INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL PROPERTIES AND SHEAR STABILITY OF HIGHLY CONCENTRATED W/O EMULSIONS

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The effect of the electrolyte concentration on the interfacial interactions, rheological properties and emulsi
on shear stability was investigated. The increase of the electrolyte concentration leads to the growth of storage
modulus and the yield stress of emulsions and enhances the emulsion stability to shearing, while interfacial
tension decreases. The observed effects were attributed to the interfacial interaction of a surfactant and an
electrolyte that was confirmed by the IRanalysis. The interaction between an electrolyte and a surfactant
provides a stable interface. 

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КОЛЛОИДНЫЙ ЖУРНАЛ, 2010, том 72, № 6, с. 798–806
798
1 2
1. INTRODUCTION
Highly concentrated emulsion (HCE) is a mixture of
two incompatible liquids, with volume concentration of
the dispersed phase exceeding the limit of the closest
packing of spherical droplets, ϕ*. This limit is equal to
app. 0.74 for monodisperse droplets and is somewhat
higher for polydisperse particles. The packing above this
limit is possible due to the compression of spherical drop
lets and their transformationinto polyhedrons. The wide
interest to HCE is dictated by both, their practical im
portance and fundamental problems of the physics of
these systems. The physical nature of HCE was examined
in several fundamental publications [1–3]. The general
concept of these studies was based on treating the osmot
ic pressure as the driving force of the droplet compres
sion. This force is balancedby the excess surface energy
stored due to the increase of the surface area in the droplet
transformation from spheres to polyhedrons. The forma
tion of such structure leads to the solidlike behaviour of
HCE in the low stress domain. This solidlike behaviour is
demonstrated as the frequency independence of storage
(elastic) modulus in a wide frequency range [4–8] at small
amplitudes. As a consequence of this conception, a pos
sibility of scaling of elastic modulus by Laplace pressure
exists.
HCE are nonlinear viscoplastic media with clearly
expressed yield stress [3, 7, 9–11]. Also, the nonlinear
behaviour of HCE was experimentally observed in mea
suring a flow curve at shear stresses beyond the yield stress
threshold [7, 8, 12–15] or measuring elastic modulus as a
1
Corresponding author: masalovai@cput.ac.za.
2
Permanent address: Russia, 119991 Moscow, Institute of Petro
chemical Synthesis, Russian Academy of Sciences.
alex_malkin@mig.phys.msu.ru.
function of amplitude of deformations in largeampli
tude oscillation sweep [8, 12, 16, 17]. 
The objects of this work are highly concentrated wa
terinoil emulsions, containing the oversaturated am
monium nitrate (AN) solution as an aqueous phase. Be
sides the usual origin of instability, these emulsions can
lose their applied properties due to the crystallization of
the dispersed phase. 
One of the important components of an emulsion is
an electrolyte, which is possibly not an inert part of a sys
tem but an active agent interacting with a surfactant and
therefore influencing the character and properties of the
interfacial layer. 
The effect of an electrolyte on emulsion properties
was described in several publications. The increase in
rheological properties [18–20] and improvement of
physical emulsion (HCE) stability [18, 21–23] were re
ported. These investigations were carried out with the use
of low molecular weight, polymeric surfactant and pro
teins. The variety of electrolytes used in these studies was
not very wide (KCl, K2SO4
, MgCl
2, MgSO
4
, AlCl
3). The
data concerning the influence of the electrolyte concen
tration on the interfacial tension are contradictory: some
authors reported about the decrease [18, 21] of the inter
facial tension with electrolyte addition while others ob
served rising interfacial tension [19]. However, it should
be mentioned that different surfactants were used for
emulsion stabilization. 
It is known that the family of the poly(isobutylene)
succinic anhydride (Pibsa) derivatives can be used as ef
fective surfactants for stabilization of liquid explosives
which are HCE of the W/O type [21]. Several publica
tions were devoted to the investigation of their monolay
ers [24, 25] and their interactions with the aqueous phase
INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL 
PROPERTIES AND SHEAR STABILITY OF HIGHLY CONCENTRATED 
W/O EMULSIONS
© 2010 K. Kovalchuk, I. Masalova1
, A. Ya. Malkin
2
Material Science and Technology Group, Engineering Faculty,
Cape Peninsula University of Technology (CPUT)
Cape Town, P.O. Box 8000, Republic of South Africa
Поступила в редакцию 20.01.2010 г.
