Adsorption mechanism of ester phosphate on baryum
titanate in organic medium. Preliminary results on the
structure of the adsorbed layer
N. Le Bars, D. Tinet, A. Faugère, H. Van Damme, P. Levitz
To cite this version:
N. Le Bars, D. Tinet, A. Faugère, H. Van Damme, P. Levitz. Adsorption mechanism of
ester phosphate on baryum titanate in organic medium. Preliminary results on the structure of the adsorbed layer. Journal de Physique III, EDP Sciences, 1991, 1 (5), pp.707-718.
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Phys.
J.
III1
(1991)
707-718
MAI
1991,
PAGE
707
Classification
Physics
Abstracts
82.00
Adsorption mechanism of ester phosphate
in organic
medium.
Preliminary results on
adsorbed
layer
N.
Le
Bars,
D.
CRSOCI-CNRS,
(Received15
Tinet,
16
rue
A.
de
M.
Ferollerie,
la
1990,
November
Faugdre, H.
rev~ed
31
Van
baryum
on
titanate
of the
structure
the
Damme
45071
Orlkans
Cedex
January
1991,
accepted
and
02,
lst
P.
Levitz
France
February
1991)
m6canisme
d'adsorption d'agents
du
organiques de BaTi03, ainsi que la
caractbrisation
rhbologique de ces suspensions. Liants et plastifiants ne sont
de la structure,
comportement
et du
de
dans le systbme. Dans
premier temps,
composants
pas utilisds, afin de rbduire le nombre
un
l'isotherme
d'adsorption est btablie par dosage en bmission plasma, puis interprbtde sur la base de
de
rbsultats
Microscopie
Electronique I Transnfission, et de spectroscopie
Rbsonance
par
effectudes
Magnbtique
Nuclbaire
rhbologiques prkliminaires sont
du ~'P.
Des
pour
mesures
caractbriser
la
des suspensions.
structure
Rksnmk.
dispersants
L'objectif
phosphatbs
de
btude
cette
dans
des
est
la
comprbhension
suspensions
of this work is to evidence
the adsorption
mechanism
and the
structure
purpose
surfactant
BaTi03 in organic suspension, and to relate
phosphate ester
stabilized
characteristics
reduce the
these
rheological
behaviour.
Binders
and plasticizers are
omitted
to
to
of system
number
Firstly adsorption
isotherm
determined
by inductively
components.
were
coupled argon plasma technique and interpretated based on transmission
electron microscopy and
studies.
rheological
then
nuclear
magnetic
Preliminary
~~P
measurements
were
resonance
performed and related to suspension
adsorption layer is critically
Structure
of the
structure.
Abstract.
of
The
commercial
discussed.
1,
Inwoduction,
of multilayer parallel plate
manufacture
Baryum titanate is a commonly used material in the
observations.
capacitor. First devices were made using processing methods based on empirical
Tape casting or doctor blading, mainly used as a fabrication
technique for producing ceramic
powder in an organic (or
sheet products, is performed using a slurry containing the
dielectric
rarely aqueous) medium, with polymers acting as dispersant,
binders
plasticizers, to
and
insure satisfactory
mechanical
properties of the casted green tape. The
microstructure
of the
microstructure
of the green tape dictates the properties
and consequently, the
product. Poorly dispersed suspensions may result in green bodies containing voids
inhomogepeities like agglomerates. One way to optimize the final capacitor performance
sintered
of the
and
tape,
final
JOURNAL
708
PHYSIQUE
DE
M
III
5
the physico-chemical properties of the slurry. The
of this
purpose
adsorption
mechanism
and the
of
adsorbed
commercial
structure
phosphate
sutfactant
in
stabilized
BaTiO~ organic suspension, and to relate these
ester
characteristics
rheological
Binders
behaviour.
and
plasticizers are
omitted
reduce
the
to
to
number of system
Firstly adsorption isotherm will be measured and interpretated
components.
according to results given by transmission
electron
microscopy (TEM) and nuclear magnetic
~IQMR) studies. Preliminary rheological
will then be performed and
measurements
resonance
related
suspension
to
structure.
is to
work
improve
is to
and
master
to
the
understand
Experhnental,
2,
Suspensions preparation is presented in figure I. BaTiO~ powder used in
MATERIALS.
study is referenced as ELMIC BT100, from Rhbne
Poulenc.
