Morphology,deformation behavior and thermomechanical properties of polypropylene/maleic anhydride grafted polypropylene/layered silicate nanocomposites

Nanocomposites polypropylene (PP) with 3 and 7 wt % of clay were prepared by melt mixing. Four types of maleic anhydride grafted PP (MAPP) in broad range of MA groups content (0.3–4 wt %) and molecular weights (MW) were used as polar compatibilizers. The effect of the MAPP kind on both the clay dispersion and miscibility with PP was studied. The mixed intercalated/exfoliated morphologies of nanocomposites in the presence of all studied compatibilizers were revealed by XRD and TEM. The oligomer compatibilizer with 4 wt % of MA groups increases the intercalation ability of polymer into clay galleries but this one has limited miscibility with PP and worsens crystalline structure of polymer matrix. The MAPPs with 0.3–1.3% of MA are characterized by the lower intercalation ability but well cocrystallize with PP. Maximum reinforcing effect is attained using high MW MAPP with 0.6% MA and for nanocomposite with 7 wt % (3.8 vol %) of clay it averages almost 1.7 times relative to neat PP and 1.3 times relative to noncompatibilized composite. Dynamic storage moduli of nanocomposites compatibilized by MAPPs with 0.3–1.3% of MA containing 7 wt % of clay increase up to 1.4–1.5 around 30–75°C and over the whole temperature range remain higher compared with both neat PP and uncompatibilized composite. On the contrary, the oligomer MAPP with 4 wt % of MA groups decreases the thermal–mechanical stability of nanocomposite at high temperature compared with both PP and uncompatibilized composites. The study of nanocomposites flammability showed that creating complex composites containing both layered silicate and relatively small amount of magnesium hydroxide can be a successful approach to reduce the combustibility of PP‐based nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Rheology of poly(propylene)/clay nanocomposites

The linear and nonlinear shear rheological behaviors of poly(propylene) (PP)/clay (organophilic‐montmorillonite) nanocomposites (PP/org‐MMT) were investigated by an ARES rheometer. The materials were prepared by melt intercalation with maleic anhydride functionalized PP as a compatibilizer. The storage moduli (G′), loss moduli (G″), and dynamic viscosities of polymer/clay nanocomposites (PPCNs) increase monotonically with org‐MMT content. The presence of org‐MMT leads to pseudo‐solid‐like behaviors and slower relaxation behaviors of PPCN melts. For all samples, the dependence of G′ and G″ on ω shows nonterminal behaviors. At lower frequency, the steady shear viscosities of PPCNs increase with org‐MMT content. However, the PPCN melts show a greater shear thinning tendency than pure PP melt because of the preferential orientation of the MMT layers. Therefore, PPCNs have higher moduli but better processibility compared with pure PP.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2427–2434,2004     

Study on dispersion and intercalation of organoclay in PP and PP‐g‐MA matrices

Understanding the complex mechanism of dispersion and intercalation of the clay tactoids can allow us to control the final morphology, homogeneity, and the macroscopic properties of clay nanocomposites. The objective of this work is a multiscale study of the dispersion state of PP/organoclay and PP‐g‐MA/organoclay composite. The microscopic investigation, WAXS diffractograms, rheological analysis, and mechanical properties were used to characterize the dispersion of organoclay in PP and PP‐g‐MA matrices during melt blending in two different shear rates. The morphological results show a system of aggregating intercalated clay particles which disperse by increasing mixing time with a strain‐controlled process and a very quick intercalation process in early mixing times for PP‐g‐MA/organoclay nanocomposite, while PP/organoclay samples only form microcomposites. The relative network modulus of these intercalated particles as a function of mixing time was obtained; and the tensile modulus of nanocomposite samples were compared with Halpin‐Tsai model prediction. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Morphological studies of polypropylene–nanoclay composites

