Influence of the surface chemistry on the structural and mechanical properties of silica‐polymer composites

Poly(vinyl alcohol) (PVA) composite films filled with nanometric, monodisperse, and spherical silica particles were prepared by the mixing of an aqueous PVA solution and SiO₂ colloidal suspension and the evaporation of the solvent. Adjusting the solution pH to 5 and 9 controlled the PVA‐SiO₂ interaction. Adsorption isotherms showed a higher PVA/surface affinity at a lower pH. This interaction influenced the composite structure and the particle distribution within the polymer matrix, which was investigated by small‐angle neutron scattering, electron microscopy, and swelling measurements. Most of the mechanical properties could be related to the composite structure, that is, the distribution of clusters within the polymer matrix. The progressive creation of a cluster network within the polymeric matrix as the silica volume fraction increased reduced the extensibility or swelling capacity of the composite. The effect was more acute at a higher pH, at which the surface interaction with PVA was weaker and promoted the interconnection between clusters. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3127–3138, 2003     

The effect of nanoparticle shape on polymer‐nanocomposite rheology and tensile strength

Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocomposites in mind, we investigate how particle shape influences the melt shear viscosity η and the tensile strength τ, which we determine via molecular dynamics simulations. Our simulations of compact (icosahedral), tube or rod‐like, and sheet‐like model nanoparticles, all at a volume fraction ? ≈ 0.05, indicate an order of magnitude increase in the viscosity η relative to the pure melt. This finding evidently can not be explained by continuum hydrodynamics and we provide evidence that the η increase in our model nanocomposites has its origin in chain bridging between the nanoparticles. We find that this increase is the largest for the rod‐like nanoparticles and least for the sheet‐like nanoparticles. Curiously, the enhancements of η and τ exhibit opposite trends with increasing chain length N and with particle shape anisotropy. Evidently, the concept of bridging chains alone cannot account for the increase in τ and we suggest that the deformability or flexibility of the sheet nanoparticles contributes to nanocomposite strength and toughness by reducing the relative value of the Poisson ratio of the composite. The molecular dynamics simulations in the present work focus on the reference case where the modification of the melt structure associated with glass‐formation and entanglement interactions should not be an issue. Since many applications require good particle dispersion, we also focus on the case where the polymer‐particle interactions favor nanoparticle dispersion. Our simulations point to a substantial contribution of nanoparticle shape to both mechanical and processing properties of polymer nanocomposites. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1882–1897, 2007     

Layered silicate‐polyamide‐6 nanocomposites: Influence of silicate species on morphology and properties

The effect of two different species of layered silicates on the morphology, mechanical properties, and methanol vapor barrier properties of polyamide‐6 (PA6) nanocomposites was examined using identical experimental conditions for both species. The layered silicate species used were natural montmorillonite (MMT) and synthetic expandable fluoro‐mica (FM), the chemical compositions of which were Na_0.43(Al_1.56Mg_0.31Fe²⁺ _0.09)(Si_3.95Al_0.05)O₁₀(OH)₂ and Na_0.66Mg_2.68(Si_3.98Al_0.02)O₁₀F₂, respectively. The layered silicates were modified with a dodecylammonium salt (DDA) using an ion‐exchange method. The resulting organically modified layered silicates were melt‐kneaded with PA6 in a twin‐screw kneader at 260 °C. By quantitative analysis of the silicate layers dispersed in the PA6, the number‐average aspect ratio was estimated to be 76 for DDAMMT‐PA6 and 85 for DDAFM‐PA6. This confirmed that the primary particle size of the initial silicate did affect the aspect ratio. The rigidity and gas barrier properties of the nanocomposites appeared to depend upon the morphology of the nanocomposite. On the other hand, the elongation at break of the nanocomposites decreased as the amount of silicate increased. This reduction in ductility was ascribed to the difference in morphology of the nanocomposites, that is, distribution of silicate nanolayers in the polymer matrix. The homogeneity of the particle fraction of exfoliated nanolayers was clearly an important factor affecting the properties of the nanocomposites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 583–595, 2009     

Compatibilization level effects on the structure and mechanical properties of rubber‐modified polyamide‐6/clay nanocomposites

