organoclay–natural rubber nanocomposites
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Polymer International Polym Int 53:1766– 1772 (2004)DOI: 10.1002/pi.1573
Organoclay–natural rubber nanocompositessynthesized by mechanical and solution mixing
methodsMA L ´ opez-Manchado,∗ B Herrero and M ArroyoInstitute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
Abstract: This investigation describes two methods to obtain rubber composites based on natural rubber
(NR) and organophilic layered silicates. In order to improve the exfoliation and compatibilization of the
organoclays with the rubber matrix, a new approach which involves swelling of the organoclays with an
elastomer solution prior to compounding has been used. The effect of the addition during swelling of a
coupling agent, namely bis(trietoxysilylpropyl)tetrasulfan (TESPT), on the behaviour of the composites
was also investigated. The results show that a low amount of organoclay (10 phr) significantly improves the
properties of natural rubber. This suggests a strong rubber–organoclay interaction which is attributed to a
high degree of rubber intercalation into the nanosilicate galleries, as was confirmed from X-ray diffraction.
In addition, an ulterior improvement in the properties of the nanocomposites prepared by solution mixing
is clearly observed, due to the better filler–rubber compatibility. An even further increase in the properties
is observed by treating the silicate with a silane coupling agent. The silane functional groups modify the
clay surface, thus reducing the surface energy, and consequently improving the compatibility with the
rubber matrix.
2004 Society of Chemical Industry
Keywords: rubber nanocomposites; organoclays; TESPT; mechanical properties
INTRODUCTION
The incorporation of fillers into elastomer matrices
leads to a significant improvement in the physical,
mechanical and electrical properties of crosslinked
elastomeric composites. This reinforcing effect is pri-
marily due to hydrodynamic interactions between
the rubber and filler surfaces.1 Traditionally, car-
bon black has been the primary filler used by the
rubber industry. However, since the 1950s non-
black fillers such as precipitated silica have been
increasingly used. At present, nanometer-scale rein-
forcing particles have attracted considerable attention
from polymer scientists. Because of their high aspect
ratio (length/diameter) and low density, they may be
used as substitutes for traditional fillers in polymermatrices. The most common reinforcements on the
nanoscale level are inorganic clay minerals consisting
of nanolayered silicate.2 – 5 Stacking of the layers of
approximately 1 nm thickness by weak dipolar forces
leads to interlayers or galleries between the layers.
These galleries are normally occupied by metallic
cations such as K +, Na+, Ca++, and Mg++. These
metalic cations can be easily exchanged by organic
ammonium salts, thus producing organophilic clays,
further known as organoclays.6 Organophilic modifica-
tion makes the silicate compatible with the polymer.
These entering guest molecules can either simply
increase the distances between the ‘still-parallel’ lay-
ers in an intercalation process or entirely randomly
disperse the separate sheets in an exfoliation process.
In recent years, these types entirely of hybrid materi-
als based on layered silicate polymer nanocomposites
have focused the attention of researchers because of
their unexpected hybrid properties derived from both
components which are not shared by their conven-
tional microcomposite counterparts.7 – 9 Such materi-
als are finding applications in areas where conventional
filled composites or microcomposites are being used.
These composites on the nanoscale level show signifi-
cant improvements in physical, chemical, mechanical
and thermal properties,8 gas permeability10 and fireretardance.11
Different methods for synthesizing polymer– layered
silicates nanocomposites have been typically described,
eg in situ intercalative polymerization, polymer inter-
calation from solution, and direct polymer melt
intercalation.12 Several studies have shown the pos-
sibility of preparing intercalated or exfoliated rub-
ber nanocomposites by different methods.13–16 It
has been reported that the nanolayered silicate dis-
persed into a rubber matrix provides an effective
reinforcement.17–21
∗ Correspondence to: MA L ´ opez-Manchado, Institute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
E-mail: lmanchado@ictp.csic.es
( Received 30 May 2003; revised version received 17 February 2004; accepted 18 February 2004 )
Published online 26 July 2004
2004 Society of Chemical Industry. Polym Int 0959–8103/2004/$30.00 1766
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Organoclay–Natural Rubber Nanocomposites
The goal of this present study is to analyse
the morphology, physical and mechanical properties
of natural rubber nanocomposites, synthesized by
two different methods using octadecylammonium-
modified saponite. A new approach is considered,
involving swelling of the organoclay with a natural
rubber/toluene solution. The effect of the intercalation
of the silane coupling agent to the filler/rubber toluenesolution is also investigated.
EXPERIMENTAL
Materials
Samples of natural rubber were kindly supplied by
Malaysian Rubber, Berhad (Malaysia), under the trade
name CV 60 (Mooney viscosity, ML(1 + 4) 100 ◦C =
60). Sodium–saponite, with a cation exchange capac-
ity (CEC) value of 70 mmol per 100 g, was provided
by Tolsa SA, Madrid (Spain). In order to increase the
spacing between the layers and improve the compati-
bility of natural rubber, the organoclay was prepared
in our laboratories by treating the sodium– saponite
with a quaternary octadecylammonium salt, follow-
ing a previously described procedure.22 Octadecy-
lamine, purchased from Aldrich, Madrid (Spain),
was used as the organic modifier for the clay.
Bis(triethoxysilylpropyl)tetrasulfan (TESPT) (Si69),
manufactured by Degussa AG, Bitterfeld (Germany),
was used as the coupling agent.
Synthesis of natural rubber/clay nanocomposites
Two methods for synthesizing elastomer–clay nano-
composites were evaluated, namely mechanical andsolution mixing methods. Figure 1 provides a con-
ceptual picture of the synthesized nanocomposites
via both methods. The solution mixing method was
carried out as follows. Natural rubber was swollen
in toluene under continuous stirring, and while the
organophilic clay was itself dispersed in toluene. This
dispersion was poured into the rubber/toluene solu-
tion and maintained under vigorous stirring for 24 h,
and the solvent was then evaporated under vacuum
at room temperature. The organoclay content in the
nanocomposite was 10 parts per hundred parts of
rubber (phr). In order to analyse the effect of a com-
mercial silane coupling agent on the behaviour of the
composite, 5 phr of bis(trietoxysilylpropyl)tetrasulfan
(TESPT) (Si69) were added to one half portion of
the solution and also maintained under continuousstirring over 24 h.
In the case of the mechanical method, rubber
composites were prepared in an open two-roll mill
at room temperature. The rotors operated at a speed
ratio of 1:1.4. The vulcanization ingredients were
added to the elastomer prior to incorporation of the
filler and finally, the sulphur was incorporated. The
proportion of organoclay was also 10 phr. The material
was vulcanized in an electrically heated press at 150◦C
for the optimum cure time (t 90), previously determined
from an oscillating disc rheometer (Monsanto MDR
2000, Alpha Technologies, Swindon, UK). Specimens
were mechanically cut out from the cured plaques. The
recipes for the rubber composites are given in Table 1.
The effects of Na+ –saponite and octadecylamine in
the absence of clay have been investigated in a previous
work.22
Measurements
For the bound rubber measurements, approximately
0.2 g of each sample were cut into small pieces
of approximately 1 mm3 in size and placed into
a stainless steel cage of known weight. Then, the
cage was immersed in 50ml of toluene for 72 h at
room temperature. Finally, the samples were takenout and vacuum dried at 60 ◦C to constant weight.
The percent-bound rubber content of the polymer,
RB, was measured as the weight percentage of the
unsolubilized rubber on the silicate surface, according
to the following equation:
RB =W fg − W [mf /(mf +mp)]
W [mp/(mf + mp)]× 100 (1)
+
Organoclay Intercalated or exfoliatednanocomposite
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Solvated organoclay
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Solvated polymer
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Evaporated
Intercalated or exfoliatedsolvated nanocomposite
Intercalated or exfoliatednanocomposite
(a)
(b)
Polymer
Figure 1. Schematic representations of the preparation of nanocomposites via the (a) mechanical and (b) solution mixing methods.
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MA L opez-Manchado, B Herrero, M Arroyo
Table 1. Recipes used for the rubber compounds
Natural rubber 100
Zinc oxide 5
Stearic acid 1
Sulfur 2.5
MBTSa 1
PBNb 1
Organoclay 10a Benzothiazyl disulfide.b Phenyl beta naphthyl amine.
where W fg is the weight of silicate and gel, mf the
weight of the filler in the compound, mp the weight of
the polymer in the compound, and W the weight of
the specimen.
Tensile stress–strain properties were measured
according to ISO 37–1977 specifications, on an
Instron dynamometer (Model 4301), at 25 ◦C at
a crosshead speed of 500 mmmin−1. Compression
set measurements were performed according toISO 815–1972 during 24h, at 70◦C with 25 %
compression. Rebound resilience measurements were
carried out on a Schob pendulum according to ISO
4662-1978. Shore hardness was measured by using a
Bareiss Rockwell tester according to ASTM D-2240.
In all of the tests, data were used as the average of at
least five measurements.
The number of active network chain segments
per unit of volume (crosslinking density) was
determined on the basis of the rapid solvent-swelling
measurements (toluene at 30 ◦C) by application of the
Flory–Rehner equations.23
The dynamic mechanical properties of the solid
polymer were determined on a dynamic mechanical
Metravib Model Mark 03 thermoanalyser. Tests were
carried out in the torsion deformation mode, at a
frequency of 5 Hz, with the temperature programmes
being run from −100 to 50 ◦C, at a heating rate of
2 ◦C min−1, under a controlled sinusoidal strain in a
flow of nitrogen.
RESULTS AND DISCUSSION
Bound rubber
Bound rubber (RB) measurements are conventionally
carried out to assess rubber–filler interactions. So,
the higher the bound rubber, then the higher is the
polymer–filler interaction.24 The results obtained are
summarized in Table 2. Organoclay-filled composites
obtained by solution blending showed higher RB values
than those prepared by simple mechanical mixing,
Table 2. Bound rubber measurements
System RB (%)
NR 0
NR –organoclay (mechanical mixing) 10.6NR –organoclay (solution mixing) 13.4
NR – organoclay – Si69 (solution mixing) 15.2
which indicates a higher compatibility between the
filler andthe polymer matrix when the nanocomposites
were synthesized by solution mixing. In addition, the
bound rubber values also increase in the presence of
the silane coupling agent. The latter has a sulfidic
linkage between two triethoxysilylpropyl groups. This
coupling agent is capable of interacting with the
O– H groups of the silicate through its –Si(OCH3)3
functionality, through hydrogen bonding. The sulfide
group of the coupling agent bonded to the silicate is
dissociated and reacts with the rubber molecule to
form crosslinks between the silicate and the rubber.
These chemical bonds lead to an enhancement of
bound rubber formation. Similar conclusions were
drawn by Manna et al ,25 when analysing precipitated
silica and epoxidized natural rubber composites in the
presence of a silane coupling agent.
Vulcanization characteristics
The vulcanization curves of the pristine natural rubber
and its composites with organoclay are graphically
represented, as obtained from the MDR 2000
measurements, in Fig 2. The curing characteristics,
expressed in terms of the vulcanization times, t S2
(scorch time) and t 90 (optimum cure time), as
well as the maximum and minimum values of the
torque, S max and S min, respectively, and delta torque
S (S = S max − S min), are deduced from the curves.
These parameters, along with the cure rate index, CRI
expressed as CRI = 100/(t 90 − t S2), are compiled in
Table 3.
Note that both vulcanization times, t S2 and t 90, weresharply reduced by the incorporation of low organoclay
amounts, showing accelerated vulcanization with
respect to that of pure NR. It is deduced that the
organoclay behaves as an effective vulcanizing agent
for natural rubber. These results are confirmed by the
cure rate index values, CRI , which show a significant
increase with addition of organoclay, attributed to the
amine functionalities in the nanosilicate structure. It
is well known that amine groups facilitate the curing
reaction of natural rubber compounds. Moreover, the
synergetic combination of a benzothiazyl accelerant
with an amine produces a particular accelerant effecton the rubber vulcanization reaction. Nevertheless, in
a previous study,26 it was demonstrated that in the
presence of organoclay a further accelerating effect
on NR curing takes place. In fact, the intercalation
of the octadecylamine within the silicate galleries
facilitates the vulcanization reaction, with a noticeable
decrease in the required time for NR vulcanization
in comparison with the blend filled with pure
octadecylamine only. In addition, it is important to
note that a further decrease in the cure time is
observed for the nanocomposite prepared by solution
mixing. On addition of the TESPT coupling agent,
a significant increase in the required time for NR
vulcanization is observed. This fact can be attributed
to interactions between the silane and amine groups
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Organoclay–Natural Rubber Nanocomposites
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30
S ′ ( d N m )
Time (min)
NR–organoclay (mechanical mixing)
NR–organoclay (solution mixing)
NR–organoclay–Si69 (solution mixing)
Unfilled NR
Figure 2. Vulcametric curves of the various systems obtained at 150 ◦C.
Table 3. Curing characteristics of the studied materials at 150 ◦C
t S2 (min) t 90 (min) Smax (dNm) Smin (dNm) S = Smax –Smin (dNm)
CRI, 100 (t 90 –t S2)
(min−1 )
NR 7.19 14.04 4.46 0.03 4.43 14.6
NR–organoclay (mechanical mixing) 3.24 6.87 8.83 0.04 8.79 27.5
NR–organoclay (solution mixing) 1.32 3.71 11.95 0.06 11.89 41.8
NR–organoclay–Si69 (solution mixing) 1.27 7.26 13.46 0.06 13.40 16.7
present in the silicate surface, so hindering theaccelerating effect of the amine groups.
On the other hand, the maximum torque and delta
torque increased by addition of the organosilicate,
showing the strong reinforcing effect of this filler. It
is of interest to point out that this effect is more
evident when the nanocomposites are prepared by
solution mixing, which suggests a higher compatibility
at the filler/elastomer interface. In addition, both
the maximum torque and differential torque were
found to increase with incorporation of a coupling
agent, thus indicating that the matrix–filler bonding
by TESPT takes place at the silicate layer surface.Furthermore, these results suggest that the natural
rubber became more crosslinked in the presence of the
organoclay, as was confirmed from crosslinking density
measurements (Table 4). Porter27 reported that the
crosslinking density of a carbon-black-reinforced
vulcanization system is enhanced by about 25 % when
compared with the corresponding unfilled one.
These results are in concordance with the bound
rubber measurements, which give an indication of the
rubber/filler interactions as a result of mixing.
Nanostructures of the vulcanizates
The organoclay nanolayers have been uniformly
dispersed (intercalated or exfoliated) in the elastomer
matrix by means of both the mechanical and
solution mixing techniques. The X-ray diffraction(XRD) patterns (Fig 3) show disappearance of the
diffraction peak at about 2θ = 5 ◦, corresponding to
the organosilicate interlayer platelet spacing.
Mechanical properties
The moduli at different elongations (50, 100, 300
and 500 %), maximum strength and elongation at
break of the studied elastomeric compounds are
compiled in Table 4. From the obtained results,
it can be deduced that the incorporation of small
amounts of organosilicate (10 phr) gives rise to a
noticeable increase in modulus, which shows thestrong reinforcing effect of these inorganic fillers. The
reinforcement is associated with the anisotropy and
high aspect ratio of organoclay nanofillers. These
act as short reinforcing fibers with a nanoscale
architecture. In addition, the modulus and maximum
tensile strength increase when the nanocomposite
is synthesized by the solution mixing method. This
fact can be attributed to the extent of dispersion
of the silicate in the NR matrix and the increased
crosslinking density resulting from polymer– filler
interactions. The silane coupling agent, which is itself a
crosslinking agent, increases the crosslinking density of
the composite, thereby enhancing the modulus. Thus,
the modulus at low strains was found to increase by
adding the silane coupling agent.28
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MA L opez-Manchado, B Herrero, M Arroyo
2 4 6 8 10 12 14
(a) Organoclay
(b) NR–organoclay (mechanical mixing)
(c) NR–organoclay (solution mixing)
I n t e n s i t y
(a)
(b)
(c)
2θ (degrees)
Figure 3. X-ray diffractograms of the various systems.
Table 4. Mechanical properties of the studied materials
Parameter Unfilled NR
NR–organoclay
(mechanical mixing)
NR–organoclay
(solution mixing)
NR–organoclay–Si69
(solution mixing)
Modulus, 50 % (MPa) 0.38± 0.02 0.95± 0.04 1.36± 0.05 1.45± 0.04
Modulus, 100 % (MPa) 0.59± 0.03 1.72± 0.08 2.25± 0.08 2.89± 0.06
Modulus, 300 % (MPa) 1.33± 0.11 4.31± 0.20 5.58± 0.25 7.77± 0.31
Modulus, 500 % (MPa) 2.60± 0.18 9.73± 0.42 11.20± 0.46 —
Maximum strength (MPa) 8.9± 0.68 20.6± 0.75 22.2± 0.68 15.2± 0.58
Elongation at break (%) 993± 38 1012 ± 52 919± 33 475± 28
Resilience (%) 63.0± 3.1 62.5 ± 2.7 64.5± 2.4 61.2± 2.1Hardness, Shore A 28.8± 2.1 43.1 ± 2.8 51.5± 2.6 54.2± 2.3
Compression set (%) 17.5± 1.1 22.4 ± 1.2 24.3± 1.0 27.4± 1.1
Crosslinking density (molml−1) 8.97± 10−5 1.32± 10−4 1.45± 10−4 1.61± 10−4
It is also worth while pointing out that the increase
in tensile strength by the addition of the organoclay
takes place without any loss in the elongation at break
of the material. However, a noticeable decrease in
this characteristic is observed, in the presence of the
silane coupling agent. This fact can be attributed to
the restriction in the chain slipping along the filler
surface due to the formation of chemical bonds in thepresence of the TESPT coupling agent. Similar results
have been reported by Ganter et al 29 when analysing
the properties of butadiene rubber (BR) containing
30 phr of organoclay and 3 phr of TESPT. These
authors concluded that the reactive coupling of the
elastomer matrix is also effective on the surface of
silicate layers containing quaternary ammonium salts.
Tensile measurements are in agreement with those
obtained from analysis of the hardness, resilience
and compression set of these materials. The increase
in hardness is related to a higher strength of the
composite. On the other hand, as can be suggested
from both the resilience and compression set results,
the elastic behaviour of the matrix hardly varies with
addition of the organoclay.
Therefore, it may be proposed that the silicate
nanolayers are well dispersed and exfoliated in the
elastomer matrix, so giving rise to the nanocompos-
ites. It has also been shown that compounding by
the solution method improves the filler/matrix com-
patibility and hence the dispersion of the filler in the
elastomeric matrix.
Dynamic mechanical properties
The dynamic mechanical properties of pristine NR and
its composites with the organosilicate were studied
over a wide temperature range (−100 to 50 ◦C).
The variation of tan δ as a function of temperature
for all of the studied materials is reported in Fig 4.
The tan δ peak, corresponding to the glass transition
temperature (T g) of the elastomer is reduced by adding
the organoclay, with this effect being more noticeable
in the case of composites prepared by the solution
mixing procedure. In fact, at low temperatures and
for a given energy input, fillers give a lower hysteresis.
This behaviour was explained by Wang30 in terms
of a reduction of the polymer volume fraction in the
presence of filler. That is, at low temperatures the
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Organoclay–Natural Rubber Nanocomposites
0
0.5
1
1.5
2
2.5
–50 0 50
Unfilled NR
NR–organoclay (mechanical mixing)
NR–organoclay (solution mixing)
NR–organoclay–Si69 (solution mixing)
t a n δ
Temperature (°C)
Figure 4. Tan δ as a function of temperature for the various systems.
polymer by itself is responsible for a high proportion of
energy dissipation, while the small solid filler particles
in the polymer matrix hardly absorb any energy.
Furthermore, the glass transition temperature (tan
δ peak) shifts to higher temperatures upon addition
of the filler. So, T g goes from −49.6 ◦C for
pristine natural rubber to −46.8 ◦C and −45.9 ◦C
for rubber composites obtained through mechanical
compounding and the solution mixing procedure,
respectively. These results suggest that there existsa strong adhesion at the filler/polymer interface, in
particular, in the case of the composite synthesized
by the solution mixing method. This interaction
restricts the mobility of the elastomer segments, which
significantly elevates the glass transition temperature.
In general, when the interaction between the filler
and the rubber is strong enough, the glass transition
temperature is shifted to a higher temperature by
adding a filler to the rubber matrix. Simultaneously,
the tan δ peak also becomes narrower, and its height
becomes smaller. In this study, the results obtained
are in concordance with the general tendency reported
in the literature.
Figure 5 shows the storage modulus (elastic
modulus) of NR and its composites with 10 phr fillerloading as a function of temperature. As observed, the
organoclay gives rise to a noticeable increase in mod-
ulus, in particular, when the composite is prepared by
the solution mixing procedure. This behaviour is due
to the hydrodynamic reinforcement arising from the
1.2 × 109
2.5 × 109
3.7 × 109
5 × 109
–80 –70 –60 –50 –40 –30 –20 –10 0
Unfilled NR
NR–organoclay (mechanical mixing)
NR–organoclay (solution mixing)
NR–organoclay–Si69 (solution mixing)
Temperature (°C)
G ′ ( P a )
Figure 5. Storage modulus as a function of temperature for the various systems.
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MA L opez-Manchado, B Herrero, M Arroyo
incorporation of solid particles into the elastomeric
matrices. It is well known that hydrodynamic rein-
forcement occurs in conventional fillers, so giving rise
to an increase in the modulus of the polymer matrix,
or an increase in the viscosity for liquids.31
This hydrodynamic effect mainly depends on two
factors, ie the volume fraction and the shape factor
of the filler particles. The shape factor is describedas the ratio between the longest dimension of the
particle to the shortest. In this case, the exfoliated
silicate shows a high shape factor. On the other hand,
it is assumed that the higher the volume fraction
of the filler, then the higher is its reinforcing effect.
The portion of rubber chains trapped on the filler
as a result of mixing (rubber portion immobilized or
occluded) act as a part of the filler rather than of
the polymer and hence, the effective volume of the
filler increases. From bound rubber measurements,
it has been deduced that this effect is higher when
the nanocomposite is prepared by the solution mixing
method, which explains the higher modulus obtained.
According to these results, it can be deduced that
by means of the solution method, a more intensive
intercalation is obtained, since the solvent gives rise
to both an increase of the ‘intergallery’ spacing and
swelling of the elastomer chains.
CONCLUSIONS
The physical and mechanical properties of nanocom-
posites based on natural rubber and a layered silicate,
prepared by two different methods, ie mechanical and
solution mixing, have been investigated.Both methods give rise to an optimal dispersion of
the filler into the elastomer matrix, as deduced from X-
ray diffraction studies. Nevertheless, the compatibility
between the filler and the rubber is improved by the
solution mixing method. Bound rubber measurements
show that when the nanocomposite is synthesized by
the solution mixing procedure a higher proportion
of polymer is fixed to the filler. This explains why
the mechanical and dynamic mechanical properties of
the nanocomposites prepared by solution mixing are
improved in relation to the nanocomposite synthesized
via mechanical compounding.On the other hand, it has been demonstrated that
TESPT (Si69) behaves as an effective coupling agent,
by improving the adhesion at the silicate/elastomer
interface. Hence, the composites containing the silane
coupling agent show a noticeable increase in tensile
modulus, strength and hardness.