Polypropylene–clay nanocomposites were prepared by a solution technique and a subsequent melt‐mixing process. A titanate coupling agent was used to improve the compatibility of the nanoclay particles with the polypropylene. The dispersion of the nanoclay particles in polypropylene was studied with X‐ray diffraction (XRD) and transmission electron microscopy (TEM). An increased d‐spacing value of the clay particles in the nanocomposites was observed, and it was compared with the values of as‐mined (pristine) and as‐received (organophilic) clay particles. The number of intercalated layers in a single clay crystallite was determined to be 4, and the number was confirmed with XRD data and TEM images. On the basis of the Daumas–Herold model (which is widely used for graphite intercalation compounds), the stage 2 and stage 3 structures of montmorillonite particles in polypropylene were recommended. A study on the stage structure suggested a way of determining the presence of polymer molecules in the clay galleries. The results confirmed the existence of single‐layered platelets with improved dispersion in polypropylene. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 218–226, 2005     

The effect of crystallization on the structure and morphology of polypropylene/clay nanocomposites

The effect of crystallization on the structure and morphology of maleic anhydride grafted polypropylene (PP‐MA)/clay (montmorillonite) nanocomposites (PPCNs) is presented. Wide‐angle X‐ray diffraction (WAXD) measurements of PPCNs crystallized at different temperatures show that the extent of intercalation increases with the crystallization temperature. The enhancement of intercalation occurs with lower clay content PPCNs, and maximum intercalation takes place for 4 wt% clay content. The mechanism of intercalation has been proposed through crystallization. Excess γ‐form of the crystallite of PP‐MA appears in presence of clay, possibly because of the confinement of the polymer chain between the clay particles. WAXD data also reveals that d‐spacing increases gradually with clay content. The decrease of spherulitic size is observed with increasing clay content, which indicates that clay particles act as nucleating agents. Lamellar textures have been explored by using small angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM), which exhibit that both the lamellar thickness and long period of the PPCNs are higher than those of PP‐MA.     

Foam processing and cellular structure of polypropylene/clay nanocomposites

Polypropylene (PP)/clay nanocomposites (PPCNs) were autoclave‐foamed in a batch process. Foaming was performed using supercritical CO₂ at 10 MPa, within the temperature range from 130.6°C to 143.4°C, i.e., below the melting temperature of either PPCNs or maleic anhydride‐modified PP (PP‐MA) matrix without clay. The foamed PP‐MA and PPCN2 (prepared at 130.6°C and containing 2 wt% clay) show closed cell structures with pentagonal and/or hexagonal faces, while foams of PPCN4 and PPCN7.5 (prepared at 143.4°C, 4 and 7.5 wt% clay) had spherical cells. Scanning electron microscopy confirmed that foamed PPCNs had high cell density of 10⁷–10⁸ cells/mL, cell sizes in the range of 30–120 μm, cell wall thicknesses of 5–15 μm, and low densities of 0.05–0.3 g/mL. Interestingly, transmission electron microscopic observations of the PPCNs' cell structure showed biaxial flow‐induced alignment of clay particles along the cell boundary. In this paper, the correlation between foam structure and rheological properties of the PPCNs is also discussed.     

Preparation and characterization of nanoclay‐filled polyurethane/polypropylene blends

Ester‐based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending at 190°C, using 3 wt% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement [TPU(C10A)]. The nanocomposites were subsequently melt‐blended with polypropylene (PP) using maleic anhydride–grafted polypropylene (MA‐g‐PP) as a compatibilizer [in the ratio of 70/30‐TPU/PP, 70/25/5‐TPU/PP/MA‐g‐PP, 70/25/5‐TPU (C10A)/PP/MA‐g‐PP]. Besides giving substantial increase in modulus, tensile strength, and other properties, organoclay reinforcement functions as a surface modifier for TPU hard segment resulting in improved dispersion. The morphology and other characteristics of the nanocomposite blends were investigated in terms of X‐ray diffraction, fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, tensile properties, scanning electron microscopy, and atomic force microscopy. The results indicate that the ester‐TPU(C10A)/PP/MA‐g‐PP exhibited better dispersion than other blend systems; abrasion resistance and water absorption resistance were also better for this system. POLYM. ENG. SCI., 50:1878–1886, 2010. © 2010 Society of Plastics Engineers     

Effects of clay contents on the dynamic mechanical and rheological properties of polypropylene/MAH‐g‐POE/clay composites

