Exfoliation and dispersion enhancement in polypropylene nanocomposites by in‐situ melt phase ultrasonication

A novel process using ultrasonics to enhance the exfoliation and dispersion of clay platelets in polypropylene‐based nanocomposites has been proposed and investigated. The materials studied were isotactic polypropylene of various molecular weights reinforced with organophilic montmorillonite clay (nanoclay) at 4–6 wt% loadings. X‐ray diffraction (XRD) and rheological measurements, on a model system of nanoclay in mineral oil, were first used to determine ultrasonic energy requirements. The effectiveness of the proposed ultrasonic processing technique on polypropylene nanocomposites was evaluated by XRD and transmission electron microscopy (TEM). The effects of added maleic anhydride–grafted polypropylene compatibilizer, polypropylene molecular weight, and pretreatment of the nanoclays on the nanocomposite exfoliation were also investigated. Results indicate that ultrasonic processing of polymer nanocomposites in the melt state is an effective method for improving exfoliation and dispersion of nanoclays. Issues regarding molecular weight degradation, optimization, mechanical properties, and continuous processing are beyond the scope of the present study and are currently being investigated in our laboratory. Polym. Eng. Sci. 44:1773–1782, 2004. © 2004 Society of Plastics Engineers.     

Particulate reinforced PC/PBT composites. II. Effect of nano‐clay particles on dimensional stability and structure–property relationships

The effect of organoclay loading and surface treatment on the dimensional stability, structure–property relationships, and rheological behavior of nanocomposites consisting of polycarbonate (PC), poly[butylene terephyhalate] (PBT), and nano‐clay was investigated at various clay loadings and with various surface modifiers for the nano‐clay particles. It was found that by using an organoclay formed with a polar amine compound that contained two hydroxyl end groups as opposed to nano‐talc, the flexural strength and tensile toughness of the nanocomposites increased by 12 and 27%, respectively, at a particle loading of 1 wt%, while maintaining the flexural modulus of the nanofilled PC/PBT blends. The flexural and tensile modulus of the nanocomposites increased with an increase in particle loading even though the viscosity was reduced due to a loss of molecular weight of the PC/PBT and/or an increase in the compability of the interface between the PC and PBT phase, which varied with organoclay structure. Possible loss of the molecular weight of the PC/PBT matrix was supported by a significant reduction in the storage modulus and complex viscosity at high frequencies of the composites generated with nano‐clay relative to that of the unfilled matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Bulk and surface mechanical properties of clay modified HDPE used in liner applications

High‐density polyethylene (HDPE)/clay nanocomposites were prepared by melt blending process. The HDPE was mixed with different organoclays and polyethylene‐grafted‐maleic anhydride was used as a compatibiliser. A masterbatch procedure was used to obtain final organoclays concentrations of 1, 2.5 and 5 wt%. The effects of various types of nanoclays and their concentrations on morphological, thermal and mechanical properties of nanocomposites were investigated. Surface mechanical properties such as instrumented nanohardness, modulus of elasticity and creep were also measured using a nanoindentation technique. Young's, storage and loss moduli, were found to be higher than that of the neat polymer at low loading (2.5 wt%) for clay Cloisite 15A and at higher loading (5 wt%) for clay Nanomer 1.44P. The ultimate strength and the toughness decreased slightly compared to pure HDPE. The differential scanning calorimetry analysis revealed that the peak temperature of the nanocomposites increased with increased clay content while the crystallinity decreased. Also, dynamic mechanical analysis revealed the storage and loss moduli are enhanced by addition of nanoclay. Both mechanical and thermal properties of HDPE/Nanomer 1.44P nanocomposite showed interesting trends. All properties first dropped when 1 wt% of the clay was added. Thereafter, a gradual increase or decrease then followed as the loading of Nanomer was increased. These trends were observed for all mechanical properties. The results obtained from nanoindentation tests for surface mechanical properties also showed similar trend to that of bulk measurements. Based on these measurements a nanoclay additive for a liner grade HDPE was selected. © 2011 Canadian Society for Chemical Engineering     

Bottle‐to‐bottle recycling of PET via nanostructure formation by melt intercalation in twin screw compounder: Improved thermal,barrier, and microbiological properties