The effect of the electrolyte concentration on the interfacial interactions, rheological properties and emulsi
on shear stability was investigated. The increase of the electrolyte concentration leads to the growth of storage
modulus and the yield stress of emulsions and enhances the emulsion stability to shearing, while interfacial
tension decreases. The observed effects were attributed to the interfacial interaction of a surfactant and an
electrolyte that was confirmed by the IRanalysis. The interaction between an electrolyte and a surfactant
provides a stable interface. 
УДК 541.182.43:532.135
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL PROPERTIES 799
(AN solution) [21, 26–28] but the electrolyte effect was
not understood. 
This work is devoted to the investigation of the effect
of the electrolyte concentration on interfacial and rheo
logical properties of HCE. The aim of the present study is
to look closely at the structure and interaction at the in
terface. This will enable better understanding of factors
governing the behaviour of emulsions of this type. 
2. MATERIALS AND METHODS 
Materials
The objects of this work were HCE used as “liquid ex
plosives”. They are emulsions of the waterinoil type.
One can find the details of the composition of these
emulsions in earlier publications [6, 10, 29]. In short, the
concentration of the dispersephase is 90–96 wt. %. This
phase in the standard technological recipes is a super
cooled aqueous solution of AN. Water comprises <20%
by mass of this phase. So, the salt concentration ϕex
ceeds 80%. 
A typical view of compressed droplets forming the in
ternal aqueous phase is shown in Fig. 1. It is evident that
the droplets really have a polyhedron shape. The equilib
rium temperature of dissolving for such concentration is
app. 65°C. For the preparation of these supercooled so
lutions, the granulated AN was added to the distillate wa
ter at a temperature of 80°C.
Experiments were performed at room temperature. It
means that an aqueous phase is a supercooled (oversat
urated) solution. These solutions are thermodynamically
unstable but kinetically they do not change over several
weeks. This means that it is possible to perform different
experiments with these materials, treating them as quasi
stable.
The size of dispersed particles is spread in the range
from 2 to app. 40 μm. The upper boundary of sizes is de
termined by the requirement of the kinetic stability of su
percooled solutions. It was proven [10] that only smaller
droplets can be kinetically stable during necessary time.
The oil phase is a solution of a surfactant in hydrocar
bon oil. MossparH oil (produced and supplied by Lake
International Technologies, Republic of South Africa)
was used for the emulsion preparation. This oil comprises
mainly isoparaffins (80–90%, where nparaffins and cy
cloparaffins constitute a part of 10–15%) and aromatics
(<0.1%). Oil density is 792 kg/m
3
at 20°C. 
The surfactant used in preparing emulsions was based
on organic derivatives of polyisobutylene succinic anhy
dride (acronym is Pibsa), especially on alkanolamine de
rivatives. The following material was used. PibsaMEA is
Pibsa of molecular weight 1048, reacted approx. 1 : 1 with
monoethanolamine to an uncondensed amide/acid head
group. The tail group is polyisobutylene. Molecular
weight of 1048 corresponds to 19 repeat units in the
chain. The hydrophiliclipophile balance of surfactant is
low (between 2 and 4). The structure of the PibsaMEA
surfactant head group is shown in Fig. 2.
Emulsions with different concentrations of AN in the
aqueous phase were used to investigate the effect of the
salt concentration on properties of emulsions. 
2.2. Methods
2.2.1. FTIR analysis. The FTIR studies were conduct
ed with use of a Perkin Elmer Spectrum 100 FTIR
Spectrometer. The spectra of the emulsions and solutions
were recorded at room temperature using Attenuated To
tal Reflectance (ATR) accessory. The ATR cell was
equipped with a Germanium (Ge) crystal. The range of
measurements was from 4000 cm–1to 500 cm
–1
. The
wavelength accuracy is 0.1 cm
–1at resolution 4 cm
–1
. A
thin film of each sample was put directly on the Ge crys
tal for measurement. No other sample preparation was
used. Experiments were performed in the temperature
range 25–30°C. 
