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Polymer Nanocomposites (polymer + nanocomposite)
Selected AbstractsNew Microshaping Concepts for Ceramic/Polymer Nanocomposite and Nanoceramic FibersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Yoram De Hazan New, general, and versatile concepts for the fabrication of continuous ceramic and ceramic/polymer nanocomposite fibers have been developed. These enable the fabrication of new ceramic and highly loaded nanocomposite fibers with controlled compositions and microstructures. Continuous fibers with dimensions of 15,500 ,m have been demonstrated using several spinning approaches. [source] Morphology and thermal behavior of organo-bentonite clay/poly(styrene- co -methacrylic acid)/poly(isobutyl methacrylate- co -4-vinylpyridine) nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009Abderrahmane Habi Abstract Poly(styrene- co -methacrylic acid) containing 29 mol % of methacrylic acid (SMA-29) and poly(isobutyl methacrylate- co -4-vinylpyridine) containing 20 mol % of 4-vinylpyridine (IBM4VP-20) were synthesized, characterized, and used to elaborate binary and ternary nanocomposites of different ratios with a 3% by weight hexadecylammonium-modified bentonite from Maghnia (Algeria) by casting method from tetrahydrofuran (THF) solutions. The morphology and the thermal behavior of these binary and ternary elaborated nanocomposites were investigated by X-ray diffraction, scanning electron microscopy, FTIR spectroscopy, differential scanning calorimetry, and thermogravimetry. Polymer nanocomposites and nanoblends of different morphologies were obtained. The effect of the organoclay and its dispersion within the blend matrix on the phase behavior of the miscible SMA29/IBM4VP20 blends is discussed. The obtained results showed that increasing the amount of SMA29 in the IBM4VP20/SMA29 blend leads to near exfoliated nanostructure with significantly improved thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Polymer nanocomposites based on needle-like sepiolite clays: Effect of functionalized polymers on the dispersion of nanofiller, crystallinity, and mechanical propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008E. Bilotti Abstract Polypropylene (PP)/sepiolite (Sep) nanocomposites are prepared by melt compounding in a mini-extruder apparatus. The often used maleic anhydride-modified polypropylene (PP-g-MA) is compared with two custom-made functionalized polymers, PP-acid and the di-block copolymer PP-PEO, with respect to the filler dispersion and filler reinforcement efficiency. For that purpose, morphological and mechanical studies are carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tensile tests. In addition, the nanocomposites are characterized by wide-angle X-ray scattering (WAXS) and differential scanning calorimetric (DSC) techniques, to assess the effect of the nanofiller on the crystalline structure of the PP matrix nano-filler. The use of PP-PEO and PP-acid resulted in a better nanofiller dispersion compared with traditional PP-g-MA-modified systems. Sepiolite acts as nucleating agent for the crystallization of PP and seems to lead to an orientation of the ,-phase crystals. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Scaling behavior of plasmon coupling in Au and ReO3 nanoparticles incorporated in polymer matricesPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010Urmimala Maitra Abstract Polymer nanocomposites containing different concentrations of Au nanoparticles have been investigated by small angle X-ray scattering and electronic absorption spectroscopy. The variation in the surface plasmon resonance (SPR) band of Au nanoparticles with concentration is described by a scaling law. The variation in the plasmon band of ReO3 nanoparticles embedded in polymers also follows a similar scaling law. Distance dependence of plasmon coupling in polymer composites of metal nanoparticles. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ultrafast Photonics: Graphene,Polymer Nanofiber Membrane for Ultrafast Photonics (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Mater. Loh and co-workers demonstrate on page 782 an electrospun graphene,polymer nanocomposite that exhibits wideband saturable absorbance for laser pulse shaping. A freestanding, mechanically robust membrane which is composed of nanofiber network of graphene-polymer nanocomposite is fabricated by electrospinning and applied as a mode locker in fiber lasers. The performance of these graphene-polymer nanocomposites is better than single-wall carbon nanotubes in terms of modulation depth and nonsaturable loss. [source] Graphene,Polymer