A series of polypropylene/maleic anhydride grafted polypropylene octane elastomer (MAH‐g‐POE)/clay (PPMC) nanocomposites were prepared with a novel compatilizer MAH‐g‐POE and different contents of octadecyl amine modified montmorillonite, and the effects of clay contents on the dynamic mechanical and rheological properties of these PPMC composites were investigated. With clay content increasing, the characteristic X‐ray diffraction peak changed from one to two with intensity decreasing, indicating the decreasing concentration of the intercalated clay layers. The gradual decrease of crystallization temperature of PPMC composites with the increase of clay loading should be attributed to the preferred intercalation of MAH‐g‐POE molecules into clay interlayer during blending, which is also reflected by scanning electron microscopy observations. By evaluating the activation energy for the glass transition process of MAH‐g‐POE and polypropylene (PP) in the PPMC composites, it is found that clay intercalation could cause the restriction effect on the glass transition of both MAH‐g‐POE and PP, and this restriction effect appears stronger for PP and attained the highest degree at 5 wt % clay loading. The melt elasticity of PP could be improved apparently by the addition of MAH‐g‐POE, and 5 wt % clay loading is enough for further enhancing the elastic proportion of PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Nonisothermal crystallization behavior of highly exfoliated polypropylene/clay nanocomposites prepared by in situ polymerization

Polypropylene/clay nanocomposites (PPCNs) were prepared via an in situ polymerization method with a Ziegler–Natta/clay compound catalyst in which the MgCl₂/TiCl₄ catalyst was embedded in the clay galleries. The wide‐angle X‐ray diffraction and transmission electron microscopy results showed that the clay particles were highly exfoliated in the polypropylene (PP) matrix. The nonisothermal crystallization kinetics of these PPCNs were investigated by differential scanning calorimetry at various cooling rates. The nucleation activity were calculated by Dobreva's method to demonstrate that the highly dispersed silicate layers acted as effective nucleating agents. The Avrami, Jeziorny, Ozawa, and Mo methods were used to describe the nonisothermal crystallization behavior of the PP and PPCNs. Various parameters of nonisothermal crystallization, such as the crystallization half‐time, crystallization rate constant, and the kinetic parameter F(t), reflected that the highly exfoliated silicate layers significantly accelerated the crystallization process because of its outstanding nucleation effect. The activation energy values of the PP and PPCNs determined by the Kissinger method increased with the addition of the nanosilicate layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

X‐ray diffraction studies and phase volume determinations in poly(ethylene glycol)–montmorillonite nanocomposites

Poly(ethylene glycol)–montmorillonite nanocomposites were prepared by both solution and melt intercalation methods with a range of polymer molecular weights and at a range of polymer loadings. Particular attention was given to the reliability of low‐angle X‐ray diffraction results for basal plane spacing and a sound correlation between three diffractometers was obtained (±0.005 nm). Expansion of the basal plane spacing from 1.23 nm to 1.82 nm by solution intercalation was independent of polymer molecular weight in the range 300–20 000. Furthermore, the clay expansion was independent of the method of intercalation; melt intercalation also gave d₀₀₁ = 1.82 nm irrespective of polymer molecular weight. The maximum amount of polymer intercalated by clay and the maximum loading of clay that polymer can sustain were also studied for the determination of nanocomposite formulations. The confined polymer exerts a reduced effective density (670 kg m^?3) in the galleries. Copyright © 2005 Society of Chemical Industry     

Dielectric properties and structures of melt‐compounded poly(ethylene oxide)–montmorillonite nanocomposites