Attempts have been made to modify the properties of the injection processing‐scraped PET (denoted as RPET) via intercalation with different levels of organically modified nanoclay (montmorillonite) by melt blending in a corotating twin screw compounder. The clay platelets dispersion state has been qualitatively correlated with the melt linear viscoelastic as well as tensile and barrier properties of the prepared nanocomposites. Oxygen permeation of the nanocomposite PET films showed significant reduction compared with the pristine PET polymer. All the PET/nanoclay composites exhibited no bacterial growth, with no potentiality to generate acetaldehyde, as measured by GC/Mass analyzer. X‐ray diffractometry and transmission electron microscopy performed on the scraped PET/organoclay nanocomposite samples showed increase in d₀₀₁ spacing of the clay layers and their dispersion throughout the PET matrix. Differential scanning calorimetry analysis showed higher crystallization temperature as well as crystallization enthalpy (ΔH_c) for the nanocomposite samples, compared with the unprocessed virgin PET. The RPET nanocomposite samples composed of 3 and 5% of nanoclay exhibited enhanced melt elastic modulus and pseudosolid‐like behavior at low shear frequencies measured by rheomechanical spectroscopy than the unfilled pristine‐scraped PET, indicating the formation of nanoscopic network structure by the clay platelets, which leads to the development of nanostructured resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of oligomeric‐modified montmorillonite on morphology and properties of polycarbonate/montmorillonite nanocomposites

Low‐molecular‐weight copolymers of styrene and vinylbenzyl ammonium salts (oligomeric surfactant) were used to modify montmorillonite (MMT). The oligomeric‐modified MMT showed good thermal stability, which made it suitable to be used for preparing polycarbonate(PC)/MMT nanocomposites at high temperature. A different series of PC/MMT nanocomposites had been prepared by melt processing using a twin screw extruder. The effect of oligomeric surfactant structure and clay loading on the morphology, mechanical property, thermal stability, and color appearance of the nanocomposites were explored. The results of X‐ray diffraction and transmission electron microscopy analyses indicated that the PC/MMT nanocomposites had partially exfoliated structures. The PC/MMT nanocomposites were found to retain light colored, which was important for optical application. Compared to neat PC, the nanocomposites showed better properties of thermal stability and heat insulation. The mechanical properties of the nanocomposites are significantly enhanced by incorporating clay into the PC matrix. The tensile strength of nanocomposites with 2 wt% clay content was up to 55 MPa, which was much higher than that of the neat PC (37 MPa). The maximum tensile modulus value was 19% higher than that of neat PC. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Morphological influence on mechanical characterization of ethylene‐vinyl acetate copolymer–clay nanocomposites

Ethylene‐vinyl acetate copolymer (EVA)/montmorillonite (MMT) clay nanocomposites with varying degree of intercalation and exfoliation have been prepared using direct melt blending techniques with various degrees of polarity (9, 18, and 28 wt% vinyl acetate [VA]) and two different types of clay modification. Morphological characterization using wide‐angle X‐ray scattering (WAXS) and transmission electron microscopy (TEM) have indicated/confirmed the presence of intercalation and/or a combination of intercalation and exfoliation existing in the nanocomposites. The effects of these (simple intercalation or mixed intercalation/exfoliation) states and the effect of changing matrix polarity (by changing VA wt% content) on the nanocomposite mechanical behavior were studied. There is sufficient evidence from the mechanical studies that 1) the presence of nanoclay can simultaneously improve modulus and strength of the nanocomposites, and 2) the mechanical properties are a combined function of the clay concentration and the nanocomposite morphology (due to the VA wt% and presence of clay). It is shown here that interrelation between the VA wt% content and the clay exfoliation affects the mechanical properties in a way that has a positive and increasing slope with increasing loading of clay. It is shown that a clear understanding of the nanocomposite mechanical properties can be obtained from its morphological analysis. POLYM. ENG. SCI., 45:889–897, 2005. © 2005 Society of Plastics Engineers     

Experimental and theoretical studies on the mechanical and structural changes imposed by the variation of clay loading on poly(vinyl alcohol)/cloisite® 93A nanocomposites