Exfoliated polyamide‐6 (PA6)/organically modified montmorillonite clay (OMMT) nanocomposites (PNs) were modified with partially maleinized styrene–ethylene/butadiene–styrene triblock copolymers (SEBS) at three maleinization levels in an attempt to link in these materials high toughness with appropriate small‐strain and fracture tensile properties. OMMT stayed only in the PA6 matrix, and no preferential location in the matrix/rubber interphase was observed. The increased dispersed phase size upon the addition of OMMT was attributed to interactions between maleic anhydride (MA) functionalized SEBS and the surfactant of OMMT. The rubber particle size generally decreased when the MA content of SEBS increased, and this indicated compatibilization. The subsequent good adhesion led to tough nanocomposites across a wide range of both strain rates and fracture modes. As the critical interparticle distance (τ_c) decreased with the MA content, and the other parameters that could influence the surface‐to‐surface mean interparticle distance did not change, it is proposed that in these PNs higher adhesion leads to a smaller τ_c value. Finally, the presence in the matrix of a nanostructured clay makes the rubber content necessary for the toughness jump to increase and τ_c to decrease. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3611–3620, 2005     

Assessing crystalline lamellae orientation impact on the properties of semi‐crystalline polymer‐clay nanocomposites

Semi‐crystalline polymer‐clay nanocomposite properties are often considered only by their clay dispersion state. The purpose of this work is to highlight texture effects on semi crystalline polymer‐clay properties. Maleic anhydride‐grafted polyethylene nanocomposites with two different processing techniques (Blown Extrusion and Compression) were studied. The processing was shown to induce different crystalline lamellae orientation in the films but with no significant changes in the crystalline lamellae long period, degree of crystallinity, clay particle orientation morphology and dispersion. The impact of these specific textures on the nanocomposites barrier and tensile properties were reported. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1966–1975, 2008     

Effect of different matrices and nanofillers on the rheological behavior of polymer‐clay nanocomposites

In this work, a comprehensive study of the rheological behavior under shear and isothermal and nonisothermal elongational flow of low density polyethylene (LDPE) and ethylene‐vinyl acetate copolymer (EVA) based nanocomposites was reported to evaluate their “filmability”, that is, the ability of these material to be processed for film forming applications. The influence of two different kinds of organoclay – namely Cloisite 15A and Cloisite 30B – and their concentration was evaluated. The presence of filler clearly affects the rheological behavior in oscillatory state of polyolefin‐based nanocomposites but the increase of complex viscosity and the shear thinning are not dramatic. A larger strain‐hardening effect in isothermal elongational flow is shown by the nanocomposites compared to that of the pure matrix, particularly for EVA based nanocomposites. The melt strength measured under nonisothermal elongational flow increases in the presence of the nanofiller, while the drawability is only slightly lower than that measured for the neat matrix. Moreover, the rheological behavior under nonisothermal elongational flow of EVA‐based nanocomposites is similar for both nanoclays used. Differently, LDPE‐based nanocomposites show a strong dependence on the type of organoclay. Finally, the mechanical properties of the materials were measured by tensile tests. They revealed that the presence of the filler provokes, in all the cases, an increase of the rigidity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 344–355, 2010     

Polypropylene/layered double hydroxide nanocomposites: Synergistic effect of designed filler modification and compatibilizing agent on the morphology,thermal, and mechanical properties

This work addresses the optimization of the morphology, thermal, and mechanical properties of polypropylene/layered double hydroxide (LDH) nanocomposites. For this, the nanofillers were modified by a calcination rehydration process using two surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate, respectively. The nanofillers were characterized at each step of the modification process by thermal gravimetry, X‐ray diffraction, and Infra red spectroscopy. Furthermore, the impact of anionic modifiers on the filler surface energy and on the interactions toward water was analyzed. Polypropylene (PP)/LDH nanocomposites were then prepared by a melt intercalation process and a high molar mass maleic anhydride functionalized polypropylene (PPgMA) was introduced as a compatibilizer. The dispersion of LDH in the PP matrix was characterized and the thermal and mechanical properties of the corresponding nanocomposites were determined and discussed as a function of the filler modification, of the nanocomposite morphology, and of the filler/matrix interfacial properties. The nanocomposites prepared from SDS modified LDH and PPgMA exhibited superior properties thanks to an optimized filler dispersion state and improved interfacial interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 782–794     

