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Morphological Structure and Surface Propertiesof Maleated Ethylene Propylene DieneMonomer/Organoclay Nanocomposites
Mihaela Homocianu,1 Anton Airinei,1 Daniela Maria Stelescu,2 Daniel Timpu,1 Aurelia Ioanid1
1‘‘Petru Poni’’ Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, Iasi 700487, Romania
2National Research and Development Institute for Textile, Leather, and Footwear Research,93, Ion Minulescu Str., Bucharest 031215, Romania
The phase morphology and surface properties of somemaleated ethylene propylene-diene/organoclay nano-composites (EPDM-g-MA/OC) were characterized byscanning electron microscopy (SEM), atomic force mi-croscopy (AFM) and contact angle measurements.The effect of organoclay and/or compatibilizing agent[maleic anhydride-grafted polypropylene (PP-g-MA)] onthe properties of the EPDM-g-MA nanocompositeswas investigated. The quality and uniformity of nano-clay dispersion were analyzed by SEM and AFMimages. The experimental results showed an interca-late structure and biphasic morphology for the binaryblends based on EPDM and clay. The surface proper-ties of the studied composites are significantly influ-enced by the presence of a compatibilizing agent—PP-g-MA. POLYM. COMPOS., 33:379–387, 2012. ª 2012 Societyof Plastics Engineers
INTRODUCTION
Ethylene propylene diene rubber (EPDM) is obtained
by copolymerization of ethylene and propylene in the
presence of an unsaturated diene and is one of the most
widely used and fastest growing synthetic rubbers. The
saturated polymer backbone results in excellent resistance
to heat, oxidation, ageing, ozone, polar solvents, or micro-
bial attack. Such characteristics assure a broad range of
applications for EPDM, as for automotive profiles, electri-
cal insulation parts, footwear, wires, cables, hoses, roofing
barriers, sealing rings, sporting goods [1–6]. The most fre-
quently used diene termonomers are mainly ethylidene
norbornene and dicyclopentadiene.
Layered clays are inexpensive, naturally occurring
products and their incorporation in polymer matrices,
even at a much lower content (\5% by weight) deter-
mines a high reinforcing effect compared with traditional
fillers. In addition, significant improvements in a range of
properties were obtained in comparison with the proper-
ties of bulk polymers or conventional composites. These
characteristics include strength and storage modulus, heat
and solvent resistance, thermal stability, excellent gas bar-
rier properties etc. [7–10]. To achieve a nanoscale disper-
sion of clay in a polymer matrix, the clay is modified
with quaternary ammonium salts to produce an organo-
clay, which permits to obtain thus a modification of clay
surface polarity and an increase of intergallery distance.
In this way, organoclays can be easily dispersed into the
polymer matrix and nanocomposites with an intercalated
or exfoliated structure are formed [9, 11–13]. The method
presenting the highest commercial interest for preparing
rubber-based nanocomposites is direct melt intercalation.
Another widely utilized method is in situ polymerization
[14].
The compatibilizing effect of organoclay and the prop-
erties of materials are dependent on clay localization and
degree of its dispersion, which is related to the clay–poly-
mer affinity [15, 16]. Since EPDM does not contain polar
groups in the backbone, the homogeneous dispersion of
silicate layers in the polymer matrix will be achieved
with difficulty. A higher interaction between EPDM
chains and silicate layers can be realized by using an
adequate compatibilizer. Maleic anhydride-grafted poly-
propylene (PP-g-MA) has been utilized as an efficient
interfacial compatibilizer to assure the diffusion of poly-
mer chains of EPDM into the galleries of organoclay [17,
18]. However, EPDM elastomers exhibit low surface
tension, low water compatibility, and hydrophilicity.
The introduction of maleic anhydride units in EPDM
can determine the modification of surface properties due
to the interaction between polar groups of maleic anhy-
dride and organoclay by the formation of hydrogen bonds
in the system. The surface properties become very
Correspondence to: Anton Airinei; e-mail: airineia@icmpp.ro
DOI 10.1002/pc.22159
Published online in Wiley Online Library (wileyonlinelibrary.com).