The solvent is a mixture of
methyl ethyl ketone (MEK) and ethanol (EtOH) in a 2/3 :1/3 ratio, corresponding to the
Sirfactants are hexaoxyethylene undecyl ester phosphate purchased
azeotropic composition.
from
different
SHPC (*), with
mono/diester ratios.
Chemical
formulation
deduced
has been
by Jorge (1990) from liquid chromatography
results
2.I
this
O
O
R
I
OH-
P
I
-&(CH~-CH~-O)~-CiiH~~
OH-
-O-(CH~CH~-O)~-CiiH~~
P
OH
OR
Diester
Monoester
Powders
Heat
Solvent
2fiMEK 1/3EtOH
treatment
j
(120°C, 24h, pfima~y
umj
vac
Surtac÷nt
-
solution
~
Suspension
ice bath
,
fi
so% pUise
Pm360W
~
Centrilugation
j~
Fig.
(*)
Suspension
I.
SHPC
Usine,
,~t~n
62112
~
~~~
Dispersion
ikickiy in
0eposiiion
cam#nom
preparation
~
and
Corbehem,
following
France.
Other
treatments
wtvem
on
TEM
grids
treatments
chart.
M
PHOSPHATE
ESTER
5
Characteristics
mono
the
in
exclusively
almost
Table
of
diester
and
a
components,
50/50 ratio,
ON
listed
are
also
and
molecules
monoester
BaTiO~ powder
I.
ADSORPTION
of
BaTi03
in
tables
I
ORGANIC
and
II.
phosphoric
residual
the
IN
kind,
same
and
ELMIC
~3ET (lll~/~)
Surfactants
contains
surfactant
second,
The
contains
phosphoric
of
acid.
BT100
~.~
d~o (~m)
II.
free
709
characteristics.
Reference
Table
One
acid.
is
MEDIUM
0.83
characteristics.
Mixture
Mixture
2
mono/diester
M~
wt9b H~PO~
50/50
99,9/0.I
596
654
6 to 10 fb
13
HLB
I fb
<
(13)
Deagglomeration is performed using a 600 W Sonificator from Biocell. In
of
particles in organic
efficiency, ultra
deagglomeration
the
sonic
suspensions has to be performed in an ice bath (Jorge 1990). The power used is 360 W, in a
50 fb pulsed mode, for 3 min.
Suspensions are then gently agitated for homogeneity during
24 h, allowing
adsorption equilibrium to be reached.
adsorption
determination,
suspensions are centrifugated in tightly closed
For
isotherm
diluted fifty
with a syringe, and
teflon
containers, at 40 x 106 g. Supematant is withdrawn
kerdane, as well as the
times
by-product commercially
referenced
with a
petroleum
as
dilution
This
is
solvent/surfactant
the suspension.
corresponding
solution
used to
prepare
reduction
carbonization
in the plasma
torch.
Phosphate
avoid
alcohol
due to
to
necessary
is
measured
by a Perkin Elmer Inductively Coupled Argon Plasma (ICP) technique
content
2.2
order
for
METHODS.
to
both
increase
series
of
solutions.