Nanofiber Membrane for Ultrafast PhotonicsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Qiaoliang Bao Abstract A freestanding membrane composed of a nanofiber network of a graphene,polymer nanocomposite is fabricated by electrospinning and applied as an optical element in fiber lasers. The functionalization of graphene with conjugated organic molecules provides a handle for improving mechanical and thermal properties as well as tuning the optical properties. A small loading (0.07,wt%) of functionalized graphene enhances the total optical absorption of poly(vinyl acetate) (PVAc) by 10 times. The electrospun graphene,polymer nanocomposites exhibit wideband saturable absorbance for laser pulse shaping, and attain a larger modulation depth and smaller nonsaturable loss than single-walled carbon nanotubes. The results show that electrospun graphene nanocomposites are promising candidates as practical and efficient photonic materials for the generation of ultrashort pulses in fiber lasers. [source] Cover Picture: Anisotropy and Dynamic Ranges in Effective Properties of Sheared Nematic Polymer Nanocomposites (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005Mater. Abstract Forest and co-workers report on p.,2029 that nematic polymer nanocomposite (NPNC) films can be processed in steady shear flows, which generate complex orientational distributions of the nanorod inclusions. Distribution functions for a benchmark NPNC (11,vol.-% of 1,nm,×,200,nm rods) are computed for a range of shear rates, yielding a bifurcation diagram with steady states at very low (logrolling) and high (flow-aligning) shear rates, and limit cycles (tumbling, wagging, kayaking) at intermediate shear rates. The orientational distributions dictate the effective conductivity tensor of the NPNC film, which is computed for all distribution functions, and extract the maximum principal conductivity enhancement (Emax, averaged in time for periodic distributions) relative to the matrix. The result is a "property bifurcation diagram" for NPNC films, which predicts an optimal shear rate that maximizes Emax. Nematic, or liquid-crystalline, polymer nanocomposites (NPNCs) are composed of large aspect ratio, rod-like or platelet, rigid macromolecules in a matrix or solvent, which itself may be aqueous or polymeric. NPNCs are engineered for high-performance material applications, ranging across mechanical, electrical, piezoelectric, thermal, and barrier properties. The rods or platelets possess enormous property contrasts relative to the solvent, yet the composite properties are strongly affected by the orientational distribution of the nanophase. Nematic polymer film processing flows are shear-dominated, for which orientational distributions are well known to be highly sensitive to shear rate and volume fraction of the nematogens, with unsteady response being the most expected outcome at typical low shear rates and volume fractions. The focus of this article is a determination of the ranges of anisotropy and dynamic fluctuations in effective properties arising from orientational probability distribution functions generated by steady shear of NPNC monodomains. We combine numerical databases for sheared monodomain distributions[1,2] of thin rod or platelet dispersions together with homogenization theory for low-volume-fraction spheroidal inclusions[3] to calculate effective conductivity tensors of steady and oscillatory sheared mesophases. We then extract maximum scalar conductivity enhancement and anisotropy for each type of sheared monodomain (flow-aligned, tumbling, kayaking, and chaotic). [source] Enhancement of photocurrent of polymer-gelled dye-sensitized solar cell by incorporation of exfoliated montmorillonite nanoplateletsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2008Chi-Wei Tu Abstract Poly(n -isopropylacrylamide) (PNIPAAm) and its nanocomposite with exfoliated montmorillonite (MMT) were prepared by soap-free emulsion polymerization and individually applied to gel the electrolyte systems for the dye-sensitized solar cells (DSSCs). Each exfoliated MMT nanoplatelet had a thickness of , 1 nm, carried , 1.8 cation/nm2, and acted like a two-dimensional electrolyte. The DSSC with the LiI/I2/tertiary butylpyridine electrolyte system gelled by this polymer nanocomposite had higher short-circuit current density (Jsc) compared to that gelled by the neat PNIPAAm. The former has a Jsc of 12.6 mA/cm2, an open circuit voltage (Voc) of 0.73 V, and a fill factor (FF) of 0.59, which harvested 5.4% electricity conversion efficiency (,) under AM 1.5 irradiation at 100 mW/cm2, whereas the latter