VVC 2012 Society of Plastics Engineers
POLYMER COMPOSITES—-2012
important in improving adhesion between EPDM and
other polymers.
A previous article reported the preparation of some
EPDM-g-MA/organoclay nanocomposites by melt inter-
calation method and their evaluation in terms of thermal,
mechanical, and X-ray characteristics [19]. In this
work, the characterization of EPDM-g-MA/organoclay
nanocomposites has been made by scanning electron
microscopy (SEM), atomic force microscopy (AFM), and
contact angle measurements and the EPDM nanocompo-
sites containing compatibilizer and/or clay were compared
with a conventional composite, prepared for this study.
EXPERIMENTAL
Materials
EPDM grafted with maleic anhydride was Royaltuf 498
(maleic anhydride content 1 wt%, Mooney viscosity at
1258C:30), PP-g-MA (Polybond 3002) with 1 wt% MA and a
melting flow index of 7 g/10 min at 2308C/2.16 kg was
used as a compatibilizing agent between EPDM-g-MA and
organoclay. The organoclay was montmorillonite modified by
octadecyltrimethyl amine with the commercial name Nano-
mer 128E. Other chemicals including zinc oxide (neutralizing
agent), stearic acid (processing aid), zinc stearate (ionic plasti-
cizer), Irganox 1010 (antioxidant) were used as received.
Preparation
EPDM/organoclay composites were prepared by the
melt blending method in a Branbender Plasti-Corder
PLV330 having a mixing chamber volume of about 70
cm3. The composition and specimen designations of the
resulting blends are given in Table 1. The mEPDM and
mEPDM/OC composites were obtained, at an operating
temperature of 1708C and a 100 rpm rotor speed for a total
mixing time of 12 min, while the mEPDM/OC/PP compos-
ite was prepared at 1908C for 12 min as mixing time. The
processing procedure for the EPDM/OC mixture included:
mixing of EPDM-g-MA with organoclay for 2 min,
followed by the addition of zinc oxide, as crosslinking
agent, stearic acid, Irganox 1010 and zinc stearate, and the
mixing lasted for another 5 min. The resultant mixtures
were sheeted on an electrically operated laboratory roller
heated at 155–1658C. Then, the test specimens were
obtained as 2-mm thick plates by compression molding at
1708C for 5 min and at a pressure of 150 MPa using an
electrical press. The plates were then cooled down at room
temperature under pressure. The ionic crosslinking degree
was determined using a Monsanto rheometer.
Measurements
X-ray diffractograms were carried out with a Bruker
A8 Advance diffractometer using nickel-filtered CuKaradiation (k ¼ 0.1541 nm) at a generator voltage of
40 kV and a generator current of 35 mA. The diffracto-
grams were obtained with a scanning rate of 28/min in the
low range of 2h (1–208) at room temperature. The basal
spacing of silicate was estimated using Bragg’s equation:
k ¼ 2d sinh, where d is the spacing between clay layers, his the diffraction angle and k is the X-ray wavelength.
The phase morphology of the EPDM-based composites
was examined using an environmental scanning electron
microscope (ESEM) Quanta 200, operating at an acceler-
ating voltage of 25 kV with secondary electrons. SEM
analysis was performed on samples fractured in liquid
nitrogen; the surface of samples was covered with a thin
layer of gold by sputtering in a sputter coater model EMI-
TECH K550X, to prevent electrostatic charging build-up
during observation. The composition and elemental map-
ping of the surfaces of these specimens were determined
using an energy dispersive X-ray (EDX) system attached
to the ESEM instrument.
The AFM images were obtained in air, at room tem-
perature, on an ‘‘SPM SOLVER Pro-M’’ instrument (NT-
MDT, Russia). An NSG10/Au silicon tip with a 6-nm
radius of curvature, 95-lm cantilever length, a force con-
stant of 11.8 N/m and an oscillation mean frequency of
256 kHz were used. The apparatus was operated in the
semi-contact mode, with a 256 3 256 scan point size,
scan velocity of 10-65 lm s21, depending on roughness
on different scan areas.