From
results,
the
one
rads
"
vi (Ct
determine
can
surface:
concentration
the powder
r~~~ (mol/m2)
on
equation
following
(mol/I),
by
the
using
:
c~~
and
the
the
surfactant
adsorbed
equilibrium
concentration
Ceq)l'~s Ss
where Vi is the volume of liquid (f), in which a mass m~ (g) of solid with specific surface
area
surfactant
(mol/I) before
equal to S~ (m2/g) is dispersed. c; is the initial
concentration
adsorption. The adsorbed
concentration
the equilibrium
concentration
plot represents
versus
isotheirn (Figs. 2-3).
the adsorption
experiments are performed on BaTiO~ recovered
NMR
after a 25 volfb solid suspension
centrifugation.
The
equipment used is a Br0cker
MSL
for
which
the
type
spectrometer,
'H
frequency is 360 MHz, and the ~'P
frequency is 145,8 MHz.
resonance
resonance
Accumulations
are
registered
after
8 000
scans
with
a
repetition
time
equal
to
10
s.
710
JOURNAL
PHYSIQUE
DE
III
M 5
~
E
~
E
'O
Z$
Ic
fi
2
.
8
8
~
l~
8
O
E
7l
l~
~
~j
O
10
5
15
20
t5
20
<
Fig.
2.
Mono/diester
adsorption
surfactant
isotherm.
"E
#
u#
b
zo
c
I
E
E
(
8
I
m
I
o
E
xJ
fl
~l
0
10
5
Equilibrium
Fig.
3.
Surface
Monoester
tension
Preliminary
mono/diester
agglomeration
surfactant
adsorption
measurements
sedimentation
are
tests
are
concentration
3
(10 molfl)
isotherm.
performed
performed
suspensions,
on
an
at
room
automatic
Lauda
tempprature,
in
tensiometer.
glass
test
tubes,
on
containing
investigate the stability and
in
order
to
of the particles. The solid
25 volffi.
state
content
was
transmission
microscopy (TEM) analysis, one drop of s&pension is rapidly
electron
For
dispersed in MEK/EtOH solution, in order to obtain a low agglomerate
concentration
from
coated grid. Preliminary rheological
which a drop is dispersed on a carbon
measurements
are
performed on 40 volfb BaTi03 suspensions containing
surfactant, using RFS8500
monoester
with simple
Rheometrics,
from
couette
geometry.
surfactant
N
5
3,
Adsorption
PHOSPHATE
ESTER
ADSORPTION
ON
BaTi03
ORGANIC
IN
MEDIUM
711
isotherm,
adsorb
solutions, ionic
surfactant
surface
charged
3.I
RESULTS.
In
the
aqueous
as
on
entity and strongly influence
stabilization.
Ionization
of
is
organic solvent
reduced
power
and
intermediate
like
compared to water,
adsorption may require
step reaction,
proton
transfer, for covalent
bond
formation.
isotherms (Figs. 2-3) present a domain of higmy energetic adsorption,
The two
adsorption
low
surfactant
surfactant, this domain exists, up to
concentration.
In the case of
at
monoester
a
of 2.5
coverage
surface
covered by
adsorption
The
performed
were
this
takes
calculated
step of
our
10-6 mole
x
each
place
about
to
up
average
surface
in
part
this
studies,
to
is
of
molecules
For
non
I
x
covered
the
m2 of powder. The
calculated
surfactant, highly energetic
lo-6 mole of adsorbedmolecules
per m2 of powder.
by one molecule is 1.70 nm2. Desorption experiments
adsorbed
0.66 nm2.
of
molecule
per
mono/diester
No desorption
adsorption, at low
isotherm.
reversible
detected.
was
We
concluded
concentration.
surfactant
at
Other
techniques, like microcalorimetry and kinetic studies could be used to determine
adsorption
energies involved in the adsorption process for this part of the isotherm (Partyka et al., 1988,
Lindheimer
1989,
et al., 1990).
surfactant
Above the
domain
of higmy energetic adsorption,
molecules keep on adsorbing
on
the
powder
molecules
until
surface
adsorbed
per
reaching a limit corresponding to 4.9
powder surface, in the case of
m2 of
x
10-6 mole
monoester
of
surfactant
molecules.
