1、Designation: D1921 12Standard Test Methods forParticle Size (Sieve Analysis) of Plastic Materials1This standard is issued under the fixed designation D1921; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 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.1. Scope*1.1 These test methods cover the measurement of thepar
3、ticle size of plastic materials in the powdered, granular, orpelleted forms in which they are commonly supplied. As thesetest methods utilize dry sieving, the lower limit of measure-ment is considered to be about 38 m (No. 400 sieve). Forsmaller particle sizes, sedimentation test methods are recom-m
4、ended.1.2 Two test methods are described:1.2.1 Test Method AThis test method uses multiple sievesselected to span the particle size of the material. This methodis used to determine the mean particle diameter and particlesize distribution.1.2.2 Test Method BThis test method is an abbreviatedversion o
5、f Test MethodAconducted with a few specific sieves.This test method determines “percent passing” or “percentretained” on a given sieve. Test Method B is applicable tomaterials which do not have a normal particle size distributionsuch as pellets and cubes.1.3 The values stated in SI units shall be co
6、nsideredstandard for dimensions of the wire cloth openings and thediameter of the wires used in the wire cloth. The values statedin inch-pound units shall be considered standard with regard tothe sieve frames.1.4 This standard does not purport to address all of thesafety concerns, if any, associated
7、 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 for this test method.2. Referenced Documents2.1 ASTM Standards:2E11
8、 Specification for Woven Wire Test Sieve Cloth and TestSievesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Methods3.1 A dry mass of plastic material is placed on a series ofsieves arranged in order of increasing fineness and the ma
9、ss isdivided into fractions corresponding to the sieve opening.4. Significance and Use4.1 These test methods are used to determine particle sizedistribution and therefore are useful for determining lot-to-lotuniformity.4.2 The particle sizes of plastic materials affect the handlingcharacteristics an
10、d sometimes will affect the processing char-acteristics of some polymers.5. Interferences5.1 Some materials develop a static charge during sieving.This charge interferes with the sieving process and results in acoarse bias. Use of an antistat is necessary to obtain meaning-ful results.5.2 The choice
11、 of antistat (or slip agent) has been known toaffect the coarse bias. Some materials are more effective inaiding the fines to separate from the mass.5.3 Too much material on a sieve causes mass blinding andresults in a coarse bias. The sieve selection and charge weightmust be chosen to avoid overloa
12、ding any sieve.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.70 on AnalyticalMethods (Section D20.70.01).Current edition approved Aug. 1, 2012. Published September 2012. Originallyapproved in 1961. Last previous
13、edition approved in 2006 as D1921 - 061. DOI:10.1520/D1921-12.2For 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
14、.*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 States15.4 Wavy, improperly stretched wire-cloth potentially al-lows wires to separate without being visually damaged. Sieveswi
15、th wavy or torn wires shall not be used, as they no longerconform to Specification E11.6. Apparatus6.1 Balance, 500-g minimum capacity with the capability ofreading to the nearest 0.1 g.6.2 Mechanical Sieving Device and Time SwitchA me-chanical sieve-shaking device equipped with an automatic timeswi
16、tch. This device shall be capable of imparting uniformrotary motion and a tapping action at a rate of 150 6 10taps/min.6.3 Wire Cloth Sieves, woven wire cloth conforming toSpecification E11, as shown in Table 1, mounted in 8-in.203-mm frames. The number of sieves and the choice of sizesshall be sele
17、cted for the material being tested. A cover and abottom pan are also required.6.4 Accessories for Cleaning the Screens:6.4.1 Brush3,6.4.2 Vacuum Cleaner, and6.4.3 Air Hose.7. Reagents and Materials7.1 Antistat (or slip) agent suitable to the material beingtested.8. Hazards8.1 The sieving operation a
18、nd cleaning of the sieves some-times introduce fine plastic particles and antistat agent into theatmosphere. Take precautions to avoid breathing these par-ticles.9. Sampling9.1 Homogenize the lot where possible before removing thetest sample to avoid segregation of particles during handling.10. Prep
19、aration of Apparatus10.1 Thorough cleaning and inspection of the sieve arerequired prior to initiating a test. Carefully clean the sieveswith a brush and vacuum cleaner or compressed air, or both.Periodic washing with soap and water or suitable solvent isrecommended with some materials.10.2 Tare eac
