Clay Hybrid Nanocomposites Research Articles

Interfacial interaction exploration and oxygen barrier potential of polyethylene/poly(ethylene-co-vinyl alcohol)/clay hybrid nanocomposites

Abstract Hybrid nanocomposites based on high-density polyethylene (HDPE)/poly (ethylene-co-vinyl alcohol) (EVOH)/clay were prepared and fully characterized. Morphological (WAXS and TEM), calorimetric (DSC), and dynamic mechanical thermal (DMTA) analyses were applied to investigate potential of nanocomposites as barrier against oxygen. Co-existence of ingredients of different nature, i.e. HDPE (general-purpose non-polar component), EVOH (engineering polar component with excellent barrier properties), nanoclay (planar one-dimensional mineral barrier nanofiller), and maleated HDPE (PE-g-MA) as coupling agent, brings about serious intricacies in view of interaction between existing phases. Conceptual/experimental analysis was performed to explore the interdependence between microstructure and oxygen barrierity of HDPE/EVOH/clay nanocomposites through the lens of interaction state in the system. Morphological measurements confirmed formation of an intercalated nanostructure, while investigations on complex viscosity, storage modulus, permeability, thermo-mechanical properties, and nanoclay interlayer galleries were all indicative of dependence of nanocomposites’ properties on molecular interactions. The performance of nanocomposite sheets as oxygen barriers was mechanistically explained.

Effect of clay and PEO-PPO-PEO block copolymer on the microstructure and properties of cyanate ester/epoxy composite

In this study, processing, morphology and properties of poly (ethylene oxide)-block-poly (propylene oxide)-block-poly (ethylene oxide) (PEO-PPO-PEO) triblock copolymer and clay modified cyanate ester/epoxy hybrid nanocomposites were investigated. The PEO-PPO-PEO triblock copolymer preferentially reaction-induced microphase separate into spherical micelles in the cyanate ester/epoxy matrix. PEO-PPO-PEO was used as both nanostructuring agent for cyanate ester/epoxy blended resin and thus the predominantly intercalated and few exfoliated platelets of were also observed with clay, which successfully reduced the brittleness of the cyanate ester/epoxy blended resin increasing the toughness of designed materials. The stiffness and heat resistance of the neat BCE/EP resin could be retained in the BCE/EP/F68/clay hybrid nanocomposites. The optimum property enhancement was observed in the hybrid nanocomposites containing 5wt% PEO-PPO-PEO and 3wt% clay. The thermo/mechanical properties of the hybrid nanocomposites depend on microstructure, dispersion state and the ratio between organic and inorganic modifiers content.

Processing and Characterization of Polypropylene Filled with Multiwalled Carbon Nanotube and Clay Hybrid Nanocomposites

Nanocomposites reinforced with hybrid fillers of carbon nanotubes (CNTs) and clays were developed, aiming at enhancing the dispersion of nanofillers with balanced mechanical properties while lowering the cost of the final product. Polypropylene-based nanocomposites were prepared by the master batch dilution technique with varying combinations of CNTs and clays as fillers by using commercially available highly concentrated master batches of polypropylene/organoclays and polypropylene/multiwalled carbon nanotubes using high-shear twin-screw extrusion. Their mechanical and morphological properties were then evaluated. It was shown that the addition of hybrid filler to polypropylene enhanced the ductility and flexural properties of nanocomposites, confirming the synergistic effect of nanofillers as a multifunctional fillers. The novelty of this work lies in the synergy arising from the combination of two nanofillers with unique dimensions and aspect ratios as well as different dispersion characteristics, which have not been specifically considered previously.