Structure and properties of polyamide‐6/vermiculite nanocomposites prepared by direct melt compounding

Polyamide‐6 (PA6)/vermiculite nanocomposites were fabricated through the direct melt compounding of maleic anhydride‐modified vermiculite (MAV) with PA6 in a twin‐screw extruder followed by injection molding. The structure and morphology of the nanocomposites were determined by X‐ray diffraction and scanning and transmission electron microscopy techniques. The results revealed the formation of intercalated and exfoliated vermiculite platelets in the PA6 matrix. Tensile measurement showed that the tensile modulus and strength of the nanocomposites tended to increase with increasing vermiculite content. The thermal properties of the nanocomposites were determined by dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetry measurements. The storage modulus of the PA6–MAV nanocomposites increased to almost twice that of the neat PA6. The thermal stability of the nanocomposites increased dramatically, and this was associated with the addition of vermiculite. The effect of the addition of maleic anhydride on the formation of the PA6–vermiculite nanocomposites was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2860–2870, 2002     

Physical properties of poly(ε‐caprolactone) layered silicate nanocomposites prepared by controlled grafting polymerization

Poly(ε‐caprolactone) (PCL) chains grafted onto montmorillonite modified by a mixture of nonfunctional ammonium salts and ammonium‐bearing hydroxyl groups were prepared. The clay content was fixed to 3 wt %, whereas the hydroxyl functionality was 25, 50, 75, and 100%, obtaining an intercalated or exfoliated system. The transport properties of water and dichloromethane vapors and the mechanical properties were investigated. The mechanical and dynamic mechanical analyses showed improvement of the nanocomposite elastic modulus in a wide temperature range. Interestingly, for the higher hydroxyl contents (50, 75, and 100%), the decrease of modulus at higher temperature, due to the PCL crystalline melting, did not lead to the loss of mechanical consistence of the samples. Consequently, they revealed a measurable modulus up to 120 °C, a much higher temperature with respect to pure PCL. Water sorption was investigated in the entire activity range, and a lower sorption was observed on increasing the hydroxyl content, up to the sample with 100% hydroxyl content, which turned to be completely impermeable, even in liquid water. The sample with 75% hydroxyl content showed a threshold activity (a = 0.4) below which it was impermeable to water vapor. Also, the diffusion parameters decreased when the hydroxyl content increased, up to the 100% sample, which showed zero diffusion. The diffusion parameters of an organic vapor, dichloromethane, also exhibited a decreasing value on increasing the hydroxyl content in the nanocomposites. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1466–1475, 2004     

Gas barrier properties of poly(ε‐caprolactone)/clay nanocomposites: Influence of the morphology and polymer/clay interactions

Poly(ε‐caprolactone)/montmorillonite nanocomposites were prepared maintaining a constant inorganic content with three means: melt blending of poly(ε‐caprolactone) with natural or organomodified clays, in situ polymerization of ε‐caprolactone in the presence of organomodified clays, and initiation of ε‐caprolactone polymerization from the silicate layer with appropriate organomodified montmorillonites and activator. In this last case, the polymer chains were grafted to the silicate layers and it was possible to tune up the grafting density. The presence of clays did not modify the polymer crystallinity. It was shown that the in situ polymerization process from the clay surface improved the clay dispersion. The gas barrier properties of the different composite systems were discussed both as a function of the clay dispersion and of the matrix/clay interactions. The highest barrier properties were obtained for an exfoliated morphology and the highest grafting density. Similar evolution of the permeability and the diffusion coefficients was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 205–214, 2005     

Effect of the C/O ratio in graphene oxide materials on the reinforcement of epoxy-based nanocomposites