20、h sieve and the pan. Record tare weights to thenearest 0.1 g.10.3 Assemble sieves so that the sieve openings decrease insize in sequence from the top of the stack. Place the pan at thebottom.10.4 Use full- or half-size screens to accommodate theholder in the shaker.11. Conditioning11.1 The plastic m
21、aterial must be in a free-flowing condi-tion.11.2 If possible, condition the material to the laboratorytemperature and humidity.TEST METHOD A12. Procedure12.1 Select sieves in sufficient number to cover the expectedrange of particle sizes, and nest them together in order ofdiminishing opening with t
22、he coarsest sieve on top and the panon the bottom.12.2 Select sieves in sufficient number to have significantmeasurable quantities on four or more sieves. Weigh the sieveson a balance reading to the nearest 0.1 g. Record these sievemasses as their tare masses, respectively.12.3 Weigh 50 g of sample
23、to the nearest 0.1 g and transferit to the top of the stack. Record the sample weight used. Largesample size causes screen blinding and will skew the results tothe coarse particle size. A screen is considered blinded if it isholding 20 or more g. For repeatable results, use a smallersample size.NOTE
24、 2For some materials an antistat (or slip agent) is needed. Add1 % of the antistat (or slip agent) to the sample and mix in with a spatula.With polyvinyl chloride resins, it has been found that the distribution willskew to either the fine or the coarse particle size depending on the antistatused. Re
25、cord the antistat (or slip agent) used.12.4 Cover the stack and place it in the mechanical sieveshaker. Start the shaker and run for 10 min. Run the shaker fora longer time if it is required by the material and the efficiencyof the shaker.12.5 After shaking, carefully separate the stack of sieves,be
26、ginning at the top, and weigh each sieve with powder to thenearest 0.1 g. Determine the net weight of the powderremaining in each sieve by subtracting the sieve tare massesfrom the total weight of the sieve and the powder in that sieve.12.6 If the cumulative total of actual weight is less than98 %,
27、carefully check the weights and operations and repeatthe work if necessary.13. Analysis of Particle Distribution13.1 Calculation of Particle Distribution:13.1.1 Obtain net weight of material retained on each sieve.Calculate percentage by dividing net weight by total sampleweight 100.13.1.2 Repeat fo
28、r each sieve.13.2 Calculation of Mean Particle Size:13.2.1 Obtain net weight of material retained on each sieve.13.2.2 Determine an average particle size for each sieve.The average particle size is defined as the nominal opening sizeof that sieve plus the nominal opening size of the next largersieve
29、 in the stack divided by two.NOTE 3Options are recommended to determine the average mesh sizeof the top sieve and the pan. On the coarse end, if the particles havealready been through a coarser screen, the screen size of the “through3The sole source of supply of the Type 8577 (W. S. Tyler) Brush kno
30、wn to thecommittee at this time is W. S. Tyler, Inc., 8750 Tyler Blvd., Mentor, OH 44060. Ifyou are aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1
31、which you may attend.D1921 122screen” can be used as the upper limit of the top screen (first screen). Acommonly used method is to place a set of sieves with openings greaterthan the desired top sieve. Select the lowest sieve where there is noparticle on or the amount of particles on the sieve is in
32、significant. Use theTABLE 1 Nominal Dimensions, Permissible Variations for Wire Cloth of Standard Test Sieves (U.S.A.) Standard SeriesSieve DesignationNominal SieveOpening, in.APermissibleVariation ofAverage Openingfrom the StandardSieve DesignationOpening DimensionExceeded By NotMore Than 5 % ofthe
33、 OpeningsMaximumIndividual OpeningNominal WireDiameter, mmBStandardCAlternative(1) (2) (3) (4) (5) (6) (7)125 mm 5 in. 5 3.70 mm 130.0 mm 130.9 mm 8.00106 mm 4.24 in. 4.24 3.20 mm 110.2 mm 111.1 mm 6.30100 mmD4in.D4 3.00 mm 104.0 mm 104.8 mm 6.3090 mm 312 in. 3.5 2.70 mm 93.6 mm 94.4 mm 6.3075 mm 3
34、in. 3 2.20 mm 78.1 mm 78.7 mm 6.3063 mm 212 in. 2.5 1.90 mm 65.6 mm 66.2 mm 5.8053 mm 2.12 in. 2.12 1.60 mm 55.2 mm 55.7 mm 5.0050 mmD2in.D2 1.50 mm 52.1 mm 52.6 mm 5.0045 mm 134 in. 1.75 1.40 mm 46.9 mm 47.4 mm 4.5037.5 mm 112 in. 1.5 1.10 mm 39.1 mm 39.5 mm 4.5031.5 mm 114 in. 1.25 1.00 mm 32.9 mm
35、 33.2 mm 4.0026.5 mm 1.06 in. 1.06 800 mm 27.7 mm 28.0 mm 3.5525.0 mmD1.00 in.D1 800 mm 26.1 mm 26.4 mm 3.5522.4 mm78 in. 0.875 700 mm 23.4 mm 23.7 mm 3.5619.0 mm34 in. 0.750 600 mm 19.9 mm 20.1 mm 3.1516.0 mm58 in. 0.625 500 mm 16.7 mm 17.0 mm 3.1513.2 mm 0.530 in. 0.530 410 mm 13.83 mm 14.05 mm 2.