Nanofibrillated cellulose, poly(vinyl alcohol), montmorillonite clay hybrid nanocomposites with superior barrier and thermomechanical properties

Nanocomposites of poly(vinyl alcohol) (PVA), nanofibrillated cellulose (NFC), and montmorillonite (MMT) clay were prepared via solvent casting. In addition to investigating the effect of clay loading, PVA matrices crosslinked with poly(acrylic acid) (PAA) were prepared and compared with linear (noncrosslinked) PVA nanocomposites. 13C NMR and infrared spectroscopy confirmed the presence of crosslinks. Scanning electron microscopy revealed effective NFC and MMT clay dispersion throughout the nanocomposites, while X-ray diffraction highlighted the effectiveness of PAA to encourage clay dispersion. MMT clay provided a barrier against the diffusion of water and oxygen (molecules) through the nanocomposite films. Permeability and adsorption were further reduced by crosslinking, while oxygen barrier properties were remarkably enhanced at elevated relative humidities. Thermal stability of the PVA segments was strengthened by the presence of MMT clay and crosslinks. MMT clay–reinforced PVA and NFC within the films, increasing the Young's modulus, tensile strength, and glass transition temperature. Crosslinking further enhanced the thermomechanical properties by imparting physical restraints on polymer chain segments, providing elasticity, and ductility. The hybrid films were successfully reinforced at elevated humidities, with nanocomposites displaying enhanced storage moduli and near-complete recovery. POLYM. COMPOS., 35:1117–1131, 2014. © 2013 Society of Plastics Engineers

Carbon black–clay hybrid nanocomposites based upon EPDM elastomer

The present study explored the effect of nanoclay on the properties of the ethylene–propylene–diene rubber (EPDM)/carbon black (CB) composites. The nanocomposites were prepared with 40 wt% loading of fillers, where the nanoclay percentage was kept constant at 3 wt%. As the modified nanoclay contains the polar groups and the EPDM matrix is nonpolar, a polar rubber oil extended carboxylated styrene butadiene rubber (XSBR), was used during the preparation of nanocomposites to improve the compatibility. Primarily the nanoclay was dispersed in XSBR by solution mixing followed by ultrasonication. After that EPDM-based, CB–clay hybrid nanocomposites, were prepared in a laboratory scale two roll mill. The dispersion of the different nanoclay in the EPDM matrix was observed by wide-angle X-ray diffraction (WAXD) and high resolution transmission electron microscopy. It was found that the mechanical properties of the hybrid nanocomposites were highly influenced by the dispersion and exfoliation of the nanoclays in the EPDM matrix. Thermo gravimetric analysis, scanning electron microscopy and dynamic mechanical thermal analysis was carried out for each nanocomposite. Among all the nanocomposites studied, the thermal and mechanical properties of Cloisite 30B filled EPDM/CB nanocomposite were found to be highest.

Evaluation of clay hybrid nanocomposites of different chain length as reinforcing agent for natural and synthetic rubbers

Polymer nanocomposites are one of the highly discussed research topics in recent time. It has been reported in the present paper the preparation and the properties of different nanoclays based on sodium montmorillonite (bentonite) and some organic amines of varying chain lengths (dodecylamine, hexadecylamine and octadecylamine) beside amine-terminated butadiene–acrylonitrile copolymer (ATBN). The hybrid clays have been characterized with the help of Fourier Transform Infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Wide angle X-ray diffractions (WXRD), and Thermogravimetric analysis (TGA). X-ray results showed that the intergallery distance of the clay is increased as a result of the intercalation of the amines and ATBN. The nanocomposite clays were incorporated in natural and synthetic rubbers (NR, SBR and NBR). The physico-mechanical properties are greatly improved with loading low concentrations of the nanocomposite clays compared with carbon black.

Synthesis and characterization of 1, 1-bis (3-methyl-4-epoxyphenyl) cyclohexane-toughened DGEBA and TGDDM organo clay hybrid nanocomposites

1,1-bis (3-methyl-4-epoxyphenyl) cyclohexane (BMEPC) was synthesized from 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane and 2-(chloromethyl) oxirane, and its structure was confirmed by Fourier transform infrared (FT-IR), 1H-, 13C-NMR and electron impact-mass spectrometry. Both diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamine diphenyl methane (TGDDM) epoxy resins were toughened with BMEPC using 4,4′-diaminodiphenylmethane (DDM) as a curing agent. Epoxy and BMEPC-toughened epoxy systems were further modified with organophilic MMT (OMMT) clay. The chemical reactions involved between epoxy and DDM with OMMT was confirmed by FT-IR. OMMT clay-filled hybrid BMEPC-epoxy resin castings were characterized for their mechanical, thermal, thermo-mechanical and morphological properties. The values of Tg and heat distortion temperature of hybrid epoxy decreased with increasing incorporation of OMMT. The data obtained from thermal studies indicated that the incorporation of nano clay into BMEPC-modified hybrid systems possess improved thermal stability. The mechanical properties were studied as per ASTM standards. The TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher when compared with that of the TGDDM system. The values of dielectric constant (ϵ′) and dielectric loss (ϵ′′) were increased with increased incorporation of OMMT clay in both systems. From the X-ray diffraction analysis it was observed that the absence of d001 reflections in OMMT-filled BMEPC-modified epoxy systems indicated the formation of exfoliated nano hybrids. The homogenous morphologies were ascertained from scanning electron microscope and transmission electron microscope.