The effect of the C/O ratio of graphene oxide materials on the reinforcement and rheological percolation of epoxy-based nanocomposites has been studied. As-prepared graphene oxide (GO) and thermally-reduced graphene oxide (TRGO) with higher C/O ratios were incorporated into an epoxy resin matrix at loadings from 0.5 to 5 wt %. Tensile testing revealed good reinforcement of the polymer up to optimal loadings of 1 wt %, whereas agglomeration of the flakes at higher loadings caused the mechanical properties of the composites to deteriorate. The level of reduction (C/O) of the graphene oxide filler was found to influence the mechanical and rheological properties of the epoxy composites. Higher oxygen contents were found to lead to stronger interfaces between graphene and epoxy, giving rise to higher effective Young's moduli of the filler and thus to superior mechanical properties of the composite. The effective modulus of the GO in the nanocomposites was found to be up to 170 GPa. Furthermore, rheological analysis showed that highly oxidized graphene flakes did not raise the viscosity of the epoxy resin significantly, facilitating the processing considerably, of great importance for the development of these functional polymeric materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 281–291     

Crystallization,mechanical, and fracture behaviors of spherical alumina‐filled polypropylene nanocomposites

The objectives of this paper are to study the crystallization behavior and fracture characteristics of spherical alumina (Al₂O₃) nanoparticle‐filled polypropylene (PP) composites. Nanocomposites containing 1.5–5.0 wt % of the Al₂O₃ nanoparticles (pretreated with silane coupling agent) were prepared for this investigation. Wide angle X‐ray diffraction (WAXD) results show that a small amount of β‐crystal of PP forms after adding the Al₂O₃ nanoparticles. According to differential scanning calorimetric (DSC) and optical microscopy (OM) measurements, the Al₂O₃ nanoparticles make PP spherulite size reduced and crystallization temperature of PP enhanced, by acting as effective nucleating agents. However, there are no obvious differences in the crystallinity for the virgin PP and the Al₂O₃/PP nanocomposites. Tensile test shows that both the Young's modulus and the yield strength of the Al₂O₃/PP nanocomposites increase with the particle content increasing, suggesting that the interfacial interaction between the nanoparticles and PP matrix is relatively strong. Under quasi‐static loading rate, the fracture toughness (K_IC) of the Al₂O₃/PP nanocomposites was found to be insensitive to nanoparticle content. Under impact loading rate, the Izod impact strength and the impact fracture toughness (G_c) indicate that the impact fracture toughness increases initially with the addition of 1.5 wt % of the Al₂O₃ nanofillers into the PP matrix. However, with the further addition of up to 3.0 and 5.0 wt % nanoparticles, both the Izod impact strength and impact G_c change very little. By observing the single‐edge‐double‐notch (SEDN) specimens with optical microscopy after four point bending (4PB) tests, it was found that numerous crazes and microcracks form around the subcritical crack tip, indicating that crazing and microcracking are the dominant fracture mechanisms. Scanning electron microscopy (SEM) observation confirms this result. In addition, when the strain rate of 4PB tests was increased, some wave‐like branches were formed along the fractured edge for the Al₂O₃/PP nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3652–3664, 2005     

Rheology of (±)‐camphor‐10‐sulfonic acid doped polyaniline‐m‐cresol conducting gel nanocomposites

The rheological behavior of polyaniline‐(±champhor‐10‐sulfonic acid)_0.5‐m‐cresol [PANI‐CSA_0.5‐m‐cresol] gel nanocomposites (GNCs) with Na‐montmorillonite clay (intercalated tactoids) is studied. The shear viscosity exhibits Newtonian behavior for low shear rate (<2 × 10^?4 s^?1) and power law variation for higher shear rate. The zero shear viscosity (η₀) and the characteristic time (λ) increase but the power law index (n) decrease with increase in clay concentration. In the GNCs storage modulus (G′) and loss modulus (G″) are invariant with frequency in contrast to the pure gel. The G′ and G′ exhibit the gel behavior of the GNCs up to 105 °C in contrast to the melting for the pure gel at 75.7 °C. The percent increase of G′ of GNCs increases dramatically (619% in GNC‐5) with increasing clay concentration. The conductivity values are 10.5, 5.65, 5.51, and 4.75 S/cm for pure gel, GNC‐1, GNC‐3, and GNC‐5, respectively, promising their possible use in soft sensing devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 28–40, 2008     

Thermal and mechanical interfacial properties of the DGEBA/PMR-15 blend system

In this work, the blend system of diglycidyl ether of bisphenol A and PMR-15 polyimide is investigated in terms of thermal and dynamic mechanical interfacial properties of the casting specimens. The thermal stabilities are studied by thermogravimetric and thermomechanical analyses, and the dynamic mechanical properties are carried out by dynamic mechanical analysis. The results show that the thermal stabilities based on the initial decomposition temperature, the integral procedural decomposition temperature, and the glass transition temperature are increased with increasing PMR-15 content. The crosslinking density (rho) of the blend system is increased at 10 phr of PMR-15, compared with that of neat epoxy. Mechanical interfacial properties measured in the context of critical stress intensity factor and critical strain energy release rate show similar behaviors with E(a) and rho, probably due to the increase in intermolecular interactions or hydrogen bondings in polymer chains.     

