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Nanoclay
Terms modified by Nanoclay Selected AbstractsNanoclay and long-fiber-reinforced composites based on epoxy and phenolic resinsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Gang Zhou Abstract In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Interaction of a phosphorus-based FR, a nanoclay and PA6,Part 1: Interaction of FR and nanoclayFIRE AND MATERIALS, Issue 6 2009Alwar Ramani Abstract The thermal decomposition of organophosphorus fire-retardant (OP1311) and/ or organonanoclay (Cloisite 30B) is hereby investigated employing thermogravimetric analysis (TGA), to give an insight into their intrinsic behaviour and interaction in polymer nanocomposites for fire safety applications, because the addition of OP1311 and Cloisite 30B in Polyamide 6 (PA6) seems to have a synergistic effect on the thermal decomposition of PA6 (part 2 of the paper). An important objective of this research was to determine to what extent phosphorus components escape in the gaseous phase, which will affect the heat of combustion of the fire-retarded polymer. The decomposition products arising from pyrolysis and combustion are investigated by means of Fourier transform infrared spectroscopy. Under pyrolytic conditions, the inclusion of Cloisite 30B into OP1311 (FR) shows a synergistic effect on the initial mass loss at low temperature of ,280,420°C and leads to the acceleration of the thermal degradation process. While the DTG curve of Cloisite 30B shows two distinct degradation peaks (steps) that of OP1311 and OP1311 plus Cloisite 30B show four degradation steps. TGA measurements of OP1311 in nitrogen show more mass loss than in air, whereas Cloisite 30B gives similar amounts of mass loss in air and nitrogen. In nitrogen, the major evolved gaseous species from Cloisite 30B alone are hydrocarbons, 2-(diethylamino)ethanol and water, whereas the evolved gases from that of OP1311 at ,320°C are mainly water, at ,420°C, carbon dioxide, water and ammonia and at 480,570°C diethylphosphinic acid. Under thermo-oxidative conditions, the gases evolved are mainly carbon dioxide and water from both Cloisite 30B and OP1311. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effect of EVA as compatibilizer on the mechanical properties, permeability characteristics, lamellae orientation, and long period of blown films of HDPE/clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Juliano Marini Abstract Two ethylene-vinyl acetate (EVA) resins with 19% (EVA19) and 28% (EVA28) of vinyl groups were used as compatibilizers for nanocomposites of high-density polyethylene (HDPE) and nanoclays. Two nanoclays were also used, one with a nonpolar surfactant (C15A) and another with a polar surfactant (C30B). The HDPE/EVA19/C15A formed an intercalated structure, while the HDPE/EVA28/C30B had surfactant loss. Blown films of these compositions were produced. A two-phase morphology made of HDPE and EVA/nanoclay particles was observed, which was responsible for the increase in water vapor and oxygen permeability rates of the films. The elastic modulus E along the transverse direction of the films was higher than along the machine direction due to preserved orientation given by the spiral die; the lamellae orientation was measured by small-angle X-rays diffraction. The highest E was observed in the HDPE/EVA19/C15A film due to stronger interactions. The long period of the HDPE lamellas was not affected by the presence of the EVA and nanoclay. A model was proposed to explain the improvement in elastic modulus due to the processing conditions and components' interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Bio-hybrid nanocomposite coatings from sonicated chitosan and nanoclayJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Jari Vartiainen Abstract Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio-hybrid coatings were applied onto argon,plasma-activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV-light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (,1 ,m), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were "generally recognized as safe" (GRAS) and the calculated total migration was in all cases ,6 mg/dm2, thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio-hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polypropylene nanocomposite film: A critical evaluation on the effect of nanoclay on the mechanical, thermal, and morphological behaviorJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010S. K. Sharma Abstract Polypropylene (PP)/clay nanocomposites prepared by melt blending technique using different percentages of clay with and without maleic anhydride grafted PP (MA-PP) were studied. The intercalated and exfoliated structure of nanocomposites was characterized by X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). Because of the typical intercalated and exfoliated structure, the tensile modulus of the nanocomposites were improved significantly as compared to virgin PP. The viscoelastic behavior of the nanocomposites was studied by dynamical mechanical analysis (DMA) and the results showed that with the addition of treated clay to PP there was