has Jsc = 7.28 mA/cm2, Voc = 0.72 V, FF = 0.60, and , = 3.17%. IPCE of the nanocomposite-gelled DSSC were also improved. Electrochemical impedance spectroscopy of the DSSCs revealed that the nanocomposite-gelled electrolytes significantly decreased the impedances in three major electric current paths of DSSCs, that is, the resistance of electrolytes and electric contacts, impedance across the electrolytes/dye-coated TiO2 interface, and Nernstian diffusion within the electrolytes. The results were also consistent with the increased molar conductivity of nanocomposite-gelled electrolytes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 47,53, 2008 [source] Acrylonitrile-butadiene-styrene nanocomposites filled with nanosized aluminaPOLYMER COMPOSITES, Issue 5 2008Kamal K. Kar A polymer nanocomposite was produced by acrylonitrile-butadiene-styrene (ABS) and ,-alumina was prepared through sol-gel process using aluminum nitrate and citric acid. The particle size was analyzed by X-ray diffraction and scanning electron microscopy (SEM) studies. The nanocomposites were characterized through tensile strength, Young's modulus, strain% at break, flexural strength, flexural modulus, and impact strength. The ABS/Al2O3 nanocomposites are found to have slightly higher Young's modulus, but lower tensile strength, strain% at break, flexural and impact strength than the virgin ABS. But its flexural modulus increases with increasing Al2O3 content in ABS matrix. The d-spacing was calculated in nanocomposites to evaluate the interaction between Al2O3 and ABS. The particle distributions in nanocomposites were studied by SEM. The fractured surfaces of tensile test samples were also examined through SEM and show that the ductile fracture of ABS is converted to brittle fracture with addition of Al2O3. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Flame retarded polymer layered silicate nanocomposites: a review of commercial and open literature systems,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2006Alexander B. Morgan Abstract This paper is a review of polymer nanocomposites used for flame retardancy applications, including commercial materials and open literature examples. Where possible, details on how the nanocomposite and flame retardant work together will be discussed. The key lesson from this review is that while the polymer nanocomposite can be considered to be flame retarded (or a flame retardant) by definition, these materials by themselves are unable to pass regulatory fire safety tests such as UL-94,V. Therefore, additional flame retardants are needed in combination with the polymer nanocomposite to pass these tests. In multiple examples, the nanocomposite works with other flame retardants in a synergistic or cooperative manner to lower the polymer flammability (heat release rate). Finally, a discussion on research needs and outlook for polymer nanocomposite flammability research is included. Copyright © 2006 John Wiley & Sons, Ltd. [source] Low Temperature Fabrication of ,-TCP,PCL Nanocomposites for Bone Implants,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Michael Bernstein Abstract A method to fabricate strong bioresorbable calcium phosphate,polymer nanocomposites with low polymer content without exposing the material to excessively high-processing temperatures is reported. Dense ,-TCP-based nanocomposites containing 5 or 15,vol% of uniformly distributed polycaprolactone (PCL) polymer were obtained by mixing ,-TCP nanopowder with PCL dissolved in chloroform followed by room temperature consolidation at the high pressure of 2.5,GPa (cold sintering). The composites had an attractive combination of compressive strength and ductility, and their dissolution behavior was similar to that of pure cold sintered ,-TCP. The immersion of ,-TCP,PCL composites in simulated body fluid (SBF) yielded in vitro deposition of a bone-like apatite layer suggesting the ability of these materials to bind to native bone tissue upon implantation. [source] High-Nanofiller-Content Graphene Oxide,Polymer Nanocomposites via Vacuum-Assisted Self-AssemblyADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Karl W. Putz Abstract Highly ordered, homogeneous polymer nanocomposites of layered graphene oxide are prepared using a vacuum-assisted self-assembly (VASA) technique. In VASA, all components (nanofiller and polymer) are pre-mixed prior to assembly under a flow, making it compatible with either hydrophilic poly(vinyl alcohol) (PVA) or hydrophobic poly(methyl methacrylate) (PMMA) for the preparation of composites with over 50 wt% filler. This process is complimentary to layer-by-layer