ASTM D5224-2000(2006) Standard Practice for Compression Molding Test Specimens of Thermosetting Molding Compounds《热固模制合成材料的压力模制试样的标准操作规程》.pdf

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1、Designation: D 5224 00 (Reapproved 2006)Standard Practice forCompression Molding Test Specimens of ThermosettingMolding Compounds1This standard is issued under the fixed designation D 5224; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev

2、ision, 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.1. Scope1.1 This practice covers the general principles to be fol-lowed when compression molding test specimen

3、s of thermo-setting molding compounds, such as phenolics, aminoplastics,melamine phenolics, epoxies, and unsaturated polyesters.NOTE 1This standard is similar in content (but not technicallyequivalent) to ISO 295-1974 (E).1.2 Molding conditions are given for amino, phenolic, andallyl molding compoun

4、ds. Materials specification standardsshould always be consulted to determine whether the materialto be molded has any special requirements.1.3 The values stated in SI units are to be regarded asstandard. The values in brackets are given for information only.1.4 This standard does not purport to addr

5、ess 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.2. Referenced Documents2.1 ASTM Standards:2D 638 Test Met

6、hod for Tensile Properties of PlasticsD 883 Terminology Relating to PlasticsD 958 Practice for Determining Temperatures of StandardASTM Molds for Test Specimens of Plastics32.2 ISO Standard:ISO 295 PlasticsCompression Molding Test Specimensof Thermosetting Materials4ISO 3167 PlasticsMultipurposeTest

7、 Specimens43. Terminology3.1 DefinitionsFor definitions of terms pertaining to plas-tics used in this practice, see Terminology D 883.3.2 Definitions of Terms Specific to This Standard:3.2.1 breathe step, nin plastics molding, the part of themolding cycle in which the mold halves are opened momen-ta

8、rily, prior to curing, to release volatiles from the molded part.3.2.2 skin, nin plastics molding, the thin resin-rich layer(skin) on the surface of the molded part.3.2.3 skin effect, nin plastics testing, the positive ornegative effect the skin may have on the results of somestandard tests.4. Summa

9、ry of Practice4.1 Compression molded test specimens are produced byloading a mold cavity with some form of the molding material,applying a specified pressure to the mating surface for aspecified time and at a specified temperature, and then remov-ing the part from the cavity.5. Significance and Use5

10、.1 The conditions at which compounds are molded areknown to influence the properties of the specimens. The degreeof cure, elimination of knit-lines between particles, density ofthe part, and degradation of the polymer are among thosefactors which will be affected by the molding conditions. Thusit is

11、 important to hold to a standard set of conditions in orderto have a valid comparison of properties between differentcompounds and different batches of the same compound.5.2 If the molded specimens show evidence of low-densityareas due to trapped gases, they should be discarded. A breathestep may be

12、 necessary to eliminate this situation. It is criticalthat the breathe step be as brief as possible to avoid precuringof the compound before full pressure is applied. This wouldlead to poorly “knitted” areas and lower strength in the moldedspecimen.6. Apparatus6.1 Molds:6.1.1 The mold shall be made

13、of steel, able to withstand themolding temperatures and pressures. The mold shall be de-signed such that the compressive mold force is transferred to1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparatio

14、n.Current edition approved March 15, 2006. Published March 2006. Originallyapproved in 1992. Last previous edition approved in 2000 as D 5224 - 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandard

15、s volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn4ISO Standards Handbook 21, Vol 2, Plastics, 2nd Ed., 1990, available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York,NY 10036.1Copyright ASTM International, 100 Barr

16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the molding material with no appreciable loss. The moldsshown in Figs. 1 and 2 are recommended for maintaining themaximum force on the material. They are of the three-platedesign; consisting of a shell or floating plate, wit

17、h upper andlower compression plates. Molds may be of single or multiplecavity design.NOTE 2Semi-positive molds may be used, and for materials such asamino compounds, may even be preferred.6.1.2 Although the actual mold cavity may have variousforms, the majority of tests will use bars 12.7 mm 0.5 in.

