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流变学基础及应用SMZHUHHWelcome使用牙膏时挤出要容易,挤出后要求挺括,在牙刷上不能下陷,刷牙时又要轻松,这就是要求牙膏遇剪切时粘度迅速下降,而静止时又要具备一定的屈服应力,以保持坚挺。牙膏—一个典型的流变学问题提纲I.流变学基础1.流变学定义及发展历史2.粘度计及流变仪简介3.稳态流变学4.动态流变学4.1弹性行为及剪切模量4.2粘弹性行为4.3蠕变测试4.4弛豫测试4.5振荡测试II.PhysicaMCR300流变仪简介III.PhysicaMCR300流变仪应用演示I.流变学基础Thepersoninthepicture:ThomasG.Mezger,RheologistofAnton-Paar1流变学及其发展历史什么是流变学?流变学:研究物质流动和变形的科学Rheology=thescienceofdeformationandflowofmatter(SocietyOfRheology,SOR)希腊语:rheos=toflow,流动流动行为变形行为•古代“万物皆流”•1676虎克定律:弹性固体(形变与受力成正比)•1687牛顿定律:粘性液体(流动阻力与流动速度成正比)•1905爱因斯坦:悬浮液粘度方程(h=hs(1+2.5f))•1920宾汉(Bingham)提出“流变学”概念•1945首台旋转粘度计面世(Brookfield)•1951首台旋转流变仪Rheogoniometer(Weissenberg)•自1970年开始,流动曲线测试代替以前的单点测试•自1980年开始,大规模使用数控和计算机,流变学得到较大发展流变学的发展历史中国的流变学“我国流变学的应用研究起步较晚,20世纪60年代还只有个别自发研究,目前的应用研究领域较少,甚至连流变学赖以发展的聚合物加工行业也知之不多。以塑料制品为例,塑料厂引进的模具‘吃’进口的聚合物粒子时,制品光滑、美观,可以和国外的同类产品相媲美,而一旦换成国产原料粒子时,产品质量就下降。这是因为所使用的模具是按国外原料的流变性能设计的,而国产原料的流变性与进口原料并不完全相同,所以制品质量下降。尽管生产厂对模具进行完善修改,但也只是凭经验做机械上的改动,并未考虑到粒子的流变性。”—江体乾流变学(Rheology)研究物质的流动及变形行为粘性(viscous)弹性(elastic)粘弹性(viscoelastic)流体(流动行为)Newton定律固体(变形行为)Hooke定律粘弹性流体(流动行为)Maxwell定律粘弹性固体(变形行为)Kelvin/Voigt定律流变学的研究内容流变学的研究范围及方法液体固体(理想)粘性流体行为粘弹性流动行为粘弹性变形行为(弹性)变形行为Newton定律Maxwell定律Kelvin/Voigt定律Hook定律流动/粘度曲线蠕变实验弛豫实验振荡实验物质状态性能表现依据原理研究方法稳态流变学动态流变学SimpleTestMethods铲刀试验(troweltest)-高粘流体:“稠”-低粘流体:“稀”手指试验(fingertest)-粘稠:“长”-稀薄:“短”2流变行为的研究工具—粘度计及流变仪定性!简单测试Bostwick稠度计(Consistometer)1samplecontainer,max.100ml2gate,tobeopenedbyaspring3scaledflowpath测定流体(如番茄酱等)在一定时间内流过的长度schematicpresentationofaBOSTWICK-constistometer粘度计Falling-BallViscometersDIN53015ISO12058measuringtubeincludingtheballstandthermometerjacket,fortemp.control落球粘度计HAAKEGENEQe.g.forpastesandpaste-likeprintinginksweightprintinginkfallingrodfallingrodviscometer(Laray)Falling-RodViscometers落杆粘度计accordingtoASTMD803andD1545checkmarkGasbubblerisesafterturningthetube.Viscosityevaluationbycomparisontoasetoftubes气泡粘度计BubbleViscometersWater-Clock(Klepsýdra)fortimemeasurementssince3500yearsinEgypte.g.5lcorrespondsto6minflowtime流杯FlowCupsmeasurementoftheflowtimedeterminationofthekinematicviscosity流杯FlowCupsISODINFord(ASTM)ZahnEnglerShellDINISO流杯CapillaryViscometers玻璃毛细管粘度计Stormer粘度计Preset:constanttorque(shearstress)appliedbyafreefallingweight(ingrams)Result:rotationalspeedofthemeasuringsystemKrebsmeasuringsystem(Paddle)asarelativemeasuringsystemdesignationinKrebsUnits,KUBrookfield粘度计spindlesasrelativemeasuringsystems:-cylinders-disks-pins-T-bar旋转流变仪—绝对测量系统圆筒状转子(Cylinder)notrecommendedforpastes(airbubbles)锥板转子(Cone-Plate)withdispersionsonlyusefulforparticlesunder5m平行板(Parallel-plates)usefulforgelsandpastes旋转及振荡流变仪(rotationalandoscillatoryrheometers)accordingtoDIN53019andISO3219HAAKE旋转流变仪HAAKEExtenCaBer1HAAKERheoScopeHAAKERheoStress1HAAKERheoStress600HAAKERotoVisco1TA旋转流变仪AR500AR1000AR2000ARESARES-1sARES-rdaARES-rfsBohlin旋转流变仪BohlinCVOBohlinC-VORBohlinGeminiBohlinV88Physica旋转流变仪RheolabMC1SmartPaveMCR300、500MCR301、501ACS16/32毛细管流变仪LrPr234rQrQPLrrr83hPoiseuille-Hagen定律毛细管流变学的基础!P2R毛细管流变仪HAAKERheoCapS20HAAKERheoCapT1000RH7D&RH10DRH2100/2200毛细管流变仪的功能在聚合物工业中,无论旋转流变仪还是毛细管流变仪,其作用都是:模仿聚合物加工过程中的流动和变形行为!log/s-1DMAOsc./Rot.rheometerHighpressurecapillaryrheometerViscosities:(low-),middle-tohigh-viscousQuantities:Shear-andextensionalviscosity,wallsliprelaxation,PVT,Flowinstabilities10-110-3Levelling104101Extrusion,InjectionMoulding100102Mixing103106RollCoating,SprayingViscosities:lowviscoustosolid-likeQuantities:Shearviscosity,yield,viscoelasticproperties,relaxationetc.Non-destructiveOscillaroryshearrot.rheometer:structural/lowshearmeasurementshigh-pressurecapillary:processingflowbehaviour.1.E+001.E+021.E+041.E+061.E+081.E-051.E-031.E-011.E+011.E+031.E+05Shearrate(s-1)Viscosity(Pa.s)RelaxationCoatingFreesurfaceMixingExtrusionInjectionmoulding聚合物加工过程对应的剪切速率LogPOWER-LAWPROCESSINGRANGE103s-1101s-1旋转流变仪毛细管流变仪3稳态流变学—流动行为液体固体(理想)粘性流动行为粘弹性流动行为Newton定律Maxwell定律粘弹性变形行为(理想)弹性变形行为Kelvin/Voigt定律Hook定律流动/粘度曲线蠕变实验、弛豫实验、振荡实验基本概念:剪切应力、剪切速率、粘度……牛顿流体的流动行为非牛顿流体(剪切依赖型)的流动行为:剪切稀释、剪切增稠、屈服值……时间依赖型:触变性、震凝性温度依赖型ShearstressPamNAF2Shearrate剪切应力及剪切速率剪切应力单位面积所受的作用力剪切速率1ss1msmhvD-×)(Strain应变单位长度的伸长constantmmhvddt单位时间的应变,也称为“剪切梯度”、“速度梯度”、“应变率”、“变形率”)TypicalShearRateRangesProcessShearRate(1/s)sedimentation0,001to0,01surfacelevelling0,01to0,1sagging0,01to1dipcoating1to100pipeflow,pumping,fillingintocontainers1to10000coating,painting,brushing100to10000spraying1000to10000(high-speed)coating,bladecoating100000to1mio.Application:SedimentationofDispersionsinthebeginningherbsinsaladdressingafter15minApplication:LevellingandSaggingofaCoating200µm0.5m/s14s2500sm102m5.0ΔhΔv--CalculationoftheshearrateApplication:Coating,Painting,BrushingApplication:AutomotiveCoatingscarbodydegreasing&phosphatizingelectrodipcoatingPVCseamsealingPVCunderbodysprayingprimerandfillertopcoatandclearcoatcavityconservationa)Plastisols:seamsealing,underbodyspraying,cavityconservationb)Primerc)Coatings:filler,basecoat,topcoat,clearcoatApplication:OffsetPrintingInksinkcontainerplatecyli
本文标题:流变学基础及应用
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