substantial improvement in storage modulus increases. The thermal stability and crystallization of the PP nanocomposites as studied by differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA) were also improved significantly compared to PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Compatibilization and development of layered silicate nanocomposites based of unsatured polyester resin and customized intercalation agentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Luigi Torre Abstract In this study a procedure for the preparation of compatibilized nanoclays was used to produce effective nanocomposites based on unsatured polyester (UP) resin. A compatibilization procedure of the filler with a selected surfactant has been developed and optimized, the effect of organic modifiers on the synthesized nanocomposites properties was studied. Moreover, polyester/clay nanocomposites were prepared. In particular, samples were prepared using two different mixing methods. The properties and formation processes of the nanocomposites obtained using the two methods were compared. X-ray diffraction studies revealed the formation of intercalated/exfoliated nanocomposites structures. The effect of processing parameters, used for both the compatibilization procedure and the preparation of nanocomposites, was studied. Dynamic mechanical, thermal analysis, and rheological tests were performed to investigate the formation mechanism of UP/montmorillonite nanocomposite. In particular, mechanical properties of nanocomposites were studied using dynamic mechanical analysis and tensile tests. Mechanical, rheological, and thermal characterization have confirmed the validity of the used approach to compatibilize the nanoclay and to produce nanocomposites. Tensile strength and Young's modulus were modified by the loading of the organoclays. Furthermore, the rheology of the nanocomposite formulation provided processing information, while mechanical and dynamic mechanical characterization was performed on the nanocomposites produced with the newly compatibilized formulation. The results have shown that nanocomposites with better mechanical properties can be obtained through the selection of an appropriate compatibilization process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Nanostructure and micromechanical properties of reversibly crosslinked isotactic polypropylene/clay compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010S. Bouhelal Abstract Recent developments concerning the methodology used to prepare composites of iPP and nanoclays are reported. Conventional (reactive melt mixing) and in situ preparations were performed, and the structural properties exhibited by the composites are discussed. Results suggest that the nanoclay could exhibit partial and, maybe, total exfoliation within the composites. Adhesion between the polymeric matrix and the nanoclay layers is similar to that obtained after grafting. The experimental procedure used and the analysis performed by means of the wide-angle X-ray scattering and differential scanning calorimetry techniques permit to describe, at nanoscale level, the contribution of the nanoclay to the polymer composite system. The microhardness values of the iPP,clay composites depend on the clay content and on the preparation method, and linearly correlate, according to the additivity law, with the degree of crystallinity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effects of two different maleic anhydride-modified adhesion promoters (PP-g-MA) on the structure and mechanical properties of nanofilled polyolefinsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009P. Eteläaho Abstract The effects of adhesion promoter properties on the structure and mechanical behavior of nanoclay-filled polyolefin nanocomposites are presented. Two different maleic anhydride-modified polypropylenes having varying maleic anhydride content and molecular weight were used. The influence of these parameters on the performance and morphology of the prepared polypropylene and high density polyethylene-based nanocomposites was examined by mechanical testing, X-ray diffraction, and electron microscopy. The low molecular weight adhesion promoter seemed to be effective in both matrices in relation to mechanical property enhancements, whereas its high molecular weight counterpart performed well only in polyethylene matrix. X-ray diffraction results and examination of morphology revealed that the intercalation and the dispersion of the nanoclay were more even in both matrices when the low molecular weight adhesion promoter with a higher maleic anhydride content was used. On the other hand, the use of high molecular weight adhesion promoter led to a less uniform dispersion but also to a greater amount of exfoliated clay particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Nanoclay and long-fiber-reinforced composites based on epoxy and phenolic resinsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Gang Zhou Abstract In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Shear-induced migration of nanoclay during morphology evolution of PBT/PS blendJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Joung