The surface tensions, polar and dispersive components
of the samples were determined by static contact angle
measurements using the sessile drop method. The equilib-
rium contact angles of the solid were determined using
CAM101 contact angle meter (KSV Instruments) at room
temperature, equipped with software for drop shape analy-
sis. Contact angles were measured on 1 lL of wetting sol-
vent and the results reported represent the average values
of 10 determinations carried out for five droplets from
separate locations. Water (W), ethylene glycol (EG), and
formamide (FA) were utilized as probe liquids.
RESULTS AND DISCUSSION
Morphological Properties
X-ray diffraction is a useful method to detect the
changes in the interlayer distance of silicate layers and to
TABLE 1. Formulation for the EPDM-based composites.
Components
Sample code
mEPDM mEPDM/OC mEPDM/OC/PP
EPDM-g-MA 100 100 100
Zinc oxide 10 10 10
Stearic acid 1 1 1
Zinc stearate 20 20 20
Irganox 1010 2 2 2
organoclay 0 7.5 7.5
PP-g-MA 0 0 22.5
Total, g 133 140.5 163
380 POLYMER COMPOSITES—-2012 DOI 10.1002/pc
monitor the intercalation behavior of organoclay and
polymer chains. If the clay diffraction pattern of the com-
posite is located at equal or higher angles compared with
that evidenced in pure clay an ordinary composite is
obtained. A shift of the diffraction peak of the composite
to smaller angles determines an increase in the interlayer
spacing of the clay, which means that an intercalation
occurs, while a broadening of the diffraction peak is con-
sidered as the result of partial exfoliation [20]. The XRD
patterns of organoclay and EPDM-based composites are
depicted in Figure 1. It can be seen that the characteristic
diffraction peaks of organoclay are located at 3.81 and
5.658, corresponding to a basal spacing of 2.32 and
1.56 nm, respectively. mEPDM does not show any peak
in this region.
The XRD patterns of mEPDM/OC and mEPDM/OC/
PP nanocomposites show that the (001) plane reflections
are shifted to smaller angles than that of organoclay (2h¼ 2.248), leading to an increase in the gallery height to
1.62 nm. The shift of the characteristic diffraction peak of
organoclay to smaller angles and the expanding of the
gallery indicate that the polymer does intercalate into the
clay interlayers and suggest the intercalate structure of
the mEPDM/OC nanocomposites. The greater polarity of
EPDM-g-MA leads to an increase in the system compati-
bility with organoclay and to a better dispersion.
In general, the phase morphology of some heterogene-
ous blends based on elastomer and nanoclay, obtained in
melt state, depends firstly on the composition, and then,
on the component viscosity blends ratio, interfacial ten-
sion, and processing conditions. The quality and uniform-
ity of nanoclay dispersion were analyzed by ESEM. SEM
images were taken from the fractured surface of the initial
sample (mEPDM) and mEPDM/OC nanocomposites. The
fractured surfaces of the EPDM-g-MA composite are pre-
sented in Figure 2. The micrographs reveal differences in
roughness on the fracture surface as well as their hetero-
geneous aspect (Fig. 2a–c). On this large enough fracture
FIG. 1. XRD patterns of EPDM-based composites.
FIG. 2. SEM micrographs of mEPDM composite.
DOI 10.1002/pc POLYMER COMPOSITES—-2012 381
surface, many irregular domains may be remarked simi-
larly to some layered configurations located within large
folding (Fig. 2b). Backscattered SEM images of the same
zone reveal granular domains containing strongly segre-
gated particles, the surface being rougher (Fig. 2c). Grey
dots were observed on the fractured surface containing
zinc. The EDX spectra taken of the mEPDM composite
(Fig. 3) confirm the presence of Zn. The elements identi-
fied on the fracture surface are given in Table 2. These
observations are in agreement with other results from the
literature, by which ionic crosslinks are formed by the
ionic interactions of maleic anhydride-grafted EPDM with
zinc cations [21, 22], these carboxylic salts tending to as-
sociate as multiplets and clusters [23, 24]. These clusters
behave as an ionic microphase immersed into a non-polar
matrix and can act as a reinforcement site, leading to the
improvement of elastomer characteristics.
