1、Designation: D 4473 08Standard 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 bothunsupported resins and resins supported on substrates sub-jected to various oscillatory deformations.1.2 This test
4、 method is intended to provide a means fordetermining the cure behavior of supported and unsupportedthermosetting resins over a range of temperatures by freevibration as well as resonant and nonresonant forced-vibrationtechniques, in accordance with Practice D 4065. Plots ofmodulus, tan delta, and d
5、amping 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 frequencies,typically from 0.01 to 100 Hz. However, it is stronglyrecommended that low-frequency test conditions, generallybelow
6、 1.5 Hz, be utilized as they generally will result in moredefinitive cure-behavior information.1.4 This test method is intended for resin/substrate compos-ites that have an uncured effective elastic modulus in sheargreater than 0.5 MPa.1.5 Apparent discrepancies may arise in results obtainedunder di
7、ffering 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 test method) the conditions underwhich the data were obtained.1.6 Due to possible instrumentatio
8、n 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 for use in engineering design.1.8 The values stated in SI units are to be regarded as thestanda
9、rd.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 practices and determine the applica-bility of regulatory limitations prior to use. Specific pr
10、ecau-tionary statements are given in Note 5.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D 4000 Classification System for Specifying Plastic Mate-rialsD 4065 Practice for Plastics: Dynamic Mechanical Proper-ties: Determination and Report of Proce
11、duresD 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 applicable to this testmethod refer to Terminology D 4092.4. Summary of Test Method4.1 A kn
12、own amount of thermosetting liquid resin or resin-impregnated substrate is placed in mechanical oscillation ateither a fixed or natural resonant frequency or by free vibrationand at either isothermal conditions, with a linear temperatureincrease or using a time-temperature relation simulating aproce
13、ssing condition. The elastic or loss modulus, or both, ofthe composite specimen are measured in shear or compressionas a function of time. The point in time when tan delta ismaximum, and the elastic modulus levels off after an increase,is calculated as the gel time of the resin under the conditions
14、ofthe test.NOTE 2The particular method for measuring the elastic and loss1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved March 1, 2008. Published April 2008. Origina
15、llyapproved in 1985. Last previous edition approved in 2003 as D4473 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, refer to the standards Document Summary page onthe AS
16、TM 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, United States.moduli and tan delta depends upon the individual instruments operatingprinciples.5. Significance and Use5.1
17、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 processing conditions.5.2 Dynamic m
18、echanical 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 indicative of cure behav-ior under a
19、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 substrate prevents an absolute measure,b
20、ut 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 braid, the gel time obtainedfrom dy
21、namic 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 affectprocessability or performance.5
22、.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 using this test method. Table 1 of Clas
23、si-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 the thermal advancement orcure behav
24、ior 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-rial acts as the elastic and dissipat
25、ive 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 amplitude, fixed frequency,7.1.2 Forced, c
26、onstant 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 and plate orparallel plates are reco
27、mmended 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 than 6 % volatiles.7.2.1.3 ClampsAclamp
28、ing 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-vibration devices, or continuouslyapplie
29、d, 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 with a precision of 61C, frequencyto
30、 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 typicaltime-temperature profiles. A temp
31、erature 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 Temperature ProfileD44730828. Test Specimen
32、s8.1 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 not fixed by this test method.Cure rat
33、es 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 nor-mally in the form of a woven-glas
34、s 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 composition should be representativ
35、e 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 the instrument using procedures rec
36、ommendedby 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 Apply the resin or uncured, self-suppor
37、ting 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 Resin:10.3.1 Allow the sample to equ
38、ilibrate 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 plates forhigher minimum-viscosity materi
39、als.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 approximately 0.5 mm. However, when low viscos
40、itymaterials 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 run only atone temperature. Any cha
41、nges in the temperature setting willrequire adjusting the gap setting to the manufacturers recom-mended value.10.3.4 Conduct cure characterization of the submitted ma-terial in accordance with the desired time and temperatureparameters recording the appropriate property values.10.4 Procedure BSuppor
42、ted Compositions:10.4.1 For self-supporting compositions in prepreg-typeform using cone and plate or parallel plate fixturing, be certainthat there is sufficient material to fill the sample volume on thelower plate completely.10.4.2 Insert the substrate between the plates of the testinstrument. A sa
43、mple 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) and then a disk die-cut.The orientation of unidirectional reinforcements may affectcure behavio
44、r 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 of plies being characterized. Agap setting of 0.5 mm would be minimum. Cone and plate testfixt
45、ures are not recommended for supported compositions.10.4.4 For self-supporting substrates where either a baresubstrate is to be impregnated with liquid resin (rectangular orcylindrical form) or where a similar prepreg-type specimenforms a rectangular specimen, clamp the substrate in placeutilizing t
46、he instruments grip system.10.4.5 Conduct the cure characterization of the submittedmaterial in accordance with the desired time and temperatureparameters recording the appropriate property values.10.5 Procedure CDynamic Compression:10.5.1 Prepare the test specimen in accordance with theprocedure de
47、scribed in 10.4.2 and 10.4.3.10.5.2 Compress slightly 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.10.5.3 Conduct the cure charac
48、terization of the submittedmaterial in accordance with the desired time and temperatureparameters recording the appropriate property values.10.6 Remove excess material by flushing or trimming thetest fixtures, using a razor blade, spatula, knife, or hot solderinggun.10.7 Isothermal Curing at Elevate
49、d 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.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 linear ramp or function, thematerial should be
