1、Designation: D731 10Standard Test Method forMolding Index of Thermosetting Molding Powder1This standard is issued under the fixed designation D731; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the measurement of the moldingindex (plasticity) of thermosetting plastics ranging in flow fromsoft to stiff by sele
3、ction of appropriate molding pressureswithin the range from 3.7 to 36.5 MPa (530 to 5300 psi).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any,
4、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.NOTE 1There is no known ISO equivalent to this test method.2. Referenced Documents2.1 ASTM Stand
5、ards:2D256 Test Methods for Determining the Izod PendulumImpact Resistance of PlasticsD883 Terminology Relating to PlasticsD957 Practice for Determining Surface Temperature ofMolds for PlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminol
6、ogy3.1 Definitions are in accordance with Terminology D883,unless otherwise specified.3.2 Definitions of Terms Specific to This Standard:3.3 plasticitya measure of the resistance of a moltenthermosetting material to flow under heat and pressure. Ameasure of the apparent viscosity of the material.4.
7、Summary of Test Method4.1 A cup mold is mounted in a semi-automatic type press.A predetermined quantity of test sample is charged into themold, controlled at a temperature dependent upon the testmaterial. The minimum force required to mold a cup having aflash or fin thickness within a specified tole
8、rance is determined.This force along with the mold closing time is reported asmolding index.5. Significance and Use5.1 This test method provides a guide for evaluating themoldability of thermosetting molding powders. This testmethod does not necessarily denote that the molding behaviorof different m
9、aterials will be alike and trials may be necessaryto establish the appropriate molding index for each material inquestion.5.2 The sensitivity of this test diminishes when the moldingpressure is decreased below 5.3 MPa (764 psi), so pressureslower than this are not ordinarily recommended. This is due
10、 tothe friction of moving parts and the insensitivity of the pressureswitch actuating the timer at these low pressures.6. Apparatus6.1 MoldA cup mold3of the flash type, to produce amolded cup as shown in Fig. 1, operated under controlledpressure and temperatures and provided with stops so that flash
11、or fin thickness cannot be less than 0.14 mm (0.0055 in.). Thearea of the mold casting creating the molded flash shall belocated on top of the cup, flat, perpendicular to the axis of thecup, and in the form of an annular ring 3.17 mm (0.125 in.) inwidth.6.2 PyrometerA calibrated pyrometer, traceable
12、 to a na-tional standard (for example, NIST), and accurate to 61Cshall be used to determine the temperature of the moldsurfaces. For properly measuring mold temperatures, referencePractice D957.6.3 Heating SystemAny conventional means for heatingthe press platens, provided the heat source is constan
13、t enough1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 Thermal Properties.30 onThermal Properties (Section D20.30.08).Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1950. Last prev
14、ious edition approved in 2008 as D731 - 08. DOI:10.1520/D0731-10.2For 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 webs
15、ite.3A detailed drawing of the mold design is available from ASTM Headquarters.Order Adjunct: ADJD0731.1*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.to maintain the
16、molding temperature within 61C of thespecified temperature (see 9.2).6.4 Pressure SystemA semiautomatic press with a fixedmold and fully insulated to minimize heat losses shall be used.The hydraulic system shall be provided with a means ofpressure regulation so that the load on the mold shall differ
17、 bynot more than 61112 N (6250 lbf) from the stated value. Thecapacity of the hydraulic system shall permit a ram travel ofapproximately 25 mm/s (1 in./s). The ram diameter shall notexceed 100 mm (4 in.).NOTE 2The use of hand molds is not recommended but may be usedto give an estimate of the molding
18、 index.7. Test Specimen7.1 To determine the weight of the test specimen formaterials having an Izod impact strength of 27 J/m (0.50ft-lb/in.) of notch, or less, a cup having a flash or fin thicknessof 0.15 to 0.20 mm (0.006 to 0.008 in.) shall be molded (seeNote 3). The adhering fin shall be removed
