this test method, but with some proceduralmodifications that take precedence when adhering to thespecification. Therefore, it is advisable to refer to that materialspecification before usi
23、ng this test method. Table 1 of Classi-fication System D 4000 lists theASTM materials standards thatcurrently exist.6. Interferences6.1 Since small quantities of resin are used, it is essentialthat the specimens be representative of the polymeric materialbeing tested.6.2 The result is a response of
24、the thermal advancement orcure behavior of the resin in combination with any substrateused to support the resin.7. Apparatus7.1 The function of the apparatus is to hold a neat (unmodi-fied) resin or uncured supported composite formulation orcoated substrate of known volume and dimensions. The mate-r
25、ial acts as the elastic and dissipative element in a mechanicallydriven oscillatory shear or dynamic compression system. Thesedynamic mechanical instruments operate in one or more of thefollowing modes for measuring cure behavior in torsional shearor dynamic compression:7.1.1 Forced, constant amplit
26、ude, fixed frequency,7.1.2 Forced, constant amplitude, resonant oscillation,7.1.3 Freely decaying oscillation.7.2 The apparatus shall consist of the following:7.2.1 Test Fixtures, a choice of the following:7.2.1.1 Polished Cone and Plate (Having a Known ConeAngle)Usually a 25 or 50-mm diameter cone
27、and plate orparallel plates are recommended for neat resins. Variations ofthis tooling, such as bottom plates with concentric overflowrims, may be used as necessary.7.2.1.2 Parallel Plates, having either smooth, polished, orserrated surfaces are recommended for neat resins or prepregshaving less tha
28、n 6 % volatiles.7.2.1.3 ClampsAclamping arrangement that permits grip-ping of the composite sample.7.2.2 Oscillatory Deformation (Strain Device)A devicefor applying a continuous oscillatory deformation (strain) tothe specimen. The deformation (strain) may be applied andthen released, as in free-vibr
29、ation devices, or continuouslyapplied, as in forced-vibration devices (see Table 1 of PracticeD 4065).7.2.3 DetectorsA device or devices for determining de-pendent and independent experimental parameters, such asforce (stress or strain), frequency, and temperature. Tempera-ture should be measurable
30、with a precision of 61C, frequencyto 61 %, and force to 61%.7.2.4 Temperature Controller and OvenA device for con-trolling the temperature, either by heating (in steps or ramps),cooling (in steps or ramps), maintaining a constant specimenenvironment, or a combination thereof. Fig. 1 illustrates typi
31、caltime-temperature profiles. A temperature controller should besufficiently stable to permit measurement of sample tempera-ture to within 1C.7.3 Nitrogen, or other inert gas supply for purging purposes.3Hedvat, S., Polymer Engineering and Science, Vol 21, No. 3, February 1981.FIG. 1 Typical Tempera
32、ture ProfileD44730328. Test Specimens8.1 The neat resin or the self-supporting composition, orboth, should be representative of the polymeric material beingtested.8.2 Due to the various geometries that might be used fordynamic mechanical curing of thermosetting resins/composites, specimen size is no
33、t fixed by this test method.Cure rates may be influenced by specimen thickness, so equalvolumes of material should be used for any series of compari-sons.8.3 For convenience, low-viscosity neat resins can be stud-ied using a supporting substrate.8.4 The substrate on which the resin is supported is n
34、or-mally in the form of a woven-glass cloth or tape or abraided-glass cord. The substrate should have negligible stiff-ness when compared to the cured resin sample in both aflexural and torsional mode of deformation. Other substratescan be used if their effect on cure mechanisms were of interest.The
35、 composition should be representative of the polymericmaterial being tested.8.4.1 To standardize the pH of the supporting substrates,soak the cloth or braid overnight in distilled water andvacuum-dry. This will avoid any extraneous results with resinsthat are pH-sensitive.9. Calibration9.1 Calibrate
36、 the instrument using procedures recommendedby the manufacturer for that specific make and model.10. ProcedureNOTE 5Precaution: Toxic or corrosive effluents, or both, may bereleased when heating the resin specimen to its cured state and could beharmful to personnel or to the instrumentation.10.1 App