The dielectric dispersion and relaxation process in melt‐compounded hot‐pressed poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay nanocomposite films of 0–20 wt % MMT concentration were investigated over the frequency range 20 Hz to 1 MHz at ambient temperature. X‐ray diffraction study of the nanocomposites evidences that the PEO has been intercalated into the MMT interlayer galleries with a helical‐type multilayer structures, which results the formation of unique parallel plane PEO–MMT layered structures. The relaxation times corresponding to PEO chain segmental motion were determined from the loss peak frequencies of different dielectric formalisms and the same is used to explore the interactions compatibility between PEO molecules and the MMT nano platelets. It is revealed that the loading of only 1 wt % MMT in PEO matrix significantly increases the PEO chain segmental motion due to intercalation, which further varies anomalously with increase of MMT concentration. The real part of dielectric function at 1 MHz, relaxation time, and dc conductivity of these melt‐compounded nanocomposites were compared with the aqueous solution‐cast PEO–MMT films. Considering the comparative changes in the values of various dielectric parameters, the effect of synthesization route on the intercalated/exfoliated‐MMT structures and the PEO chain dynamics were discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structure and melt rheology of long‐chain branching polypropylene/clay nanocomposites

Long‐chain branching polypropylene (LCB‐PP)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder. The microstructure and melt rheology of these nanocomposites were investigated using x‐ray diffraction, transmission electron microscopy, oscillatory shear rheology, and melt elongation testing. The results show that, the clay layers are intercalated by polymer molecular chains and exfoliate well in LCB‐PP matrix in the presence of maleic anhydride grafted PP. Rheological characteristics, such as higher storage modulus at low‐frequency and solid‐like plateau in tan‐ω curve, indicate that a compact and stable filler network structure is formed when clay is loaded at 4 phr (parts per hundred parts of) or higher. The response of the nanocomposite under melt extension reveals an initial decrease in the melt strength and elongational viscosity with increasing clay concentration up to 6 phr. Later, the melt strength and elongational viscosity show slight increases with further increasing clay concentration. These results might be caused by a reduction in the molecular weight of the LCB‐PP matrix and by the intercalation of LCB‐PP molecular chains into the clay layers. Increases in the melt strength and elongational viscosity for the nanocomposites with decreasing extrusion temperature are also observed, which is due to flow‐induced crystallization under lower extrusion temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of the molecular weight of maleated polypropylenes on the melt compounding of polypropylene/organoclay nanocomposites

Maleic anhydride grafted polypropylene (PP‐g‐MA) and organically modified clay composites were prepared in a plasticorder. PP‐g‐MAs, including Polybond PB3150, Polybond PB3200, Polybond PB3000, and Epolene E43, with a wide range of maleic anhydride (MA) concentrations and molecular weights were used. The structure was investigated with X‐ray diffraction (XRD) and transmission electron microscopy (TEM). PP‐g‐MA compatibilizers gave rise to similar degrees of dispersion beyond the weight ratio of 3/1, with the exception of E43, which had the highest MA content and the lowest molecular weight. The thermal instability and high melt index were responsible for the ineffective modification by E43. Furthermore, PP‐g‐MA with a lower molecular weight and a higher melt index had to be compounded at a lower mixing temperature to achieve a reasonable level of torque for clay dispersion. Polypropylene/organoclay nanocomposites were then modified with different levels of PP‐g‐MA compatibilizers with a twin‐screw extruder. The polypropylene/E43/clay system, as shown by XRD patterns and TEM observations, yielded the poorest clay dispersion of the compatibilizers under investigation. The curves of the relative complex viscosity also revealed a systematic trend with the extent of exfoliation and showed promise for quantifying the hybrid structure of the nanocomposites. The mechanical properties and thermal stability were determined by dynamical mechanical analysis and thermogravimetric analysis, respectively. Although PP‐g‐MA with a lower molecular weight led to better clay dispersion in the polypropylene nanocomposites, it caused deterioration in both the mechanical and thermal properties of the hybrid systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1667–1680, 2005     

Cocontinuous phase morphology of asymmetric compositions of polypropylene/high‐density polyethylene blend by the addition of clay