19、 and the cupweighed to the nearest 0.1 g. This weight multiplied by 1.1shall be the weight of the test specimen used. For materialshaving an impact above 27 J/m (0.50 ft-lb/in.) of notch, thespecimen weight is determined in a similar manner, except thatcup flash shall not be more than 0.66 mm (0.026
20、 in.) or lessthan 0.51 mm (0.020 in.), and the amount of material shall be1.05 times the weight of this cup. The test specimen shall be inthe form of loose powder unless preforming is necessary formaterials of high bulk. Minimum pressure shall be employed inthe preforming operation to minimize the i
21、ncrease in closingtime resulting from the use of preforms.NOTE 3While the mold is provided with stops so that the flash or finthickness cannot be less than 0.15 6 0.013 mm (0.006 6 0.0005 in.), themolded cup itself may have a flash thickness of 0.15 to 0.20 mm (0.0066 0.0008 in.) as the micro switch
22、 controlling the closing time must haveFIG. 1 Cup MoldD731 102a tolerance in which to operate.8. Conditioning8.1 Materials are normally tested in the “as received”condition, except in referee tests, when they shall be condi-tioned in accordance with 8.2 (see Note 4).8.2 For referee testing, all mate
23、rials shall be shipped andstored in sealed moisture barrier containers. These materialsshall be stored for a minimum period of 48 h at standardlaboratory temperature before breaking the seal on the carton.A representative sample shall be taken from this cartonimmediately after opening and tested wit
24、hin 3 min in order topreserve the original moisture content. Alternative methods ofconditioning samples are acceptable provided they are mutu-ally agreed upon between the manufacturer and the purchaser.NOTE 4Conditioning may alter the moisture content of most materialsand thereby change their moldin
25、g index or molding behavior.9. Procedure9.1 Mount the mold in the semi-automatic press. The rate offlow is sensitive to the condition of the mold surfaces. To avoiderroneous results, any residue deposited from prior tests shallbe completely removed from the mold surfaces. Discard thefirst few cups m
26、olded and accept the flow time as correct whentwo successive cups molded under test do not differ by morethan1sintime of flow.9.2 The preferred mold temperature for testing the moldingindex for the following materials shall be:C (F)Phenolic 165 6 1 (330 61.8)Melamine155 6 1 (310 61.8)Urea150 6 1 (30
27、0 61.8)Epoxy 150 6 1 (300 61.8)Diallyl phthalate1506 1 (300 61.8)Alkyd150 6 1 (300 61.8)Other temperatures are acceptable provided they are mutu-ally agreed upon between the manufacturer and the purchaser.9.3 First determine the proper weight to be used as outlinedin 6.1. Then begin the test with a
28、load sufficient to close themold to the fin thickness specified for the type of materialbeing tested as defined in 6.1. For example, if a 44482 N(10,000 lb) load is applied on the mold to make the initial cupand the required fin thickness is obtained, the next lower load,3362 N (37500 lb) is applied
29、 as indicated in the followingtable. If the mold closes to the required thickness again, thenthe 22241 N (5000 lb) load is applied. If the mold then does notclose, the “molding index” is the closing time obtained with the33362 N (7500 lb) load. It is recommended that the mold loadsused be selected f
30、rom the following table (see Note 5):Total ForceBetweenPlatensPlasticPressureN (lb) MPa (psi)16 014 (3600) 5.3 (764)22 241 (5000) 7.3 (1060)33 362 (7500) 11 (1591)44 482 (10 000) 14.6 (2121)59 161 (13 300) 19.4 (2821)66 723 (15 000) 21.9 (3181)88 964 (20 000) 29.2 (4242)111 206(25 000) 36.5 (5302)NO
31、TE 5These fixed mold loads are recommended based upon com-mon practice and materials and plasticities currently available. Other moldloads may be defined, if agreed to by supplier and customer, to betterdefine the plasticity of a material.9.4 The time of flow in seconds shall be measured from theins
32、tant that the hydraulic gage indicates an applied load of4448 N (1000 lb) to the instant that the fin has reached 0.20mm (0.008 in.) in thickness for materials with an Izod impactstrength of 27 J/m (0.50 ft-lb/in.) of notch, or less, and 0.66mm (0.026 in.) for materials with an impact above 27 J/m (
33、0.50ft-lb/in.) of notch.NOTE 6The molding pressure is calculated by dividing the total loadby the projected area of the mold cavity.NOTE 7A convenient method for determining fin thickness is toindicate the final movement of the platen with a dial micrometer.10. Report10.1 Report the following inform
