流变学基本及应用.ppt
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1、流变学基础及应用,S,MZ,HU,HH,Welcome,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. Physica MCR300流变仪简介 III. Physica MCR300流变仪应用演示,I. 流变学基础,The person in t
2、he picture: Thomas G. Mezger, Rheologist of Anton-Paar,1 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 = the science of deformation and flow of matter (Society Of Rheology, SOR),希腊语: rheos = to flow,流动,流 动 行 为,www.physica.de,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
3、 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
4、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, 流变学的研究内容, 流变学的研究范围及方法,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,Simple Test Methods,铲刀试验(trowel test) - 高粘流体:“稠” - 低粘流体:“稀”,手指试验(finger test) - 粘稠:“长” - 稀薄:“短”,2 流变行为的研究
5、工具粘度计及流变仪,定性!, 简单测试,Bostwick稠度计(Consistometer),1 sample container, max. 100 ml 2 gate, to be opened by a spring 3 scaled flow path,测定流体(如番茄酱等)在一定时间内流过的长度,schematic presentation of a BOSTWICK-constistometer, 粘度计,Falling-Ball Viscometers,DIN 53015ISO 12058,measuring tubeincluding the ball,stand,thermo
6、meter,jacket,for temp. control, 落球粘度计,HAAKE,GENEQ,e.g. for pastes andpaste-like printing inks,weight,printing ink,falling rod,falling rod viscometer(Laray),Falling-Rod Viscometers, 落杆粘度计,according to ASTM D803 and D1545,check mark,Gas bubble rises afterturning the tube.Viscosity evaluationby compari
7、son to a set of tubes, 气泡粘度计,Bubble Viscometers,Water-Clock (Klepsdra) for time measurements since 3500 years in Egypt e.g. 5 l corresponds to 6 min flow time, 流杯,Flow Cups,measurement of theflow time determination of the kinematic viscosity, 流杯,Flow Cups,ISODINFord (ASTM) ZahnEnglerShell,DIN ISO, 流
8、杯,Capillary Viscometers, 玻璃毛细管粘度计, Stormer 粘度计,Preset: constant torque(shear stress) applied by a freefalling weight (in grams) Result: rotational speed of the measuring system,Krebs measuring system (Paddle)as a relative measuring systemdesignation in Krebs Units, KU, Brookfield 粘度计,spindles as rel
9、ative measuring systems: cylinders disks pins T-bar, 旋转流变仪绝对测量系统,圆筒状转子(Cylinder) not recommendedfor pastes(air bubbles),锥板转子(Cone-Plate) with dispersionsonly useful forparticlesunder 5m,平行板(Parallel-plates) useful for gels and pastes,旋转及振荡流变仪(rotational and oscillatory rheometers)according to DIN 53
10、019 and ISO 3219, HAAKE旋转流变仪,HAAKE Exten CaBer1,HAAKE RheoScope,HAAKE RheoStress1,HAAKE RheoStress600,HAAKE RotoVisco1, TA旋转流变仪,AR500,AR1000,AR2000,ARES,ARES-1s,ARES-rda,ARES-rfs, Bohlin旋转流变仪,BohlinCVO,BohlinC-VOR,BohlinGemini,BohlinV88, Physica旋转流变仪,RheolabMC1,SmartPave,MCR300、500,MCR301、501,ACS16/
11、32, 毛细管流变仪,Poiseuille-Hagen定律,毛细管流变学的基础!,DP,2R, 毛细管流变仪,HAAKE RheoCap S20,HAAKE RheoCap T1000,RH7D 2. wide MMD,w %rel. amountM g/molmolar mass,Relaxation Test,Relaxation Test,Relaxation Modulus,Relaxation Time Spectrum,Relaxation Time Spectrum,Molar Mass Distribution,Oscillatory Tests: Basics (1),Two
12、-Plate-Model Idealelastic Behavior of a totally stiff sample(e.g. stone, or steel) no shift betweenthe sine curves of shear stress and shear deformation: the curves of and are in phase,4.5 振荡实验(Oscillatory Test),Oscillatory Tests: Basics (2),Presetting: constant frequency andconstant amplitude,here:
13、 with the strain (deformation) amplitude Result: In most cases the samples showviscoelastic behavior with the phase shift between the sine curves ofpresetting and result.,physically:G for the strored and G for the lost (dissipated) deformation energy tan d 1 = G/G damping or loss factor(衰减或损耗因子)as q
14、uotient of the viscous and elastic portions,Oscillatory Tests: Basics (3),Vector diagram G* Pa complex shear modulus 复(数)剪切模量 elasticity law of Hooke (for oscillation): G Pa storage modulus, elastic portion 储能模量 弹性模量 G Pa loss modulus, viscous portion 耗能模量 粘性模量of the viscoelastic behavior,Oscillator
15、y Tests: Basics (4),Vector diagram h* Pas complex shear viscosity 复(数)剪切粘度 h Pas=G/w=(tAsind)/(gA w) h Pa s=G/w=(tAcosd)/(gA w),h,h,h*,d,Raw Data and Rheological Parameters, 振幅扫描(Amplitude Sweep),Presetting: Result: constant frequency and Storage Modulus G (elastic behavior),variable strain (deforma
16、tion) Loss Modulus G (viscous behavior), limiting value ot the linear viscoelastic (LVE) range,limiting value of theviscoelastic range,Amplitude Sweep,Amplitude Sweep, = 10 1/sT = 25C,Amplitude Sweep, = 10 1/sT = 25C,coat 1: GG,coat 2: GG,comparison of two spray coatings,Amplitude Sweep,comparison o
17、f two coatings,Amplitude Sweep, = 10 1/s,temperature dependence of butter,Amplitude Sweep, = 10 1/sT = 23C,comparison of two starch gels,Amplitude Sweep, = 10 1/sT = 23C,comparison of four starch gels, 频率扫描(Frequency Sweep),Presetting: constant amplitude (within the LVE range) and variable frequency
18、,Frequency Sweep of an Unlinked Polymer,g = 10 %T = 23C,Frequency Sweep: Unlinked Polymers,Maxwell liquid the position of the crossover point(based on a single of G and G is depending on theMaxwell model) molar mass M (here: M1 M2),Frequency Sweep,g = 10 %T = 180C,comparison of two PE melts,Frequenc
19、y Sweep,g = 1 %T = 170C,crosslinked PE: GG,unlinked PE: GG,comparison of unlinked and cross-linked polymers,Frequency Sweep: Cross-linked Polymers, Gels, Dispersions,polymers with different (1) polymer with unlinked molecules degrees of cross-linking and a narrow MMD (2) polymer with unlinked molecu
20、les and a wide MMD (3) sparsely cross-linked polymer, flexible gel or dispersion with low structural strength at rest (4) densely cross-linked polymer, rigid gel or dispersion with high structural strength at rest,Frequency Sweep,g = 1 %T = 23C,stable dispersion: gel character with GG at low frequen
21、ciesinstable dispersion: liquid character with GG at low frequencies,comparison of two coatings,Frequency Sweep,g = 1 %T = 23C,stable dispersion: no h0 plateau instable dispersion: with h0 plateau,comparison ot two coatings,Frequency Sweep,g = 0,3 %T = 20C,stable dispersion: gel character with GG at
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