The morphology of binary blends based on EPDM and
clay was biphasic. The continuous elastomer phase under-
goes a complex process of microstructuration due to
crosslinking (Figs. 4 and 5). If in the initial stage of a
binary blend, layers are formed, these layers undergo a
coalescence process presenting a fibrilar or co-continuous
structure. Depending on the blend composition and com-
ponent characteristics, this structure can rapidly turns into
a disperse structure, which is determined by the crosslink-
ing process. In this case, on the micrographs of the frac-
ture surface, a granular phase morphology was observed,
having different dimensional particles of crosslinked
EPDM arranged as round layers. At higher magnifica-
tions, a variation in the granular structure of the round
layers was observed, making evident some hollows and
FIG. 3. EDX spectrum taken from mEPDM composite. [Color figure can
be viewed in the online issue, which is available at wileyonlinelibrary.
com.]
TABLE 2. EDX quantitative analysis of EPDM composites.
Samples
Elements (wt%)
C O Zn Na Mg Al Si Ca
mEPDM 90.29 6.40 3.31 – – – – –
mEPDM/OC 82.93 7.51 5.05 2.41 0.20 0.55 1.25 0.09
mEPDM/OC/PP 87.04 7.57 2.62 1.72 0.04 0.25 0.71 0.05FIG. 4. SEM micrographs taken from fracture surface of mEPDM/OC
nanocomposite.
382 POLYMER COMPOSITES—-2012 DOI 10.1002/pc
prominences. In the same time, a coalescence process
may occur among particles, so that the size of the cross-
linked elastomer particles depends on the competition
between the fracture and the coalescence processes occur-
ring during blending. A similar observation was also
reported in the literature [25, 26]. A good adhesion does
not exist between phases in all cases during the fracture
process, since many domains were taken out of their
initial location, thus remaining cavities, and the most
particles leaving the phase in which some hollows are
observed.
The particle sizes depend on different factors such as
the rheological properties of each phase, blending power,
reactive group content, and the technological conditions
of crosslinking. The microstructure of mEPDM/OC nano-
composites is biphasic, clay aggregates were observed in
the EPDM matrix due to the formation of the hydrogen
bonds between hydroxyl groups of the clay surface and
the carboxyl groups of maleated EPDM. By adding
maleated polypropylene (mPP) as compatibilizer, a better
dispersion of nanoclay particles was not observed
(Fig. 5). However, the nanoclay dispersion in the two
samples of mEPDM/OC and mEPDM/OC/PP was practi-
cally similar, but not complete.
On the backscattered images of fracture surface of
mEPDM/OC and mEPDM/OC/PP specimens, both nano-
clay aggregates of micronic sizes and some Zn agglomer-
ated domains were observed (Figs. 4c and 5c). Figures 6
and 7 show the EDX spectra of mEPDM/OC composites,
where Si, Na, Ca, O, Al elements represent the compo-
nents of organoclay (Table 2). SEM elemental mapping
technique was used to evidence the elemental distribution
on the fracture surface. Some agglomerations were
observed mainly for the Zn element. The results presented
in Figure 8 confirm the X-ray data regarding the good dis-
persion of nanoclay within the polymer matrix. EDX
microanalysis was carried out in different locations on the
composite samples giving nearly constant values of the
relative silicon amount, which suggests a quite uniform
dispersion of clay nanoparticles in the polymer.
AFM shows a strong potential in investigating the sur-
face and cross section morphology of nanocomposites,
FIG. 5. SEM micrographs taken from fracture surface of mEPDM/OC/
PP composite.
FIG. 6. Elemental composition of mEPDM/OC. [Color figure can be
viewed in the online issue, which is available at wileyonlinelibrary.com.]