The
energetic and probably
reversible.
When
the
plateau is reached, the
calculated
covered by each
molecule is equal- to 0.34 nm2. In the case of mono/diester
surface
surfactant, the adsorption pattern is more complicated. A first plateau is observed for a 2, I x
10-6 mole
calculated
of 0.80nm2
corresponding to an
surface
coverage,
average
per m2
occupied by each molecule. The process
limited
to a 4.5 x 10-6 mole
to be
seems
per m2
surfactant
molecules.
Molecular
value, comparable to the adsorption limit for
monoester
from the plateau is about half the value
calculated
calculated
section
at the
upper point
cross
domain.
of the highly energetic adsorption
sectional
Cross
equal to o.34 nm2 for the polar phosphate head is in good agreement
area
molecular
section of o.35 nm2 for alkyl amine
with other
works.
Cases (1979) found a
cross
adsorbed
in a full monolayer
configuration on oxide powder surface in aqueous
molecules,
dodecyl sulfate on Zirconia powder
medium.
studied
the adsorption of sodium
Grine (1990)
surface
in
medium, and found that sulfate polar head occupies 0.39 nm2 on the
aqueous
pbwder surface.
adsorption, the
interpretation is difficult and requires
the
mono/diester
surfactant
For
the
values
between
molecular
further
investigations.
There is no simple
relation
coverage
isotherm.
for
mono/diester
surfactant
found for the
different
domains
of the
The
the
pattem
and
adsorption is more complex to analyze, because of residual phosphoric acid
presence,
adsorbed
only
the
interactions
molecules
in
these
complexe
between
For
state.
reasons,
more
molecules
will be emphasized.
adsorption of illonoester
surfactant
adsorption
3.2
is
less
INTERPRETATION.
At,
this
step-
of
our
studies,
we
can
propose
two
different
which is close
double
layer
adsorbed
model
organizations for the
layer. A first
to
a
Firstly, polar heads
mechanism.
organization can be discussed. It results from a two steps
strongly adsorb on the solid surface, with nonpolar part of the molecule being free in the
oriented
A
second
layer is formed in a following step, with polar heads
solvent
medium.
and
polar
shared
by
the
layers.
towards
the solvent,
two
groups
non
during
Such
adsorption with an inner
polar region, can be observed
«bilayer»
non
«hydrophobic
The
called
interaction»
between
alkyl
adsorption from
solution.
water
so
considered
the
main
driving
force
organization,
chains and water is generally
for
such
at the
as
712
JOURNAL
solid/liquid
interface.
However,
solution, through a micellization
this
PHYSIQUE
DE
interaction
process,
and
acts
the
two
in
N
III
similar
a
in
way
aggregative
the
mechanisms
bulk
are
5
water
strongly
connected.
The
question
surfactant
be
strong
is
Whether
molecules
enough
such
promote
to
of hydrophobic
and hydrophilic
study, and the azeotropic MEK/EtOH
alkyl groups aggregation in solution.
notion
in this
used
groups
exist
solvent,
and
between
would
it
surfactant/MEK/EtOH
solutions
for increasing
has
been
measured
(Fig. 4). Surface
tension
did
large
of
not
vary
over
a
range
(10-3 to 10-~ mol/I). We have no proof of micelle
concentration
formation
in the bulk using
classical
formation
micelle
investigation technique. We cannot, based on the available datas,
notion of hydrophobic
the
interaction
first
model.
to justify this
use
model for the
A second
adsorbed layer organization,
also be discussed, especially from
can
Surface
tension
surfactant
isotherm
surface.
of
concentrations
datas.
This
Molecules
step
would
first
adsorbe
followed
by the
may
be
~
~~
in
a
i
i
monolayer
densification
«
I
I
»
I
configuration
of
this
lajer.
on
the
powder
I
c
©
fi
20
1
4J
I
li
W
0,00
Fig.
4,
4.
