ASTM_D_4883_-_18.pdf

Designation:D488318Standard Test Method forDensity of Polyethylene by the Ultrasound Technique1This standard is issued under the fixed designation D4883;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.1.Scope*1.1 This test method covers the determination of the densityof polyethylene through the utilization of ultrasound equip-ment.1.2 This test method is based on the distinct behaviors of theamorphous and crystalline phases of polyethylene in responseto ultrasound.Polyethylene shall be viewed as a compositestructure where high-density crystalline regions are connectedby lower-density amorphous material.The ratio of crystallineto amorphous material determines the final density of thematerial.The amorphous and crystalline phases exhibit verydistinct behaviors with regard to the propagation of soundwaves.The propagation characteristics in the composite willdepend on the relative amount of the two phases(the degree ofcrystallinity).1.3 Inorganic materials increase density as measured by TestMethods D792 and D1505,but they have little or no effect onultrasonic density.The ultrasonic measurement is basically abase resin density.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 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 to this standard.1.6 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:2D618 Practice for Conditioning Plastics for TestingD792 Test Methods for Density and Specific Gravity(Rela-tive Density)of Plastics by DisplacementD883 Terminology Relating to PlasticsD1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD3350 Specification for Polyethylene Plastics Pipe and Fit-tings MaterialsD4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens,Plaques,or SheetsD4976 Specification for Polyethylene Plastics Molding andExtrusion MaterialsE494 Practice for Measuring Ultrasonic Velocity in Materi-alsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE2935 Practice for Conducting Equivalence Testing inLaboratory Applications3.Terminology3.1 DefinitionsThe definitions given in TerminologyD883,as well as in Test Methods D792 and D1505,areapplicable to this test method.4.Significance and Use4.1 The density of polyethylene is a conveniently measur-able property which is frequently useful as a means offollowing physical changes in a sample,as an indication ofuniformity among samples,and as a means of identification.4.2 This test method is designed to yield results with aprecision of 60.08%or better.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Nov.1,2018.Published November 2018.Originallyapproved in 1989.Last previous edition approved in 2008 as D488308,which waswithdrawn January 2017 and reinstated in November 2018.DOI:10.1520/D4883-18.2For 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 5.Apparatus5.1 Use an instrument which utilizes a sonic technique toevaluate the density of polyethylene.The DS 500 instrument3utilizes a sonic sensing head(transducer)which measures thevelocity of sound in a molded specimen.Because sonicvelocity is positively correlated to density in polyethylene,ameasurement of this velocity is used to determine specimendensity.The infor