ASTM_D_5422_-_17.pdf

Designation:D542217Standard Test Method forMeasurement of Properties of Thermoplastic Materials byScrew-Extrusion Capillary Rheometer1This standard is issued under the fixed designation D5422;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.INTRODUCTIONThis test method uses capillary rheometry to measure the rheological properties of thermoplasticsand thermoplastic compounds.This test method utilizes a screw-extrusion-type capillary rheometer.1.Scope*1.1 This test method covers the use of a screw-extrusion-type capillary rheometer for the measurement of flow proper-ties of thermoplastics and thermoplastic compounds.Themeasured flow properties,which are obtained through labora-tory investigation,may help to describe the material behaviorthat occurs in factory processing.1.2 Since a screw-type capillary rheometer imparts shearenergy to the material during testing,the measurements willusually differ from those obtained with a piston-type capillaryrheometer(see Test Method D3835).1.3 Capillary rheometer measurements for thermoplasticsand thermoplastic compounds are described in Test MethodD3835.1.4 The values stated in SI units are to be regarded asstandard.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.The scopeof this standard is mentioned in ISO 11443:2014,PlasticsDeterminationof the fluidity of plastics using capillary and slit-die rheometers,”AnnexC,“Uncertainties in the determination of shear viscosity by capillaryextrusion.”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 TestingD883 Terminology Relating to PlasticsD1238 Test Method for Melt Flow Rates of Thermoplasticsby Extrusion PlastometerD3835 Test Method for Determination of Properties ofPolymeric Materials by Means of a Capillary RheometerE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:(See Terminology D883):3.1.1 apparent shear rate(a)shear strain rate(or velocitygradient)of the thermoplastic or thermoplastic compoundextrudate as it passes through the capillary die.3.1.1.1 DiscussionThis velocity gradient is not uniformthrough the cross-section of the capillary die.The shear rate iscalculated for the region of highest shear,which is at the wallof the capillary.By selecting a die diameter and controlling thevolume flow per unit time through the die,a specific level ofapparent shear rate is achieved.Alternately,the shear stress(entrance pressure)is controlled,and the apparent shear ratemeasured.3.1.1.2 DiscussionMathematically,the apparent shear rateat the wall of the capillary for a Newtonian fluid at the capillarywall is given by the following:a532QD3(1)1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties(Section D20.30.08).Current edition approved Dec.1,2017.Published January 2018.Originallyapproved in 1993.Last previous edition approved in 2009 as D5422 09.DOI:10.1520/D5422-17.2For 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 where:a=apparent shear rate,s1,Q=quantity of fluid extruded per time,mm3/s,=3.142,andD=diameter of the measuring capillary,mm.3.1.2 apparent shear stress(a)the measured resistance tothe flow through a capillary die.It may be determined bymeasuring the die entrance pressure for a specific die,thenapplying appropriate geometric factors.3.1.2.1 DiscussionMathematically,apparent shear stressis given by t