OS18-2-2 Creep Behavior of Nylon 6 Clay Hybrid Nanocomposites at Room and High Temperatures

OS18-2-2 Creep Behavior of Nylon 6 Clay Hybrid Nanocomposites at Room and High Temperatures

OS18F020 Creep Behavior of Nylon 6 Clay Hybrid Nanocomposites at Room and High Temperatures

OS18F020 Creep Behavior of Nylon 6 Clay Hybrid Nanocomposites at Room and High Temperatures

Synthesis and characterization of 1,1-bis(3-methyl-4-hydroxy phenyl)cyclohexane polybenzoxazine–organoclay hybrid nanocomposites

Typical high-performance polybenzoxazines were prepared from benzoxazines based on 1,1-bis(3-methyl-4-hydroxy phenyl) cyclohexane, paraformaldehyde and three distinctive aromatic diamines, namely 4,4’-diaminodiphenylmethane, 4,4’-diaminodiphenylether and 4,4’-diaminodiphenylsulfone, through ring-opening self-polymerization upon heating. The formation of benzoxazines was confirmed by Fourier transform infrared, 1H and 13C nuclear magnetic resonance spectra. Polybenzoxazine–clay hybrid nanocomposites were prepared by a solvent method using polybenzoxazine precursors and organoclay (OMMT) (up to 5 wt.%). The hybrid mixture was subjected to ultrasonication for effective blending. The thermal properties of the resulting polybenzoxazine–clay nanocomposites were studied using differential scanning calorimetry and thermogravimetric analysis. The dispersion of OMMT in the polybenzoxazine and nanostructure of the composites was confirmed by X-ray diffraction analysis. The d spacing of the organoclay interlayers was found to be increased from 1.69 to 2.10 nm. Thermal decomposition temperatures of the nanocomposites were in the range 294–637 °C. These nanocomposites exhibited a high char yield relative to unfilled polybenzoxazines depicting interfacial interactions between the organic and inorganic phases. The homogeneous morphological behavior was studied by scanning electron microscopy.

PPgMA/APTS compound coupling compatabilizer in PP/clay hybrid nanocomposite

AbstractA compound coupling compatibilizer employing coupled use of γ‐(aminopropyl) triethoxy silane (APTS) and maleic anhydride‐graft‐polypropylene (PPgMA) was synthesized for the preparation of polypropylene (PP)/clay hybrid nanocomposites. The designed PPgMA/APTS compound coupling compatabilizer, through condensation of the amino groups of APTS with the anhydride groups of MA moieties in PPgMA, is capable of forming chemical bonding with the organo clay (org‐clay) while maintaining compatibility with the organic PP compartment. Various PPgMA to APTS ratios of these compound coupling compatibilizers were first reacted with clay to form PPgMA/clay masterbatches. The obtained masterbatches were then compounded with PP to produce PP/clay hybrid nanocomposites possessing different characteristics. The composition effects were studied. For org‐clay content of 5 wt %, intercalated‐exfoliated structure of the nanocomposite could be maintained for better reinforcement. Td of 484°C was achieved, indicating significant improvement over neat PP (Td was 386°C) in thermal property. The ultimate tensile strength (30% higher than control) and Young's modulus (57% higher than control) measurements also justified the application of the PPgMA/APTS compound coupling compatibilizer in the incorporation of org‐clay in PP matrix. The use of the PPgMA/APTS compound coupling compatibilizer can provide design flexibility in manufacturing PP/clay hybrid nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d001 reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).

