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Large amplitude oscillatory shear (LAOS) on thixotropic materials Speaker: Sun, Weixiang Advisor: Prof. Tong, Zhen Researc...
Locations
Group members Prof. Zhen Tong ( 童真) Ruiwen Shu ( 疏瑞文 ) Yanrui Yang ( 杨燕瑞 ) Weixiang Sun ( 孙尉翔 ) May, 2010
Contents <ul><li>LAOS methods for thixotropic materials </li></ul><ul><li>Our work: LAOS study on  Laponite?  gel </li></u...
Viscoelastic materials as a  system <ul><li>Causal </li></ul>G ( t )
Viscoelastic materials as a  system <ul><li>Causal </li></ul><ul><li>Linear </li></ul>G ( t )
Viscoelastic materials as a  system <ul><li>Causal </li></ul><ul><li>Linear </li></ul><ul><li>Time-invariant </li></ul>G (...
Viscoelastic materials as a  system G ( t ) Fourier transform G * ( ω ) =  G’  +  iG’’ Oscillatory shear
The structure of Laponite gel charged discs suspension in water   House of Cards a synthetic hectorite,  [Mg 5.34 Li 0.66 ...
Rheology of Laponite gel <ul><li>Thixotropy </li></ul><ul><ul><li>Yielding –  nonlinear </li></ul></ul><ul><ul><li>Aging –...
Nonlinear  viscoelasticity G ( t, γ ) Fourier transform G * ( ω , γ )
Dealing with nonlinear viscoelasticity <ul><li>Fourier expansion </li></ul>σ 1 σ 3 σ 5 σ 7
Dealing with nonlinear viscoelasticity <ul><li>Fourier expansion </li></ul>σ 1 σ 3 σ 5 σ 7 Medium Amplitude Oscillatory sh...
Dealing with nonlinear viscoelasticity <ul><li>Lissajous figure </li></ul>R. Ewoldt  et al. J. Rheol.   2008 ,  52 , 1427-...
Dealing with nonlinear viscoelasticity <ul><li>Lissajous figure </li></ul>R. Ewoldt  et al. J. Rheol.   2008 ,  52 , 1427-...
ARES in our lab ARES RFS Transducers: 20g & 1K FRT Software: TA Orchestrator 7.2.1, “Arbitrary Waveshape Tests”.
LAOS of time stable gel <ul><li>Experiment window: </li></ul>t w G Sample loading Pre-shear Aging LAOS
LAOS of time stable gel The windows for MAOS is small. Laponite 2.0 wt% NaCl 5.0 mM Fourier transform rheology:
LAOS of time stable gel Laponite 2.0 wt% NaCl 5.0 mM Fourier transform rheology: Plateau values
LAOS of time stable gel MCT prediction Fourier transform rheology: J. M. Brader  et al.   Phys. Rev. E , 2010,  82 , 06140...
LAOS of time stable gel Fourier transform rheology: Laponite 2.0 wt% Varying NaCl concentrations Effect of salt concentrat...
LAOS of time stable gel Fourier transform rheology: Styrene-BA particle suspension Effect of salt concentration S. Kallus ...
LAOS of time stable gel Fourier transform rheology: Laponite 2.0 wt% NaCl 6.0 mM Maxima in higher harmonics.
LAOS of time stable gel Fourier transform rheology: Maxima in higher harmonics. V. Carrier and G. Petekidis,  J. Rheol. , ...
LAOS of time stable gel Fourier transform rheology: Maxima in higher harmonics. Occurs at decreasing particle concentratio...
LAOS of time stable gel γ 0  = 5 % γ 0  = 250 % The gel is turned into viscous fluids under LAOS. Lissajous figures: Lapon...
LAOS of time stable gel Lissajous figure parameters: The proposed parameters reproduce the trend of the fundamental harmon...
LAOS of time stable gel Lissajous figure parameters: All but the fundamental harmonics are extracted. W. Sun  et al. ,  Po...
LAOS of time stable gel Lissajous figure parameters: W. Sun  et al. ,  Polymer , 2011,  52 , 1402-1409. <ul><li>Avoid sele...
LAOS of time stable gel Problems in current method of obtaining  G L ,  G M , etc.: Software: MITlaos It uses the Fourier ...
Time-variant  viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w )
Time-variant  viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w ) <ul><li>Examples: </li></ul><ul><li>T...
Time-variant  viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w ) Shortest time of data acquisition: on...