Preparation and enhanced properties of poly(propylene)/ silica‐grafted‐hyperbranched polyester nanocomposites

A series of poly(propylene) silica‐grafted‐hyperbranched polyester nanocomposites by grafting the modified hyperbranched polyester (Boltorn? H20), possessing theoretically 50% end carboxylic groups and 50% end hydroxyl groups, which endcapped with octadecyl isocyanate (C19), onto the surface of SiO₂ particles (30 nm) through 3‐glycidoxy‐propyltrimethoxysilane (GPTS) was prepared. The effect of silica‐grafted‐modified Boltorn? H20 on the mechanical properties of polypropylene (PP) was investigated by tensile and impact tests. The morphological structure of impact fracture surface and thermal behavior of the composites were determined by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The melt viscosity of composites was investigated by melt flow index (MFI). The obtained results showed that: (1) the modified Boltorn? H20 was successfully grafted onto the SiO₂ surface confirmed by FT‐IR and X‐ray photoelectron spectroscopy (XPS) analysis; (2) the incorporation of silica‐grafted‐modified Boltorn? H20 (3–5 wt% SiO₂) greatly enhanced the notched impact strength as well the tensile strength of the composites; (3) the incorporation of silica‐grafted‐modified Boltorn? H20 had no influence on the melting temperature and crystallinity of PP phase; (4) the MFI of PP composites increased when the silica‐grafted‐modified Boltorn? H20 particles were added compared with PP/SiO₂ or PP/SiO₂‐GPTS composites. Copyright © 2004 John Wiley & Sons, Ltd.     

Plasticized polylactide/clay nanocomposites. I. The role of filler content and its surface organo‐modification on the physico‐chemical properties

Polylactide (PLA)‐layered silicate nanocomposites plasticized with 20 wt % of poly(ethylene glycol) 1000 were prepared by melt blending. Three kinds of organo‐modified montmorillonites—Cloisite® 20A, Cloisite® 25A, and Cloisite® 30B—were used as fillers at a concentration level varying from 1–10 wt %. Neat PLA and plasticized PLA with the same thermomechanical history were considered for comparison. Nanocomposites based on amorphous PLA were obtained via melt‐quenching. The influence of both plasticization and nanoparticle filling on the physicochemical properties of the nanocomposites were investigated. Characterization of the systems was achieved by size exclusion chromatography (SEC), thermogravimetric analysis (TGA), thermally modulated differential scanning calorimetry (TMDSC), X‐ray diffraction (XRD), and dynamic mechanical analysis (DMTA). SEC revealed a decrease of the molecular weight of the PLA matrix with the filler content. Thermal behavior on heating showed one cold crystallization process in the reference neat PLA sample, while two cold crystallization processes in plasticized PLA and plasticized nanocomposites. The thermal windows of these processes tend to increase with the filler content. The crystalline form of PLA developed upon heating was affected neither by the plasticization nor by the type and content of Cloisite used. It was found that the series of organo‐modified montmorillonites with decreasing affinity to PLA is Cloisite® 30B, Cloisite® 20A, and Cloisite® 25A, respectively. The dynamic mechanical properties were sensitive to the sample composition. Generally, the storage modulus increased with the filler content. Glassy PEG, well dispersed within unfilled PLA matrix, exhibited also a reinforcing effect, since the storage modulus of this sample was higher than for unplasticized reference at temperature region below the glass transition of PEG. Moreover, loss modulus of all plasticized samples revealed an additional maximum ascribed to the glass transition of PEG–rich dispersed phase, indicating partial miscibility of organic components of the systems investigated. The magnitude of this mechanical loss was correlated with the filler content, and to some extent, also with the nanofiller ability to be intercalated by polymer components. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 299–311, 2006     