DOI 10.1002/pc POLYMER COMPOSITES—-2012 383
permitting to obtain two dimensional (2D; plane) and
three dimensional (3D; relief) images. Also, the ‘‘phase
contrast’’ (pc) technique is an additional procedure that
affords the visualization of areas with different physical
properties (mechanical, density), providing data about
phase separations, presence of different particles or struc-
tures at nano or micro levels. To analyze the internal
morphology of EPDM composites, the samples were frac-
tured in liquid nitrogen and the cross section surface was
studied by AFM. Figure 9 shows the cross section images
of the mEPDM composite, with a root mean square
roughness of 5.44 nm. The phase contrast image reveals a
homogeneous material, as the phase shift is only of 38(Fig. 9c). Typical cross section images of the mEPDM/
OC/PP nanocomposite are presented in Figure 10. Here,
the root mean square roughness is of 6.29 nm, which is
very close to the value for the mEPDM sample. In this
case, the phase shift is much higher, of about 908 (Fig.
10c), which means that there are two very different com-
ponents in system, one is the polymer matrix and the sec-
ond the organoclay particles of 50–150 nm thickness, uni-
formly dispersed in the EPDM matrix with a planar orien-
tation. The phase separation of the two components in the
fractured area is revealed very clearly (Fig. 10b). The 2D,
3D, and pc images (Fig. 10) show that the organoclay
particles are parallelepipedic and do not present a sheet
architecture, which implies that the polymer was interca-
lated into the clay galleries, but exfoliation did not occur,
as evidenced by the X-ray investigations.
Surface Properties
The incorporation of organoclay in composite would
be expected to have an important influence on the surface
properties of the composites based on EPDM-g-MA. The
contact angles of the EPDM composites with water, EG,
and FA are listed in Table 3. EPDM is basically a hydro-
phobic material [18] and thus high values of contact angle
are expected. From Table 3, it appears that the contact
angles for the composite with nanoclay (mEPDM/OC) are
considerably higher than those of the unfilled sample
(mEPDM) and of the compatibilized nanocomposite
(mEPDM/OC/PP). This increase may be due to the
increase of surface polarity. Considering the contact angle
with water as a measure of hydrophobicity of a solid sur-
face, the data listed in Table 3 reveal that the addition of
organoclay in the composition increased substantially the
hydrophobicity (h ¼ 1238 for mEPDM/OC). PP-g-MA
incorporation into the matrix diminished the contact
angle. The composite surface can contain some mPP
added and thus the hydrophobicity of the material
decreases.
Then, the surface tension, dispersion and polar compo-
nents of the materials can be evaluated from the contact
FIG. 8. SEM image and the corresponding maps of elements for
mEPDM/OC/PP. [Color figure can be viewed in the online issue, which
is available at wileyonlinelibrary.com.]
FIG. 7. EDX spectrum of mEPDM/OC/PP composite. [Color figure can
be viewed in the online issue, which is available at wileyonlinelibrary.
com.]
384 POLYMER COMPOSITES—-2012 DOI 10.1002/pc
angle data, according to the geometric mean model [27–
29], using the following equations:
1þ cosh2
:clvffiffiffiffifficdlv
q ¼ffiffiffiffiffifficpsv
p:
ffiffiffiffifficplvcdlv
sþ
ffiffiffiffiffifficdsv
q(1)
csv ¼ cdsv þ cpsv (2)
where h is the contact angle of the test liquid with polymer,
subscripts lv and sv refer to the interfacial tensions between
liquid–vapor and surface–vapor, respectively, and super-
scripts p and d refer to the polar and dispersive or non-polar
component, respectively, of total surface tension, csv.To obtain information regarding the interaction
between the test liquid and the composite surfaces, the
work of adhesion, the interfacial energy, the spreading
coefficient and the Girifalco-Good’s interaction parameter
were calculated.
The work of adhesion, WA, the work required to sepa-
rate two surfaces in contact, is given by the expression
[30, 31]:
WA ¼ clvð1þ coshÞ (3)
FIG. 10. AFM images of the cryogenic fracture surface of mEPDM/
OC/PP composite: (a) 2D view, (b) 3D view, and (c) phase contrast
view. [Color figure can be viewed in the online issue, which is available
at wileyonlinelibrary.com.]
TABLE 3. Contact angle (8) results for composites.
Samples hW hEG hFA
mEPDM 107.05 67.81 83.24
mEPDM/OC 123.78 87.49 92.93
mEPDM/OC/PP 96.01 73.09 76.31
FIG. 9. AFM images of the cryogenic fracture surface of mEPDM
composite: (a) 2D view, (b) 3D view, and (c) phase contrast view.