Preparation and Properties of New in-situ Acrylic Copolymer/Terpolymer- Clay Hybrid Nanocomposites

Abstract Acrylic copolymer- and 5% acrylic acid (AA) modified terpolymer-hybrids with unmodified montomorilonite clay (Cloisite Na) and organo-modified clay (Cloisite 10A) were synthesized by in-situ free radical bulk polymerization. Hybrid nanocomposites were investigated by Atomic Force Microscopy (AFM), X-ray diffraction (XRD) technique, thermogravimetric analysis (TGA), dynamic mechanical and mechanical properties. XRD results suggested polymer intercalation in both unmodified and organo-modified clay in the copolymer and terpolymer hybrids. AFM analysis further confirmed these results. Cloisite 10A hybrids and the terpolymeric nanocomposites demonstrated superior mechanical and dynamic mechanical properties. Terpolymer-clay hybrids with 9 wt% Cloisite 10A also showed higher thermal stability. The possible reasons for improvement of mechanical properties and thermal stability were discussed with reference to the structure and interaction.

Synthesis and characterization of poly(urethane‐benzoxazine)/clay hybrid nanocomposites

AbstractPoly(urethane‐benzoxazine)/clay hybrid nanocomposites (PU/Pa–OMMTs) were prepared from an in situ copolymerization of a polyurethane (PU) prepolymer and a monofunctional benzoxazine monomer, 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine (Pa), in the presence of an organophilic montmorillonite (OMMT), by solvent method using DMAc. OMMT was made from cation‐exchange of Na‐montmorillonite (MMT) with dodecyl ammonium chloride. The formation of the exfoliated nanocomposite structures of PU/Pa‐OMMT was confirmed by XRD from the disappearance of the peak due to the basal diffraction of the layer‐structured clay found in both MMT and OMMT. DSC showed that, in the presence of OMMT, the curing temperature of PU/Pa lowered by ca. 60°C for the onset and ca. 20°C for the maximum. After curing at 190°C for 1 h, the exothermic peak on DSC disappeared. All the obtained films of PU/Pa–OMMT were deep yellow and transparent. As the content of OMMT increased, both the tensile modulus and strength of PU/Pa–OMMT films increased, while the elongation decreased. The characteristics of the PU/Pa–OMMT films changed from plastics to elastomers depending on OMMT content and PU/Pa ratio. PU/Pa–OMMT films also exhibited excellent resistance to the solvents such as tetrahydrofuran, N,N‐dimethylformamide and N‐methyl‐2‐pyrrolidinone. The thermal stability of PU/Pa were enhanced remarkably even with small amount of OMMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4075–4083, 2003

Uniaxial Deformation of Nylon 6–Clay Nanocomposites by In-Situ Synchrotron X-Ray Measurements

An in-situ uniaxial deformation study of nylon 6–clay hybrid (NCH) nanocomposites was carried out using simultaneous wide-angle x-ray diffraction (WAXD) and small-angle x-ray scattering (SAXS) techniques with synchrotron radiation. This nanocomposite system exhibited the partial exfoliated clay morphology. The WAXD patterns along the through-and edge-views from the as-pressed film samples indicated that both clay platelets and nylon 6 crystallites were parallel to the film plane but oriented randomly in the plane. During uniaxial deformation, the orientation of the molecular axis in the crystals increased with strain but decreased with the clay content. This behavior could be attributed to the rotation of clay platelets during deformation, which hindered the orientation of nylon 6 crystals. The corresponding tensile mechanical properties indicated that the elongation at break decreased and the tensile modulus and strength increased with the clay concentration, which has been observed before.

