Showing papers on "Polymer nanocomposite published in 2001"

Polymer Nanocomposites: Status and Opportunities

Abstract: Reinforcement of polymers with a second phase, whether inorganic or organic, to produce a polymer composite is common in the production of modern plastics. Polymer nanocomposites (PNCs) represent a radical alternative to these conventional polymer composites.

Rheology of polymer layered silicate nanocomposites

Abstract: Layered silicate based polymer nanocomposites have gained significant technological interest because of the recent commercialization of nylon 6 and polypropylene based materials. Aside from the natural interests in understanding and improving the processing of these hybrids, viscoelastic measurements have also proven to be a sensitive tool to probe the mesoscale structure and the strength of polymer–nanoparticle interactions.

Thermal behaviour of poly(propylene) layered silicate nanocomposites

Abstract: The thermal degradation behaviour of nanocomposites based upon poly(propylene)/organoclay, modified with protonated octadecyl amine (C18) in comparison to that of non-exfoliated microcomposites based upon organoclay, modified with protonated butyl amine (C4), was studied by thermogravimetry. In the case of the nanocomposite, the temperature at which volatilisation occurs increases as compared of the microcomposite. Moreover, the thermal oxidation process of the polymer is strongly slowed down in the nanocomposite with high char yield both by a physical barrier effect, enhanced by ablative reassembling of the silicate, and by a chemical catalytic action due to the silicate and to the strongly acid sites created by thermal decomposition of the protonated amine silicate modifier.

Polymer nanocomposites : synthesis, characterization, and modeling

Abstract: Preface 1. Polymer Nanocomposites: Introduction 2. Commercialization of Polymer Nanocomposites 3. PMMA Nanocomposites Synthesized by Emulsion Polymerization 4. Boron Nitride Fillers for Organic Polymer Composites 5. Surface-Initiated Anionic Polymerization: Tethered Polymer Brushes on Silicate Flat Surfaces 6. Predicting the Phase Behavior of Polymer-Clay Nanocomposites: The Role of End-Functionalized Chaines 7. Carbon Black Structure and Associations in Filled Rubbers 8. An Investigative Study of Polymer Adsorption to Smectite Clay: Polyelectrolytes and Sodium Montmorillonite 9. Mesoscopic Structure of Polymer-Inorganic Nanocomposites 10. Solution and Solid-State NMR Spectroscopy of Nylon 6-Montmorillonite Clay Nanocomposites 11. Studies of Organically Modified Clays by Scattering Techniques 12. Thin Film Organically Modified Layered Silicate-Polymer Hybrid Materials 13. Influence of Layered-Silicates on the Rheological Properties of Diblock Copolymer Nanocomposites 14. Dispersion and Nucleating Effects of Clay Fillers in Nanocomposite Polymer Films 15. Molecular Simulations of Ultra-Confined Polymers: Polystyrene Intercalated in Layered-Silicates 16. A Coarse-Grained Simulation Study of Polymer Melt Intercalation in Layered Nanostructures AUTHOR INDEX SUBJECT INDEX

Hydrophobically modified clay polymer nanocomposites

Abstract: The present invention is directed, in part, to improved nanocomposite compositions and processes for preparing same. Specifically, in one embodiment, there is provided a process for preparing an aqueous nanocomposite dispersion, wherein the process comprises: polymerizing via suspension polymerization a suspension comprising at least one ethylenically unsaturated monomer and a hydrophobically modified clay to form the nanocomposite dispersion after polymerization, wherein the hydrophobically modified clay is dispersed in the monomer. Other embodiments include processes for preparing aqueous nanocomposite particles, colloids, and dispersions using hydrophobically modified clays in aqueous systems and compositions comprising same.

Nanofillers based upon organophilic layered silicates

Abstract: A wide variety of polymer nanocomposites exhibiting novel property combinations were obtained via in-situ formation of silicate nanofillers during polymerization and processing. Key intermediates were tailor-made silicates which were rendered organophilic by means of cation exchange and exfoliated upon applying shear forces. As a function of organophilic modification, interfacial coupling, and processing conditions it was possible to control nanostructure formation and to improve thermal and mechanical properties such as toughness/stiffness balance, heat distortion temperature, and flame retardency. Basic structure/property correlations were established for nanocomposites based upon in-situ nanofillers and polymers such as polystyrene, polyamide 12, polypropylene, polymethylmethacrylate, polyurethane, and epoxy resins.

Surface Nanomechanical Properties of Polymer Nanocomposite Layers

Abstract: The nanomechanical behavior of molecularly thick (8−10 nm) compliant polymeric layers with the nanodomain microstructure from poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS or Kraton) was probed with micromechanical surface analysis based on scanning probe microscopy. The microprobing with high lateral resolution revealed the bimodal character of the nanomechanical surface behavior with different elastic responses shown by the rubber matrix and the glassy nanodomains. High-resolution probing showed virtually constant elastic response for the compliant layer compressed to 60% of its initial thickness followed by a sharp increase of the resistance when the tip reached within 3 nm from a stiff solid substrate. Application of the double-layer model allowed the estimation of the actual elastic moduli of different nanophases within the grafted polymer monolayer: 7 ± 3 MPa for the rubber phase and 20 ± 7 MPa for the glassy domains. The relatively high elastic modulus of the rubber matrix is caused by a ...

A Study of the Mechanical and Permeability Properties of Nano- and Micron-Tio2 Filled Epoxy Composites:

Abstract: Polymer nanocomposites consisting of 32 nm diameter TiO2 nanoparticles and epoxy resin were ultrasonically processed and the mechanical and permeability properties of the resulting composites were ...

Laser-based processing of polymer nanocomposites for chemical sensing applications

Abstract: characterized using Fourier transform infrared spectroscopy ~FTIR!, Raman scattering, and transmission and scanning electron microscopy ~TEM!. An analysis of the FTIR spectra indicates that a film deposited using an undoped EVA target is primarily polyethylene, suggesting that the acetate group is photochemically or photothermally removed from the starting material. Gas phase measurements of the laser-evaporated material using a quadrupole time of flight mass spectrometer confirm the production of the acetyl radical on the target surface. Analysis of TEM of films deposited using C-doped targets shows that the carbon black particles ~initially 50 nm particles in 1 mm agglomerates! are broken down into particles that are <50 nm in the deposited film. Incorporation of carbon into the target reduces the degree of photochemical damage of the starting material, as shown in the FTIR spectra of the deposited film. The sensitivity and response time of chemiresistors fabricated from 6 mm thick composite films on top of gold electrodes were measured using toluene vapor ~548 ppm!. The chemiresistors exhibited a reversible and fast ~,1.3 s! response to the vapor. In comparison to data reported in the literature, chemiresistors fabricated from PLD films are significantly better than devices fabricated using a more conventional polymer film growth technique. © 2001 American Institute of Physics. @DOI: 10.1063/1.1362405#

Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications

Abstract: Polymer-single wall carbon nanotube (SWNT) composite films were prepared and characterized as part of an effort to develop polymeric materials with improved combinations of properties for potential use on future spacecraft. Next generation spacecraft will require ultra-lightweight materials that possess specific and unique combinations of properties such as radiation and atomic oxygen resistance, low solar absorptivity, high thermal emissitivity, electrical conductivity, tear resistance, ability to be folded and seamed, and good mechanical properties. The objective of this work is to incorporate sufficient electrical conductivity into space durable polyimides to mitigate static charge build-up. The challenge is to obtain this level of conductivity (10(exp -8) S/cm) without degrading other properties of importance, particularly optical transparency. Several different approaches were attempted to fully disperse the SWNTs into the polymer matrix. These included high shear mixing, sonication, and synthesizing the polymers in the presence of pre-dispersed SWNTs. Acceptable levels of conductivity were obtained at loading levels less than one tenth weight percent SWNT without significantly sacrificing optical properties. Characterization of the nanocomposite films and the effect of SWNT concentration and dispersion on the conductivity, solar absorptivity, thermal emissivity, mechanical and thermal properties were discussed. Fibers and non-woven porous mats of SWNT reinforced polymer nanocomposite were produced using electrospinning.

