Morphology and Rheology of Immiscible Polymer Blends under Electric - - PowerPoint PPT Presentation

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Morphology and Rheology of Immiscible Polymer Blends under Electric - - PowerPoint PPT Presentation

May 17, 2023 874 likes •1.48k views

Morphology and Rheology of Immiscible Polymer Blends under Electric Fields H. Orihara 1 , Y. Nishimoto 1 , K. Aida 1 , Y. H. Na 1 , T. Nagaya 2 1 Hokkaido University, 2 Oita University Immiscible polymer blends Rheology Morphology Close

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  • H. Orihara1, Y. Nishimoto1, K. Aida1, Y. H. Na1,
  • T. Nagaya2

1Hokkaido University, 2 Oita University

Morphology and Rheology of Immiscible Polymer Blends under Electric Fields

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Morphology

Immiscible polymer blends

Rheology

Close relationship

Doi and Ohta, 1991 Interface tensor Excess stress from Interfacial tension(Batchelor, Doi, Onuki) Experimental tests (Takahashi et al.) Interface area density Constitutive equations

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Immiscible polymer blend electro-rheological (ER) fluid

CH 3 CH 3 SiO (CH 2 ) 3 OCH 2 CH 2 O SiO CH 3 CH 3 CH 3 COO CN

m n

m/(m+n) = 0.2, m+n =50

（Inoue et al. 1995）

＋ PDMS PIB MPS LCP OIL

ER effect is due to morphological change.

Tajiri, K., K. Ohta, T. Nagaya, H. Orihara, Y. Ishibashi, M. Doi and M. Inoue,

  • J. Rheol. 41, 335-341 (1997).

Kimura, H., K. Aikawa, Y. Masubuchi, J. Takimoto, K. Koyama and K. Minagawa, Rheol. Acta 37 54-60 (1998).

Effect of electric fields

3D observations!

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System combining CLSM and rheometer

MCR301, Anton Paar CSU22, YOKOGAWA

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Subjected to a step electric field without shear flow

  • 1. Coalescence of droplets
  • 2. Shear modulus of columnar structure

Subjected to a step electric field with shear flow

  • 3. Interface tensor
  • 4. Separation of viscous, interfacial and electric stresses
  • 5. Relationship between excess stress and interface tensor

Outline

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Experiment

Rheometer Sample Glass Plate with ITO Objective Lens CSLM

Shear flow Electric field z y x Focal plane Gap: 200mm, Diameter: 35 mm Piezo-actuator 5Hz Frame rate 500 f/s 400x390x50 pixels 163x163x56 µm3

Blend of LCP and PIB(Polyisobutylene)

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Coalescence of droplets and column formation without shear flow

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168mm 113mm

0 s 20 s 35 s 100 s 0 s 20 s 35 s 100 s

(a) 2 kVamp/mm

E

(b) 4 kVamp/mm

Blend: LCP(65 Pa s)/PIB(7.8 Pa s) at 25℃ Preshear of 200 s-1 for 20 min Application of ac electric field (512 Hz) without shear flow

LCP:PIB=1:6 (φ =0.14)

Elongation Coalescence

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2 kVamp/mm 5 kVamp/mm Movies (8 times as fast)

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3D spatial correlation function Average lenghts of semi-axes

Spheroid

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Scaling property

Assuming that all the droplets keep spherical shape, Scaling property holds ? No ! Yes ?

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Growth kinetics on the basis of hierarchical model

E Viscous friction Dipole-dipole interaction

Exponential growth t=0

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Volume fraction dependence

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5/3

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Sphere Spheroid

t Deformation

(Torza et al, 1971)

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Numerical calculation

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Storage Shear Modulus of Columnar Structure

200µm 75µm

100 sec later after applying an ac electric field with an amplitude of 5kV/mm and a frequency of 2Hz. E

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Emergence of elasticity

Oscillatory measurement f=2 Hz LCP:DMS=1:6

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Dependence of G’ on electric field strength

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Electric stress on slant column

Interfacial stress Electric stress

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E dependence f dependence

Interfacial tension

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Transient process subjected to a step electric field with shear flow

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Eamp=6 kV/mm (1000Hz)

E on

Transient shear stress

Blend with the same viscosity LCP:PIB=1:6 (η=33.5 Pa s at 28℃)

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3D images in the transient process

163µm 56µm

x z y

163µm

0 s 1 s 4 s 3 s 2 s

E Flow

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Movie in the transient process

163µm 56µm x z y 163µm E Flow

Real time speed

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Interface tensor

Sphere Ellipsoid Slant ellipsoid Symmetrical and traceless

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Time evolution of interface tensor

diagonal

spheroid

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Off-diagonal elements shear stress

  • qzx

close relation

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Mapping from structure to ellipsoid

Structure Ellipsoid

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c a b

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x z y

Flow

E

Real time speed

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(Batchelor 1970, Doi 1987, Onuki 1987)

Maxwell stress tensor

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c ?

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Electric stress

Shear flow Electric torque on ellipsoid Electric stress (Halsey et al., 1992)

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approximation 240 Pa

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200 Pa

(theory 240 Pa)

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E on E off

Relaxation process to droplets after removing E

From columnar structure

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Real time speed

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E on E off

From network structure

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Real time speed

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Removal of both electric field and shear flow

E on

From columnar structure

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Real time speed

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E on

From network structure

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Real time speed

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Subjected to a step electric field without shear flow

  • 1. Coalescence of droplets in electric filed
  • 2. Shear modulus of columnar structure

Summary

Hierarchical model is applicable Exponential growth Non-exponential growth Sphere Spheroid Emergence of elasticity under electric fields Dependences of field strength and frequency

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SLIDE 55
  • 3. 3D images
  • 4. Separation of viscous, interfacial and electric stresses
  • 5. Interface tensor

Subjected to a step electric field under shear flow

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Future subject

Can Doi-Ohta theory describe the change from droplet-dispersed structure to network one? Topology changes! Structure

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Different viscosities

(Batchelor, 1970)

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Calculation of interface tensor