34、ation:10.1.1 A statement indicating the nature of the materialtested and the manufacturers material number and batchnumber,10.1.2 The molding index expressed as the total minimumforce in newtons (pounds) required to close the mold, with theclosing time in seconds (for example, 445/13.4 N (100/13.418
35、),10.1.3 Temperature of the mold,10.1.4 Weight of the test sample in grams, and form ofsample (loose powder or preform),10.1.5 Thickness of flash or fin measured to the nearest0.025 mm (0.001 in.),TABLE 1 Molding Index in SecondsNOTE 1Sris the within-laboratory standard deviation of the average,SRis
36、 the between-laboratories standard deviation of the average, r = 2.8Sr, and R = 2.8 SR.Material Average Load, N(lb)SrSRrRPolyester (B)A4.78 112 (25) 0.025 0.909 0.070 2.545Glass-Filled (B)B8.99 112 (25) 0.038 0.727 0.106 2.036Polyester (A)A9.63 112 (25) 0.072 0.577 0.202 1.616Mineral Filled (A)B11.5
37、4 112 (25) 0.072 0.881 0.202 2.467Mineral Filled (B)A11.57 112 (25) 0.098 1.736 0.274 4.861General Purpose (B)A11.78 112 (25) 0.041 1.264 0.115 3.539DAP (B)A12.64 112 (25) 0.054 0.892 0.151 2.498Impact Type (B)A14.92 168 (36) 0.090 0.965 0.252 2.702Glass-filled (A)B16.06 224 (50) 0.083 0.912 0.232 2
38、.554General Purpose (A)B18.37 168 (36) 0.056 1.331 0.157 3.727ASample B obtained from Occidental Chemical Corp., Fort Green, Ontario,Canada.BSample A obtained from Occidental Chemical Corp., Tonawanda, NY.D731 10310.1.6 Description of any unusual characteristics of the testsample, such as discolorat
39、ion and sticking,10.1.7 Details of conditioning,10.1.8 Impact strength of the material expressed as Izod inJ/m (ft-lb/in.) of notch in accordance with Test Methods D256,and11. Precision and Bias411.1 Table 1 is based on a round robin conducted in 1988 inaccordance with Practice E691 involving ten te
40、st samples. Thetest results in Table 1 were from four laboratories with eachlaboratory obtaining four test results for each sample.(WarningThe following explanations of r and R (11.3through 11.3.3) are only intended to present a meaningful wayof considering the approximate precision of this test met
41、hod.The data in Table 1 is not to be rigorously applied to theacceptance or rejection of material, as those data are specific tothe round robin and are not necessarily representative of otherlots, conditions, materials, or laboratories. In particular withdata from less than six laboratories, the bet
42、ween-laboratoriesresults are likely to have a very high degree of error.)11.2 Apply the principles outlined in Practice E691 togenerate data specific to their laboratory and materials orbetween specific laboratories. The principles of 11.3 through11.3.3 would then be valid for such data.11.3 Concept
43、 of r and RIf Srand SRhave been calculatedfrom a large enough body of data, (use Table 1 with caution asonly four laboratories participated) and for test results thatwere averages from testing four specimens.11.3.1 Repeatability Limit, rComparing two test resultsfor the same material, obtained by th
44、e same operator using thesame equipment on the same day, the two test results shall bejudged not equivalent if they differ by more than the r value forthat material.11.3.2 Reproducibility Limit, RComparing two test resultsfor the same material, obtained by different operators usingdifferent equipmen
45、t on different days, the two test results shallbe judged not equivalent if they differ by more than the R valuefor that material.11.3.3 Any judgment in accordance with 11.3.1 and 11.3.2would have an approximate 95 % (0.95) probability of beingcorrect.11.4 Bias is systematic error that contributes to
46、 the differ-ence between a test result and a true (or reference) value. Thereare no recognized standards on which to base an estimate ofbias for this test method.12. Keywords12.1 molding index; plasticity; thermosetsSUMMARY OF CHANGESCommitteeD20 has identified the location of selected changes to th
47、is standard since the last issue (D731 - 08)that may impact the use of this standard. (May 1, 2010)(1) Removed permissive language.(2) Made SI units standard.(3) Added Note 2 and renumbered subsequent notes.ASTM International takes no position respecting the validity of any patent rights asserted in
48、 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 of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the re
49、sponsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is