18、 inwidth by 127 mm 5 in. or 64 mm 2.5 in. in length, discs 51mm 2 in. or 102 mm 4 in. in diameter or an appropriatetensile bar as described in Test Method D 638. The multi-purpose design from ISO 3167 may also be used. The moldshall be capable of molding thickness from 1.5 mm 0.06 in.to 12.5 mm 0.5

19、in. If the specimens are to be used for flametesting, even thinner specimens may be needed. In all cases theASTM Standard Test Procedure to be used shall be consultedfor the dimensions of the required test specimens.NOTE 3If at all possible, specimens shall be molded directly todimension, rather tha

20、n machined from a plaque. This maintains theintegrity of any skin effect.NOTE 4If specimens are to be machined from plates or plaques, theyshould not be taken from the edge of the plaque.Aminimum margin of 10mm 0.5 in. is recommended.6.1.3 A cavity draft angle not exceeding 3 may be used tofacilitat

21、e specimen removal.6.1.4 The clearance between the vertical wall of the cavityand that of the force shall not exceed 0.1 mm 0.004 in.6.1.5 Mold surfaces should be finished to a roughness of 0.4to 0.8 m (SPI-SPE #2 or equivalent5), unless it is known thatthe particular test is not affected by a coars

22、er surface finish.Chrome plating is recommended but not necessary. All cavitysurfaces should be draw polished in the direction parallel to theforce to facilitate specimen removal.6.1.6 If ejector pins are used, they shall not deform thespecimens and their placement shall be such that the pin marksar

23、e not in the area of test.6.1.7 The mold shall have a loading chamber of sufficientvolume to allow the introduction of the entire charge ofmaterial in a single loading. Preforms may be used to decreasethe required loading volume of high bulk materials. Theconditions of such preforming shall be inclu

24、ded in the report.6.1.8 As the specimen surface facing the lower die is heatedfor a longer time and at a higher temperature in the timeinterval between filling and compression, it is recommendedthat a mark be placed on one cavity face in such a position thatit will not interfere with the testing. Wh

25、en reporting the resultsof tests that affect the surfaces unequally, the tested surfaceshall be indicated.6.2 PressThe hydraulic press shall have a range ofpressures sufficient to insure that the specified pressure isapplied and maintained during the entire molding operation,and of maintaining that

26、pressure within 61.5 MPa (6218 psi).6.2.1 In order to prevent precure, the press shall be capableof closing within 15 s after the placement of the material in themold. A two-speed press is preferred for this purpose. The fastapproach speed can be in the range of 200 to 400 mm/s 8 to16 in./s while th

27、e slow closing speed of 5 mm/s 0.2 in./s isused to prevent gas entrapment.6.3 Heating SystemThe molds may be heated by conduc-tion from heated platens, heaters inserted into the mold itself,or by hot fluids circulated through passageways in the mold.The heating system shall be capable of controlling

28、 the moldtemperature to 63C 65F from point-to-point on the moldand for the duration of the molding time.5Mold comparison kits are available from the D-M-E Company, 29111 Stephen-son Highway, Madison Heights, MI 48071.FIG. 1 Single-Cavity Positive-Compression Mold for Bar TestSpecimensFIG. 2 Compress

29、ion Mold for Disk Test SpecimensD 5224 00 (2006)26.3.1 If the mold is heated directly, it shall be insulated fromthe press platens with a sheet of insulating material.NOTE 5It is generally preferable to heat the mold electrically.6.4 Temperature-Measurement System:6.4.1 Mold TemperatureA thermometer

30、 or pyrometershall be used in accordance with Practice D 958.6.4.2 Preheated Compound Temperature If the compoundis to be preheated to a definite temperature, a needle-probepyrometer sensitive to 62C shall be used.7. Conditioning7.1 Except for referee testing and preparation of samples forelectrical

31、 tests, prior conditioning of the material is notrequired.7.2 Referee Testing: Phenolic and Amino Molding Com-pounds:7.2.1 For the referee testing of all but electrical specimens,place a sufficient quantity of material in an open tray to amaximum depth of 13 mm (0.5 in.) for 72 h in a standardlabora

32、tory atmosphere (23 6 1C, 50 6 2 % relative humid-ity).7.2.2 For the preparation of electrical test specimens, placea sufficient sample of the molding material in an open tray toa maximum depth of 13 mm 0.5 in. Dry in an air-circulatingoven for 30 min at 90 6 3C. Mold the material immediatelyafter c

33、onditioning.7.3 Referee Testing: Allyl Molding Compounds:7.3.1 For referee testing of all test specimens, place asufficient quantity of material in an open tray to a depth of 25mm 1 in. for 72 h in a standard laboratory atmosphere (23 61C, 50 6 2 % relative humidity).7.4 Electronic Preheating:7.4.1

34、When electronic preheating is to be used (refer toMolding Condition, Table 1), the objective is to attain aparticular temperature as rapidly as possible. Determine theconditions necessary to attain that temperature with sparepreforms which are then discarded. Do not use this type ofpreheating when p