NAIR
Variation
of
surface
0,02
tension
0,08
0,10
Sudactant
concentration
(molfl)
surfactant
solutions
0,04
of
0,06
with
increasing
0,12
surfactant
concentration.
specwoscopy,
~~P NMR
spectroscopy is well suited for the study of the
shape changes with
surfactant
concentration
(Fig. 5), In the
irreversible
increases
part of the isotherm, the peak is broad and its area
steeply with the
«
surface
Above this domain, broad peak area slightly -increases and stabilizes.Broad
coverage.
peaks are related to low mobility, that is to say, to strongly adsorbed
molecules.
In the
reversible
adsorption domain, a narrow peak appears and increases linearly with equilibrium
mobile
Sharper peak corresponds to more
concentration.
molecules, its width is about the
obtained
surfactant.
for
related
than the
It is
dispersant
molecules
to free
one
pure
same
concentration
equal ti the equilibrium
present in the interstitial liquid of the wet residue, with
4,I
METHOD
adsorbed
layer
AND
RESULTS.
structure.
Peak
N
5
PHOSPHATE
ESTER
ADSORPTION
c~~$~~~$~n
BaTi03
ON
IN
ORGANIC
MEDIUM
713
(#$~$
(io-3moYl)
15.5
0.74
7.8
0.867
1.9
0.946
0.8
0.970
0.3
0.975
o
i
peak
100
200
Fig.
~'P
5.
signal
NMR
for
various
-100
0 ppm
equilibrium
-200
concentration.
concentration,
and to relatively
mobile
adsorbed
species. NMR samples are weighed before
after drying. For each sample, total
of sqrfactant
molecules
is then
calculated
number
from
adsorption
isotherm
data. The overall
NMR signal area is plotted
total dispersant
versus
molecules
quantity (Fig. 6). The equation of this
calibration
is used
normalize
to
curve
experimental peak areas.
calculated
Proportion of sharp over broad peak areas,
from
spectra
decomposition,
increases,
witnessing an increasing
mobile/fixed
ratio,
with
molecules
concentration
concentration.
and dry sample weight,
of
equilibrium
From
broad peak area
and
adsorbed
domain,
as
well
calculated
is
molecules
(determined by
in figure 7. The
supematant
two
as
curves
in the
ICP
and plotted
corresponding equilibrium
versus
analysis). This NMR
isotherm is compared to
similar.
very
reversible
one,
more
are
We
than
can
say
that, in the
90 fb of the
Differences
observed
the two
peak signal.
between
experimental
by a possible
contribution
and
accuracy,
population in sharp peak formation.
broad
adsorbed
isotherms
of
lightly
irreversible
species
can
be
adsorbed
concentration
ICP
isotherm
adsorption
contribute
to
explained by
molecules
714
JOURNAL
DE
PHYSIQUE
N
III
5
«
(
d
~
.
T
~
.
~
Z
0
20
Number
Fig.
NMR
6.
normalization
60
40
sudaclant
of
molecules
in the
80
100
sample (10' ~mol)
curve.
(
«
?
E
w
o
=
c
I
fi
~
8
8
a
.
o
.
~
fl
#
#
7l
l~
$
Fig.
Comparison
either by
7.
determined
Size
5,
and
shape
of
0
of
NMR
the
10
adsorbed
or
by
20
Equilibrium
concentration
surfactant
concentration
ICP.
(~l)
ICP
results
(.)
(I O" ~molfl)
versus
from
equilibrium
NMR
concentration
curves
results.
agglomerates,
Generally, because powder grains have
SEDIMENTATION
EXPERIMENT.
higher than that of the dispersing medium, large aggregates (~ 10~ nm) tend
agglomeration, of course
sediment
under gravity force.