assembly, where the assembling components are required to interact strongly (e.g., via Coulombic attraction). The nanosheets within the VASA-assembled composites exhibit a high degree of order with tunable intersheet spacing, depending on the polymer content. Graphene oxide,PVA nanocomposites, prepared from water, exhibit greatly improved modulus values in comparison to films of either pure PVA or pure graphene oxide. Modulus values for graphene oxide,PMMA nanocomposites, prepared from dimethylformamide, are intermediate to those of the pure components. The differences in structure, modulus, and strength can be attributed to the gallery composition, specifically the hydrogen bonding ability of the intercalating species [source] Electrical Percolation Behavior in Silver Nanowire,Polystyrene Composites: Simulation and ExperimentADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Sadie I. White Abstract The design and preparation of isotropic silver nanowire-polystyrene composites is described, in which the nanowires have finite L/D (< 35) and narrow L/D distribution. These model composites allow the L/D dependence of the electrical percolation threshold, ,c, to be isolated for finite- L/D particles. Experimental ,c values decrease with increasing L/D, as predicted qualitatively by analytical percolation models. However, quantitative agreement between experimental data and both soft-core and core,shell analytical models is not achieved, because both models are strictly accurate only in the infinite- L/D limit. To address this analytical limitation, a soft-core simulation method to calculate ,c and network conductivity for cylinders with finite L/D are developed. Our simulated ,c results agree strongly with our experimental data, suggesting i) that the infinite-aspect-ratio assumption cannot safely be made for experimental networks of particles with L/D < 35 and ii) in predicting ,c, the soft-core model makes a less significant assumption than the infinite- L/D models do. The demonstrated capability of the simulations to predict ,c in the finite- L/D regime will allow researchers to optimize the electrical properties of polymer nanocomposites of finite- L/D particles. [source] A Versatile Solvent-Free "One-Pot" Route to Polymer Nanocomposites and the in situ Formation of Calcium Phosphate/Layered Silicate Hybrid NanoparticlesADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Hans Weickmann Abstract Poly(methyl methacrylate) (PMMA), polystyrene (PS), and polyurethane (PU) nanocomposites containing well-dispersed calcium phosphate/layered silicate hybrid nanoparticles were prepared in a versatile solvent-free "one-pot" process without requiring separate steps, such as organophilic modification, purification, drying, dispersing, and compounding, typical for many conventional organoclay nanocomposites. In this "one-pot" process, alkyl ammonium phosphates were added as swelling agents to a suspension of calcium/layered silicate in styrene, methyl methacrylate, or polyols prior to polymerization. Alkyl ammonium phosphates were prepared in situ by reacting phosphoric acid with an equivalent amount of alkyl amines such as stearyl amine (SA) or the corresponding ester- and methacrylate-functionalized tertiary alkyl amines, obtained via Michael Addition of SA with methyl acrylate or ethylene 2-methacryloxyethyl acrylate. Upon contact with the calcium bentonite suspension, the cation exchange of Ca2+ in the silicate interlayers for alkyl ammonium cations rendered the bentonite organophilic and enabled effective swelling in the monomer accompanied by intercalation and in situ precipitation of calcium phosphates. According to energy dispersive X-ray analysis, the calcium phosphate precipitated exclusively onto the surfaces of the bentonite nanoplatelets, thus forming easy-to-disperse calcium phosphate/layered silicate hybrid nanoparticles. Incorporation of 5,15,wt% of such hybrid nanoparticles into PMMA, PS, and PU afforded improved stiffness/toughness balances of the polymer nanocomposites. Functionalized alkyl ammonium phosphate addition enabled polymer attachment to the nanoparticle surfaces. Transmission electron microscopy (TEM) analyses of PU and PU-foam nanocomposites, prepared by dispersing hybrid nanoparticles in the polyols prior to isocyanate cure, revealed the formation of fully exfoliated hybrid nanoparticles. [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] Cover Picture: Anisotropy and Dynamic Ranges in Effective Properties of Sheared Nematic Polymer Nanocomposites (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005Mater. Abstract Forest and co-workers report on p.,2029 that nematic polymer nanocomposite (NPNC) films can be processed in steady shear flows, which generate complex orientational distributions of the nanorod inclusions. Distribution functions for a benchmark NPNC (11,vol.-% of 1,nm,×,200,nm rods) are computed for a range of shear rates, yielding a bifurcation diagram with steady states at very low (logrolling) and high (flow-aligning) shear rates, and limit cycles (tumbling, wagging, kayaking) at intermediate shear rates. The orientational distributions dictate the effective conductivity tensor of the NPNC film, which is computed for all distribution functions, and extract the maximum principal conductivity enhancement (Emax, averaged in time for periodic distributions) relative to the matrix. The result is a "property bifurcation diagram" for NPNC films, which predicts an optimal shear rate that maximizes Emax. Nematic, or liquid-crystalline, polymer nanocomposites (NPNCs) are composed of large aspect ratio, rod-like or platelet, rigid macromolecules in a matrix or solvent, which itself may be aqueous or polymeric. NPNCs are engineered for high-performance material applications, ranging across mechanical, electrical, piezoelectric, thermal, and barrier properties. The rods or platelets possess enormous property contrasts relative to the solvent, yet the composite properties are strongly affected by the orientational distribution of the nanophase. Nematic polymer film processing flows are shear-dominated, for which orientational distributions are well known to be highly sensitive to shear rate and volume fraction of the nematogens, with unsteady response being the most expected outcome at typical low shear rates and volume fractions. The focus of this article is a determination of the ranges of anisotropy and dynamic fluctuations in effective properties arising from orientational probability distribution functions generated by steady shear of NPNC monodomains. We combine numerical databases for sheared monodomain distributions[1,2] of thin rod or platelet dispersions together with homogenization theory for low-volume-fraction spheroidal inclusions[3] to calculate effective conductivity tensors of steady and oscillatory sheared mesophases. We then extract maximum scalar conductivity enhancement and anisotropy for each type of sheared monodomain (flow-aligned, tumbling, kayaking, and chaotic). [source] Multicolor Polymer Nanocomposites: In Situ Synthesis and Fabrication of 3D Microstructures,ADVANCED MATERIALS, Issue 5 2008Z.-B. Sun The multiphoton polymerization of CdS,polymer nanocomposites is used to fabricate 3D luminescent structures such as the multicolor "microbull" shown in the figure. The CdS nanoparticles are synthesized in situ within the polymer matrices with their size controlled by the amount of added crosslinker. [source] Development of sustainable resource-based nanostructured polyaniline/castor oil polyurethane compositesADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009Sharif Ahmad Abstract Processibility is one of the important requirements for the commercial utilization of conducting polymers. Studies on composites and blends based on nano polyaniline (PANI) dispersions have become the subject of scientific curiosity with regard to their morphology, stability, and electron transport properties. In general, polymer nanocomposites are made by dispersing inorganic or organic nanoparticles into either a conventional thermoplastic or thermoset polymer. The present study reports the synthesis of nanostructured MO-PANI and castor oil polyurethane (COPU),based composites. The effect of loading of nanostructured MO-PANI in COPU on the spectral, physicochemical and morphological properties has been analyzed. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:26,31, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20143 [source] Carboxylated multiwall carbon nanotube-reinforced thermotropic liquid crystalline polymer nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Sang Ki Park Abstract Thermotropic liquid crystalline polymer (TLCP) nanocomposites reinforced with carboxylated multiwall carbon nanotube (c-MWCNT) were prepared through melt compounding in a twin screw extruder. The thermal stability of TLCP/c-MWCNT nanocomposites increased with even a small amount of c-MWCNT added. The rheological properties of the TLCP/c-MWCNT nanocomposites were depended on the c-MWCNT contents. The contents of c-MWCNT have a slight effect on the complex viscosity of TLCP/c-MWCNT nanocomposites due to the high-shear thinning of TLCP. The storage modulus of TLCP/c-MWCNT nanocomposites was increased with increasing c-MWCNT content. This result can be deduced that the nanotube,nanotube interactions were more dominant, and some interconnected or network-like structures were formed in the TLCP/c-MWCNT nanocomposites. Incorporation of very small amount of c-MWCNT improved the mechanical properties of TLCP/c-MWCNT nanocomposites, and this was attributed to the reinforcement effect of c-MWCNT with high aspect ratio and their uniform dispersion through acid treatment in the TLCP matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and characterization of novel poly(o -toluidine) montmorillonite nanocomposites: Effect of surfactant on intercalationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Rahul Singhal Abstract The investigation of clay based polymer nanocomposites has opened the door for the development of novel, ecofriendly advanced nano materials that can be safely recycled. Because of their nanometer size dispersion, these nanocomposites often have superior physical and mechanical properties. In this study, novel nanocomposites of poly(o -toluidine) (POT) and organically modified montmorillonite (MMT) were synthesized using camphor sulfonic acid (CSA), cetyl pyridinum chloride (CPCl), and N -cetyl- N,N,N -trimethyl ammonium bromide (CTAB) to study the role of surfactant modification on the intercalation. The in situ intercalative polymerization of POT within the organically modified MMT layers was analyzed by FTIR, UV,visible, XRD, SEM as well as TEM studies. The average particle size of the nanocomposites was found to be in the range 80,100 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Combinatorial development of polymer nanocomposites using transient processing conditions in twin screw extrusionAICHE JOURNAL, Issue 7 2008Arun K. Kota Abstract A new approach is presented for combinatorial development of polymer nanocomposites with compositional gradients (CGs). The CGs were developed using transient processing conditions in twin screw extrusion with small quantities of expensive nanoscale fillers. Convolution of step input with normalized residence volume distributions (RVDs) was used to establish the processing,structure relationship for the CGs. The normalized RVD was established as a process characteristic independent of processing conditions and measured in situ using an optical probe. The CG determined nondestructively using the new combinatorial approach was validated through comparison with more time-consuming and destructive thermogravimetric analysis. The CG could also be established with relatively inexpensive microscale fillers using the normalized RVD obtained with nanoscale fillers, suggesting that transient effects of the mixing process are independent of the size of the filler. Finally, structure,property relationship of combinatorially developed polymer nanocomposites was established by characterizing their dynamic mechanical behavior (storage modulus, G,, and loss modulus, G,). The dynamic mechanical behavior of the combinatorially developed composites correlated well with the batch-processed ones, indicating that the transient mixing conditions in extrusion do not affect the material properties. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Monitoring the synthesis of new polymer nanocomposites based on different polyhedral oligomeric silsesquioxanes using Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2009Nicoleta Mihaela Sulca Abstract The kinetic behavior of the urethane dimethacrylate (UDMA) copolymerized and reinforced by different concentrations of polyhedral oligomeric silsesquioxane (POSS) with methacrylic groups was studied through Raman spectroscopy. UDMA-POSS networks have been synthesized with three different types of POSS, two monofunctional POSS (1-propylmethacrylate)-heptaisobutyl substituted (HISO-POSS) and heptacyclopentyl-octasiloxan-1-yloxy) dimethylsilyl] propyl methacrylate (CPENTYL-POSS) and one octafunctional POSS-methacryl substituted (MA-POSS). In order to show the influence of POSS on the final conversion, the hybrid systems were cured using three types of initiators which decompose at different temperatures: azobisisobutyronitrile (AIBN) (65 °C), benzoyl peroxide (BP) (80 °C) and di- tert -butyl peroxide (DTBP) (120 °C). The structure of the hybrid's surface was investigated by X-ray photoelectron spectroscopy (XPS) and the Tg values were calculated from dynamic mechanical analysis (DMA) tests. Copyright © 2009 John Wiley & Sons, Ltd. [source] Influence of Stabilizer Concentration on Transport Behavior and Thermopower of CNT-Filled Latex-Based CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2010Yeon Seok Kim Abstract The influence of the stabilizer/SWNT ratio on the transport behavior of latex-based polymer nanocomposites is examined in an effort to improve electrical conductivity while maintaining or improving the Seebeck coefficient (i.e., thermopower). Results show that phonon and electron transport are significantly affected by tube/tube junctions, and the carrier transport across the junctions can be manipulated by altering the stabilizer concentration. Electrical conductivity of composites containing 10,wt.