Emulsion polymerization methods involving lightly modified clay and compositions comprising same

Abstract: Processes for utilizing various emulsion polymerization procedures for preparing aqueous nanocomposite dispersions are disclosed. The disclosed processes include both in-situ polymerizations in the presence of at least partially exfoliated, lightly modified clays as well as admixtures of polymer dispersions with at least partially exfoliated, lightly modified clay dispersions. The disclosed nanocomposite dispersions are useful for preparing a variety of materials, such as coatings, adhesives, caulks, sealants, plastics additives, and thermoplastic resins. Processes for preparing polymer nanocomposite powders and use of these powders as plastic resin and plastics additives are also disclosed.

Colorant-containing aqueous polymer dispersion

Abstract: The present invention relates to colorant-containing polymer dispersions comprising a. colorant-containing polymer particles PC having an average particle diameter d 50 below 1000 nm, comprising: i. a polymer matrix constructed from ethylenically unsaturated monomers M and ii. at least one organic colorant C homogeneously distributed within the polymer matrix and chosen from dyes, UV absorbers and optical brighteners, in an amount of from 0.5 to 50% by weight, based on the polymer matrix; b. at least one nonionic surface-active compound NS in an amount of from 0.1 to 20% by weight, based on the polymer matrix; and c. at least one amphiphilic polymer PA which has 0.5 to 10 mol/kg of anionic functional groups, in an amount of from 1 to 50% by weight, based on the polymer matrix. The invention also relates to a process for their preparation and to cosmetic compositions which comprise this dispersion or polymer powder prepared therefrom.

Interfacial interaction in Ag/polymer nanocomposite films

Abstract: Metallic nanoparticles possess a wide range of novel physical properties, such as electrical, optical, magnetic properties, etc. due to their intermediate structures between atomic state and the bulk [1–3]. For example, strong third-order nonlinear optical susceptibility and ultrafast time response of noble metal (i.e. gold, silver, copper, etc.) nanoparticles have been observed around the surface plasma resonance peaks in the visible region as a result of local-field enhancement [4, 5]. From the practical point of view, these particles have to be dispersed in a solid-state matrix, made of polymers or glasses, to form nanocomposites for the purposes of gaining the necessary stability and processability for making devices [6, 7]. Noble metal nanoparticle/organic polymer composite films are of particular interest because of their potential applications for photonics and electro-optics. Polymer matrices can prevent oxidation and coalescence of the particles and provide them with a long-time stability. As a result, the specific optical and electrical properties of the nanoparticles can be brought into full play, while the typical advantages of organic polymers (e.g., elasticity, transparency, relatively simple ways of synthesis, etc.) are retained in the composite films [8– 10]. Up to now, several methods have been developed for the fabrication of nanocomposite films containing noble metal nanoparticles dispersed in polymer matrix, including in-situ formation of nanoparticles in the matrix of a polymer film, simultaneous plasma polymerization associated with metal evaporation, thermal relaxation technique, etc. [11–16]. However, performance tailoring and optimization of the nanocomposite films are limited, because the factors that affect their performance, including size, shape, microstructure, aggregated structure and concentration of nanoparticles, structure and properties of polymer matrices, and interfacial structure of composites [3, 17, 18], are difficult to be controlled simultaneously by the above approaches. In an earlier report of the authors, a simple fabrication process was developed to obtain 0–3 polymer-based silver nanocomposite films through direct mixing of polymer solution with microemlusionsynthesized silver nanoparticles [19]. It was found that nanoparticles with different geometries (e.g. sphere

Polymer composite structures useful for controlled release systems

Abstract: Solid polymer composites comprising a matrix of at least one water-soluble polymer and at least one chemically distinct species forming a dispersed phase are disclosed. Such composites are suitable for controlled release systems in, for example, laundry and dishwashing applications. Methods of making the solid polymer composites are also disclosed.