2.2.2. The measurements of interfacial tension. Interfa
cial tension between the oil phase with the surfactant and
aqueous phases with the AN was measured with the use
of KrüssK100 tensiometer (Germany). The principle of
operation of the K100 is straightforward. About 15 cm
3
AN solution is placed in a clean 70 mm diameter glass
dish. A hydrophilic platinum (Wilhelmy) plate is sus
pended vertically from a sensitive force transducer with
its lower edge penetrating the surface of the AN solution.
About 50 cm
3
of the oil phase is added, so that the plate is
Fig. 1.Microscopic image depicting the emulsion with the
average droplet size 8 µm (×500).
C
OH
O CH2
CH
R C
O
NH
H2C
CH2
OH
Fig. 2.Chemical structure of PibsaMEA surfactant head
group (R – polyisobutylene).
800
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
KOVALCHUK и др.
wholly submerged. The interfacial tension is given by fol
lowing equation:
γ= F/Lcosθ,(1) where F[mN] is the vertical force acting on the plate,
after a correction has been made for the plate buoyan
cy, L[m] is the wetted plate length, θis the contact an
gle. Since the plate is hydrophilic, the contact angle is
taken as zero.
2.2.3. Emulsion preparation. The Hobart N50 mixer was
used to manufacture the samples under study. The hot
(80°C) AN solution was slowly added to the oil phase at
low mixing speed. After the emulsion was formed the
samples with different droplet sizes were taken at differ
ent mixing times. 
2.2.4. Rheological analysis. All rheological studies were
made with a rotational stress rheometer MCR 300 (Paar
Physica). The geometry of the measuring unit was plate
andplate with a sandblasted surface (the plate diameter
was 50 mm). The experiments were made in the follow
ing regimes of deformation:
• Oscillatory measurements for measuring the strain am
plitude dependencies of the (storage and loss) compo
nents of dynamic modules; the frequency (1 Hz) was kept
constant in the amplitude sweep test. Strain was con
trolled between 0.01 and 200%.
• Steady state flow measuring flow curves (shear stress
versus shear rate).
Experiments were performed in the temperature range
25–30°C.
2.2.5. Droplet size measurements.Measuring the size of
dispersed particles was carried out with the Mastersizer
2000 device (Malvern Instruments Co). The measure
ment procedure is based on sample dispersion under soft
ware control and the measurement of angle dependence
of the intensity of scatteringof a collimated HeNe laser
beam. Particle size in the range from 0.26 to 1500 μm can
be measured; this range is much wider than sizes of the
real samples used in this work. The size distribution cal
culations are based on the rigorous Mie theory and using
the standard software applied to the instrument. Each
emulsion sample (a small quantity of the sample was tak
en) was dispersed in the large volume of oil to reach a very
diluted concentration of water droplets in oil and to avoid
agglomerates formation. The average value D32was used
as a measure of droplet size in the investigation. 
3. RESULTS AND DISCUSSION
3.1 FTIR analysis
The effect of salt content on the structure of solutions
was investigated by IR spectroscopy. The results are
present in Table 1.
The intensity of the nitrate ion peak increases with in
creasing AN concentration. The peak in range from
3300 cm
–1to 3200 cm
–1
which assigned to NH covalent
80
70
60
50
40
30
20
10
2200 2400 2600 3000 3200 3400 3600 2000 1800 1600 1400 1200 2800
90
100
110
1, 2, 3, 4
5
6
7
OH
stretching
stretching
stretching
bending
OH
NH+
4
NO–
3
Transmittance, %
Wavenumber, см–1
Fig. 3.FTIR spectra of aqueous solutions with different AN concentrations: 1– 0, 2 – 5, 3– 10, 4– 20, 5– 30, 6– 40, 7– 60%.
Table 1.The variation of IR frequencies with the AN con
centration in solution
C, % ν(N–H), cm
–1
ν(N–O), cm
–1
0–– 5 – 1348
10 – 1347
20 – 1347
30 3273 1344
40 3241 1335
60 3207 1311
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL PROPERTIES 801
bond in ammonium ion begins to appear (can be distin
guished and separated from OH stretching vibration peak
in water molecule) at the salt concentration equal to 30%
and shifts to the lower frequency value as well as NO
stretching vibration peak (the values are given in Table 1).