35、reparing electrical test specimens. Thematerial shall be transferred to the mold immediately afterpreheating to prevent cooling or premature curing.7.5 Preplastification:7.5.1 Preplastification is permissible to insure thermal andmechanical homogenization of the material. The preplasticizedmaterial

36、shall be molded immediately after preplastification toprevent cooling or premature curing. Preplastification condi-tions shall be the subject of an agreement between theinterested parties and shall be included in the molding report.8. Procedure8.1 Mold test specimens under the conditions listed in T

37、able1.8.1.1 The “breathe step,” if used, is done by opening themold for a few seconds to release volatiles generated by thecuring process. The mold opening should be slight and is doneafter it has already been closed at the molding temperature.8.1.2 Release agents are not normally needed as moldingc

38、ompounds have internal lubricants to facilitate mold release.If release agents are used it shall be shown that they have noinfluence on the test specimen properties. They shall be notedin the report.8.1.3 Cooling fixtures may be used to prevent warpage uponremoval of the specimens from the mold.8.2

39、Phenolic Molding Compounds:8.2.1 Use conditions A or B from Table 1 for impact,flexure, tension, water absorption, heat deflection, heat-agingtests.8.2.2 Use Condition C from Table 1 for electrical testspecimens.8.3 Amino Molding Compounds:8.3.1 For urea-formaldehyde compounds use Condition Dfrom Ta

40、ble 1.8.3.2 For melamine-formaldehyde compounds use Condi-tion E from Table 1.8.4 Allyl Molding CompoundsUse conditions F, G, or Hfrom Table 1.8.5 Molding Pressures:8.5.1 The molding pressures shown in Table 1 are recom-mended and shall be used for all referee molding and testing.If other pressures

41、are to be used, the oil pressure p0inmegapascals (MPa), to be displayed on the pressure gauge inorder to obtain the specified pressure p, in megapascals, isgiven by the equation:TABLE 1 Molding Conditions for Compression Molding of Thermoset Molding CompoundsMolding Condition A B C D E F G HCharge p

42、owder preformApowder or preformBpowder, pill, or granular powder or preformBpowder powder preformPreheating none electronic air oven air oven none air oven electronicPreheat temperature 104 to 115C 90C 90C 120C 107CPreheat time 30 min 60 min 10 min 25 to 30 sMolding temperatureC170C 170C 170C 150C 1

43、50C 160C 160C 160CMolding pressureD,E17 MPaE17 MPa 17 MPa 28 MPa 28 MPa 20 MPa 20 MPa 20 MPaMolding time3.2 mm thickness 5 min 3 min 5 min 4 min 5 min 5 min 3 min 3 min6.4 mm thickness 5 min12.7 mm thickness 5 minBreathing allowed allowed allowed allowed allowed when necessary (keep brief)AA single

44、preform, preferably approximating the molded shape, shall be used. If more than one preform is used, weld lines may affect the test value of the specimen.BWhen using preforms, the material should be preheated in powder form, then preformed and molded immediately.CMolding temperatures should be held

45、to within 3C of the specified level.DMolding pressure should be held to within 2 MPa of the specified level.EHighly plastic materials may flash excessively under the molding pressure specified. If that occurs, molding pressure may be reduced to a minimum of 10 MPa, in whichcase the pressure used sha

46、ll be reported.D 5224 00 (2006)3p05 p 3 A1!/A (1)where:A = the area of the press piston head, m2, andA1= the total area of the cavities, m2.9. Report9.1 Report the following information:9.1.1 Type and description of material used,9.1.2 Description of the mold,9.1.3 State of material molded (as recei

47、ved or with “refereetest” conditioning),9.1.4 Molding condition used (A, B, C, D, E, F, G, or H) andany variations from the listed condition, and9.1.5 Whether or not a “breathe step” was used duringmolding.9.1.6 The report form (Fig. 3) may be used and identifies allpertinent information.FIG. 3 Comp

48、ression Molding ReportD 5224 00 (2006)410. Precision and Bias10.1 Inasmuch as this practice does not generate a numeri-cal result, a precision and bias estimate is not possible.However, the procedures used during molding of test speci-mens will affect the numerical results from tests done on thespec

49、imens. Thus variabilities in the molding procedure willcontribute to variability in the final test results.11. Keywords11.1 allyl molding compound; amino molding compound;compression molding; phenolic molding compound; plastics;thermosetASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement