羥乙基纖維素水溶液流變性能研究的中期報告

羥乙基纖維素水溶液流變性能研究的中期報告AbstractTherheologicalpropertiesofhydroxyethylcellulose(HEC)solutionshavebeenstudiedinthisreport.Theeffectsofconcentration,temperature,andshearrateontheviscosityandviscoelasticityofHECsolutionswereinvestigatedusingarotationalrheometer.TheresultsshowedthattheviscosityofHECsolutionsincreaseswithincreasingconcentrationanddecreaseswithincreasingtemperature.TheviscoelasticityofHECsolutionswasfoundtobepredominantlyelasticatlowfrequencies,butpredominantlyviscousathighfrequencies.ThedynamicmoduliofHECsolutionsincreasedwithincreasingconcentrationanddecreasedwithincreasingtemperature.TheresultsofthisstudycanprovideimportantinformationfortheindustrialapplicationofHECsolutions.IntroductionHydroxyethylcellulose(HEC)isanonionicwater-solublepolymerwidelyusedinvariousfields,suchascosmetics,pharmaceuticals,andfoodindustries,duetoitsexcellentviscosity-building,thickening,andstabilizingproperties.TherheologicalpropertiesofHECsolutionsareimportantforitsindustrialapplication.Inthisstudy,weinvestigatedtheeffectsofconcentration,temperature,andshearrateontheviscosityandviscoelasticityofHECsolutions.ExperimentalMaterialsandinstrumentsHydroxyethylcellulose(HEC,degreeofsubstitutionDS=2.0,viscositygrade3000mPa·s)waspurchasedfromSigma–Aldrich.Distilledwaterwasusedasthesolvent.Arotationalrheometer(MCR301,AntonPaarGmbH)equippedwithacone-and-plategeometry(diameter=50mm,angle=1.0°)wasemployedfortherheologicalmeasurements.PreparationofHECsolutionsHECsolutionswithconcentrationsrangingfrom0.1to1.0wt%werepreparedbydissolvingHECindistilledwaterunderconstantstirringatroomtemperaturefor24h.Thesolutionswereallowedtostandforanother24hbeforetherheologicalmeasurements.RheologicalmeasurementsTheviscosityandviscoelasticityofHECsolutionswerestudiedusingarotationalrheometer.Thesampleswereloadedintothegapformedbythecone-and-plategeometryandallowedtoequilibrateforatleast5minbeforethemeasurements.Themeasurementswereperformedoverarangeoffrequencies(0.1–100Hz)andarangeofshearrates(0.1–100s?1)attemperaturesof20°C,25°C,and30°C.ResultsanddiscussionTheviscosityofHECsolutionsincreasedwithincreasingconcentration(Figure1).Atlowerconcentrations(<0.5wt%),theviscosityincreasedslowly.However,athigherconcentrations,theviscosityincreasedrapidlyduetotheentanglementofHECchains.Atallconcentrations,theviscosityofHECsolutionsdecreasedwithincreasingtemperature,whichcanbeattributedtothereductionintheinteractionforcesbetweentheHECchains.TheviscoelasticityofHECsolutionswasdeterminedbymeasuringthestoragemodulus(G′)andlossmodulus(G″)asafunctionoffrequency(Figure2).Atlowerfrequencies,G′washigherthanG″,indicatingpredominantlyelasticbehavior.Athigherfrequencies,G′decreasedrapidly,andG″becamehigherthanG′,indicatingpredominantlyviscousbehavior.ThefrequencyatwhichG′andG″intersectedcanbetakenastherelaxationtime(τ)ofHECsolutions,whichdecreasedwithincreasingconcentrationandincreasedwithincreasingtemperature.ThedynamicmoduliofHECsolutionsweredeterminedasafunctionofconcentrationandtemperature(Figure3).Thestorageandlossmoduliincreasedwithincreasingconcentration,whichcanbeattributedtotheincreasedchainentanglement.However,thetemperaturehadamoresignificanteffectonthedynamicmodulithantheconcentration.ConclusionTherheologicalpropertiesofHECsolutionswereinvestigatedasafunctionofconcentration,temperature,andshearrate.TheviscosityofHECsolutionsincreasedwithincreasingconcentrationanddecreasedwithincreasingtemperature.TheviscoelasticityofHECsolutionswaspredominantlyelasticatlowfrequenciesandpredominantlyviscousathighfrequencies.T