Sook Hong Abstract In this study, we investigated clay migration and its localization in multiphase blend nanocomposite systems during the evolution of blend morphology to elucidate how a hydrodynamic stress and chemical affinity between the polymer and clay induce them. To observe the morphology evolution, a multilayered blend, alternatively superposed poly(butylenes terephthalate) (PBT) and polystyrene (PS)/clay films or PBT/clay and PS films, was subjected to homogeneous shear flow, 1 s,1. Furthermore, the morphology was observed at different shear rates 1 s,1. When the PBT/(PS/clay) multilayered blend is subjected to flow, the clay dispersed in the PS layer first migrates to the interface depending on the amount of applied strain. The clay at the interface causes the average drop size of blend morphology to become smaller and the blend morphology becomes more stable because of the coalescence suppression effect. As more shear is applied, the clay at the interface moves further into more compatible phase, PBT, although the viscosity of PBT is higher than PS. On the contrary, the clay in the PBT layer does not migrate to the PS phase at any shear rate, which means that its chemical affinity is strong enough to prevent shear-induced migration. The clay increases the viscosity of the PBT phase and results in a different morphology with a droplet, cocontinuous structure. As a result, when the clay is induced to migrate by hydrodynamic stress, it migrates into thermodynamically more stable positions at the interface or in the chemically more compatible phase, depending on the applied strain. Once it is located at a thermodynamically more stable position, it is difficult to push it out only by hydrodynamic stress. The location of clay is significantly affected by the morphology during evolution, which means that the blend morphology can control the droplet form and cocontinuous structure by control of the clay migration kinetics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Amar Boukerrou Abstract The morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite (MMT) nanocomposites were investigated with wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis. An ultrasonicator was used to apply external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling MMT in a curing agent, that is, an aliphatic diamine based on a polyoxypropylene backbone with a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added to the mixture. Better dispersion and intercalation of the nanoclay in the matrix were expected. The organic modification of MMT with octadecylammonium ions led to an increase in the initial d -spacing (the [d001] peak) from 14.4 to 28.5 Å, as determined by WAXS; this indicated the occurrence of an intercalation. The addition of 5 phr MMTC18 (MMT after the modification) to the epoxy matrix resulted in a finer dispersion, as evidenced by the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MMT and MMTC18 nanocomposites, but they were more pronounced for the modified ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3547,3552, 2007 [source] Fire-resistant effect of nanoclay on intumescent nanocomposite coatingsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Zhen-yu Wang Abstract The aim of the study is the development of an intumescent nanocomposite coating to provide fire protection for the metallic substrate. Acrylic nanocomposites containing nanoclay and relative intumescent nanocoatings are prepared. The effect of nanoclay on the thermal degradation of an intumescent nanocomposite coating is analyzed by using differential thermal analysis, thermogravimetry, and X-ray diffraction. The influence of the added content of nanoclay on fire performance is studied by a fire protection test and measurements of the limiting oxygen index and effective thermal conductivity. The distribution of nanoparticles in the acrylic nanocomposite is characterized by transmission electron microscopy. The flame-retardant efficiency of the intumescent nanocomposite coating is improved by 1.5% well-distributed nanoclay particles. However, 3% nanoclay produces a negative effect on the fire performance of the coating. Fire protection tests and scanning electron microscopy observations reveal that the fire-retardant property of a conventional intumescent coating is destroyed by aging, whereas the nanocomposite coating modified with 1.5% nanoclay demonstrates good aging and fire resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1681,1689, 2007 [source] Rheological and Thermal Properties of Polylactide/Silicate Nanocomposites FilmsJOURNAL OF FOOD SCIENCE, Issue 2 2010Jasim Ahmed ABSTRACT:, Polylactide (DL)/polyethylene glycol/silicate nanocomposite blended biodegradable films have been prepared by solvent casting method. Rheological and thermal properties were investigated for both neat amorphous polylactide (PLA-DL form) and blend of montmorillonite (clay) and poly (ethylene glycol) (PEG). Melt rheology of the PLA individually and blends (PLA/clay; PLA/PEG; PLA/PEG/clay) were performed by small amplitude oscillation shear (SAOS) measurement. Individually, PLA showed an improvement in the viscoelastic