Polymer nanocomposites (PNC) structures are promising materials due to their novel properties. However, many of their characteristic physical, mechanical, and chemical behavior have not been quantified. Depending on the interface interactions between polymeric chains and clay sheets, various classes of polymer/clay nanocomposite exist: Intercalated, flocculated and exfoliated nanocomposites. In this work, we present an experimental study of poly(vinyl alcohol) (PVA)‐cloisite® 93A followed by a classical molecular dynamic (MD) simulations. The structural properties of the system were studied using X‐ray diffraction (XRD), nanoscanning electron microscopy (NSEM). Both revealed intercalation between PVA chains and cloisite® 93A nanoclay. Another evidence of the intercalation between PVA and cloisite® 93A nanoclay was realized from the differential scanning calorimetry (DSC) which confirmed as surge in crystallinity upon intercalation. A main focus for the intercalated structure was to investigate the impact of nanofillers content on the mechanical performance. Intercalation significantly influenced both Young's modulus and the % of elongation of PVA/cloisite® 93A blends. Young's modulus and tensile stress were raised with the content of the filler content up to 3 wt%. For higher content, opposite observations are addressed owing to the formation of aggregates of nanofillers and as consequence construction of microvoids. From the MD simulations, the intercalation has been shown by the increase of the d‐spacing with the clay loading. By calculating the density profile, it has been demonstrated that in case of low clay loading, the cloisite® 93A has its nitrogen groups on the clay surface and the long tails form layers. For the high loading of clay, nitrogen and carbon groups are together on the surface. Young modulus calculated theoretically follows the same experimental trend where an increase of the values has been observed with a clay loading up to 3 wt%, followed by a decrease of the values for higher clay loading. J. VINYL ADDIT. TECHNOL., 25:172–181, 2019. © 2018 Society of Plastics Engineers     

Extrusion of linear polypropylene–clay nanocomposite foams

This work presents new results on using organoclay with an appropriate polymeric compatibilizer as rheology‐modifying additives for extrusion foaming of a linear polypropylene (PP), which by itself does not display strain hardening in extensional flow of the melt. The uniaxial melt‐extensional viscosity behavior of several nanocomposites prepared with varying ratio of bound maleic anhydride to clay as well as varying compatibilizer molecular weight was investigated. A chemical‐blowing agent was used at a fixed concentration for foaming these nanocomposites in a single‐screw extruder. Among nanocomposites with similar levels of clay dispersion or intercalation, the ones that displayed significant strain hardening in the melt state along with slower crystallization led to extruded PP nanocomposite foams with smaller cell sizes and greater cell density by reducing cell coalescence. This was achieved with as little as 3 wt% organoclay and a high‐molecular weight PP‐g‐MA compatibilizer in linear PP. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effects of process conditions and mixing protocols on structure of extruded polypropylene nanocomposites

Polymer melt‐direct intercalation or exfoliation is a promising approach for the preparation of nanocomposites. The structure of nanoclay platelets in the nanocomposites depends not only on the properties of polymer matrix and nanoclay, but also on the operating conditions during processing. The objective of the present work is to investigate the effects of clay chemical modifiers, mixing protocols, and operating conditions upon the clay structure in nanocomposites prepared with a corotating twin‐screw extruder. Two mixing methods were used for the nanocomposite preparation: two‐step mixing and one‐step mixing. Experimental results obtained from melt flow index and complex viscosity measurements suggest that nanoclay C15A is more exfoliated than C30B in a polypropylene homopolymer containing a maleic anhydride grafted PP (PB) as compatibilizer. The two‐step mixing method results in better exfoliation for the nanofillers than the one‐step mixing method. A numerical simulation has been carried out to evaluate the mean residence time and shear rate in different screw configurations under various process conditions. X‐ray diffraction experiments indicate that the residence time is a dominant factor in producing satisfactory nanocomposites in extruders. However, high shear rate coupled with long residence time might result in poor exfoliation of clay. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1891–1899, 2004     

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     

Synthesis of shape memory polyurethane/clay nanocomposites and analysis of shape memory,thermal, and mechanical properties

In this study, shape memory polyurethane/clay nanocomposites were synthesized by using two‐step in situ polymerization. The effects of nanoparticle content on mechanical, thermal, and shape memory properties were studied. Soft and hard segments of polyurethanes were based on polycaprolactone (PCL) diol and 4,4′‐diphenylmethane diisocyanate/1,4‐butanediol molar ratio with 70/30, respectively. The differential scanning calorimetry, tensile test, dynamic mechanical thermal analysis, parallel plate rheometer, and X‐ray diffraction were used to evaluate the properties of the nanocomposites. To evaluate shape memory properties, a tensile device equipped with a thermal chamber was used. Glass transition temperature of soft segments has been increased by nanoclay loading. Addition of nanoclay to polyurethane matrix caused to disrupt ordering in hard domains, decrease in elongation and tensile strength. The results show that crystallinity of soft segments and dispersion of nanoparticles affect on the mechanical properties and shape memory behavior of nanocomposites, distinctly. Nanocomposite containing 1 wt% shows the best shape memory properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

The structure and properties of PA6/MMT nanocomposites prepared by melt compounding

Polyamide 6 (PA6)/organo‐montmorillonite nanocomposites prepared by melt compounding using a co‐rotating twin‐screw extruder were intercalated nanocomposites. The modulus, bending strength and heat distortion temperature of these nanocomposites increased with increasing clay content, and tensile strength increased up to 4.3 wt% and then decreased with further increases in montmorillonite content. The notched Izod impact strength decreased slightly with montmorillonite content. Nanocomposites based on the higher‐molecular‐weight PA6 yielded higher moduli, tensile strengths, and heat distortion temperatures at the same montmorillonite content. Polym. Eng. Sci. 44:2070–2074, 2004. © 2004 Society of Plastics Engineers.     