Dealing with time-variant viscoelasticity Traditional frequency sweep: t w G * ( ω ; t w ) … ω t w1 t w2 t w3 Not fast eno...
Dealing with time-variant viscoelasticity E. E. Holly  et al.   J. Non-Newtonian Fluid Mech. , 1988,  27 , 17-26. Multiwav...
Dealing with time-variant viscoelasticity J. C. Scanlan  et al.   Macromolecules , 1991,  24 , 47-54. O ( ω min -1 ) <<  O...
Dealing with time-variant viscoelasticity t w Δ t  > 2 π / ω   (one cycle) O ( ω min -1 ) <<  O ( t w ) Repeated time sweep:
Dealing with time-variant viscoelasticity Repeated time sweep: ω ↑   The phenomena should be exactly repeated at each  ω ....
Rheology of Laponite gel <ul><li>Experiment window: </li></ul>t w G Sample loading Pre-shear Aging LAOS time sweep
LAOS time sweep of Laponite gel Aging occurs at large strains γ 0  = 1 ~ 20% ω   = 5.0 rad/s Laponite 2.0 wt% NaCl 6.0 mM
LAOS time sweep of Laponite gel Yielding occurs earlier at larger strains Laponite 2.0 wt% NaCl 6.0 mM γ 0  = 1 ~ 20% ω   ...
LAOS time sweep of Laponite gel Laponite 2.0 wt% Varying NaCl concentrations Times and strains of  G’ ,  G’’  crossover:
LAOS time sweep of Laponite gel What about the higher harmonics? The NonLinMon parameter in Orchestrator is  I 3/1 . γ 0  ...
LAOS time sweep of Laponite gel What about the higher harmonics? The Arbitrary Waveshape Test of Orchestrator is not optim...
LAOS time sweep of Laponite gel <ul><li>NI USB-9215A with BNC </li></ul><ul><li>4 channels / 16 bits / 100 kS/s </li></ul>...
LAOS time sweep of Laponite gel Just-in-time calculation and saving of  I n /1  data. <ul><li>In progress… </li></ul><ul><...
Thank you! Open for questions …
4 月份做的事 <ul><li>编 MATLAB 程序 </li></ul><ul><li>看 Scheutjens-Fleerg 理论 </li></ul><ul><li>计算势能 </li></ul><ul><li>调试 ARES 损耗角 ...
把 Laponite 当成半径 a  = 15 nm = 1.5 ×10 -8 m 的球体来考虑。 范德华力: , x  =  h /2 a 位阻作用: , ( h  < 2 δ ) 双电层重叠:
Scheutjens-Fleer <ul><li>划格子 </li></ul><ul><li>放链段和溶剂 </li></ul><ul><li>数构象数、相互作用  G </li></ul><ul><li>Min{ G } </li></ul...
Langevin 函数
Langmuir 吸附
DLVO Total
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LAOS for thixotropy

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LAOS for thixotropy

  1. 1. Large amplitude oscillatory shear (LAOS) on thixotropic materials Speaker: Sun, Weixiang Advisor: Prof. Tong, Zhen Research Institute of Materials Science, South China University of Technology, Guangzhou (510641), P. R. China
  2. 2. Locations
  3. 3. Group members Prof. Zhen Tong ( 童真) Ruiwen Shu ( 疏瑞文 ) Yanrui Yang ( 杨燕瑞 ) Weixiang Sun ( 孙尉翔 ) May, 2010
  4. 4. Contents <ul><li>LAOS methods for thixotropic materials </li></ul><ul><li>Our work: LAOS study on Laponite? gel </li></ul><ul><ul><li>LAOS under time-stable condition </li></ul></ul><ul><ul><li>LAOS time sweep (in progress) </li></ul></ul>
  5. 5. Viscoelastic materials as a system <ul><li>Causal </li></ul>G ( t )
  6. 6. Viscoelastic materials as a system <ul><li>Causal </li></ul><ul><li>Linear </li></ul>G ( t )
  7. 7. Viscoelastic materials as a system <ul><li>Causal </li></ul><ul><li>Linear </li></ul><ul><li>Time-invariant </li></ul>G ( t )
  8. 8. Viscoelastic materials as a system G ( t ) Fourier transform G * ( ω ) = G’ + iG’’ Oscillatory shear
  9. 9. The structure of Laponite gel charged discs suspension in water House of Cards a synthetic hectorite, [Mg 5.34 Li 0.66 Si 8 O 20 (OH) 4 ]Na 0.66 Layer size: 30 nm in diameter & 1 nm in thickness t w
  10. 10. Rheology of Laponite gel <ul><li>Thixotropy </li></ul><ul><ul><li>Yielding – nonlinear </li></ul></ul><ul><ul><li>Aging – time-dependent </li></ul></ul>t w G Sample loading Pre-shear Aging