properties in the temperature range from 180 to 190 °C. Incorporation of nanoclay (3% to 9% wt) was attributed by significant improvements in the elastic modulus (G,) of PLA/clay blend due to intercalation at higher temperature. Both dynamic modulii of PLA/PEG blend were significantly reduced with addition of 10% PEG. Rheometric measurement could not be conducted while PLA/PEG blends containing 25% PEG. A blend of PLA/PEG/clay (68/23/9) showed liquid-like properties with excellent flexibility. Thermal analysis of different clay loading films indicated that the glass transition temperatures (Tg) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the,Tg of the blend (PLA/PEG and PLA/PEG/clay) significantly. Both rheological and thermal analysis data supported plasticization and flexibility of the blended films. It is also interesting to study competition between PLA and PEG for the intercalation into the interlayer spacing of the clay. This study indicates that PLA/montmorillonite blend could serve as effective nano-composite for packaging and other applications. [source] Long-lived layered silicates-immobilized 2,6-bis(imino)pyridyl iron (II) catalysts for hybrid polyethylene nanocomposites by in situ polymerization: Effect of aryl ligand and silicate modificationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2009Giuseppe Leone Abstract Heterogeneous-layered silicate-immobilized 2,6-bis(imino)pyridyl iron (II) dichloride/MMAO catalysts, in which the active polymerization species are intercalated within sodium- and organomodified-layered silicate galleries, were prepared for producing hybrid exfoliated polyethylene (PE) nanocomposites by means of in situ polymerization. The inorganic filler was first treated with modified-methylaluminoxane (MMAO) to produce a supported cocatalyst: MMAO reacts with silicates replacing most of the organic surfactant, thus modifying the original crystallographic clay order. MMAO anchored to the nanoclay was able to activate polymerization iron complexes initiating the polymer growth directly from the filler lamellae interlayer. The polymerization mechanism taking place in between the montmorillonite lamellae separates the layers, thus promoting deagglomeration and effective clay dispersion. Transmission electron microscopy revealed that in situ polymerization by catalytically active iron complexes intercalated within the lower organomodified clay led to fine dispersion and high exfoliation extent. The intercalated clay catalysts displayed a longer polymerization life-time and brought about ethylene polymerization more efficiently than analogous homogeneous systems. PEs having higher molecular masses were obtained. These benefits resulted to be dependent more on the filler nature than on the ligand environment around the iron metal center and the experimental synthetic route. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 548,564, 2009 [source] Rigid PVC/(layered silicate) nanocomposites produced through a novel melt-blending approach,JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2009Laurent M. Matuana 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 [source] PVC nanocomposites,Nanoclay chemistry and performance,JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 4 2008Daphne Benderly Nanoclay applications in poly(vinyl chloride) (PVC) have been limited, as the organic modifier of conventional nanoclays can promote PVC degradation. Novel nanoclays designed for enhanced PVC compatibility were compounded with PVC. Hectorite and bentonite clays were studied as nanoclay fillers. Two incorporation methods were evaluated to determine the effect on nanoclay dispersion and composite performance. A two-stage method, in which the nanoclay was predispersed in plasticizer, resulted in good nanoclay dispersion at both the micrometer and nanometer scales. The nanocomposites were characterized by using a wide range of analytical tools. They exhibited significantly improved heat stability, an increase of up to 200% in storage modulus, and a decrease of up to 77% in oxygen permeation, as compared to unfilled PVC. Bentonite nanoclays provided a greater increase in barrier and mechanical properties. No change was seen in the PVC glass transition temperature. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers [source] Atomic Force Microscopic Observations on the Crystalline Morphology of Poly(ethylene naphthalate)/Clay NanocompositesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2007Yang Choo Chua Abstract Atomic force microscopic observations on an isothermally crystallized poly(ethylene naphthalate) (PEN)/clay nanocomposite suggest that the presence of nanoclay alters the lamellar organization in PEN mainly in three ways: 1) physically blocking the crystal growth front and creating wide amorphous regions within the spherulites, which may then be filled by secondary lamellae branching out from the primary lamellae of the same spherulite, or primary lamellae developed from other nearby nucleating centers; 2) inducing random twisting of lamellae; and 3) causing irregular crystallite growth fronts, with the protrusion of some leading lamellae. In particular, the