The spectra are shown in Fig. 3. The shift becomes more
significant at 30% AN concentration followed by 40%
and 60%. This effect can probably arise from more inten
sive interactions between  and  ions when in
creasing their concentration in water. The strong evi
dences for direct cationanion contacts at high AN con
centration in an aqueous phase were reported in the
literature: decrease in the coordination number forming
a weakly defined hydration shell around the ammonium
ion [30, 31] and hydration shell moves closer to the am
monium ion at higher AN concentration [30]. These
support the obtained results.
The effect of AN concentration on the IRspectra of
emulsions was observed. It is important to mention that
the effect of the salt on the stability of the interface was
clearly observed even to the naked eye. This forced us to
carry out more detailed investigation of the samples.
4 NH
+
NO3

As the images (Figs. 4, 5) demonstrate, the ruff film
starts to grow at the interface of the droplet after 30 min
(Fig. 4) and continues to develop during the next
19 hours at least. The origin of this interfacial film is
probably the surfactant coming out of solution or sponta
neous emulsification (formation of micro droplets at the
oil/water boundary) [18]. A similar film appears when
the interface is formed away from the tensiometer in a
123 Fig. 4.Interfacial film growth without AN salt in an aqueous phase: 1– after 30 min, 2– 7, 3– 19 hrs.
123 Fig. 5.Wateroil interface in presenceof AN salt (5%) in an aqueous phase at different time: 1– initial moment, 2– after 10,
3–20 hrs.
R
N
H
HO
R1
O
O
NH
HO
R1
O
O
R
H
N
+
H
H
H
Fig. 6.Possible hydrogen bonds formation between two
molecules of PibsaMEA head group and  ion
(R –CH
2–CH2–OH, R1 
– polyisobutylene).
NH4
+
6
802
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
KOVALCHUK и др.
small vial. Figure 5 shows very clear interface in the pres
ence of electrolyte in the aqueous phase. The formation
of a bright and shiny interface was also observed in [18]
when the electrolyte is incorporated in the aqueous
phase. This observation raises the possibility that AN salt
stabilises the W/O interface due to the interaction with a
surfactant [21, 26–28]. One of the interesting suggestions
about the interaction between a surfactant and ammoni
um ion was advanced in [27]. The authors assumed that
and  participate as the bridging component
between the head groups. Based on this assumption we
tried to express it schematically (Fig. 6).
We suppose that these interactions are quite possible
and even the formation of a persistent membrane (unin
terrupted monolayer), since the ions in such super con
centrated solution (melt) are very close to each other due
to the lack of water molecules and increased ionion in
teractions as discussed above. Moreover, the NH bond in
AN was found to be sensitive to the AN concentration.
Obtained results are given in Table 2. 
From the above experimental data it is clear that along
with the increasing AN concentration, the NH peak
shifts to the lower frequency value in the emulsion state as
4 NH
+
NO3

well as in the solution state but a much stronger effect is
observed in the case of an emulsion. If a pure solution is
considered, the observed effect is related to the increased
ionion interactions (as discussed above). But if an emul
sion is considered, the larger shift can be attributed to the
stronger surfactantelectrolyte interactions with increas
ing AN content.
It is obvious that the presence of AN in the aqueous
phase of an emulsion results in the interaction of Pibsa
MEA polar head group with AN due to the formation of
hydrogen bonds and possible salt complex formation
with the ammonium nitrate ions. Moreover, the changes
in surfactant molecular conformation owing to the mod
ification of the head groups and increased association of
the salt ions or ion pairs with the head groups can influ
ence the packing of acyl chains at the interface: due to
electrostatic interactions between the head groups [26, 27]
and due to the hydrogen bonding network [32]. Further
more, the increasing of ions association around the head
groups leads to their dehydration and increased lateral in
teractions between the surfactant chains [19]. Based on
the above discussion, we assume that the orientation of
adsorbed surfactant molecules at the interface depends on
the strength of surfactantelectrolyte interactions and
therefore on the electrolyte concentration in the aqueous
phase. It is reasonable to assume that the increase in the
AN concentration leads to the more stable and structured
interface due to the hydrogen bonding network and elec
trostatic interactions between the head groups. 
