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1、HighPressureCapillaryRheometry1IntroductionPolymersareusedbecause:TheyarecheaptoformintoshapeinmoltenstateTherefore,Weneedtounderstandhowtheyflowwhenmoltenalsoimportantin:foodprocessing,pharmaceuticals,paints,inks,pastes,slurriesetc...VeryimportantinPolymerProcessingBut,moltenpolyme
2、rsarecomplicatedsystems...TemperaturedependentRatedependentTimedependentWorkdependent(andthat’sbeforeweaddlubricants,fillers,plasticisers,foamingagentsetc…!)InbetweenaliquidandasolidInfluencesonViscositymolecularstructureofsampletemperaturepressuretimeshearrate(T,p,t,g)=g..Shearvi
3、scositydefinitiong-shearrate.t-shearstress=g.-shearviscosityViscosityisameasureofresistanceofafluidagainsttheappliedshearforce.ShearviscosityisonlyonepartofRheology.Itisthedominanteffectforpressureinextruders,injectionmouldingmachinesanddies.TypicalprocessshearratesRelaxationCoat
4、ingFreesurfaceMixingExtrusionInjectionmouldingWhydoweneedahigh-pressurecapillaryrheometer?Theapplicationisimportantlog/s-1DMAOsc./Rot.rheometerHighpressurecapillaryrheometerViscosities:(low-),middle-tohigh-viscousQuantities:Shear-andextensionalviscosity,wallslip relaxation,PVT,Flow
5、instabilities10-110-3Levelling104101Extrusion,InjectionMoulding100102Mixing103106RollCoating,SprayingViscosities:lowviscoustosolid-likeQuantities:Shearviscosity,yield,viscoelasticproperties,relaxationetc.Non-destructiveOscillaroryshearrot.rheometer:structural/lowshearmeasurements– h
6、igh-pressurecapillary:processingflowbehaviour2.Structure2.16kgSinglepointtest(generatesonenumber)MFIdie(2.095mmdiameter)Definedbystandards(ISO1133)SimpleCheapEasytousePressuredrivenMeltFlowIndexer(MFI)MeltFlowIndexer(MFI)SinglepointtestDoesnotgenerateengineeringunits-(gramsper10minu
7、tes)Mainlyashearflowmeasurement-neglectsextensionVerylowshearratetest(app=2.4MFI)But,TypicalprocessshearratesRelaxationCoatingFreesurfaceMixingExtrusionInjectionmouldingMFItestCapillaryRheometerMeasure:PressuredropPistonCapillarydiePressuretransducerPolymermeltSet:PistonspeedDieDim
8、’sCapillaryrheometr
