流变学基础及应用

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 53015 ISO 12058,measuring tube including the ball,stand,ther

6、mometer,jacket, for temp. control, 落球粘度计,HAAKE,GENEQ,e.g. for pastes and paste-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 after turning the tube. Viscosity evaluation by

7、 comparison 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 the flow time determination of the kinematic viscosity, 流杯,Flow Cups,ISO DIN Ford (ASTM) Zahn Engler She

8、ll,DIN ISO, 流杯,Capillary Viscometers, 玻璃毛细管粘度计, Stormer 粘度计,Preset: constant torque (shear stress) applied by a free falling weight (in grams) Result: rotational speed of the measuring system,Krebs measuring system (Paddle) as a relative measuring system designation in Krebs Units, KU, Brookfield 粘度

9、计,spindles as relative 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 recommended for pastes (air bubbles),锥板转子（Cone-Plate） with dispersions only useful for particles under 5m,平行板（Parallel-plates） useful for gels and pastes,旋转及振荡流变仪（rotational and oscillatory rheomete

10、rs） according to DIN 53019 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,MCR30

11、0、500,MCR301、501,ACS16/32, 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. amount M g/mol molar mass,Relaxation Test,Relaxation Test,Relaxation Modulus,Relaxation Time Spectrum,Relaxation Time Spectrum,Molar Mass Distribution,Oscilla

12、tory Tests: Basics (1),Two-Plate-Model Idealelastic Behavior of a totally stiff sample (e.g. stone, or steel) no shift between the 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

13、 and constant amplitude, here: with the strain (deformation) amplitude Result: In most cases the samples show viscoelastic behavior with the phase shift between the sine curves of presetting and result.,physically: G for the strored and G for the lost (dissipated) deformation energy tan d 1 = G/G da

14、mping or loss factor（衰减或损耗因子） as quotient 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 t

15、he viscoelastic behavior,Oscillatory 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

16、 behavior), variable strain (deformation) Loss Modulus G (viscous behavior), limiting value ot the linear viscoelastic (LVE) range,limiting value of the viscoelastic range,Amplitude Sweep,Amplitude Sweep, = 10 1/s T = 25C,Amplitude Sweep, = 10 1/s T = 25C,coat 1: GG,coat 2: GG,comparison of two spra

17、y coatings,Amplitude Sweep,comparison of two coatings,Amplitude Sweep, = 10 1/s,temperature dependence of butter,Amplitude Sweep, = 10 1/s T = 23C,comparison of two starch gels,Amplitude Sweep, = 10 1/s T = 23C,comparison of four starch gels, 频率扫描（Frequency Sweep）,Presetting: constant amplitude (wit

18、hin the LVE range) and variable frequency,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 the Maxwell model) molar mass M (here: M1 M2),Frequency Sweep,g = 10 %

19、 T = 180C,comparison of two PE melts,Frequency 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

20、 a narrow MMD (2) polymer with unlinked molecules 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 d

21、ispersion: gel character with GG at low frequencies instable 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

22、 = 20C,stable dispersion: gel character with GG at low frequencies instable dispersion: liquid character with GG at low frequencies,comparison of two cosmetic lotions, 步进实验：触变性（Step Test: Thixotropy）,low-shear conditions high-shear conditions low-shear conditions,state of rest structure decompositio

23、n structure regeneration,as oscillatory test with 3 intervals,Time-Dependent Structure Decomposition and Regeneration,g1 = g3 = 0,2 % g2 = 100 % = 10 1/s T = 23C,3x oscillation,What are you doing?,Waiting for ketchup,Time-Dependent Structure Decomposition and Regeneration,g1 = g3 = 0,3 % = 10 1/s dg

24、/dt = 100 1/s T = 23C,Osc./Rot/Osc.,Application: Automotive Coatings,a) Plastisols: seam sealing, under body spraying, cavity conservation b) Primer c) Coatings: filler, base coat, top coat, clear coat,Time-Dependent Structure Regeneration,g1 = g3 = 0,2 % dg/dt2 = 15000 1/s = 10 1/s T = 23C,comparis

25、on of 3 spray coatings,Step Test: Decomposition and Regeneration of the Structure (Thixotropic Behavior),a) rotational tests (3 intervals),result: time-dependent viscosity (only viscous behavior!) b) oscillatory tests (3 intervals),result: two time-dependent functions G (viscous) and G (elastic): vi

26、scoelastic behavior,Temperature-Dependent Softening and Melting,g = 1 % = 10 1/s melting temperature Tm = 215C,Temperature Curve,1 = 0, 1 % (for T 35C) = 10 1/s,polymer modified bitumen (PMB),Temperature Curves of Polymers,amorphous partially crystalline cross-linked Tg.glass transition temperature

27、Tm.melting temperature,Temperature Curve,= 0,1 %; 1%; 10% = 10 1/s glass transition temperature: Tg = -62C (G max) Tg = -39C (tand max),polymer melt with GG at high temperatures,unlinked partially crystalline polymer,Temperature Curve,glass transition temperature Tg = -22C (G max) Tg = -16C (tand ma

28、x) no melting as G G at high temperatures,g = 0,25 % = 10 1/s,cross-linked polymer,Temperature Curves of Polymers,Comparison of G(T) curves of polymers with different internal structures: (1) amorphous, (2) partially crystalline, (3a) densely cross-linked (thermoset) and (3b) sparsely cross-linked (

29、elastomer).,Temperature-Dependent Behavior,melting or crystallization of dispersions presetting: constant shear conditions (amplitude and frequency),Tk.crystallization temperature,result: steep decrease or increase, resp., in a narrow temperature range,Temperature-Dependent Crystallization,g = 0, 1

