ASTM_D_5225_-_14.pdf

Designation:D522514Standard Test Method forMeasuring Solution Viscosity of Polymers with a DifferentialViscometer1This standard is issued under the fixed designation D5225;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 solu-tion viscosity of polymers using a differential or the modifieddifferential viscometer.It is applicable to all polymers thatdissolve completely without chemical reaction or degradationto form solutions that are stable with time and temperature.Results of the test are usually expressed as specific viscosity,intrinsic viscosity(limiting viscosity number),inherent viscos-ity(logarithmic viscosity number),or relative viscosity(vis-cosity ratio).1.2 Since there is more than one type of viscometer avail-able to measure a differential pressure,follow the manufactur-ers directions applicable to the equipment being used.1.3 The solution viscosity values are comparable with thoseobtained using a glass capillary of Test Method D2857.Thistest method differs from the glass capillary in that the solventand the solution are compared at the same time that a test isrun.With a glass capillary,each solution must be referencedback to the solvent run in the same capillary at the sametemperature.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 and health practices and determine the applica-bility of regulatory limitations prior to use.For specific hazardstatements,see Section 8.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D1243 Test Method for Dilute Solution Viscosity of VinylChloride PolymersD2857 Practice for Dilute Solution Viscosity of PolymersE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 inherent viscositythe ratio of the natural logarithmof the relative viscosity to the concentration.The IUPAC termfor inherent viscosity is logarithmic viscosity number.3.1.2 intrinsic viscositylimit of the reduced and inherentviscosities as the concentration of the polymeric solute ap-proaches zero and represents the capacity of the polymer toincrease viscosity.The IUPAC term for intrinsic viscosity islimiting viscosity number.3.1.3 reduced viscositythe ratio of the specific viscosity tothe concentration.Reduced viscosity is a measure of thespecific capacity of the polymer to increase the relativeviscosity.The IUPAC term for reduced viscosity is viscositynumber.3.1.4 relative viscositythe ratio of the polymer solutionpressure to the pressure of the solvent.3.1.5 specific viscositythe relative viscosity minus one.3.1.6 viscosity constant,Kbaseline reading when solventis present in both capillaries.4.Summary of Test Method4.1 Differential Viscometer(Fig.1):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 May 1,2014.Published June 2014.Originallyapproved in 1992.Last previous edition approved in 2009 as D5225-09.DOI:10.1520/D5225-14.2For 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 States1 4.1.1 The viscosity measurement with the differential vis-cometer is based on a fluid analog of the Wheatstone Bridge.Pure solvent at constant inlet pressure Pienters a balancedcapillary network and flows through,producing a zero orbaseline pressure on the differential pressure transducer.Solu-tion is loaded into the sample reservoir A and then injectedonstream by means of the switching valve SA.The differentialpressure begins to rise until it reaches a steady state value ofP proportional to the specific viscosity of the solution.Thedifferential pressure is monitored continuously on a strip chartrecorder or computer,providing a baseline where P ismeasured.The equation relating P to specific viscosity is:sp54PPi2 2P(1)4.1.2 Derivation of the equation is in Annex A1.4.2 Modified Differential Viscometer(Fig.2):4.2.1 The modified differential viscometer has two stainlesssteel capillaries connected in series with a sample loading/injection valve before the second capillary.Two