Preparation and characterization of nanocomposite hydrogels based on polyacrylamide for enhanced oil recovery applications

In the present work, attempts have been made to prepare nanocomposite type of hydrogels (NC gels) by crosslinking the polyacrylamide/montmorillonite (Na‐MMT) clay aqueous solutions with chromium (III). The X‐ray diffraction patterns of the NC gels exhibited a significant increase in d₀₀₁ spacing between the clay layers, indicating the formation of intercalated as well as exfoliated type of morphology. Exfoliation of the clay layers through out the gel network was found to be predominated, which evidences the high interaction between the polyacrylamide segments and montmorillonite layers. Gelation time as well as variation of viscoelastic parameters such as storage modulus (G′) of the gel network during gelation process at 75°C was studied and followed by rheomechanical spectroscopy (RMS). The NC gels prepared with lower crosslinker concentration showed higher strength and elastic modulus compared with the similar but unfilled polyacrylamide gel. This distinct characteristic of the NC gels yields a gel network structure with high resistance towards syneresis at high temperature in the presence of the oil reservoir formation water. The effects of the composition, such as clay content, crosslinker concentration, and also water salinity upon the gelation rate, gel strength as well as rate of syneresis have been investigated. To optimize the injectivity of the intercalated polyacrylamide solution before the onset of gelation with the gel strength of the final developed gel, sodium lactate was employed as retarder. This was found to be effective to balance these two characteristics of the NC gels, which are aimed to be used for water shut‐off and as profile modifier in enhanced oil recovery (EOR) process during water flooding process. The nanocomposite gels showed much more elasticity and extensibility at low crosslinker concentration compared with the similar but unfilled gel, which makes the NC gels suitable as an in‐depth profile modifier, and also as an oil displacing agent in the heterogeneous oil reservoir in chemical EOR. Effects of the clay content on the thermal stability of the gel network have also been investigated by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) has been performed upon the NC‐gel samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2096–2103, 2006     

Synthesis and mechanical properties of unsaturated polyester based nanocomposites

Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X‐ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite expanded from 1.25 nm to 4.5 nm, indicating intercalation. Glass transition values of these composites increased from 72°C, in the unfilled unsaturated polyester, to 86°C in the composite with 10% organically modified montmorillonite. From Scanning Electron Microscopy, it is seen that the degree of intercalation/exfoliation of the modified montmorillonite is higher than in the unmodified one. The mechanical properties also supported these findings, since in general, the tensile modulus, tensile strength, flexural modulus, flexural strength and impact strength of the composites with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. The tensile modulus, tensile strength, flexural modulus and flexural strength values showed a maximum, whereas the impact strength exhibited a minimum at approximately 3–5 wt% modified montmorillonite content. These results imply that the level of exfoliation may also exhibit a maximum with respect to the modified montmorillonite content. The level of improvement in the mechanical properties was substantial. Adding only 3 wt% organically modified clay improved the flexural modulus of unsaturated polyester by 35%. The tensile modulus of unsaturated polyester was also improved by 17% at 5 wt% of organically modified clay loading.     

Morphology,Thermal and Mechanical Properties of Biodegradable Poly(butylene succinate)/Poly(butylene adipate-co-terephthalate)/Clay Nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay.     

Impact modified epoxy/montmorillonite nanocomposites: synthesis and characterization

Diglycidyl ether of bisphenol A type epoxy resin-polyether polyol-organically treated montmorillonite ternary nanocomposites were synthesized in this study. The effects of addition of polyether polyol as an impact modifier on morphological, thermal and mechanical properties of nanocomposites were investigated by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry, impact and tensile testing. The results showed that organically treated montmorillonite is intercalated by epoxy, since the interlayer spacing expanded from 1.83 to 3.82 nm upon nanocomposite synthesis. The addition of polyether polyol impact modifier had no effect on the interlayer spacing. SEM examination showed that polyol forms an immiscible phase in the epoxy matrix. Thermal characterization of nanocomposites indicated an increase in T_g with respect to both polyether polyol and montmorillonite contents. The impact strength of the samples with no clay was improved approximately 160% upon adding 7 wt% polyether polyol. In polyether polyol modified nanocomposites, the impact and tensile strengths decreased with respect to increasing amount of montmorillonite and showed a maximum with respect to the polyether polyol content at constant clay loading. The Young's modulus of the nanocomposites exhibited an increase with respect to the montmorillonite loading and showed a maximum with respect to the polyol content at each clay loading.     

Thermal and mechanical properties of melt processed intercalated poly(methyl methacrylate)–organoclay nanocomposites over a wide range of filler loading

BACKGROUND: Poly(methyl methacrylate) (PMMA)–organoclay nanocomposites with octadecylammonium ion‐modified montmorillonite, prepared via melt processing, over a wide range of filler loading (2–16 wt%) were investigated in detail. These hybrids were characterized for their dispersion structure, and thermal and mechanical properties, such as tensile modulus (E), break stress (σ_brk), percent break strain (ε_brk) and ductility (J), using wide‐angle X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile and impact tests. RESULTS: Intercalated nanocomposites were formed even in the presence of 16 wt% clay (high loading) in PMMA matrix. PMMA intercalated into the galleries of the organically modified clay, with a change in d‐spacing in the range 11–16 Å. TGA results showed improved thermal stability of the nanocomposites. The glass transition temperature (T_g) of the nanocomposites, from DSC measurements, was 2–3 °C higher than that of PMMA. The ultimate tensile strength and impact strength decreased with increasing clay fraction. Tensile modulus for the nanocomposites increased by a significant amount (113%) at the highest level of clay fraction (16 wt%) studied. CONCLUSION: We show for the first time the formation of intercalated PMMA nanocomposites with alkylammonium‐modified clays at high clay loadings (>15 wt%). Tensile modulus increases linearly with clay fraction, and the enhancement in modulus is significant. A linear correlation between tensile strength and strain‐at‐break is shown. Thermal properties are not affected appreciably. Organoclay can be dispersed well even at high clay fractions to form nanocomposites with superior bulk properties of practical interest. Copyright © 2007 Society of Chemical Industry     

Preparation of polystyrene/clay nanocomposite by suspension and emulsion polymerization

Organophilic montmorillonite was prepared using ion‐exchange method between sodium ions in clay layers and four kind of quaternary ammonium salt. The montmorillonite has the largest d₀₀₁‐spacing, as determined by X‐ray diffraction in modified by di(hydrogenated tallowalkyl) dimethyl ammonium chloride. Polystyrene montmorillonite nanocomposites were obtained by suspension and emulsion polymerization of styrene in the dispersed organophilic montmorillonite. The d₀₀₁‐spacing of clay was determined by X‐ray diffraction (XRD). The thermal stability of organophilic montmorillonite was investigated by thermogravimetric analysis (TGA). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Synthesis and characterization of epoxy based nanocomposites

Epoxy‐clay nanocomposites were synthesized to examine the effects of the content and type of different clays on the structure and mechanical properties of the nanocomposites. Diglycidyl ether of bisphenol‐A (epoxy) was reinforced by 0.5–11 wt % natural (Cloisite Na⁺) and organically modified (Cloisite 30B) types of montmorillonite. SEM results showed that as the clay content increased, larger agglomerates of clay were present. Nanocomposites with Cloisite 30B exhibited better dispersion and a lower degree of agglomeration than nanocomposites with Cloisite Na⁺. X‐ray results indicated that in nanocomposites with 3 wt % Cloisite 30B, d‐spacing expanded from 18.4 Å (the initial value of the pure clay) to 38.2 Å. The glass transition temperature increased from 73°C, in the unfilled epoxy resin, to 83.5°C in the nanocomposite with 9 wt % Cloisite 30B. The tensile strength exhibited a maximum at 1 wt % modified clay loading. Addition of 0.5 wt % organically modified clay improved the impact strength of the epoxy resin by 137%; in contrast, addition of 0.5 wt % unmodified clay improved the impact strength by 72%. Tensile modulus increased with increasing clay loading in both types of nanocomposites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1081–1086, 2005     

Enhanced dyeability of poly(ethylene terephthalate)/organoclay nanocomposite filaments

This study deals with the generation of poly(ethylene terephthalate)/organoclay nanocomposite filaments by the melt‐spinning method and with the investigation of their morphological and dyeing properties. Different montmorillonite types of clay (Resadiye and Rockwood) were modified using different intercalating agents, and poly(ethylene terephthalate) nanocomposite filaments containing 0.5 and 1 wt% organoclays were prepared. Afterwards, the filaments were dyed with two disperse dyes (Setapers Red P2G and Setapers Blue TFBL‐NEW) at different temperatures (100, 110, and 120 °C) in the absence/presence of a carrier. Organoclays and poly(ethylene terephthalate)/organoclay nanocomposites showed an increased d‐spacing between clay layers. Irrespective of clay and surfactant type, poly(ethylene terephthalate)/organoclay nanocomposite filaments dyed at 120 °C in the presence of only a very small amount of carrier showed appreciable dyeability in comparison with neat poly(ethylene terephthalate). The dyeability of the organoclay‐containing poly(ethylene terephthalate) samples was found to be better in spite of having increased degrees of crystallinity. Moreover, the colour fastness properties of the clay‐containing samples were not affected adversely.     

Effect of montmorillonite on the properties of thermosensitive poly(N‐isopropylacrylamide) composite hydrogels

Thermosensitive composite hydrogels containing various amounts of sodium montmorillonite (NaMM) and poly(N‐isopropylacrylamide) (pNIPAAm) were synthesized. Their equilibrium degree of swelling (DS) was measured in NaCl solutions of different ionic strength and at various temperatures. The DS decreased when increasing the clay content and no substantial shift in the phase transition temperature was noticed. The composite hydrogels investigated had a NaMM content ranging between 1.0 and 5.7 wt % (in 0.1M NaCl at 25°C). A considerable enhancement in the response to thermal stimuli was observed for NaMM contents >2–3 wt %. It is suggested that when the NaMM concentration approaches a critical value, the clay platelets can inhibit the formation of the hydrophobic skin layer that hinders shrinking in conventional pNIPAAm hydrogels. The effect of montmorillonite on the mechanical properties of the hydrogels was investigated by uniaxial compression tests, which showed that the modulus increases with the NaMM content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1964–1971, 2004     

Chitosan‐modified nanoclay–poly(AMPS) nanocomposite hydrogels with improved gel strength

BACKGROUND: Making (nano)composite structures is one of the efficient approaches for strengthening hydrogels extended in recent years. The present paper deals with the synthesis and properties of novel nanocomposite hydrogels based on 2‐acrylamido‐2‐methylpropane‐1‐sulfonic acid (AMPS). Initially, a bio‐modified clay, chitosan‐intercalated montmorillonite (chitoMMT), was prepared. Then, this was incorporated into the polymerization of AMPS in the presence of a macro‐crosslinker, i.e. poly(ethylene glycol) dimethacrylate, to yield super‐swelling nanocomposite hydrogels. The swelling capacity as well as some structural, rheological and thermomechanical properties of the hydrogels were studied and compared with those of the clay‐free counterpart. RESULTS: ChitoMMT exhibited no toxicity, which was confirmed using cell‐culture testing. A chitoMMT content of ca 6% was found to be the most favourable content of the bio‐modified clay for achieving a product with improved properties (i.e. the highest gel content, the highest gel strength and optimal thermal stability). Based on a dynamic mechanical thermal analysis study, an increased glass transition temperature (98.2 °C) and improved rubbery modulus (up to 238% higher than that of the clay‐free counterpart) were recorded. Thermogravimetric analysis verified that the thermal stability of nanocomposite samples was higher than that of clay‐free samples. CONCLUSION: Owing to the non‐toxicity of the incorporated chitoMMT, the strengthened hydrogels may be considered as potential candidates for bio‐applications. Copyright © 2009 Society of Chemical Industry     

HES-HEMA nanocomposite polymer hydrogels: swelling behavior and characterization

Organophilic sodium montmorillonite (Na-MMT) and Laponite-RD clays were incorporated into photopolymerizable hydroxyethyl starch (HES) modified with 2-hydroxyethyl methacrylate (HEMA). Swelling, mechanical properties and thermal stability of obtained crosslinked nanocomposite polymers were evaluated. A camphorquinone-amine system was used as photoinitiating system in visible light. The interaction between nano-sized filler particles and polymer hydrogel was evaluated by FT-IR spectroscopy and the platelet distribution was investigated by SEM. An increased thermal stability of nanocomposite polymers upon addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicating interaction between the clay platelets and the polymer chains. The crosslinking density for HES-HEMA/MMT nanocomposite hydrogels as investigated by swelling measurements increases with increasing the organo-clay content. The mechanical properties of virgin hydrogels were improved by the introduction of organo-clay as evidenced by oscillation rheology measurements. Whereas, the increase in crosslink density and storage modulus with clay content for laponite was found to be increasing for all concentrations investigated, for MMT there is an optimum content of ca. 1.5 wt%.     

Preparation and characteristics of nitrile rubber (NBR) nanocomposites based on organophilic layered clay

The effect of clay modification on organo‐montmorillonite/NBR nanocomposites has been studied. Organo‐montmorillonite/NBR nanocomposites were prepared through a melt intercalation process. NBR nanocomposites were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and a universal testing machine (UTM). XRD showed that the basal spacing in the clay increased, which means that the NBR matrix was intercalated in the clay layer galleries. On TEM images, organo‐montmorillonite (MMT) particles were clearly observed, having been exfoliated into nanoscale layers of about 10–20 nm thickness from their original 40 µm particle size. These layers were uniformly dispersed in the NBR matrix. The DMTA test showed that for these nanocomposites the plateau modulus and glass transition temperature (T_g) increased with respect to the corresponding values of pure NBR (without clay). UTM test showed that the nanocomposites had superior mechanical properties, ie strength and modulus. These improved properties are due to the nanoscale effects and strong interactions between the NBR matrix and the clay interface. Copyright © 2003 Society of Chemical Industry     

A new application of biosurfactant for the preparation of polycaprolactone/layered silicate nanocomposites

In this study, by using the biosurfactant as the clay modifier, one first attempted to prepare polycaprolactone (PCL)/montmorillonite nanocomposites via a melt‐blending method. The production of biosurfactant (surfactin) and the modification of clay proceeded simultaneously by the incubation of Bacillus subtilis CWS1. The evidence for the formation of intercalated/exfoliated nanocomposites was assessed by X‐ray diffraction spectroscopy, scanning electron microscopy, and transmission electron microscopy observations. The conclusions were also supported by the result of dynamic mechanical thermal analysis, thermogravimetric analyzer, and differential scanning calorimetry. As a result, the modified clay can be well dispersed into the PCL matrix in nanoscale sizes, because the biosurfactant is partially compatible with PCL chains intercalating into clay layers. As for mechanical properties, a marked increase in tensile strength and Young's modulus can be observed when the biosurfactant‐pretreated clay was used to replace the neat clay for the preparation of nanocomposites. Based on the considerations of thermal and mechanical properties, it was also found that 10 wt% of clay content was optimal for the preparation of nanocomposite. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Barrier and mechanical properties of injection molded montmorillonite/polyesteramide nanocomposites

Properties of injection‐molded biodegradable polyesteramide composites containing 5 and 13 wt% octadecylammonium‐treated montmorillonite clay have been studied. Oxygen transmission rates and mechanical properties were measured. X‐ray diffraction was used to assess the degree of intercalation of the clay layer stacks, and transmission electron microscopy (TEM) was used to assess the morphology and degree of layer delamination. A substantial reduction in oxygen permeability was observed when clay was added to the composites. The oxygen permeability of the 13 wt% clay sample was only 20% of that of the pure polymer. The in‐plane stiffness and in‐plane strength of the sheets were greatly improved without any embrittlement. These beneficial effects were probably due to the high degree of clay layer exfoliation and orientation observed by TEM. Heat shrinkage, toughness analysis, and cutting operations suggested that the polymer chains and the clay layers were oriented parallel to the plane of the sheet. TEM and X‐ray showed that stacked layers were still present but that these were significantly intercalated. The clay‐layer periodic spacing increased from 25 Å to approximately 35 Å during processing. POLYM. ENG. SCI. 45:135–141, 2005. © 2004 Society of Plastics Engineers     

Fabrication and properties of thermoplastic starch/montmorillonite composite using dialdehyde starch as a crosslinker

The poor mechanical properties and high water solubility of biodegradable thermoplastic starch (TPS) represent the main disadvantages of TPS in many applications. In this work, TPS film was prepared from a water solution of corn starch modified by 5 wt% dialdehyde starch (DAS) as crosslinking agent and 3 wt% montmorillonite (MMT) as reinforcing additive. Interactions occurring in the TPS films were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, XRD, DSC, dynamic mechanical thermal analysis (DMTA) and TGA. The results obtained fom FTIR spectroscopy and DSC suggest the formation of hydrogen bond interactions between the hydroxyl group of starch, DAS, the MMT layers and glycerol. DMTA indicated that the relaxation of films with DAS and MMT appears in a higher and broader temperature range due to the starch backbone stiffness; the extreme increase in the storage modulus confirmed the suggested interactions. The determination of the weight loss of the films in water indicated a significant increase of the water resistance of TPS due to incorporation of DAS and MMT. Changes in mechanical properties of the films containing DAS and clay were determined, showing a substantial increase in tensile strength from 2.7 to 6.7 MPa, while Young's modulus increased by 15 times for TPS modified with 5% DAS and 3% MMT. Therefore, the outcomes of this study confirmed that DAS is a suitable biomacromolecule crosslinker for starch and can significantly enhance TPS and TPS/MMT properties. © 2019 Society of Chemical Industry     

Structure and properties of phenolic resin/nanoclay composites synthesized by in situ polymerization

An in situ semibatch polymerization process for making phenolic resin/montmorillonite clay nanocomposites is developed. It is found that auxiliary mixing in phenol allows intercalation of the monomer and polymer between montmorillonite clay layers. At 2.7% clay by mass the montmorillonite is predominantly exfoliated (fully dispersed). At higher clay loading, a substantial amount of the clay remains in aggregate or intercalated form. When the montmorillonite is exfoliated, the material is mechanically superior. The composite has a tensile modulus that is 21% higher than the neat resin and has 87% improved fracture strength, 100% larger fracture energy, and strain to failure 13% above the pure resin. Thermogravimetric analysis shows the montmorillonite system maintains its thermal stability up to 200°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1169–1174, 2005     

Preparation and properties of montmorillonite‐based polyimide nanocomposites

Montmorillonite (MMT)‐based polyimide (PI) nanocomposites were prepared via two‐stage polymerization of PI using polyamic acid (PAA). The clay was organically modified using various alkylammonium ions to examine the effect of changes in alkyl length on the intercalation spacing of both the treated clays and their hybrids with PAA and PI. The intercalation behavior of clay in the PI matrix and its thermal and mechanical properties were investigated as a function of clay concentration. The d‐spacing of organically modified MMT (O‐MMT) increased with increasing length of the alkylammonium chain. PI/O‐MMT hybrids form exfoliated nanocomposites at clay concentrations below 2 wt%, while they form intercalated nanocomposites together with some exfoliated ones at clay contents exceeding 4 wt%. Young's modulus increased rapidly to a clay loading of 2 wt%, and leveled off with further increases in clay loading. The tensile strength at break increased rapidly up to a clay loading of 1 wt%, and then decreased sharply, while the strain at break showed a monotonic decrease with increasing clay loading from 0 to 8 wt%. The storage modulus, E′, in the temperature range below the glass transition temperature T_g, generally increased with increasing clay content, except at the highest clay content of 8 wt%. Copyright © 2004 Society of Chemical Industry     

EPDM/silicone blend layered silicate nanocomposite by solution intercalation method: Morphology and properties