A novel method of developing cocontinuous morphology in 75/25 and 80/20 w/w polypropylene/high density polyethylene (PP/HDPE) blends in the presence of small amount (0.5 phr) of organoclay has been reported. SEM study indicated a reduction in average domain sizes (D) of disperse HDPE when PP, HDPE, and the organoclay were melt‐blended simultaneously at 200°C. However, when the two‐sequential heating protocol was employed, (that is, the organoclay was first intercalated by HDPE chains at 150°C, followed by melt blending of PP at 200°C), very interestingly a cocontinuous morphology was found even for very asymmetric blend compositions. WAXD study revealed the intercalation of both PP and HDPE chains inside the clay galleries, when PP/HDPE and clay were melt‐mixed together at 200°C. However, when the two‐sequential heating protocol was used the organoclay platelets were selectively intercalated by the HDPE chains. Addition of SEPS in the blend decreased the D of HDPE domains in both the blending methods. Thus, the observed cocontinuous morphology in asymmetric composition of PP/HDPE blend in presence of clay is because of the barrier effect of the clay platelets in the HDPE phase that restrict the phase inversion into the domain/matrix morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Morphology and mechanical properties of polypropylene/organoclay nanocomposites

Polypropylene (PP) nanocomposites were prepared by melt intercalation in an intermeshing corotating twin‐screw extruder. The effect of molecular weight of PP‐MA (maleic anhydride‐ modified polypropylene) on clay dispersion and mechanical properties of nanocomposites was investigated. After injection molding, the tensile properties and impact strength were measured. The best overall mechanical properties were found for composites containing PP‐MA having the highest molecular weight. The basal spacing of clay in the composites was measured by X‐ray diffraction (XRD). Nanoscale morphology of the samples was observed by transmission electron microscopy (TEM). The crystallization kinetics was measured by differential scanning calorimetry (DSC) and optical microscopy at a fixed crystallization temperature. Increasing the clay content in PP‐ MA330k/clay, a well‐dispersed two‐component system, caused the impact strength to decrease while the crystallization kinetics and the spherulite size remained almost the same. On the other hand, PP/PP‐MA330k/clay, an intercalated three‐component system containing some dispersed clay as well as the clay tactoids, showed a much smaller size of spherulites and a slight increase in impact strength with increasing the clay content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1562–1570, 2002     

Polypropylene–nanosilica‐filled composites: Effects of epoxy‐resin‐grafted nanosilica on the structural,thermal, and dynamic mechanical properties

This article reports a comparative study of polypropylene (PP) nanocomposites synthesized with nanosilica (NS) and diglycidyl ether of bisphenol A, an epoxy‐resin‐grafted nanosilica (ENS), as nanofillers. These nanocomposites were prepared with the melt‐mixing method at a constant loading level of 2.5 wt %; this loading level was much lower than that used for fillers in conventional composites. The effects of pure NS and ENS on the thermal, structural, mechanical, and dynamic mechanical properties of PP were analyzed with wide‐angle X‐ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and scanning electron microscopy. The transmission electron microscopy studies showed a better dispersion of ENS in the PP matrix, that is, in the polypropylene‐epoxy‐resin‐grafted nanosilica (PP–ENS) nanocomposite, in comparison with NS in the PP matrix, that is, in the polypropylene–nanosilica (PP–NS) nanocomposite. Also, the thermogravimetric analysis results showed a higher thermal stability for PP–ENS than PP–NS. Furthermore, the dynamic mechanical analysis studies showed an increase in the elastic modulus and glass‐transition temperature for PP–ENS with respect to PP–NS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2117–2124, 2006     

The effect of clay type and of clay–masterbatch product in the preparation of polypropylene/clay nanocomposites

Clay containing polypropylene (PP) nanocomposites were prepared by direct melt mixing in a twin screw extruder using different types of organo‐modified montmorillonite (Cloisite 15 and Cloisite 20) and two masterbatch products, one based on pre‐exfoliated clays (Nanofil SE 3000) and another one based on clay–polyolefin resin (Nanomax‐PP). Maleic anhydride‐grafted polypropylene (PP‐g‐MA) was used as a coupling agent to improve the dispersability of organo‐modified clays. The effect of clay type and clay–masterbatch product on the clay exfoliation and nanocomposite properties was investigated. The effect of PP‐g‐MA concentration was also considered. Composite morphologies were characterized by X‐ray diffraction (XRD), field emission gun scanning electron microscopy (FEG‐SEM), and transmission electron microscopy (TEM). The degree of dispersion of organo‐modified clay increased with the PP‐g‐MA content. The thermal and mechanical properties were not affected by organo‐modified clay type, although the masterbatch products did have a significant influence on thermal and mechanical properties of nanocomposites. Intercalation/exfoliation was not achieved in the Nanofil SE 3000 composite. This masterbatch product has intercalants, whose initial decomposition temperature is lower than the processing temperature (T ～ 180°C), indicating that their stability decreased during the process. The Nanomax‐PP composite showed higher thermal and flexural properties than pure PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interfacially compatibilized poly(lactic acid) and poly(lactic acid)/polycaprolactone/organoclay nanocomposites with improved biodegradability and barrier properties: Effects of the compatibilizer structural parameters and feeding route