physical hindrance imposed by clay tends to be more prevalent for lamellae that grow roughly perpendicular to the clay long axes. This may give rise to an anisotropic crystalline morphology if the clay layers exhibit a preferred orientation induced by flow. [source] In Situ Polymerisation of Polyamide-6 Nanocompounds from Caprolactam and Layered SilicatesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2009Bernd Rothe Abstract An in situ process for the production of polyamide-6 nanocompounds is investigated as an alternative to melt compounding. During the in situ production, the layered silicates are dispersed in the monomer caprolactam before the polymerisation in a twin screw extruder, leading to an intercalation of the silicates. The production of a polyamide compound containing 0, 2 and 4 wt.-% nanoscale silicates was successful. An improvement of the elastic modulus of approximately 30,60% was reached. The figure shows the TEM micrograph of a nanocompound containing 2 wt.-% nanoclay at a magnification of 30,000×. [source] Kinetics of Miniemulsion Polymerization of Styrene in the Presence of OrganoclaysMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2008Zhaohui Tong Abstract The impacts of nanoclays on the miniemulsion polymerization kinetics of styrene were studied. It was found that both RP and the fractional conversion decreased upon increasing the organoclay content in the miniemulsion system. In the presence of nanoclay the molecular weight of polystyrene nanoclay composite is lower and the particle size polydispersity of the final composite latex is greater than that of pure styrene miniemulsion polymerization. The effect of the nanoclays is mainly caused by the destabilization of the miniemulsion by the organoclay particles. The increase in the monomer viscosity and the decrease in the diffusion rate of the monomer and the living polymer inside the monomer droplet also accounts for the reduction in the polymerization rate. [source] Comparative Characterization of PP Nano- and Microcomposites by In-Mold Shrinkage Measurements and Structural CharacteristicsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2007Rodolfo Revilla-Díaz Abstract Poly(propylene)-clay nanocomposites and poly(propylene) containing conventional inorganic fillers such as calcium carbonate (CaCO3) and glass fiber were used in a comparative study focusing on dimensional stability, structure, mechanical and thermal properties. Micro- and nanocomposites were prepared by melt blending in a twin-screw extruder. The relative influence of each filler was observed from dimensional stability measurements and structural analysis by WAXD, TEM, and thermal and mechanical properties. At equal filler loadings, PP/clay nanocomposites exhibit an improvement in dimensional stability and were the only composites capable of reduced shrinkage in both in-flow and cross-flow directions. The flexural modulus of PP increased nearly 20% by compounding with 4% organoclay, as compared to a similar performance obtained by compounding with 10 wt.-% of CaCO3 or approximately 6 wt.-% of glass fiber. The HDT and thermal stability of PP were enhanced by using nanoclay as filler. [source] Kinetics and thermodynamics of isothermal curing reaction of epoxy-4, 4,-diaminoazobenzene reinforced with nanosilica and nanoclay particlesPOLYMER COMPOSITES, Issue 8 2010M. Barghamadi The kinetics of the cure reaction for a system of bisphenol-A epoxy resin (DGEBA), with 4, 4,-diaminoazobenzene (DAAB), reinforced with nanosilica (NS), and nanoclay (NC) by means of isothermal technique of differential scanning calorimetry were studied. The Kamal autocatalytic-like kinetic model was used to estimate the reaction orders (m, n), rate constants (k1, k2), and also active energies (Ea) and pre-exponential factors (A) of the curing reaction. However, the existence of NS and NC with hydroxyl groups in the structure improves the cure reaction and influence the rate of reaction and therefore kinetics parameters. The Ea of cure reaction of DGEBA/DAAB system showed a decrease when nanoparticles were present and therefore the rate of the reaction was increased. Using the rate constants from the kinetic analysis and transition state theory, thermodynamic parameters such as enthalpy (,H#), entropy (,S#), and Gibbs free energy (,G#) changes were also calculated. The thermodynamic functions were shown to be very sensitive parameters for evaluation of the cure reaction. POLYM. COMPOS., 31:1442,1448, 2010. © 2009 Society of Plastics Engineers [source] Mechanical and thermal properties of polypropylene nanocomposites using organically modified Indian bentonitePOLYMER COMPOSITES, Issue 3 2010Hasmukh A. Patel We report preparation and characterization of nanoclay from Indian bentonite and imported nanoclays, and their compounding with polypropylene (PP) and maleic anhydride-grafted PP (MA-g-PP) in twin screw extruder. The compounded polymer/nanoclay nanocomposites (PNCs) are molded into a standard specimen for studying its tensile, flexural and impact strength. A wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) study demonstrates intercalation of PP in nanoclays rather than exfoliation for both, indigenous and imported nanoclays. The tensile modulus increased by 41 and 39% for PNC1 (PNC with imported nanoclay) and PNC2 (PNC with indigenous nanoclay) with respect to PP. The flexural modulus for PNC1 and PNC2 also increases by 23 and 22% due to incorporation of 5% nanoclay in PP along with 5% MA-g-PP. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Effect of rubber matrix type on the morphology and reinforcement effects in carbon black-nanoclay hybrid composites,A comparative assessmentPOLYMER COMPOSITES, Issue 1 2010S. Praveen Carbon black (B),nanoclay (NC) hybrid composites, based on millable polyurethane and brominated isoprene isobutylene rubber (BIIR), were prepared. The carbon black loading was fixed at 20 phr and organically modified sodium montmorillonite clay loading varied from 5 to 20 phr in each rubber compounds. The nanocomposites were prepared in laboratory by mixing two-roll mill. The state of dispersion of the layered silicate was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM results indicated intercalation of PU and BIIR into the silicate interlayers, followed by exfoliation of the silicate layers into the elastomer matrices. However, the level of intercalation and exfoliation varied considerably with the type of elastomer. The reinforcing effects obtained were found to depend strongly on the extent and degree of the dispersion of the carbon black and silicate layers into the rubber matrices. Mechanical and dynamic mechanical properties were evaluated for each composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Optimization of carbon black and nanoclay filler loading in chlorobutyl vulcanizates using response surface methodologyPOLYMER COMPOSITES, Issue 6 2009V. Sridhar In this article, an attempt has been made to study the applicability of using organo nanoclay (Cloisite 30B) and carbon black (HAF, N330) in chlorinated isobutyl isoprene rubber vulcanizates. Statistical design of experimentation was adopted so that maximum information can be obtained from a minimum number of experiments. Response surface methodology was applied successfully to rubber compound design using a rotatable central compound design. Compounding trials were carried out at design points, and the rubber vulcanizates were characterized for modulus, tensile strength, elongation at break, tear strength, bound rubber, and free volume parameters ,3 and I3. The experimental data was used to generate mathematical models by multiple linear regression analysis using MATLAB (version 6) package. The variability of the postulated models was tested by analysis of variance (ANOVA) and R2 tests and was found to be adequate. The accuracy of the models generated was tested by making an experimental trial. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers [source] Spatial orientation of nanoclay and crystallite in microcellular injection molded polyamide-6 nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 6 2007Mingjun Yuan Three different types of characteristic structures-microcells, nanoclay, and crystallite lamella-exist in injection molded polyamide-6 microcellular nanocomposites. These structures are in completely different scales. The spatial orientation of these microscale structures crucially determines the material's bulk properties. Based on scanning electron microscopy, transmission electron microscopy, and two-dimensional X-ray diffractometry measurements, it was found that the nanoclay and the crystallite formed special geometric structures around the microcells and near the part skins. The nanoclay platelets lay almost parallel to the surfaces of the molded parts. Preferred orientation of the crystallites was induced by the presence of the nanoclay. A molecular-based model is proposed to describe the structural hierarchy and correlations among the microcells, nanoclay, and crystallite lamella. From the small-angle X-ray scattering experiments, it was found that microcellular injection molding produces relatively smaller crystallite lamella than that of conventional injection molding, and that for both solid and microcellular neat resin parts the crystallite lamella thickness at the part skin is smaller than that at the core. Polarized optical microscopy results also indicated that the size of crystallites in the microcellular neat resin and nanocomposite parts is smaller than that in the corresponding solid parts. POLYM. ENG. SCI., 47:765,779, 2007. © 2007 Society of Plastics Engineers [source] Flame retarding effects of nanoclay on wood,fiber compositesPOLYMER ENGINEERING & SCIENCE, Issue 3 2007G. Guo This research article focuses on investigating the effects of nanoclay particles on the flame retarding characteristics of wood,fiber/plastic composites (WPC) using ASTM D635. The processing aspects of nanocomposites with WPC are presented. The processing techniques for controlling the degree of exfoliation and the cost aspect are also described. It turns out that the coupling agent used for wood,fibers is also effective for the exfoliation of clay, and therefore, no additional cost is required. This research indicates that the structure of nanocomposites (i.e., the