[Color figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
DOI 10.1002/pc POLYMER COMPOSITES—-2012 385
The spreading coefficient, Sc, and Girifalco and
Good’s interaction parameter, F, between the solid sur-
face and the test liquid were determined using Eqs. 4 and
6 [30, 31]:
Sc ¼ csv � csl � clv (4)
where csl is interfacial energy, between the studied sur-
faces and test liquid, determined by Dupre’s Eq. 5 [30]:
csl ¼ csv þ clv �WA (5)
U ¼ clvð1þ coshÞ2ðclvcsvÞ1=2
(6)
The properties of the three probe liquids: water, EG,
and FA are given in Table 4 [32–34].
The solid surface tension, csv, dispersion and polar com-
ponents, cdsv and cpsv, of the composites can be calculated
from the contact angle by using Eqs. 1 and 2, knowingthe surface tension components of different liquids from
Table 4 and the contact angles from Table 3. A linear
plot of ð1þ cosh=2Þðclv=ðcdlvÞ0:5 versus ðcplv=cdlvÞ0:5 (due to
Eq. 1, [35]) produced a straight line, where ðcplvÞ0:5 is
given by the slope and ðcdlvÞ0:5 is the intercept. The total
surface tension, csv is the sum of cdsv and cpsv (Eq. 2).The resulting values of surface tension, csv, and its dis-
persive, cdsv, and polar, cpsv components, for all samples
are listed in Table 5. The csv values showed a slightly
increasing trend upon the addition of organoclay. Both
the dispersive as well as the polar components increased
for the mEPDM/OC composite containing organoclay
only, whereas no significant variation in csv occurred
when mPP was incorporated into the composition (Table
5). The results indicate that csv is mainly due to dispersive
forces, cdsv, and to a lesser degree, to polar forces, cpsv.The increase in the contribution of polar component, cpsv,to the surface energy can be due to the enrichment in po-
lar groups on the surface and to the enhanced total solid
surface free energy. For the simple mEPDM composite,
the csv value was 24.3, this value increasing to 28.2 for
the mEPDM/OC composite, suggesting that the nature of
the forces acting on the surface is different.
The work of adhesion, WA depends only on the contact
angle and the surface tension of the liquid [30]. The work
of adhesion, WA, for the composites under study, for the
three test liquids was calculated from Eq. 3, using the val-
ues h and clv from Tables 3 and 4, and its values are
given in Table 5. Generally, the values of WA are higher
for EG and FA compared with water. The adhesion work
can be correlated with the degree of interaction between
the polymer matrix and organoclay and/or compatibilizer.
High values of WA indicate a strong interaction between
components. For the mEPDM/OC composite, the values
of adhesion work are lower in the three test liquids, these
values increasing again when mPP was added. This indi-
cates that the absence of compatibilizing agent from the
mEPDM composite determined a good dispersion of the
components in the system, thus none of the selected
liquids can penetrate into the sample, which is more evi-
dent from the contact angle values (Table 3). Also, for all
test liquids, the values of interfacial energy csl are much
lower for the mEPDM/OC sample (Table 5).
The spreading coefficients of the test liquids used for
contact angle measurements, calculated according to Eq.4 are listed in Table 6. If their values are positive (Sc [0), the liquid will spontaneously wet and spread on a
solid surface, whereas if it is negative (Sc \ 0), the (par-
tial) absence of wetting and spreading can be evidenced
[30]. The spreading coefficient values are less negative
for EG and FA than those for water. The spreading coeffi-
cient for water becomes more negative and the wetting
will be difficult on the surface. This observation is in
good agreement with the highest contact angle values for
water (Table 3). From Table 6, it can be concluded that
EG (less negative values of Sc) is the better wetting agent
for these composites.