A comparative study of nanocomposites based on a recycled poly(methyl methacrylate) matrix containing several nanoclays

Nanocomposites of recycled poly(methyl methacrylate) (PMMA) and both natural (Nanomer PGV MMT), and organically modified Nanomer I44P, Nanomer I30P and Cloisite 30B montmorillonites (O‐MMT) were prepared by solution dispersion method with the use of two miscible solvents, followed by melt intercalation process in a twin‐screw miniextruder. The final product has been found to show a homogeneous structure with a uniform dispersion/intercalation of the silicate layers. The effect of MMT and O‐MMT layers on the properties of the nanocomposites was investigated and characterized by UV–vis spectroscopy, differential scanning calorimetry, atomic force microscopy, and mechanical testing. Higher contents of nanoclay in nanocomposites exhibited worse light transmittance capacity but higher tensile modulus. Properties of the samples depended not only on the clay contents (up to 10 wt%) but also on the clay type employed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Rigid PVC/(layered silicate) nanocomposites produced through a novel melt‐blending approach

On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na⁺‐MMT) and organically modified montmorillonite (Org.‐MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X‐ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na⁺‐MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.‐MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Shear rheology and melt compounding of compatibilized‐polypropylene nanocomposites: Effect of compatibilizer molecular weight

Direct melt compounding was used to prepare nanocomposites of organophilic montmorillonite (o‐mmt) clay dispersed in maleated polypropylenes (PPgMA) as well as nanocomposites of organoclay and polypropylene (PP) modified with various grades of PPgMA compatibilizers. The thermal effect on the rheology and melt compounding was first investigated with a plasticorder. The shear viscosities and the melt flow indices (MFI) of the PPgMA compatibilizers were sensitive to the blending temperature, which had to be varied with the compatibilizer grade to achieve desirable level of torque for extensive exfoliation of organoclay in the plasticorder. However, for low molecular weight oligomer, the clay dispersion was poor because of low shear viscosity and thermal instability. Next, the PPgMA‐modified PP/organoclay nanocomposites were prepared on a corotating twin‐screw extruder. The nanoscale dimensions of the dispersed clay platelets led to significantly increased linear viscoelastic properties, which were qualitatively correlated with the state of exfoliation in the nanocomposites. The relative viscosity (relative to the silicate‐free matrix) curves revealed a systematic trend with the extent of clay exfoliation. Furthermore, the degree of clay dispersion was found to increase with the loading of compatibilizers; however, high loading of compatibilizer compromised the final moduli of the nanocomposites. POLYM. ENG. SCI. 46:289–302, 2006. © 2006 Society of Plastics Engineers     

Preparation of nanoclay‐dispersed polystyrene nanofibers via atom transfer radical polymerization and electrospinning

In this study, clay‐dispersed polystyrene (PS) nanocomposites were prepared with the in situ atom transfer radical polymerization method and were subsequently electrospun to form nanofibers 450–650 nm in diameter. The polymer chains extracted from the clay‐dispersed nanofibers exhibited a narrow range of molecular weight distribution. Thermogravimetric analysis (TGA) confirmed a higher thermal stability of the resulting nanocomposites compared to PS. The effect of the weight ratio of montmorillonite on the thermal properties of the nanocomposites was also studied by TGA. Differential scanning calorimetry revealed that the addition of the nanoclay increased the glass‐transition temperature. Moreover, degradation of the bromide chain‐end functionality took place at low temperatures. Scanning electron microscopy showed that the average diameter of the fibers was around 500 nm. The dispersion of clay layers was also evaluated by Al atoms in the PS matrix with the energy‐dispersive X‐ray detection technique. Transmission electron microscopy confirmed the exfoliation of the nanoclay within the matrix. However, the clay layers were oriented along the nanofiber axis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Sound isolation properties of polycarbonate/clay and polycarbonate/silica nanocomposites