Nanocomposites with enhanced biodegradability and reduced oxygen permeability were fabricated via melt hybridization of organomodified clay and poly (lactic acid) (PLA) as well as a PLA/polycaprolactone (PCL) blend. The nanocomposite microstructure was engineered via interfacial compatibilization with maleated polypropylene (PP‐g‐MA). Effects of the compatibilizer structural parameters and feeding route on the dispersion state of the nanolayers and their partitioning between the PLA and PCL phases were evaluated with X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Although highly functionalized PP‐g‐MA with a low molecular weight was shown to be much more effective in the intercalation of PLA and the PLA/PCL blend into the clay gallery spaces, composite samples compatibilized by high‐molecular‐weight PP‐g‐MA with a lower degree of maleation exhibited lower oxygen permeability as well as a higher rate of biodegradation, which indicated the accelerating role of the dispersed nanolayers and their interfaces in the enzymatic degradation of PLA and PLA/PCL matrices. This evidenced a correlation between the nanocomposite structure and rate of biodegradation. The size of the PCL droplets in the PLA matrix was reduced by nanoclay incorporation, and this revealed that the nanolayers were preferentially wetted by PCL in the blend. However, PCL appeared as fine and elongated particles in the microstructure of the PLA/PCL/organoclay hybrids compatibilized by higher molecular weight and less functionalized PP‐g‐MA. All the PLA/organoclay and PLA/PCL/organoclay hybrids compatibilized with high‐molecular‐weight PP‐g‐MA displayed a higher dynamic melt viscosity with more pseudo solid‐like melt rheological responses, and this indicated the formation of a strong network structure by the dispersed clay layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Nanocomposites from plasticized high‐amylopectin,normal and high‐amylose maize starches

Three types of maize starch with different amounts of amylose and amylopectin were used to prepare plasticized starch/clay nanocomposite films by casting. Studies by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the intercalation/exfoliation of the plasticized starch molecules took place into the clay galleries for the three types of starch. However, the plasticized waxy starch molecules were the easiest of them all to be intercalated/exfoliated, which was reflected in the highest increment of the stress at peak of these nanocomposites. Moreover, the lowest water uptake was showed by the plasticized high‐amylose starch/clay nanocomposites. It was concluded that varying contents of amylose and amylopectin influenced the formation of intercalated/exfoliated clay structures and also affected the interactions of clay with water. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Comparing styrene butadiene rubber–clay nanocomposites prepared by melt intercalation and latex‐coagulation methods

Among different methods for preparation of rubber–clay nanocomposites, melt intercalation and latex‐coagulation methods are more practiced. In this study, dispersion of pristine nanoclay by the latex‐coagulation method and organically modified nanoclay by the melt‐intercalation method in styrene butadiene rubber were compared, based on the same amount of mineral clay in the composites. Dispersion of nanoclay was examined by X‐ray diffraction before and after vulcanization, and by atomic force microscopy after vulcanization. It was shown that final structure of nanoclay in the composites was intercalated by both methods, with better dispersion resulting from coagulation of latex over mixing in the melt state. Dynamic–mechanical–thermal analysis and tension tests were used to further assess dispersion and polymer–filler interactions. These tests confirmed better dispersion and larger interfacial area for pristine nanoclay in the latex‐coagulated rubber through observing lower peak loss factor, higher growth of stress in stretching, and lower elongation at break when compared with those for the nanocomposite prepared by the melt mixing. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012