《高分子流变学》PPT课件

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1、I.1ShearThinning/ThickeningDilatants(Shearthickening)NewtonianFluidsPseudoplastics(Shearthinning)Dilatants(Shearthickening)NewtonianFluidsPseudoplastics(Shearthinning)0pleatau(a)Shearstressvsshearrateand(b)logviscosityvslogshearrateforDilatants,Newto

2、nianfluidsandPseudoplastics.ForveryhighshearratesthepseudoplasticmaterialreachesasecondNewtonianpleatau.[ReproducedfromG.M.KavanaghandS.B.Ross-Murphy,“Rheologicalcharacterisationofpolymergels”,Prog.Polym.Sci.,23,533(1998).]I.1ShearThinning/Thickening(

3、cont.)Tubeflowand“shearthinning”.Ineachpart,theNewtoninabehaviorisshownontheleft(N);thebehaviorofapolymerontheright(P).(a)Atinyspherefallsatthesameratethrougheach;(b)thepolymerflowsoutfasterthantheNewtonianfluid.[ReproducedfromR.B.Bird,R.C.Armstrongan

4、dO.Hassager,DynamicsofPolymericLiquids.VolI:FluidMechanics,2ndedition,Wiley-Interscience(1987),p.61.][RetrievedfromthevideoofNon-NewtonianFluidMechanics(UniversityofWalesInstituteofNon-NewtonianFluidMechanics,2000)]I.2NormalStressDifferenceandElastici

5、tyRod-ClimbingFixedcylinderwithrotatingrod.(N)TheNewtonianliquid,glycerin,showsavortex;(P)thepolymersolution,polyacrylamideinglycerin,climbstherod.[ReproducedfromR.B.Bird,R.C.ArmstrongandO.Hassager,DynamicsofPolymericLiquids.VolI:FluidMechanics,2ndedi

6、tion,Wiley-Interscience(1987),p.63.][RetrievedfromthevideoofNon-NewtonianFluidMechanics(UniversityofWalesInstituteofNon-NewtonianFluidMechanics,2000)]I.2NormalStressDifferenceandElasticity(cont.)ExtrudateSwell(alsocalled“dieswell”)Behavioroffluidissui

7、ngfromorifices.AstreamofNewtonianfluid(N,siliconefluid)showsnodiameterincreaseuponemergencefromthecapillarytube;asolutionof2.44gofpolymethylmethacrylate(Mn=106g/mol)in100cm3ofdimethylphthalate(P)showsanincreasebyafactorindiameterasitflowsdownwardoutof

8、thetube.[ReproducedfromA.S.Lodge,ElasticLiquids,AcademicPress,NewYork(1964),p.242.][RetrievedfromthevideoofNon-NewtonianFluidMechanics(UniversityofWalesInstituteofNon-NewtonianFluidMechanics,2000)]TubelessSiphonWhenthesiphontubeisliftedoutofth