-% SWNT nearly doubles, becoming greater than 900,S,·,m,1, by changing the SWNT:GA ratio from 1:3 to 10:1, while thermal conductivity and Seebeck coefficient remain relatively constant (near 0.25,W,·,m-K,1 and 40,µV,·,K,1, respectively). [source] Polyamide-12/Functionalized Carbon Nanofiber Composites: Evaluation of Thermal and Mechanical PropertiesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2010Ricardo Chávez-Medellín Abstract This work aims at improving the interfacial bonding between polyamide-12 and CNFs. CNFs were oxidized and dispersed in polyamide-12 giving rise to polymer nanocomposites. The oxidation caused an increase in the specific surface area and structural defects of the fibers, as indicated by surface area and Fourier-transform Raman spectroscopy. The nanocomposites exhibited improved thermal and thermo-oxidative stabilities. The oxidized nanofibers had marginal effect on the crystallinity and crystallization of the polyamide-12. An over-proportional enhancement of stiffness due to the fibers could be achieved. In spite of these improvements the fiber/polymer adhesion should be further improved. [source] Functionalized Graphenes and Thermoplastic Nanocomposites Based upon Expanded Graphite OxideMACROMOLECULAR RAPID COMMUNICATIONS, Issue 4-5 2009Peter Steurer Abstract Exfoliation of expanded GO represents an attractive route to functionalized graphenes as versatile 2D carbon nanomaterials and components of a wide variety of polymer nanocomposites. Thermally reduced graphite oxides (TrGO) with specific surface areas of 600 to 950 m2,·,g,1 were obtained by oxidation of graphite followed by thermal expansion at 600,°C. Thermal post treatment at 700,°C and 1,000,°C increased carbon content (81 to 97 wt.-%) and lowered resistivity (1,600 to 50 ,,·,cm). During melt extrusion with PC, iPP, SAN and PA6, exfoliation afforded uniformly dispersed graphenes with aspect ratio,>,200. In comparison to conventional 0D and 1D carbon nanoparticles, TrGO afforded nanocomposites with improved stiffness and lower percolation threshold. Recent progress and new strategies in development of functionalized graphenes and graphene-based nanocomposites are highlighted. [source] Creep Resistant Polymer Nanocomposites Reinforced with Multiwalled Carbon NanotubesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 8 2007Jinglei Yang Abstract Poly(propylene) (PP) nanocomposites filled with shorter- and longer-aspect-ratio multiwalled carbon nanotubes (MWNTs) were compounded using a twin-screw extruder and an injection moulding machine. It is shown that with only 1 vol.-% of MWNTs, creep resistance of PP can be significantly improved with reduced creep deformation and creep rate at a long-term loading period. Additionally, the creep lifetime of the nanocomposites has been considerably extended by 1,000% compared to that of a neat PP. Three possible mechanisms of load transfer were considered that could contribute to the observed enhancement of creep resistance, which are: (1) fairly good interfacial strength between MWNTs and polymer matrix, (2) increasing immobility of amorphous regions due to nanotubes acting as restriction sites, and (3) high aspect ratio of MWNTs. DSC results showing crystallinity changes in the specimens before and after creep deformation present evidence to confirm these mechanisms. Our results should lead to improved grades of creep resistant polymer nanocomposites for engineering applications. [source] A Facile Approach to Single-Wall Carbon Nanotube/Poly(allylamine) Nanocomposites,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2007Jong-Boem Kim Abstract A facile approach to polymer nanocomposites with single-wall carbon nanotubes and cationic polymers is reported. The composite material was synthesized by producing carboxylic acid groups at the nanotube termini followed by a reaction with poly(allylamine) in water. Fourier transform infrared spectral and thermogravimetric analyses corroborate that the poly(allylamine) chains were wrapped on the surface of the carbon nanotubes. The scanning electron microscopic (SEM) image shows that