  11. 11. Nonlinear viscoelasticity G ( t, γ ) Fourier transform G * ( ω , γ )
  12. 12. Dealing with nonlinear viscoelasticity <ul><li>Fourier expansion </li></ul>σ 1 σ 3 σ 5 σ 7
  13. 13. Dealing with nonlinear viscoelasticity <ul><li>Fourier expansion </li></ul>σ 1 σ 3 σ 5 σ 7 Medium Amplitude Oscillatory shear (MAOS): avoid varying number of harmonics K, Hyun et al. J. Rheol. 2007 , 51 , 1319-1342
  14. 14. Dealing with nonlinear viscoelasticity <ul><li>Lissajous figure </li></ul>R. Ewoldt et al. J. Rheol. 2008 , 52 , 1427-1458
  15. 15. Dealing with nonlinear viscoelasticity <ul><li>Lissajous figure </li></ul>R. Ewoldt et al. J. Rheol. 2008 , 52 , 1427-1458 Pedal mucus of snails
  16. 16. ARES in our lab ARES RFS Transducers: 20g & 1K FRT Software: TA Orchestrator 7.2.1, “Arbitrary Waveshape Tests”.
  17. 17. LAOS of time stable gel <ul><li>Experiment window: </li></ul>t w G Sample loading Pre-shear Aging LAOS
  18. 18. LAOS of time stable gel The windows for MAOS is small. Laponite 2.0 wt% NaCl 5.0 mM Fourier transform rheology:
  19. 19. LAOS of time stable gel Laponite 2.0 wt% NaCl 5.0 mM Fourier transform rheology: Plateau values
  20. 20. LAOS of time stable gel MCT prediction Fourier transform rheology: J. M. Brader et al. Phys. Rev. E , 2010, 82 , 061401. Plateau values
  21. 21. LAOS of time stable gel Fourier transform rheology: Laponite 2.0 wt% Varying NaCl concentrations Effect of salt concentration γ 0 = 500%
  22. 22. LAOS of time stable gel Fourier transform rheology: Styrene-BA particle suspension Effect of salt concentration S. Kallus et al. Rheol. Acta , 2001, 40 , 552-559.
  23. 23. LAOS of time stable gel Fourier transform rheology: Laponite 2.0 wt% NaCl 6.0 mM Maxima in higher harmonics.
  24. 24. LAOS of time stable gel Fourier transform rheology: Maxima in higher harmonics. V. Carrier and G. Petekidis, J. Rheol. , 2009, 53 , 245-273. 1 Hz 10 Hz Occurs at increasing ω I 3/1 I 5/1 I 7/1 % PS@PNIPAM suspension
  25. 25. LAOS of time stable gel Fourier transform rheology: Maxima in higher harmonics. Occurs at decreasing particle concentrations I 3/1 (%) V. Carrier and G. Petekidis, J. Rheol. , 2009, 53 , 245-273. PS@PNIPAM suspension φ v ↑
  26. 26. LAOS of time stable gel γ 0 = 5 % γ 0 = 250 % The gel is turned into viscous fluids under LAOS. Lissajous figures: Laponite 2 wt% NaCl 5 mM
  27. 27. LAOS of time stable gel Lissajous figure parameters: The proposed parameters reproduce the trend of the fundamental harmonic. G M G L
  28. 28. LAOS of time stable gel Lissajous figure parameters: All but the fundamental harmonics are extracted. W. Sun et al. , Polymer , 2011, 52 , 1402-1409.
  29. 29. LAOS of time stable gel Lissajous figure parameters: W. Sun et al. , Polymer , 2011, 52 , 1402-1409. <ul><li>Avoid selecting arbitrary number of harmonics </li></ul><ul><li>Normalized by the fundamentals </li></ul>
  30. 30. LAOS of time stable gel Problems in current method of obtaining G L , G M , etc.: Software: MITlaos It uses the Fourier transformed results to calculate G M , etc. Based on a limited number of harmonics
  31. 31. Time-variant viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w )
  32. 32. Time-variant viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w ) <ul><li>Examples: </li></ul><ul><li>Thixotropy </li></ul><ul><li>Physical aging of amorphous polymers </li></ul><ul><li>Chemical reactions </li></ul>
  33. 33. Time-variant viscoelastic materials G ( t ; t w ) Fourier transform G * ( ω ; t w ) Shortest time of data acquisition: one cycle (2 π / ω ).
