Showing papers on "Polymer nanocomposite published in 2000"

Device Applications of Polymer-Nanocomposites

Abstract: In recent years significant progress has been achieved in the synthesis of various types of polymer-nanocomposites and in the understanding of the basic principles which determine their optical, electronic and magnetic properties. As a result nanocomposite-based devices, such as light emitting diodes, photodiodes, photovoltaic solar cells and gas sensors, have been developed, often using chemically orientated synthetic methods such as soft lithography, lamination, spin-coating or solution casting.

Nylon 11/silica nanocomposite coatings applied by the HVOF process. II. Mechanical and barrier properties

Abstract: Nylon 11 coatings filled with nominal 0–15 vol % of nanosized silica or carbon black were produced using the high velocity oxy-fuel combustion spray process. The scratch and sliding wear resistance, mechanical, and barrier properties of nanocomposite coatings were measured. The effect of powder initial size, filler content, filler chemistry, coating microstructure, and morphology were evaluated. Improvements of up to 35% in scratch and 67% in wear resistance were obtained for coatings with nominal 15 vol % contents of hydrophobic silica or carbon black, respectively, relative to unfilled coatings. This increase appeared to be primarily attributable to filler addition and increased matrix crystallinity. Particle surface chemistry, distribution, and dispersion also contributed to the differences in coating scratch and wear performance. Reinforcement of the polymer matrix resulted in increases of up to 205% in the glass storage modulus of nanocomposite coatings. This increase was shown to be a function of both the surface chemistry and amount of reinforcement. The storage modulus of nanocomposite coatings at temperatures above the glass transition temperature was higher than that of unfilled coatings by up to 195%, depending primarily on the particle size of the starting polymer powder. Results also showed that the water vapor transmission rate through nanoreinforced coatings decreased by up to 50% compared with pure polymer coatings. The aqueous permeability of coatings produced from smaller particle size polymers (D-30) was lower than the permeability of coatings produced from larger particles because of the lower porosities and higher densities achieved in D-30 coatings. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2272–2289, 2000

α-RuCl3/Polymer Nanocomposites: The First Group of Intercalative Nanocomposites with Transition Metal Halides

Abstract: Different types of polymers can be intercalated into α-RuCl3 with different synthetic methodologies. Polyaniline/α-RuCl3 nanocomposite was prepared by the in situ redox intercalative polymerization...

Nylon 11/silica nanocomposite coatings applied by the HVOF process. I. Microstructure and morphology

Abstract: Nylon 11 coatings filled with nanosized silica and carbon black have been produced using the high velocity oxy-fuel (HVOF) combustion spray process. The physical properties and microstructure of coatings produced from nylon 11 powders with starting particle sizes of 30 and 60 μm have been evaluated as a function of the filler content, filler chemistry, and processing conditions. The nominal filler content was varied from 5 to 20 vol %. Co-milling of the nano-sized fillers with the polymer powders produced an embedded 4–8 μm thick filler layer on the surfaces of the polymer particles. Optimization of the HVOF processing parameters based on an assessment of the degree of splatting of polymer particles was accomplished by varying the jet temperature (via hydrogen/oxygen ratio). Gas mixtures with low hydrogen contents minimized polymer particle degradation. The filler was found to be agglomerated at the splat boundaries in the final coating microstructures. Aggregates of silanated silica and carbon black were of the order of 50 nm in size, whereas the aggregates of untreated silica and hydrophilic silica were of the order of 100 nm. The morphology of the polymer and the microstructure of the coatings depended on the filler surface chemistry and the volume fraction of the filler, as well as the initial nylon 11 particle size. Although all filled coatings had higher crystallinities than pure nylon 11 coatings, coatings produced from a smaller starting polymer particle size exhibited improved spatial distribution of the silica in the matrix and lower crystallinity. In addition, coatings prepared from smaller polymer particles had a higher density and lower porosity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1684–1699, 2000

Hybrid mixed ion clay structures for polymer nanocomposite formation

Abstract: Hybrid layered silicates with galleries between the layers containing both inorganic and organic ions with different compositions in different galleries are described. The resulting hybrid layered silicates provide economical starting materials for polymers and the like.