The soundproofing properties of polycarbonate (PC)/nanoclay and PC/nanosilica nanocomposites were studied through testing and theoretical analysis. Nanocomposite sheets with a 3 mm thickness were fabricated by direct hot-compression molding process. The nanoclay and nanosilica particles were incorporated into the PC matrix by a twin-screw extruder. The dispersion efficiency of 1, 3 and 5 wt% nanoclay and nanosilica in the PC matrix was investigated by transmission electron microscopy. Dynamic mechanical analysis was performed for evaluation of mechanical properties of nanocomposites. Sound transmission loss (STL) was measured by an impedance tube over the frequency range of 1600–6300 Hz, and further employed in sound proofing characterizations of nanocomposites. A new finite element model was developed to model the sound transmission loss in impedance tube test. The results showed that the PC/3 wt% nanoclay and 3 wt% nanosilica nanocomposites had an average maximum increase of 5.5 and 6 dB in STL values in the stiffness control region (1600–3600 Hz), respectively. On the other hand, the PC/3 wt% nanoclay and PC/3 wt% nanosilica nanocomposites showed the same sound isolation characteristics in the frequency range of 1600–3600 Hz. In addition, the finite element model developed for modeling the sound transmission loss in the impedance tube demonstrated a good correlation between the theoretical curves and the experimental results in the stiffness control region for both nanocomposites.     

Nanoindentation and morphological studies on nylon 66 nanocomposites. I. Effect of clay loading

Nanoindentation technique has been used to investigate the mechanical properties of exfoliated nylon 66 (PA66)/clay nanocomposites in present study. The hardness, elastic modulus and creep behavior of the nanocomposites have been evaluated as a function of clay concentration. It indicates that incorporation of clay nanofiller enhances the hardness and elastic modulus of the matrix. The elastic modulus data calculated from indentation load-displacement experiments are comparable with those obtained from dynamic mechanical analysis and the tensile tests. However, the creep behavior of the nanocomposites shows an unexpected increasing trend as the clay loading increases (up to 5 wt%). The lowered creep resistance with increasing clay content is mainly due to the decrease of crystal size and degree of crystallinity as a result of clay addition into PA66 matrix, as evidenced by optical microscopy and X-ray diffraction. At lower clay concentration (here ≤5 wt%), morphological changes due to addition of clay plays the dominant role in creep behavior compared with the reinforcement effect from nanoclay.     

Thermal,mechanical, and barrier properties of polyethylene/surlyn/organoclay nanocomposites blown films prepared by different mixing methods

(Low‐density polyethylene) (LDPE)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder by using different mixing methods. Zinc‐neutralized carboxylate ionomer was used as a compatibilizer. Blown films of the nanocomposites were then prepared. The effect of mixing method on the clay dispersion and properties of the nanocomposites was evaluated by wide‐angle X‐ray diffraction analysis, mechanical properties, thermal properties, and barrier properties. The structure and properties of nanocomposites containing different amounts of nanoclay prepared by selected mixing techniques were also investigated. It was found that melt compounding of Surlyn/clay masterbatch with pure LDPE and Surlyn (two‐step‐a method) results in better dispersion and intercalation of the nanofillers than melt mixing of LDPE/Surlyn/clay masterbatch with pure LDPE and surlyn (two‐step‐b method) and direct mixing of LDPE with clay. The films containing ionomer have good barrier properties. A wide‐angle X‐ray diffraction pattern indicates that intercalation of polymer chains into the clay galleries decreases by increasing the clay content. Barrier properties and tensile modulus of the films were improved by increasing the clay content. In addition, tensile strength increased in the machine direction, but it decreased in the transverse direction by increasing the clay content. DSC results showed that increasing the clay content does not show significant change in the melting and crystallization temperatures. The results of thermogravimetric analysis showed that the thermal stability of the nanocomposites decreased by increasing the clay content more than 1 wt%. J. VINYL ADDIT. TECHNOL., 21:60–69, 2015. © 2014 Society of Plastics Engineers     

Morphology and melt rheology of nylon 11/clay nanocomposites

Nylon 11 (PA11)/clay nanocomposites have been prepared by melt‐blending, followed by melt‐extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler loading. Melt rheological properties of PA11 nanocomposites have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit much higher storage modulus (G′) and loss modulus (G″) values than neat PA11. The values of G′ and G″ increase steadily with clay loading at low concentrations, while the G′ and G″ for the sample with 5 wt % clay show an inverse dependence and lie between the modulus values of the samples with 1 and 2 wt % of clay. This is attributed to the alignment/orientation of nanoclay platelets in the intercalated nanocomposite induced by capillary extrusion. In the nonlinear regime, the nanocomposites show increased shear viscosities when compared with the neat resin. The dependence of the shear viscosity on clay loading has analogous trend to that of G′ and G″. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox‐Merz rule. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 542–549, 2006