Stiffness constants prediction of nanocomposites using a periodic 3D‐FEM model

Predictive models, which enable the prediction of nanocomposite properties from their morphologies and account for polymer orientation, could greatly assist the exploitation of this new class of materials in more diversified and demanding market fields. This article focuses on the prediction of effective elastic properties (Young's moduli) of polymer nanocomposite films (copolyamide‐6/nanoclay) using 3D analytical (based on the Mori‐Tanaka theory) and 3D finite element (FE) models. The analytical model accounts for the orientation of polymer chains induced by drawing. 3D FE model exploits the representative volume element concept and accounts for the nanocomposite morphology as determined from transmission electron microscopy experiments. Model predictions were compared with experimental results obtained for nanocomposite films produced by means a pilot‐scale film blowing equipment and collected at different draw ratios. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Selective localization of organoclay and effects on the morphology and mechanical properties of LDPE/PA11 blends with distributed and co‐continuous morphology

A study was made on the effect of small amounts of organically modified clay on the morphology and mechanical properties of blends of low‐density polyethylene and polyamide 11 at different compositions. The influence of the filler on the blend morphology was investigated using wide angle X‐ray diffractometry, scanning and transmission electron microscopy and selective extraction experiments. The filler was found to locate predominantly in the more hydrophilic polyamide phase. Although such uneven distribution does not have a significant effect on the onset of phase co‐continuity of the polymer components, it brings about a drastic refinement of the microstructure for the blends both with droplets/matrix and co‐continuous morphologies. In addition to the expected reinforcing action of the filler, the resulting fine microstructure plays an important role in enhancing the mechanical properties of the blends. This is essentially because of a good quality of stress transfer across the interface between the constituents, which also seems to benefit for a good interfacial adhesion promoted by the filler. Our results provide the experimental evidence for the capabilities of nanoparticles added to multiphase polymer systems to act selectively as a reinforcing agent for specific domains of the material and as a medium able to assist the refinement of the polymer phases during mixing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 600–609, 2010     

Bio‐based hyperbranched polyurethane/clay nanocomposites: adhesive,mechanical, and thermal properties

The unison of vegetable oil‐based hyperbranched polymers with nanotechnology can unhook myriad of avant‐garde applications of such materials. Thus Mesua ferrea L. seed oil‐based hyperbranched polyurethane (HBPU)/clay nanocomposites and their performance, with special reference to adhesive strength, are reported for the first time. The nanocomposites of the hyperbranched polyurethane with organically modified nanoclay were obtained by ex situ solution technique and cured by bisphenol‐A‐based epoxy with poly(amido amine) hardener system. The partially exfoliated and well‐distributed structure of nanoclay was confirmed by XRD, SEM, and TEM studies. FTIR spectra indicate the presence of H‐bonding between nanoclay and the polymer matrix. Two times improvement in the adhesive strength and scratch hardness, 10 MPa increments in the tensile strength and 112°C more thermo‐stability have been observed without much affecting the impact resistance, bending, and elongation at break of the nanocomposites compared to the pristine epoxy modified HBPU system. Thus, the resulted nanocomposites are promising materials for different advanced applications including adhesive. Copyright © 2009 John Wiley & Sons, Ltd.     

Syndiotactic poly(propylene)/organoclay nanocomposite fibers: influence of the nano‐filler and the compatibilizer on the fiber properties

Melt spinning of nanocomposites prepared from syndiotactic poly(propylene) (sPP) and organolayered silicate (M‐ODA), containing bound octadecyl ammonium chains, was investigated. The influence of the nano‐filler reinforcement and the role of the addition of maleic anhydride grafted isotactic poly(propylene) (iPP‐g‐MA) as compatibilizer with respect to the fiber proportion was examined. The presence of nano‐filler, the drawing ratio, and the compatibilizer addition afforded increased tenacity of the fibers. Only in the presence of the compatibilizer high drawing ratio of the sPP nanocomposite fibers was achieved. Transmission electron microscopy (TEM) was applied to monitor morphology development during nanocomposite fiber spinning in the presence and the absence of the compatibilizer. Copyright © 2005 John Wiley & Sons, Ltd.