37、ly the resin or uncured, self-supporting compositeonto the test fixture. In the case of two-part room-temperaturecure resins, mixing should be carried out in less than 1 % of theexpected gel time.10.2 Out-time effects and moisture-effect data must berecorded and reported.10.3 Procedure AUnsupported
38、Resin:10.3.1 Allow the sample to equilibrate to room temperaturein a desiccator. In case of a solid sample, place it in an oven at100C for 5 to 10 min in order to soften. Use a vacuum ovento degas, if necessary. Use 50-mm diameter test plates for lowminimum-viscosity systems and 25-mm diameter plate
39、s forhigher minimum-viscosity materials.10.3.2 For neat resins, be certain that there is sufficientmaterial to cover the bottom plate uniformly.10.3.3 Lower the upper test fixture so that it is touching thematerial to be cured.10.3.3.1 The distance between the two parallel plates shouldbe approximat
40、ely 0.5 mm. However, when low viscositymaterials are being evaluated using cone and plate test fixtures,the recommended minimum gap setting is equipment-dependent and reference should be made to the manufacturersoperational manual for correct gap setting.10.3.3.2 Cone and plate experiments should be
41、 run only atone temperature. Any changes in the temperature setting willrequire adjusting the gap setting to the manufacturers recom-mended value.10.4 Procedure BSupported Compositions:10.4.1 For self-supporting compositions, be certain thatthere is sufficient material to fill completely the sample
42、volumeon the lower plate.10.4.2 Mount the substrate in the grips of the test instru-ment. A sample disk (usually 25 mm in diameter) of theself-supporting composition can be die-cut, or several plies ofprepreg can be compressed into a sheet (for example, for 3 minat 77C at 75 atmospheres, 1000 psi) a
43、nd then a disk die-cut.The orientation of unidirectional reinforcements may affectcure behavior and the orientation should be reported in 12.1.4.10.4.3 For three to five plies, the recommended gap settingis 1 to 2 mm. This gap setting is arbitrary and dependent on thetype of material and the number
44、of plies being characterized. Agap setting of 0.5 mm would be minimum. Cone and plate testfixtures are not recommended for supported compositions.10.5 Procedure CDynamic Compression:10.5.1 Prepare the test specimen in accordance with theprocedure described in 10.4.2 and 10.4.3.10.5.2 Compress slight
45、ly the specimen disk and monitorand record the preload force by observing the normal forcegage or indicator. Adjust the gap as necessary to accommodateany material expansion or contraction during the thermaladvancement.10.6 Remove excess material by flushing or trimming thetest fixtures, using a raz
46、or blade, spatula, knife, or hot solderinggun.10.7 Isothermal Curing at Elevated Temperature:10.7.1 In cases where the specimen can be introduceddirectly into the test chamber at elevated temperatures, preheatand stabilize the chamber to the desired temperature prior tointroducing the test specimen.
47、10.7.2 Prevent the material from entering a variable tensilestress mode by adjusting the fixture to compensate for thecontraction of the resin during curing.10.7.3 Ramped or Simulated Process Program HeatingFor materials that are to be cured starting at a low temperatureand programmed for either a l
48、inear ramp or function, thematerial should be applied to the test tooling and the testchamber closed and heated at the desired rate. Although thetemperature gradient is process- and product-dictated, a tem-perature increase of 0.5 (minimum) and a recommended rangefrom 2 to 5C should be monitored dur
49、ing this heat-up. Theactual environmental chamber as well as the measured materialtemperature should be monitored, recorded, and reported.NOTE 6For an isothermal curing experiment at a temperature wherethe uncured resin is in a liquid state, the system may form branchedmolecules and gel with a dramatic increase in viscosity, and then vitrify toa glassy solid. In such cases, two peaks in the damping curve may beobserved. The first peak has been associated with gelation and the secondpeak with vitrification. In other words, only a single peak is observed, thatca