Girifalco-Good’s interaction parameter F was calcu-
lated using the Eq. 6 and the values for all studied com-
posites are presented in Table 6. This parameter allows us
to evaluate the degree of interaction between the test
liquids and the composite surface, higher values of Fpoints out a greater interaction. FW, FEG, and FFA are
the Girifalco-Good’s interaction parameters due to water,
EG and FA, respectively. The greatest values of Giri-
falco-Good’s interaction parameter were obtained for EG
and FA. Thus, the interaction between EG and FA and
the composite surface is more relating to water and the
TABLE 4. Surface energy parameters for test liquids (in mN/m) [32–
34].
Test liquid clv cdlv cplv
Water 72.8 21.8 51.0
Ethylene glycol 48.0 29.0 19.0
Formamide 58.0 39.0 19.0
TABLE 5. Dispersive, cdsv, and polar, cpsv, components and surface tension, csv (in mN/m), work of adhesion, WA, and interfacial energy, cs1, for allstudied samples.
Samples cdsv cpsv csv WA(w) WA(EG) WA(FA) cs1W cs1EG cs1FA
mEPDM 24.14 0.16 24.29 51.46 66.13 64.83 45.63 6.17 17.47
mEPDM/OC 26.94 1.27 28.20 32.32 50.10 55.04 31.92 10.34 10.57
mEPDM/OC/PP 22.05 2.25 24.30 65.17 61.96 71.73 68.68 26.10 31.16
386 POLYMER COMPOSITES—-2012 DOI 10.1002/pc
composite surface. The incorporation of organoclay in the
composite without maleated PP (mEPDM/OC) leads to
the decrease of interaction between composite surface and
probe liquid.
The changes in the surface properties such as WA, Sc,and F with the composition of samples can be due to var-
iations in the surface roughness. The presence of a com-
patibilizing agent—maleated polypropylene (PP-g-MA),
generally, further improved the wettability and slightly
hydrophilicity in organoclay nanocomposites.
CONCLUSIONS
EPDM-g-MA nanocomposites were prepared by melt
blending method in a Branbender Plasti-Corder. XRD pat-
terns, SEM, and AFM results revealed the intercalate
structure of studied EPDM-based nanocomposites, the
good dispersion of nanoclay within the polymer matrix
and that the PP-g-MA was an efficient compatibilizing
agent for studied composites. Also, by EDX elemental
mapping technique was evidenced the distribution of ele-
ments of organoclay on the fracture surface of nanocom-
posites. These results confirm the dispersion of nanoclay
within the polymer matrix excepting some agglomeration
observed mainly for Zn element. The surface properties
such as wettability and slightly hydrophilicity of the stud-
ied organoclay nanocomposites are clearly improved by
the addition of compatibilizing agent, maleated polypro-
pylene (PP-g-MA) in polymer matrix.
NOMENCLATURE
AFM Atomic force microscopy
EG Ethylene glycol
EPDM Ethylene propylene diene rubber
ESEM Environmental scanning electron microscope
FA Formamide
MA Maleic anhydride
OC Organoclay
PP Polypropylene
SEM Scanning electron microscopy
REFERENCES
1. R.D. Allen, J. Elast. Plast., 15, 19 (1983).
2. A. Acharya, M. Pramanik, S.K. Srivastava, and A.K. Bhow-
mick, J. Appl. Polym. Sci., 93, 2429 (2004).
3. S.J. Ahmadi, Y. Huang, and W. Li, Compos. Sci. Technol.,65, 1069 (2005).
4. B. Kumar, S. Rana, and R.P. Singh, Exp. Polym. Lett., 1,748 (2007).
5. J. Lu, S. Chen, J. Zhang, and Z. Xu, J. Appl. Polym. Sci.,117, 1741 (2010).
6. E.E.B. Meuleman, J.H.A. Willemsen, M.H.V. Mulder, and
H. Strathmann, J. Membr. Sci., 199, 235 (2001).
7. S.S. Ray and M. Okamoto, Prog. Polym. Sci., 28, 1539 (2003).
8. S. Pavlidou and C.D. Papaspyrides, Prog. Polym. Sci., 33,1119 (2008).
9. D. Kang, D. Kim, S.H. Yoon, D. Kim, C. Barry, and J.
Mead, Macromol. Mater. Eng., 292, 329 (2007).