Particle
enhances
this
phenomenon.
to
sedimentation
volume
of the final
lvhen
takes place, the
sediment
depends on the extent of
agglomeration. Compact agglomerates pack efficiently to give dense
the
sediment
which is
5, I
a
PRELIMINARY
density
much
N
PHOSPHATE
ESTER
5
difficult
redisperse,
to
ADSORPTION
where
ON
ORGANIC
IN
agglomerates
branched
as
BaTi03
bridge
MEDIUM
readily
715
give
and
loose
a
sediment.
Despite
difference
the
(0.8g/cm3),
solvent
(Fig. 8).
size is
Particle
motion.
loose
A
evolution
from
slower
suspensions
between
strong
is
observed
attraction
between
containing
could
structure
surfactant.
or
from
unlikely
interaction
molecules
either
density (60 volfb of solid). It seems
between
particles. Small compact
pack slowly under gravity forces.
volume
that
forces
addition
by
Brownian
instantaneously
from
Sedimentation
limit
a
of
by
formation,
is
much
corresponding
inhibits
surfactant
covered
without
electrostatic
strong
agglomerates
reaches
aggregates
suspension
free
stabilization
highly branched
charged faces.
Sediment
MEK/EtOH
and
surfactant
in
result
effective
60 fb
to
loose
likely charged particles
repulsion
resulting
in
no
Such
months.
BaTiO~ particles (6 g/cm3)
between
sedimentation
large (~10~ nm) to explain colloidal
(30volfb of solid) is obtained
almost
to
sediment
over
density
of
almost
the
the
surfactant
1
Fig. 8.
Preliminary
surface
mono/diester
5.2
TEM
sedimentation
coverage
(fJ
=
performed
test
r~~Jr~~~~~~).
on
25
volfb
BaTiO~
suspensions,
for
increasing
observed
for
different
surfactant
concentrations.
Agglomerates are
agglomerates are observed from
surfactant
free suspensions. Agglomdramatically when
surfactant
is used (Fig. 9), higher compacity and
Isolated
agglomerate shapes are registered and computerized, as
observed.
are
enveloppe which are drawn by hand. A shape factor equal to the shape
convex
enveloppe area is used to quantify the agglomerates compacity on a two
convexe
RESULTS.
Large highly branched
shape changes
erates
smaller
well
area
sizes
their
as
over
the
dimensional
The
visible
level.
efficiency of
effect
on
surfactant
agglomerate
in
size
the
and
deagglomeration
compacity.
process
has
been
proved here, by
a
DE
JOURNAL
716
m~
e=o
BaTi03
9.
6,
Discussion.
6.I
agglomerates
PRELIMINARY
forms
by
TEM
for
MEASUREMENTS.
RHEOLOGICAL
5
JW-
~~-
art
observed
N
III
e=o.55
4W-
en0.84
Fig.
PHYSIQUE
increasing
surface
Rheology
allows
coverage.
measurement
Of
long as
as
weak
strains
dynamic
and
used
mode.
the
of
rigid
spheric
small
be
in
In
stresses
case
can
particles dispersed in newtonian fluid, Einstein law can be used to approximate the viscosity
of the suspension, assuming an infinitely low
concentration.
concentrations, a
For higher solid
surrounding particles influence on each particle
# ~ term must be added to take into
account
General
proposed, the best known being that of
motion.
forms of
Einstein's
law have been
suspension
stability
Guth
Simha
and
fluid
and
(1966)
characterization
structure
without
its
modification,
:
~
=
7~s(1+
2.5 #
+14.1#
~+
)
fraction
viscosity of a suspension containing a solid volume
equal to #, in a
viscosity is equal to 7~s.
influence of the agglomerate shape can be predicted. AgglomerFrom this expression, the
parts. Traped solvent does not participate as lubricant,
ates
trape solvent in their
concave
can
underestimation
of the volume
fraction
but
constitutes
of
part of the agglomerate. It results an
particles, and an
overestimation
of the
solvent
One expects a lower viscosity for a
content.
suspension containing more
agglomerates.
compact
suspensions with
For
corresponding to the highly energetic adsorption
concentrations
domain, Elastic
modulus
is
and
viscosity about 10 Poise at low oscillating
about
10 Pa,
modulus
and viscosity
frequency (~ l rad/s). When
surfactant
increases, elastic
concentration
when
the
of the
Poise
respectively,
increase
again
plateau
decrease
0.5
but
down to I Pa and
fluidifiant
behaviour:
viscosity
have
reached.