  34. 34. Dealing with time-variant viscoelasticity Traditional frequency sweep: t w G * ( ω ; t w ) … ω t w1 t w2 t w3 Not fast enough
  35. 35. Dealing with time-variant viscoelasticity E. E. Holly et al. J. Non-Newtonian Fluid Mech. , 1988, 27 , 17-26. Multiwave method – valid only under linear viscoelastic condition. O ( ω min -1 ) << O ( t w )
  36. 36. Dealing with time-variant viscoelasticity J. C. Scanlan et al. Macromolecules , 1991, 24 , 47-54. O ( ω min -1 ) << O ( t w ) t w ω Dynamic frequency sweep direction Continuous frequency sweep: Data interpolation t w1 t w2 t w3 ω G * ( ω ) ω G * ( ω ) ω G * ( ω )
  37. 37. Dealing with time-variant viscoelasticity t w Δ t > 2 π / ω (one cycle) O ( ω min -1 ) << O ( t w ) Repeated time sweep:
  38. 38. Dealing with time-variant viscoelasticity Repeated time sweep: ω ↑ The phenomena should be exactly repeated at each ω . O ( ω min -1 ) << O ( t w ) A. S. Negi and C. O. Osuji, Phys. Rev. E , 2010, 82 , 031404. Laponite gelation
  39. 39. Rheology of Laponite gel <ul><li>Experiment window: </li></ul>t w G Sample loading Pre-shear Aging LAOS time sweep
  40. 40. LAOS time sweep of Laponite gel Aging occurs at large strains γ 0 = 1 ~ 20% ω = 5.0 rad/s Laponite 2.0 wt% NaCl 6.0 mM
  41. 41. LAOS time sweep of Laponite gel Yielding occurs earlier at larger strains Laponite 2.0 wt% NaCl 6.0 mM γ 0 = 1 ~ 20% ω = 5.0 rad/s
  42. 42. LAOS time sweep of Laponite gel Laponite 2.0 wt% Varying NaCl concentrations Times and strains of G’ , G’’ crossover:
  43. 43. LAOS time sweep of Laponite gel What about the higher harmonics? The NonLinMon parameter in Orchestrator is I 3/1 . γ 0 = 1 ~ 20% ω = 5.0 rad/s
  44. 44. LAOS time sweep of Laponite gel What about the higher harmonics? The Arbitrary Waveshape Test of Orchestrator is not optimized for prolonged tests.
  45. 45. LAOS time sweep of Laponite gel <ul><li>NI USB-9215A with BNC </li></ul><ul><li>4 channels / 16 bits / 100 kS/s </li></ul><ul><li>LabView SignalExpress (Full Edition) </li></ul>The raw data manipulation is formidable manually!
  46. 46. LAOS time sweep of Laponite gel Just-in-time calculation and saving of I n /1 data. <ul><li>In progress… </li></ul><ul><li>Identify real fundamental frequency </li></ul><ul><li>Obtain G M , etc. avoiding Fourier transform </li></ul><ul><li>Multi-frequency sweep </li></ul>
  47. 47. Thank you! Open for questions …
  48. 48. 4 月份做的事 <ul><li>编 MATLAB 程序 </li></ul><ul><li>看 Scheutjens-Fleerg 理论 </li></ul><ul><li>计算势能 </li></ul><ul><li>调试 ARES 损耗角 </li></ul>
  49. 49. 把 Laponite 当成半径 a = 15 nm = 1.5 ×10 -8 m 的球体来考虑。 范德华力: , x = h /2 a 位阻作用: , ( h < 2 δ ) 双电层重叠:
  50. 50. Scheutjens-Fleer <ul><li>划格子 </li></ul><ul><li>放链段和溶剂 </li></ul><ul><li>数构象数、相互作用  G </li></ul><ul><li>Min{ G } </li></ul>吸附浓度 平均回转半径
  51. 51. Langevin 函数
  52. 52. Langmuir 吸附
  53. 53. DLVO Total

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