36、8012.5 mmD 12 in.D0.500 390 mm 13.10 mm 13.31 mm 2.5011.2 mm716 in. 0.438 350 mm 11.75 mm 11.94 mm 2.509.5 mm38 in. 0.375 300 mm 9.97 mm 10.16 mm 2.248.0 mm516 in. 0.312 250 mm 8.41 mm 8.58 mm 2.006.7 mm 0.265 in. 0.265 210 mm 7.05 mm 7.20 mm 1.806.3 mmD 14 in.D0.250 200 mm 6.64 mm 6.78 mm 1.805.6 m
37、m No. 312E0.223 180 mm 5.90 mm 6.04 mm 1.604.75 mm No. 4 0.187 .150 mm 5.02 mm 5.14 mm 1.604.00 mm No. 5 0.157 .130 mm 4.23 mm 4.35 mm 1.403.35 mm No. 6 0.132 .110 mm 3.55 mm 3.66 mm 1.252.80 mm No. 7 0.110 .095 mm 2.975 mm 3.070 mm 1.122.36 mm No. 8 0.0937 .080 mm 2.515 mm 2.800 mm 1.002.00 mm No.
38、10 0.0787 .070 mm 2.135 mm 2.215 mm 0.9001.7 mm No. 12 0.0661 .060 mm 1.820 mm 1.890 mm 0.8001.4 mm No. 14 0.0556 .050 mm 1.505 mm 1.565 mm 0.7101.18 mm No. 16 0.0469 .045 mm 1.270 mm 1.330 mm 0.8301.00 mm No. 18 0.0394 .040 mm 1.080 mm 1.135 mm 0.560850 mFNo. 20 0.0331 35 m 925 m 970 m 0.500710 m N
39、o. 25 0.0278 30 m 775 m 815 m 0.450600 m No. 30 0.0234 25 m 660 m 695 m 0.400500 m No. 35 0.0197 20 m 550 m 585 m 0.315425 m No. 40 0.0165 19 m 471 m 502 m 0.280355 m No. 45 0.0139 16 m 396 m 426 m 0.224300 m No. 50 0.0117 14 m 337 m 363 m 0.200250 m No. 60 0.0098 12 m 283 m 306 m 0.160212 m No. 70
40、0.0083 10 m 242 m 263 m 0.140180 m No. 80 0.0070 9 m 207 m 227 m 0.125150 m No. 100 0.0059 8 m 174 m 192 m 0.100125 m No. 120 0.0049 7 m 147 m 163 m 0.090106 m No. 140 0.0041 6 m 126 m 141 m 0.07190 m No. 170 0.0035 5 m 108 m 122 m 0.06375 m No. 200 0.0029 5 m 91 m 103 m 0.05063 m No. 230 0.0025 4 m
41、 77 m 89 m 0.04553 m No. 270 0.0021 4 m 66 m 76 m 0.03645 m No. 325 0.0017 3 m 57 m 66 m 0.03238 m No. 400 0.0015 3 m 48 m 57 m 0.03032 m No. 450 0.0012 3 m 42 m 50 m 0.02825 mDNo. 500 0.0010 3 m 34 m 41 m 0.02520 mDNo. 635 0.0008 3 m 29 m 35 m 0.020AOnly approximately equivalent to the metric value
42、s in Column 1.BThe average diameter of the wires in the x and y direction, measured separately, of any wire cloth shall not deviate from the nominal values by more than 15 %.CThese standard designations correspond to the values for test sieve openings recommended by the International Standards Organ
43、ization, Geneva, Switzerland, exceptwhere noted.DThese sieves are not in the standard series, but they have been included because they are in common usage.EThese numbers (312 to 635) are the approximate number of openings per linear inch, but it is preferred that the sieve be identified by the stand
44、ard designation inmillimetres or micrometres.F1000 m1 mm.D1921 123opening size of this sieve for calculation. Similar analog can be used to thepan by using smaller opening sieves.Amore practical way is to divide theopening size of the sieve above the pan by two and use it as the averageparticle size
45、 of the pan.13.2.3 For materials that have a normal distribution, calcu-late the mean particle size asDm5(Pi3Di!where:Dm= mean particle diameter, m,Pi= material retained on sieve (or pan), %, andDi= average particle size of material on sieve, m.14. Report14.1 Report the following information:14.1.1
46、Percentage of material retained on each sieve, withits corresponding sieve size,14.1.2 Sample weight,14.1.3 Antistat (or slip agent) used, and14.1.4 Mean particle size and method used for calculation.TEST METHOD B15. Procedure15.1 Choose the sieve(s) to be used and weigh each of themto the nearest 0
47、.1 g. Record these sieve masses as their taremasses, respectively. If a single sieve is being used, stack it onthe pan and transfer a sample weighing 100 6 0.1 g to thatsieve. If two sieves are to be used in the analysis of the sample,stack the coarse sieve over the fine sieve and transfer theweighe
48、d sample to the coarse sieve. For those finely dividedpowders which tend to clog the sieves, add 1.0 % of an antistat(see Note 2).15.2 Cover the stack and place it in the mechanical sieveshaker. Start the shaker and run for 10 min 6 15 s.15.3 After shaking, carefully separate the stack of sieves,beg
49、inning at the top, and weigh each sieve with powder to thenearest one tenth of a gram.16. Report16.1 Report the following information:16.1.1 Percentage of material retained on each sieve, withits corresponding sieve size,16.1.2 Sample weight, and16.1.3 Antistat (or slip agent) used.17. Precision and Bias417.1 PrecisionTable 2 and Table 3 are based on a roundrobin conducted in 1985 in accordance with Practice
