Morphology and Rheology of Immiscible
Polymer Blends under Electric Fields
H. Orihara1, Y. Nishimoto1, K. Aida1, Y. H. Na1,T. Nagaya2
1Hokkaido University, 2 Oita University

Immiscible polymer blends
RheologyMorphology

Close relationshipDoi and Ohta, 1991
Constitutive equations
Interface tensor

Interface area density

Excess stress from Interfacial tension(Batchelor, Doi, Onuki)

Experimental tests (Takahashi et al.)Effect of electric fields
Immiscible polymer blend electro-rheological (ER) fluid（Inoue et al. 1995）
LCPCH3OIL

CH 3CH3SiO

SiO(CH2)3CH3m

OCH 2CH2O

PDMS
CH3＋nCOO

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

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).

3D observations!

System combining CLSM and rheometer

CSU22, YOKOGAWA

MCR301, Anton PaarOutline
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

Experiment
Shear flow

Rheometer

Focalplanezyx
Glass Platewith ITO
SampleObjective Lens
CSLM

Piezo-actuator 5Hz
Frame rate 500 f/s
400x390x50 pixels
163x163x56 µm3

Gap: 200mm, Diameter: 35 mm

Blend of LCP and PIB(Polyisobutylene)

ElectricfieldCoalescence of dropletsand column formation
without shear flow

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)113mm

ECoalescence
0s

168mm

20 s

35 s

100 s

(a) 2 kVamp/mm

Elongation
0s

20 s

35 s

(b) 4 kVamp/mm

100 s

Movies (8 times as fast)

2 kVamp/mm

5 kVamp/mm

3D spatial correlation function
Average lenghts of semi-axes

SpheroidScaling property
Assuming that all the droplets keep spherical shape,

Scaling property holds ?
Yes ?

No !

Growth kinetics on the basis of hierarchical modelE

t=0

Viscous friction Dipole-dipole interaction

Exponential growthVolume fraction dependence

5/3

SphereSpheroidtDeformation(Torza et al, 1971)

Numerical calculation

Storage Shear Modulus of Columnar Structure

75µm

E

200µm

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

Emergence of elasticity
LCP:DMS=1:6
Oscillatory measurement
f=2 HzDependence of G’ on electric field strengthElectric stress on slant column

Interfacial stress

Electric stressInterfacialtension

E dependence

f dependenceTransient process
subjected to a step electric fieldwith shear flow

Transient shear stress
Blend withthe same viscosity
LCP:PIB=1:6(η=33.5 Pa s at 28℃)

Eamp=6 kV/mm (1000Hz)E on

3D images in the transient process

Ez 56µm

163µm

y163µmx Flow 0 s

1s

2s

3s4s

Movie in the transient process

E163µmz56µmy163µmx Flow

Real time speed

Interface tensor

Symmetrical and tracelessSphereEllipsoid

Slant ellipsoid

Time evolution of interface tensor

diagonalspheroid

Off-diagonal elements-qzx
shear stressclose relation

Mapping from structure to ellipsoid

Structure

EllipsoidcabzEyFlowx

Real time speed

(Batchelor 1970, Doi 1987, Onuki 1987)

Maxwell stress tensor

c?

Electric stress
Electric torque on ellipsoid

Electric stress (Halsey et al., 1992)

Shear flow

approximation

240 Pa200 Pa(theory 240 Pa)

Relaxation process to droplets after removing E
From columnar structure

E oﬀ
E on

Real time speed

From network structure

E oﬀ
E on

Real time speedRemoval of both electric field and shear flow
From columnar structure

E onReal time speedFrom network structure

E onReal time speed

Summary
Subjected to a step electric field without shear flow
1. Coalescence of droplets in electric filed

Hierarchical model is applicable
Exponential growthSphereNon-exponential growthSpheroid

2. Shear modulus of columnar structure
Emergence of elasticity under electric fields
Dependences of field strength and frequency

Subjected to a step electric field under shear flow
3. 3D images

4. Separation of viscous, interfacial and electric stresses

5. Interface tensor

Future subjectStructure

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

Different viscosities(Batchelor, 1970)

Calculation of interface tensor