30、% = 10 1/s crystallization temperature Tk = -1C,Time or Temperature-Dependent Behavior,gel formation, hardening or curing process presetting: constant shear conditions (amplitude and frequency),result: time-dependent time-dependent temperature-dependent G curve G and G curves G and G curves tCR.time

31、 point at the tSG.time point of TCR.temperature at the beginning of sol / gel transition beginning of gel formation, hardening, (with G = G) gel formation, hardening, curing or chemical curing or chemical reaction reaction,Time-Dependent Curing,g = 0,1 % = 10 1/s,epoxy powder coating at 3 different

32、temperatures,Time-Dependent Curing,g = 0,1 % = 10 1/s preset: T = T(t),Time-Dependent UV Hardening,g = 0,1 % = 10 1/s,Temperature peak due to the exothermic crosslinking reaction,Temperature-Dependent Gel Formation and Curing,g = 0,2 % = 10 1/s,onset of gellation T = 65C end of curing T = 96C,from a

33、 plastisol paste to an elastomer,Temperature-Dependent Melting Behavior and Curing Reaction,g = 0,1 % = 10 1/s,Ih*minI at T = 129C,epoxy powder coat,Film reference temperature: T = 170C,.,Master Curve of a PS melt,Time / Temperature Shift,Master Curve of PS melt 2,Molar Mass Distribution,based on th

34、e Master Curve of diagram 10.10,Rotational and Oscillatory Rheometers,functional principles:,components: A.drive L.bearing MS.measuring system (here CP) PS.position sensor R.controller parameters: M.torque n.rotational speed .deflection angle,presetting: presetting: presetting: or n M or n Here the

35、drive is separated from the MS test result: test result: test result: M or n M,基础研究 产品开发 质量控制,MCR 500 MCR 300 MCR 100 MCR 50 MC 10, Physica MCR300：应用范围,MCR=Modular Compact Rheometer, Physica MCR300测量系统：同轴圆柱转子, 同轴圆柱转子（Coaxial Cylinder）系统 别称：同心圆筒式（Concentric Cylinder）, 组成：悬锤（bob）+ 测量杯（cup） 方式： - Searl

36、e模式：悬锤运动，杯子不动 大多数流变仪采用，缺点：采用高速测量低粘液体样品时易出现Taylor漩涡 - Couette模式：悬锤不动，杯子运动 极少流变仪采用，可克服Taylor漩涡，但杯子必须密封，以防止控温水浴的流体进入 要点：- 低粘流体宜采用较大的转子系统（直径大，剪切面积大），高粘流体宜采用宜采用较小的转子；- 所有的ISO转子，剪切速率仅与转速有关而与直径大小无关。, 优点：- 即使在高剪切速率下，液体都不会流出测量杯；- 测量杯的表面积较大，控温效果好；- 即使出现爬杆效应，环空中也会充满被测样品；- 砂磨和有刻痕的转子可防止“壁滑效应”；- 可使用样品盖防止容积蒸发 缺点：-

37、 试样用量大；- 在浆状样品中易产生气泡；- 清洗耗时, Physica MCR300测量系统：双间隙转子, Double-Gap系统, 适合测量低粘样品 外壁和内壁都受剪切力作用，剪切面积大 控温容易，可通过测量杯的中央突出部分控温,圆柱状转子的特点 圆柱状转子主要针对需要高剪切速率的实验而设计的，因此剪切间距较小 在旋转试验中，可能会出现试样的剪切发热现象，尤其是在剪切速率高于10,000 1/s时很容易发生 由于制造的困难，间距只能销到一定程度，对于超高剪切速率，例如，1,000,000 1/s，宜采用高压毛细管流变仪, Physica MCR300测量系统：锥板转子, Cone-Pla

38、te系统, 1976年左右标准化，1993年左右开始大量使用 在测量低粘样品时，容易出现二次流动现象，并导致湍流和增大流动阻力，样品也会飞溅出测量范围 低粘液体宜采用较大的转子，因为其剪切面积较大；反之，高粘样品宜采用较小的转子, 一旦角度确定，剪切速率就确定，与半径无关 锥尖有一较小的平面，因此锥板之间有一定间距，现在的恶流变仪都采用自动设定此间距 装样,理想状况实际操作很难,正确,试样偏少, Physica MCR300测量系统：锥板转子, 优点 - 剪切十分均匀因为锥-板之间的间距中的剪切速率都相同（大部分研究人员都偏好锥板系统） - 试样用量小 - 不容易在试样中产生气泡 - 清洗方便

39、, 缺点 - 如果测量分散液体系，其离子尺寸受限；不能测量固体和具有三维结构的试样 - 高粘试样，需要很长的弛豫时间达到平衡，有时长达30分钟 - 无法使用砂磨或带刻痕的转子，因为无法确定精确尺寸 - 试样容易飞溅，容积易挥发 - 控温不方便, Physica MCR300测量系统：平行板转子, Parallel-Plate系统, 间距H 圆板半径R 利用高剪切速率测定低粘液体时，已出现二次流动效应，从而导致湍流和流动阻力增大, 低粘液体宜采用较大的测量体系，高粘试样宜采用半径较小的转子 剪切速率不恒定，因为其取决于到轴心的距离,优点 - 可以测定含有较大颗粒的分散也和具有三维结构的试样、软固体和硬化材料 - 可以快速测定硅橡胶之类的高粘试样 - 可以通过调节板的间距而改变剪切速率范围 -