All suspensions
adsorption
isotherm
is
with increasing oscillating frequency.
decreases
plotted versus shear rate values de/dt, an empiric law, called
values
When shear
stress
rare
data
used
fit
the experimental
law is
Ostwald
to
power
where
solvent
7~
is the
which
r
K(de/dt)n
=
N
K
n,
PHOSPHATE
ESTER
5
Values
tend
results,
Table
found
behave
to
since
value
like
the
tableIII.
Newtonian
a
(n)
can
Such
with
that
seen
evolution
was
initial
717
behaviour
when
surfactant
increases, suspenexpected from TEM
larger and less
are
surfactant
MEDIUM
newtonian
from
concentration
agglomerates
variation
ORGANIC
be
surfactant
fluid.
concentration
constant
IN
deviation
It
When
increases.
surfactant
Ostwald
III.
n
more
low
at
reported
BaTiO~
ON
characterizes
n
are
increases,
concentration
sion
values.
constant
are
I).
(n=
ADSORPTION
concentration,
compact.
surface
and
coverage.
Concentration
fl
n
(10-3 mol/I)
7,
lo
0.2
0,1
25
0.5
0.7
35
0.7
0.8
40
0.8
0.9
Conclusion,
Adsorption
mechanism
hexaoxyethylene undecyl ester
phosphate on baryum
of
titanate
medium
has been
powder, in methyl ethyl ketonelethanol
characterized.
NMR
spectroscopy
investigation of the adsorbed layer
allowed
the
and the species mobility.
Results
structure
adsorption
isotherm
determined
ICP.
with
the
by
Adsorption
in
good
agreement
was
were
surfactant
adsorption is highly
mechanism.
At low
concentration,
shown to be a two steps
concentrations, a reversible
reversible.
For higher
surfactant
energetic, and probably non
completion
of a monolayer
mechanism
involving
the
adsorption phenomenon
A
appears.
study has
has
proposed.
A
parallel
formation
diffuse
layer
been
followed by the
of a
more
adsorption on agglomeration state, which is a
been presented on the effect of
surfactant
behaviour.
and rheological
In the case of mono/diester
fundamental
stabilization
parameter of
deagglomeration state, probably associated with a minimum viscosity
surfactant, a minimum
behaviour
between the two
value, appeared. Phosphoric acid could explain the difference in
will be performed to
studies
Complementary rheological and thermodynamical
surfactants.
surfactant
the following question : how to relate
results, and to
confirm
the present
answer
nanometric
layer adsorption and structuration, or destructuration, of a colloidal suspension.
Acknowledgements,
This
the
work
french
greatfully
Messier,
is part
of the
GIS
entitled
government
and
the
the
staff
of
thanks
and
the
CRSOCI
Rhbne
the
staff
for
poudre
financially
De la
«
industries
their
Poulenc
au
composant
involved
Center
precious help
in this
at
and
We
».
would
project.
Aubervilliers,
support.
One
like
of
to
us
especially
thank
OQLB)
Dr
A.
718
JOURNAL
DE
PHYSIQUE
III
N
5
References
(1979) 684-707.
de Montpellier II, Propridtds
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1990).
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M., KEH E., ZAINI S. and PARTYKA S., J. Colloid Interface Sci. 138 (1990) 83-91.
PARTYKA S., KEH E.,
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PARTYKA S., RUDZINSKI W., BOTTERO J. Y., KEH E.,
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M., J. Chim. Phys. 85 (1988) 405~
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