10. S.J. Ahmadi, Y.D. Huang, and W. Li, J. Compos. Mater.,39, 745 (2005).
11. B.L. Liu, Q.J. Ding, Q.H. He, J. Cai, B.X. Hu, and J. Shen,
J. Appl. Polym. Sci., 99, 2178 (2006).
12. L.L. Wang, Y.P. Tong, L.Q. Zhang, and M. Tiau, J. Appl.Polym. Sci., 116, 3184 (2010).
13. E.P. Giannelis, Adv. Mater., 8, 29 (1996).
14. P.L. Teh, I.Z.A. Mohd, A.S. Hashim, J. Karger-Kocsis, and
U.S. Ishiaku, Eur. Polym. J., 40, 2513 (2004).
15. S.S. Ray and M. Bousmina, Macromol. Rapid Commun., 26,1639 (2005).
16. I. Kelnar, V. Khunova, J. Kotek, and L. Kapralkova, Poly-mer, 48, 5332 (2007).
17. A. Mirzadeh, P.G. Lafleur, M.R. Kamal, and C. Dubois,
Polym. Eng. Sci., 50, 2131 (2010).
18. P. Svoboda, C. Zeng, H. Wang, L.J. Lee, and D.L. Toma-
sko, J. Appl. Polym. Sci., 85, 1562 (2002).
19. D.M. Stelescu, A. Airinei, M. Homocianu, D. Timpu, and
C. Grigoras, Mater. Plast., 47, 411 (2010).
20. M. Frouchi, S. Dadbin, Z. Salhpour, and M. Nofersti, J.Membr. Sci., 282, 142 (2006).
21. A.Y. Coran, Rubber Chem. Technol., 61, 281 (1988).
22. H. Zhang, R.N. Data, A.G. Talma, and J.W.M. Noorder-
meer, Eur. Polym J., 46, 754 (2010).
23. M.E.L. Wouters, V.M. Litvinov, F.L. Binsbergen, J.G.P.
Goossens, M. van Duin, and H.G. Dikland, Macromolecules,36, 1147 (2003).
24. A. Eisenberg, Macromolecules, 3, 147 (1970).
25. B.D. Favis, Polymer Formulations Blends,Vol. 1, D.R. Paul,C.B. Bucknall, Eds., Wiley, New York, 501 (2000).
26. L.A. Utracki and Z.H. Shi, Polym. Eng. Sci., 32, 1824 (1992).
27. D.K.Owens andR.C.Wendt, J. Appl. Polym. Sci., 13, 1741 (1969).
28. D.H. Kaelble, J. Adhesion, 1, 102 (1969).
29. Y. Ni and S. Zheng, Macromolecules, 40, 7009 (2007).
30. S.P. Thomas, S. Thomas, R. Abraham, and S. Bandyopad-
hyay, Exp. Polym. Lett., 2, 528 (2008).
31. K.F. Grythe and F.K. Hansen, Langmuir, 22, 6109 (2006).
32. C.J. Van Oss, R.J. Good, and M.K. Chaudhury, J. ColloidInterface Sci., 111, 378 (1986).
33. G. Strom, M. Fredrikson, and P. Stenius, J. Colloid Inter-face Sci., 119, 352 (1987).
34. D.Y. Kwok, D. Li, and A.W. Neumann, Langmuir, 10, 1323 (1994).
35. M. Rankl, R. Laib, and S. Seeger, Colloids Surf. B: Bioin-terfaces, 30, 177 (2003).
36. L.A. Girifalco and R.J. Good, J. Phys. Chem., 61, 904 (1957).
TABLE 6. Spreading coefficient, Sc and Girifalco-Good’s interaction
parameters, F, between water, ethylene glycol or formamide, and surface
composites.
Samples Scw ScEG ScFA FW FEG FFA
mEPDM 294.14 229.87 251.17 0.61 0.97 0.86
mEPDM/OC 2113.28 245.90 260.96 0.36 0.68 0.68
mEPDM/OC/PP 280.42 234.04 244.27 0.77 0.91 0.95
DOI 10.1002/pc POLYMER COMPOSITES—-2012 387