the nanotubes were dispersed with little aggregation, thus, strongly suggesting that the poly(allylamine) chains have covered the single-wall carbon nanotubes, which was further evidenced by transmission electron microscopy. The composites are soluble in water, and this solubilization process opens up new opportunities in the solution chemistry on pristine nanotubes. [source] Molecular Dynamics Simulation of the Fracture in Polymer-Exfoliated Layered Silicate NanocompositesMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006Mo Song Abstract Summary: The MD technique was used to investigate the fracture behavior in fully exfoliated layered silicate (nanoplatelet)-polymer nanocomposites. MD results reveal that the addition of the nanoplatelets can improve the fracture strength of polymers. The interactions between the surface of the nanoplatelets and the segments of the polymer, and the relaxation time of polymer chains have significant influences on the fracture strength of the polymer. For polymers with Tg below room temperature, such as polyurethane, or close to room temperature, such as nylon, the nanoplatelets are always working for the enhancement of the mechanical properties. However, for polymers with Tg above room temperature, such as epoxy and polystyrene, the addition of the nanoplatelets is not working well for toughening these polymers. If the nanoplatelets are to enhance the mechanical properties of these polymers, it is necessary to build up a stress relaxation interface between the polymer and the nanoplatelet in order to reduce the effect of the difference between the relaxation time of nanofillers and that of polymers. Force per area versus distance curves as a function of the difference of the relaxation times of the nanoplatelets and polymer chains. [source] A comparative study on camphorsulphonic acid modified montmorillonite clay based conducting polymer nanocompositesPOLYMER COMPOSITES, Issue 5 2010Ufana Riaz Nanotechnology has emerged as a subject of immense academic interest and excitement in the past few decades. The immediate goal of this science aims at the production of high performance nanomaterials. The present study reports comparative investigations on the in situ polymerization of polyaniline (PANI), and its derivatives poly(1-naphthylamine) (PNA) and poly(o -toluidine) (POT) within the camphor sulphonic acid (CSA) modified montmorillonite (MMT) layers. The polymerization as well as intercalation of the conducting polymers was confirmed by FT-IR, UV-visible spectroscopies, and XRD studies, whereas the morphology of the nanocomposites was analyzed by TEM studies. It was found that the PANI derivatives (PNA and POT) revealed higher intercalation as compared with PANI. The morphology of nanocomposites was found to be governed by the type of conducting polymer intercalated. A large variation in the morphology as well as particle size was observed between the nanocomposites of PANI and its derivatives. The conductivity was found to be in the range of 10,3,10,2 S·cm,1. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Preparation of photodegradable polypropylene/clay composites based on nanoscaled TiO2 immobilized organoclayPOLYMER COMPOSITES, Issue 5 2009Xiangfu Meng Photodegradable polypropylene (PP) composites were prepared via melting blending using PP and titanium dioxide (TiO2) immobilized organically modified montmorillonite (organoclay). TiO2 immobilized organoclay (TiO2 -OMT) was synthesized by immobilizing anatase TiO2 nanoparticles on organically modified clay via sol,gel method. The structure and morphology of TiO2 -OMT were characterized by XRD and scanning electron microscope (SEM), which showed that anatase TiO2 nanoparticles with the size range of 8,12 nm were uniformly immobilized on the surface of organoclay layers. Diffuse reflection UV,vis spectra revealed TiO2 -OMT had similar absorbance characters to that of commercial photocatalyst, Degussa P25. The solid-phase photocatalytic degradation of PP/TiO2 -OMT composites was investigated by FTIR, DSC, GPC and SEM. The results indicated that TiO2 -OMT enhanced the photodegradation rate of PP under UV irradiation. This was due to that immobilization of TiO2 nanoparticles on organoclay effectively avoided the formation of aggregation, and thereby increased the interface between PP and TiO2 nanoparticles. After 300 h irradiation, the average molecular weight was reduced by two orders of magnitude. This work presented a promising method for preparation of environment-friendly polymer nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers. [source] | ||||||||||||||||||||||||||||