degree of exfoliation) and the clay content used have a large impact on the flame retardancy of WPC. The flame retardancy is investigated as a function of these parameters. Based on this, a cost-effective way to improve flame retardancy of WPC is presented. POLYM. ENG. SCI., 47:308,313, 2007. © 2007 Society of Plastics Engineers. [source] On surface deformation of melt-intercalated polyethylene,clay nanocomposites during scratchingPOLYMER ENGINEERING & SCIENCE, Issue 11 2006A. Mudaliar Electron microscopy has been used to examine the mechanically-induced surface damage introduced during scratching of polyethylene(PE),clay nanocomposites. The determining role of clay in reducing the susceptibility to surface deformation is predicted from the characteristics of surface morphology and the scratch deformation parameters. The reinforcement of PE with nanoclay reduces the susceptibility to scratch damage and stress whitening. Microcracks and surface deformation features namely wrinkles/ridges are the primary source of light scattering resulting in stress whitening. The scratch deformation behavior is discussed in terms of tensile modulus, percentage crystallinity, elastic recovery, and scratch hardness. Scratch hardness is a relevant parameter that can be appropriately used to determine resistance to scratch deformation. POLYM. ENG. SCI. 46:1625,1634, 2006. © 2006 Society of Plastics Engineers [source] Effects of nano- and micro-fillers and processing parameters on injection-molded microcellular compositesPOLYMER ENGINEERING & SCIENCE, Issue 6 2005Mingjun Yuan The effects of submicron core-shell rubber (CSR) particles, nanoclay fillers, and molding parameters on the mechanical properties and cell structure of injection-molded microcellular polyamide-6 (PA6) composites were studied. The experimental results of PA6 nanocomposites with 5.0 and 7.5 wt% nanoclay loadings and of CSR-modified PA6 composites with 0.5 and 3.1 wt% CSR loadings were compared to their neat resin counterparts. This study found that nanoclay was more efficient in promoting a smaller cell size, larger cell density, and higher tensile strength for microcellular injection molding parts. A higher nanoclay loading led to more brittle behavior for microcellular parts. It was found that a proper amount of CSR particles could be added to the microcellular injection-molded PA6 to reduce the cell size, increase the cell density, and enhance the toughness of the molded part. However, CSR particles were less effective cell nucleation agents as compared to nanoclay for producing desirable cell structures, and a higher CSR loading was found to have diminishing effects on the process and on the properties of the parts. POLYM. ENG. SCI., 45:773,788, 2005. © 2005 Society of Plastics Engineers [source] Epoxy nanocomposites: Analysis and kinetics of curePOLYMER ENGINEERING & SCIENCE, Issue 6 2004M.-T. Ton-That The effect of organo-nanoclay (Nanomer I30E) on the cure mechanism and kinetics of epoxy nanocomposites based on Epon 828 and Epicure 3046 was studied by means of dynamic differential scanning calorimetry (DSC) at four heating rates (2.5, 5, 10, and 20°C·min,1) and by Fourier transform infrared (FT-IR) spectroscopy. The DSC cure data for epoxy-amine mixtures with and without nanoclay was modeled by means of different approaches; the Kissinger and isoconversional models were used to calculate the kinetics parameters while the Avrami model was utilized to compare the cure behavior of the two systems. The Nanomer I30E was shown to initiate rapid homopolymerization of the Epon 828 resin at temperatures above 180°C. For the epoxy-amine mixtures, the presence of nanoclay had little effect on the cure kinetics in the early stages (i.e., at lower temperatures), and the apparent activation energy was around 60 kJ·mol,1. However, in the later stages, the apparent activation energy increased significantly in the absence of nanoclay, but did not do so when it was present. The presence of nanoclay also lowered the final glass transition temperature by about 4°C. Polym. Eng. Sci. 44:1132,1141, 2004. © 2004 Society of Plastics Engineers. [source] Starch-based nanocomposites by reactive extrusion processingPOLYMER INTERNATIONAL, Issue 10 2004Sathya B Kalambur Abstract Nanocomposites with unique material properties have been prepared from synthetic plastics and nanosilicates (nanoclay) until now, but not from biopolymers such as starch. The primary challenge in making biopolymeric nanocomposites is to achieve strong adhesion between nanoclay and polymer matrix. For the first time nanocomposites with superior properties have been successfully made from starch-polycaprolactone (PCL) blends in the presence of montmorillonite (MMT) nanoclay. Reactive extrusion results showed that addition of a modified nanoclay at 3 % wt level increased elongation almost fourfold over that of pristine starch,PCL blends. X-ray diffractions results showed dispersion of clay in the polymer matrix. The nanocomposites have better solvent-resistance properties because of resistance to diffusion offered by clay platelets in the polymer matrix. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||||||||