3.2 Interfacial tension measurements
The effect of AN concentration con the interfacial
tension was observed. The results are shown in Fig. 7. The
linear decrease of interfacial tension with the increase in
salt concentration in the aqueous phase can probably be
12
11
10
9
8
7
6
70 50 40 30 20 10 0 60
γ, mN/m
C,%
Fig. 7.Dependence of the interfacial tension of Pibsa
MEA surfactant (8% wt. in oil phase) at the W/O interface
on the electrolyte concentration in the aqueous phase.
16
14
12
10
8
6
4
2
0
–4 –5 –6 –7 –8 –10 –12
18
20
–9 –11
1
2
γ, mN/m
lnc[M]
Fig. 8.Dependence of interfacial tension on surfactant
concentration for systems with 10 (1) and 60% (2) of AN
in aqueous phase.
Table 2.The variation of IR frequencies with AN concen
trations
C, %
ν(N–H) in emul
sion, cm
–1
ν(N–H) in 
solution, cm
1
ν(N–H) shift, 
cm
1
30 3264 3273 9
40 3226 3241 15
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL PROPERTIES 803
attributed to the different packing behaviour of surfactant
at the interface due to interactions of the PibsaMEA
surfactant head group with the matter of a drop since no
extra adsorption of the surfactant was found at the inter
face with increasing AN concentration in the aqueous
phase (Fig. 8). From Fig. 8 one can see that the slope
dγ/dlnc(cis the concentration of surfactant) for both AN
concentrations is the same. This reflects about the same
surfactant adsorption at the interface at both used AN
concentrations.
The decrease in interfacial tension shown in Fig. 7
might also be influenced by the changes in structure of
AN solution at the interface. 
3.3 Emulsification
The evolution of droplet burst during the emulsifica
tion process was followed by taking samples from the
evolving emulsion at different processing times, and
analysing their size distribution. 
All the emulsions were mixed for a long time to reach
the limiting diameter value (Dlim); this is a minimal value
of the size that does not change regardless of how long
further deformation continues. Typical experimental re
sults of droplet size evolution for emulsions with different
AN content in aqueous phase are shown in Fig. 9.
As illustrated in Fig. 9, the droplet breakup is fast
during the first 15 min. The droplet size reaches the lim
iting constant value Dlimafter app. 40 min of mixing. The
evolution of the average size in time fits the following
equation: 
(2) ()
()() lim 0 lim
,
t
Dt D e D D −θ
=+ −
where, D(t) are experimental values of D32
; D0 is the
initial droplet size; Dlim
is the limiting Dvalue and θis
the characteristic time of the emulsification process.
From Fig. 9 and Table 3 it is seen that the increase in
the AN concentration in the aqueous phase leads to
higher Dlim
values and longer characteristic time. Mean
while, it is clearly seen that, generally speaking, the in
crease of the AN concentration results in more shear sta
ble emulsions. However, all curves can be separated into
two groups: emulsions with low AN concentration in
aqueous phase (0–30%) and emulsions with high AN
concentration in the aqueous phase (40–80%). This pro
20
18
16
14
12
10
8
6
4
60 50 40 30 20 10 0 70
1
3
5
7
9
2
4
6
8
10
D32
, μm
t, min
Fig. 9.Droplet size as a function of mixing time for emulsionwith different concentration of AN in aqueous phase: 1– 0, 2– 2,
3– 5, 4– 10, 5– 20, 6– 30, 7– 40, 8– 50, 9– 60, 10– 80%.
Table 3.Limiting diameter of emulsion droplets contained
different AN concentrations
AN concentra
tion, %
D0
, μm Dlim
, μm θ,min
0 14.8 6.4 4.2
2 14.0 6.3 4.3
5 14.0 6.3 4.5
10 14.5 6.3 4.5
20 14.5 6.3 5
30 15.5 6.8 5.1
40 15.7 8.2 5.1
50 16.0 8.2 7.5
60 17.8 8.2 8.5
80 18.0 8.4 12.8
×
+


6*
804
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
KOVALCHUK и др.
nounced difference between 30% and 40% AN solutions
can probably be attributed to the structural changes of
AN solution. 
