ASTM_D_1921_-_18.pdf

Designation:D192118Standard 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.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 U.S.Department of Defense.1.Scope*1.1 These test methods cover the measurement of theparticle 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-mended.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 of 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 are to be regarded asstandard for dimensions of the wire cloth openings and thediameter of the wires used in the wire cloth.1.4 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.NOTE1There is no known ISO equivalent for this test method.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2E11 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 mass 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 and 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 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 overloading any sieve.5.4 Wavy,improperly stretched wire-cloth potentially al-lows wires to separate without being visually damaged.Sieveswith wavy or torn wires shall not be used,as they no longerconform to Specification E11.1These 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 April 1,2018.Published April 2018.Originallyapproved in 1961.Last previous edition approved in 2012 as D1921-12.DOI:10.1520/D1921-18.2For 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.*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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 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 timeswitch.This