Polymeric Nanocomposite Material with a Periodic Structure

Abstract: A new approach to producing polymer nanocomposite materials with optically sensitive matrixes is developed. Core−shell latex particles with rigid cores and relatively soft shells are synthesized, p...

A polymer nanocomposite comprising a matrix polymer and a layered clay material having a low quartz content

Abstract: The invention is directed to a polymer-clay nanocomposite material comprising a melt-processible matrix polymer and a layered clay material having low quartz content. This invention is also directed to a process for preparing polymer-clay nanocomposites, and articles or products produced from nanocomposite materials.

A polymer nanocomposite comprising a matrix polymer and a layered clay material having an improved level of extractable material

Abstract: The invention is directed to a polymer-clay nanocomposite material comprising a melt-processible matrix polymer and a layered clay material having decreased levels of extractable material, such as extractable salts of organic cations. This invention is also directed to processes for preparing polymer-clay nanocomposites, and articles or products produced from nanocomposite materials.

Molecular motion in nanocomposites of poly(ethylene oxide) and montmorillonite

Abstract: Motion of chains of poly(ethylene oxide) within the interlayer spacing of 2:1 phyllosilicate/montmorillonite was studied with H-1 and C-13 NMR spectroscopy. Measurements of the H-1 NMR line widths and relaxation times across a large temperature range were used to determine the effect of bulk thermal transitions on polymer chain motion within the nanocomposites. The results were consistent with previous reports of low apparent activation energies of motion. Details of the frequency and geometry of motion were obtained from a comparison of the C-13 cross-polarity/magic-angle spinning spectra and relaxation times of the nanocomposite with those of the pure polymer. (C) 2001 John Wiley & Sons, Inc.

Drag-reducing polymers and drag-reducing polymer suspensions and solutions

Abstract: A drag-reducing polymer is described, along with a method for manufacturing the drag-reducing polymer. The drag-reducing polymer is manufactured by bulk polymerizing a vinyl aromatic with an α-olefin, wherein the α-olefin has a carbon chain length of between two and twenty carbons. A drag-reducing polymer suspension and drag-reducing polymer solution are also described.

Laminated TaS2/polymer nanocomposites through encapsulative precipitation of exfoliated layers

Abstract: Several TaS2/polymer nanocomposites prepared through the encapsulative precipitation method are described. Namely, the encapsulation of poly(ethylene oxide) (PEO), polyethylene imine (PEI), and poly(vinylpyrrolidinone) (PVP) into TaS2 was examined in detail, and the nanocomposites were characterized by a wide variety of techniques. The nanocomposites disperse in water and are easily cast into free-standing films. The flexible metallic TaS2/polymer nanocomposite films display bulk superconductivity. In addition, in this work the exfoliation properties of LixTaS2 were systematically explored, and it was found that material prepared from controlled lithiation with 0.2 equiv of LiBH4 exfoliates well in water and has high affinity for various polymers. The likely conformation of PEO molecules sandwiched between the TaS2 slabs was explored with analysis of the X-ray diffraction patterns of a highly oriented Lix(PEO)yTaS2 nanocomposite films. The one-dimensional electron density maps, obtained for Lix(PEO)yTaS2,...

Polymer matrix composite

Abstract: Fiber-reinforced polymer matrix composites with anisotropic properties are produced by extruding a mixture of very short fibers and a polymer through a die having a surface to volume ratio of at least about 10 in−1.

Polymer nanocomposites and the process of preparing the same

Abstract: The present invention relates to a polymer nanocomposite and the process for preparation of the same, wherein a positive-electric polyelectrolyte, a layer-structured inorganic material, such as silicate clay, and a polymer latex comprising an negative-electric surface are “co-agglutinated” to result in a polymer nanocomposite.