3.4 Rheological investigation
Samples with the same droplet sizes (8 μm) were cho
sen for the rheological investigation in order to exclude
the effect of the droplet size and to separate the role of the
AN in an aqueous phase. The main results of these stud
ies are presented as the amplitude dependence of storage
modules (Fig. 10) and flow curves (Fig. 11) for emulsions
with different concentration of the AN in the internal
phase droplets. The initial parts of flow curves – constant
values of stress – give the yield stress values, τY
.
Figures 10 and 11 demonstrate that the storage mod
ulus as well as the yield stress significantly increases along
with the salt concentration, though the more pro
nounced effect is observed between 30% and 40% AN
content. These results are in accordance with the struc
tural changes at the interface as described above. Indeed,
it was found that ionion interactions begin to dominate
1.00E + 04
1.00E + 03
1.00E + 02
1000 100 10 1 0.1
1
3
5
7
9
2
4
6
8
G, Pa
γ, %
Fig. 10.Amplitude dependence of storage modulus for emulsions with different AN concentration: 1– 0, 2– 2, 3– 5, 4– 10,
5– 20, 6– 30, 7– 40, 8– 50, 9– 60%. D32
= 8 μm.
1.00E + 03
1.00E + 02
1.00E + 01
1E + 00 1E – 02 1E – 04 1E – 06 1E + 02
1
3
5
7
9
2
4
6
8
τ, Pa
γ, 1/s
Fig. 11.Flow curves of emulsions withdifferent AN concentration: 1– 0, 2– 2, 3– 5, 4– 10, 5– 20, 6– 30, 7– 40, 8– 50,
9– 60%. D32
= 8 μm.
×
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
INFLUENCE OF ELECTROLYTE ON INTERFACIAL AND RHEOLOGICAL PROPERTIES 805
in the aqueous phase at high AN concentration [30] that
probably results in a more shearresistant microstructure
of the material.
It is worth stressing that the elastic modulus as well as
the yield stress have an opposite trend compared to the
interfacial tension as a function of the AN concentration.
This implies an important conclusion that it is not the in
terfacial tension that is responsible for the rise of the stor
age modulus and yield stress and cannot explain the ex
perimental results presented in Fig. 12. It means that the
additional sources of elasticity have to be taken into ac
count as was discussed in [33]. It is reasonable to suppose
that the electrolyte effect influencing the surfactantelec
trolyte interactions and dropletdroplet interactions
should be treated as this additional source of elasticity.
The droplet interface becomes more stable and presum
ably rigid, which probably makes shearing more difficult
due to interaction of salt with the surfactant head group.
Similar observations were made in publications [19, 20].
In discussing the influence ofelectrolyte on shear stabili
ty of emulsions, it is necessary to take into account the ef
fect of the double electrical layer, because electrostatic
(Coulomb) forces are more longdistance acting. This
seems especially important for highlyconcentrated
emulsions because the interdroplet gap between neigh
bouring droplets is rather narrow. 
The increase in the AN concentration results in the
compression of the double electrical layer. Thus, this is
the only force adding to the Laplace pressure, thereby in
creasing the stability of droplets. The role of electrostatic
forces was also mentioned in [21, 34], though it is rather
difficult to give the quantitative estimation of this effect. 
4. CONCLUSION
The systematic experimental investigations of the role
of the electrolyte in an aqueous phase in the W/O highly
concentrated emulsions showed that the increase of the
electrolyte concentration leads to the decrease of the in
terfacial tension but to the increase of shear stability of
emulsions as well as to the increase of elastic modulus and
the yield stress of emulsions. The IRstudies demonstrat
ed the existence of the interaction between the hydro
philic end groups of a surfactant and an electrolyte. The
strength of surfactantelectrolyte interactions increases
with the addition of an electrolyte to the aqueous phase.
The most pronounced changes in the effect of the elec
trolyte concentration occur inthe range from 30 to 40%
of the salt in an aqueous phase.
ACKNOWLEDGMENT
The authors thank the Lake International Technolo
gies and African Explosives Limited for their financial
support, for providing the materials and for permission to
publish the results.
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G, Pa
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806
КОЛЛОИДНЫЙ ЖУРНАЛ том 72  № 6  2010
KOVALCHUK и др.
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