ACKNOWLEDGEMENTS
The authors acknowledge the Ministerio de Ciencia y
Tecnologıa (Spain) for provision of a Ramon y Cajal
contract, to Dr Lopez-Manchado, and CICyT (MAT
2001-1634) for financial support.
REFERENCES1 Medalia AI and Krauss G, Reinforcement of elastomers by
particulate fillers, in Science and Technology of Rubber , 2nd
Edn, ed by Mark JE, Eman B and Erich FR, Academic Press,
San Diego, CA, USA, pp 387–418 (1994).
2 Le Baron PC, Wang Z and Pinnavaia T, Appl Clay Sci 15:11
(1999).
3 Xu W, Ge M and He P, J Polym Sci Polym Phys Ed 40:408
(2002).
4 Hambir S, Bulakh N, Kodgire P, Kalgaonkar R and Jog JP,
J Polym Sci Polym Phys Ed 39:446 (2001).
5 Wu Z, Zhou C and Zhu N, Polym Testing 21:479 (2002).
6 Lagaly G and Beneke K, Colloid Polym Sci 269:1198 (1991).
7 Richard A, Jandt KD, Edward JK and Giannelis EP, Macro-
molecules 28:8080 (1995).
8 Ususki A, Kawasumi M, Kojima Y, Fukushima Y, Okada A,
Kurauchi T and Kamigaito O, J Mater Res 8:1179 (1993).
9 Pramanik M, Srivastava SK, Samantaray BK and Bhowmick
AK, J Mater Sci Lett 20:1377 (2001).
10 Messersmith PB and Giannelis EP, Chem Mater 6:1719 (1994).
11 Gilman JW and Kashiwagi T, Sampe J 33:42 (1997).
12 Oriakhi C, Chem Br 34:59 (1998).
13 Okada A, Usuki A, Kurauchi T and Kamigaito O, Rubber
clay hybrids, in Hybrid Organic– Inorganic Composites, ed byMark JE, Lee CYC and Bianconi PA, ACS Symposium Series,
Vol585, AmericanChemical Society, Washington, DC,USA,
pp 55–65 (1995).
14 Usuki A, Tukigase A and Kato M, Polymer 43:2185 (2002).
15 Chang YW, Yang Y, Ryu S and Nah C, Polym Int 51:319
(2002).
16 Zhang L, Wang Y, Wang Y, Sui Y and Yu D, J Appl Polym Sci
78:1873 (2000).
17 Wang Z and Pinnavaia TJ, Chem Mater 10:3769 (1998).
18 Kojima Y, Fukumori K, Usuki A, Okada A and Kurauchi T,
J Mater Sci Lett 12:889 (1993).
19 Wang S, Long C, Wang X, Li Q and Qi Z, J Appl Polym Sci
69:1557 (1998).
20 Wang Y, Zhang L, Tand C and Yu D, J Appl Polym Sci 78:1879
(2000).21 Arroyo M, L opez Manchado MA and Herrero B, Polymer
44:2447 (2003).
22 L opez Manchado MA, Herrero B and Arroyo M, Polym Int
52:1070 (2003).
23 Flory PJ, Principles of Polymer Chemistry, Cornell University
Press, Ithaca, NY, pp 576 (1953).
24 Hantan E, Wolf S, Ademan M, Grewatto HP and Wang MJ,
Rubber Chem Technol 66:594 (1993).
25 Manna AK, De PP, Tripathy DK, De SK and Peiffer DG,
J Appl Polym Sci 74:389 (1999).
26 L opez-Manchado MA, Herrero B and Arroyo M, J Appl Polym
Sci 89:1 (2003).
27 Porter M, Kautsch Gummi Kunst 22:419 (1969).
28 Debnath S, De SK and Khastigir D, J Appl Polym Sci 37:1449
(1989).29 Ganter M, Gronski W, Reichert P and Mulhaupt R, Rubber
Chem Technol 74:221 (2000).
30 Wang MJ, Rubber Chem Technol 71:520 (1998).
31 Boonstra MM, Polymer 20:691 (1979).
1772 Polym Int 53:1766– 1772 (2004)
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