ASTM_D_6474_-_20.pdf

Designation:D647420Standard Test Method forDetermining Molecular Weight Distribution and MolecularWeight Averages of Polyolefins by High Temperature GelPermeation Chromatography1This standard is issued under the fixed designation D6474;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 molecularweight distributions and molecular weight averages of poly-olefins by high temperature gel permeation chromatography(GPC).This test method uses commercially available polysty-rene standards and equipment and is applicable to polyethyl-enes(excluding high pressure low density polyethylene(LDPE)and ultra-high molecular weight polyethylene(UHM-WPE)and polypropylenes soluble in 1,2,4-trichlorobenzene(TCB)at 140C.This test method is not absolute and requirescalibration.NOTE1Size exclusion chromatography(SEC)often is used as analternative name for gel permeation chromatography(GPC).NOTE2Specific methods and capabilities of users may vary withdifferences in columns,instrumentation,applications software,and prac-tices between laboratories.NOTE3One general method is outlined herein;alternative analyticalpractices can be followed and are attached in notes where appropriate.NOTE4There is no known ISO equivalent to this standard.1.2 The values stated in SI units,based on IEEE/ASTMS1-10,are to be regarded as the standard.1.3 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.1.4 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:2D883 Terminology Relating to PlasticsD3016 Practice for Use of Liquid Exclusion Chromatogra-phy Terms and RelationshipsD5296 Test Method for Molecular Weight Averages andMolecular Weight Distribution of Polystyrene by HighPerformance Size-Exclusion ChromatographyE685 Practice for Testing Fixed-Wavelength PhotometricDetectors Used in Liquid ChromatographyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM S1-10 Standard for Use of the InternationalSystem of Units(SI):The Modern System(replacesASTM E 380 and ANSI/IEEE Standard 268-1992)3.Terminology3.1 DefinitionsDefinitions of terms applying to plasticsappear in Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 polyolefin,nused in this context,refers to PE(exceptLDPE)and PP thermoplastics.4.Summary of Test Method4.1 In this test method,a polyolefin sample is dissolved in asolvent and injected onto a chromatographic column(s)packedwith a substrate,which separates the molecules according totheir size in solution.The separated molecules are detected andrecorded as they elute from the column according to size by aconcentration sensitive detector.Through calibration,retentiontimes are converted to molecular weights.Molecular weightaverages and molecular weight distributions are determinedfrom the calibration curve and detector response.5.Significance and Use5.1 This test method measures the molecular weight distri-bution and molecular weight averages of polyethylene(except1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommitttee D20.70 on Analytical Methods.Current edition approved April 1,2020.Published April 2020.Originallyapproved in 1999.Last previous edition approved in 2019 as D647419.DOI:10.1520/D6474-20.2For 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.LDPE and UHMWPE)and polypropylene resins.Differencesin molecular weight and molecular weight distribution signifi-cantly affect physical properties,such as morphology,stre