Ethylene–propylene–diene terpolymer (EPDM)/silicone blend nanocomposites are prepared by solution method for the first time. EPDM and silicone rubber in their 50:50 (by weight) blend is intercalated within the silicate sheets of organically modified montmorillonite. Organic modification to the pristine sodium montmorillonite (Na‐MMT) surfaces is carried out by ion‐exchange reaction using hexadecyl ammonium chloride. The incorporation of such organic functional group makes Na‐MMT hydrophobic and expands the interlayer spacing between silicate sheets. The intercalated structure of EPDM/silicone blend nanocomposites is characterized by the X‐ray diffraction. Transmission electron microscopic characterization visualized the presence of both exfoliated and intercalated layered silicate in the polymer nanocomposites. The mechanical properties of the nanocomposites show a maximum improvement in tensile strength and elongation at break of 23 and 68%, respectively, compared with EPDM/silicone blend. The dielectric measurement demonstrates the increase in relative permittivity for the nanocomposite than the pure blend. The increase in the onset temperature of the thermal degradation of nanocomposites (∼52°C) corresponding to 1 wt% decomposition indicates the enhancement of thermal stability of (EPDM)/silicone blend due to interaction with silicates. POLYM. COMPOS., 35:1834–1841, 2014. © 2014 Society of Plastics Engineers     

Swelling behavior of sulfonated polyacrylamide nanocomposite hydrogels in electrolyte solutions: comparison of theoretical and experimental results

Nanocomposite hydrogels were prepared by cross-linking of aqueous solutions of sulfonated polyacrylamide/sodium montmorillonite with chromium triacetate as ionic cross-linker. The effect of montmorillonite content on equilibrium swelling in NaCl and CaCl₂ solutions, ultimate storage modulus and effective cross-link density was evaluated. The limiting storage modulus of the nanocomposite (NC) hydrogels dropped by increasing montmorillonite content up to 1,000?ppm, and then it increased by further montmorillonite loading. A mechanism is proposed for the formation of PAMPS/Na⁺-MMT/Cr³⁺ NC hydrogels. According to this mechanism, the drop in limiting storage modulus of the NC gels at low Na⁺-MMT concentration is due to ionic interactions between the negative layers of sodium montmorillonite and Cr³⁺, leading to decreased cross-link density. However, the increase of the limiting storage modulus of the NC gels at high clay concentration results from the strong interactions between the polyacrylamide chains and clay platelets. The equilibrium swelling ratio of the NC networks decreased with increase of montmorillonite content in both aqueous NaCl and CaCl₂ solutions. In addition, the experimental swelling data of these NC hydrogels were described by a modified Flory?CRehner theory. The modified model was sensitive to montmorillonite concentration and it described adequately the swelling data for NC gels in NaCl solutions. Nevertheless, theoretical predictions showed some deviations from experimental results for swelling of NC hydrogels in CaCl₂ solutions.     

Synthesis and evaluation of high‐performance ethylene–propylene–diene terpolymer/organoclay nanoscale composites

The main objective of this study was to synthesize and characterize the properties of ethylene–propylene–diene terpolymer (EPDM)/clay nanocomposites. Pristine clay, sodium montmorillonite (Na⁺–MMT), was intercalated with hexadecyl ammonium ion to form modified organoclay (16Me–MMT) and the effect of intercalation toward the change in interlayer spacing of the silicate layers was studied by X‐ray diffraction, which showed that the increase in interlayer spacing in Na⁺–MMT by 0.61 nm is attributed to the intercalation of hexadecyl ammonium ion within the clay layers. In the case of EPDM/16Me–MMT nanocomposites, the basal reflection peak was shifted toward a higher angle. However, gallery height remained more or less the same for different EPDM nanocomposites with organoclay content up to 8 wt %. The nanostructure of EPDM/clay composites was characterized by transmission electron microscopy, which established the coexistence of intercalated and exfoliated clay layers with an average layer thickness in the nanometer range within the EPDM matrix. The significant improvement in thermal stability and mechanical properties reflects the high‐performance nanocomposite formation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2429–2436, 2004