Fiber Structure Formation in High-Speed Melt Spinning of Polyamide 6/Clay Hybrid Nanocomposite

Polyamide 6 (PA 6)/clay hybrid (NCH) nanocomposites containing 2 and 5 wt% of clay were melt spun at take-up velocities from 1 to 5 km/min, and the effect of clay on the fiber structure formation was investigated. As the reference, neat PA 6 was spun at take-up velocities from 1 to 7 km/min. The NCH fibers showed higher crystallinity in the whole take-up velocity range, although there was no remarkable crystallinity dependence on the clay content. The birefringence of NCH fibers exceeded that of neat polymer only in the low take-up velocity region (i.e., up to 3 km/min). The orientation-induced crystallization was observed to start at about 2 km/min for NCH and at 4 km/min for neat PA 6. Also, at these take-up velocities, the peaks of α-form crystals appeared in the wide-angle X-ray diffraction equatorial (WAXD) scans, indicating that the orientation-induced crystallization was related to the direct formation of α-form crystals in the spinline. The NCH fibers were superior in Young's modulus; however, their tenacity was higher only in the low take-up velocity region in which the crystallization in the spinline of neat PA 6 did not occur yet. That variation of tenacity was attributed to the molecular orientation, whereas the modulus was supposed to be determined by the stiffness of intercrystalline regions.

Polybenzoxazine–montmorillonite hybrid nanocomposites: synthesis and characterization

Polybenzoxazine–clay hybrid nanocomposites were prepared from a polybenzoxazine precursor ( B-a) and organically modified-montmorillonite ( OMMT) as a type of layered silicates. OMMTs were prepared by surface treatment of montmorillonite ( MMT) by octyl, dodecyl or stearyl ammonium chloride. The curing behavior of B-a in the presence of dispersed OMMT was followed by IR and DSC. DSC showed that the onset of the ring opening polymerization of pristine B-a started at 223°C. The ring opening polymerization of B-a in the presence of OMMT started at 177–190°C, however, suggesting the catalytic effect of the OMMT surface on the ring opening polymerization. DSC and IR indicated that the curing of B-a was completed by the end of the 230°C cure cycle. The dispersion of OMMT in the polybenzoxazine matrix was confirmed by XRD, which indicated the collapse of the registry of the OMMT. The absence of basal spacings diffractions of OMMTs from the XRD patterns suggests the dispersion of OMMT layers on the molecular level when the surface was pretreated with long chain surfactants like dodecyl or stearyl ammonium chloride. However, in case of OMMT, which was pretreated with short chain surfactants like octyl ammonium chloride, the intercalation of polybenzoxazine into the clay galleries occurred with a regularly stalked layered structure. Viscoelastic measurements showed that the T gs of the hybrid materials were higher than that of the pristine resin. In addition, the storage modulii of the hybrid materials were maintained up to higher temperatures suggesting the reinforcement attained by OMMT. Isothermal and dynamic TGA showed that nanocomposites have delayed decomposition temperatures when compared with pristine polybenzoxazine indicating the enhancement in the thermal stability.

Polymer-layered silicate nanocomposites: an overview

An overview of polymer–clay hybrid nanocomposites is provided with emphasis placed on the use of alkylammonium exchanged smectite clays as the reinforcement phase in selected polymer matrices. A few weight percent loading of organoclay in nylon 6 boosts the heat distortion temperature by 80°C, making possible structural applications under conditions where the pristine polymer would normally fail. A similar loading of clay nanolayers in elastomeric epoxy and polyurethane matrices dramatically improves both the toughness and the tensile properties of these thermoset systems. Glassy epoxy nanocomposites exhibit substantial improvement in yield strength and modulus under compressive stress–strain conditions. The latest development in polypropylene hybrids have yielded nanocomposites with improved storage moduli. Polyimide hybrids in thin-film form display a 10-fold decrease in permeability toward water vapor at 2 wt.% clay loading. In situ and melt intercalation processing methods are effective in producing reinforced polystyrene hybrids. Nitrile rubber hybrids show improved storage moduli and reduced permeabilities even toward gases as small as hydrogen. Poly(ε-caprolactone)–clay nanocomposites prepared by in situ polymerization of ε-caprolactone in organoclay galleries show a substantial reduction in water adsorption. Polysiloxane nanocomposites produced from poly(dimethylsiloxane) and organoclay mixtures have improved in tensile properties, thermal stability and resistance to swelling solvents. Organoclay-poly( l-lactide) composite film was obtained by solvent casting technique. Clay nanolayers dispersed in liquid crystals act as structure directors and form hybrids composites that can be switched from being highly opaque to highly transparent by applying an electric field of short duration.