Polymer Nanocomposites Based on Layer Aluminum-silicates

Abstract: The structure particular to layer aluminumsilicates is discussed permitting the intercalation of polymers. This process ultimately leads to nanocomposites that exhibit interesting properties. It will be shown that many improvements of physical properties can be achieved by polymer-clay nanocomposites.

Preparation of clay-dispersed polymer nanocomposite

Abstract: Disclosed is a method for preparing a clay-dispersed polymer nanocomposite. In this method, a polymer, which carries oxygen atoms within the repeating units of its backbone and is thermodynamically compatible with a binder resin, is used as a matrix resin. Useful is poly(e-caprolactone) owing to its thermodynamic compatibility with poly(styrene-co-acrylonitrile)copolymers, poly(acrylonitrile-co-butadiene-co-styrene) copolymers, and poly(vinylchloride) resins. Poly(e-caprolactone) resins aid the binder resins to penetrate into silicate layers so that the silicate of the organophilic clay was completely delaminated to silicate lamellas.

Oriented nanocomposites of ultrahigh-molecular-weight polyethylene and gold

Abstract: Polymer nanocomposites were prepared by mixing ultrahigh-molecular-weight polyethylene and gold colloids coated with a self-assembled monolayer of dode-canethiol. Subsequently, these materials were oriented by solid state drawing which induced the formation of uniaxially oriented arrays of gold particles. As a result of the orientation of the gold arrays, the VIS-NIR spectra of the drawn composites strongly depended in polarized light on the angle between polarization direction and the orientation axis of the particle arrays, with shifts in the absorption maxima up to ca. 100 nm. It is assumed that these color shifts originated from the small dimensions of the dispersed metal phase in combination with their uniaxial orientation.

Polymer film for smart window

Abstract: This invention relates to a polymer film for smart window which can optionally modulate the intensity of light passing through a window on the part of users and more particularly, to the polymer film for smart window, prepared in a manner such that a polyalkylacrylate dispersion polymer containing dispersed dichroic particles, so synthesized via reaction between nickel picolinate and polyiodide, are dispersed in a polymethylphenyl-dimethylsiloxane copolymer as a film medium polymer, using dichlorodimethylsilane and dichloromethylphenylsilane as starting monomers where their molar ratios can be modulated. As such, the film medium polymer, so prepared by modulating its molecular weight distribution and dispersion degree of polymer, has an excellent combination of properties such as (1) the compatibility of the polymer to a dispersion polymer can be enhanced, (2) the dichroic particles can be homogeneously dispersed with the size of less than visible light wavelength, and (3) the permeability of light is modulated from the arrangement of particles induced by electric field, thus increasing the transparency of film itself.

Morphological Control of Polymer Network in Ferroelectric Liquid Crystal

Abstract: The morphology of polymer fiber network formed in ferroelectric liquid crystal devices was closely observed by optical and scanning electron microscopes, and the formation mechanism of the polymer was investigated for obtaining a rigid polymer structure supporting substrates. It was found that aligned polymer fibers are formed with fibril aggregation, which is induced by photopolymerization of monofunctional acrylate monomer aligned in parallel with the liquid crystal molecular alignment. As the monomer concentration increases, the polymer fibers are transformed into thicker and harder structures. This self-assembling phenomenon is thought to be induced by the interfacial tension of the liquid-state polymer with comparatively low molecular weight during the polymerization, and the transient unstable polymer morphology that appears in the phase separation process can be fixed by rapid curing of the polymer material.

Heat-resistant polymer foam

Abstract: A heat-resistant polymer foam is disclosed which has excellent heat resistance, a fine cellular structure, and a low apparent density. The heat-resistant polymer foam comprises a heat-resistant polymer having a glass transition point of 120°C or higher, e.g., a polyimide or polyether imide, and has an average cell diameter of from 0.01 µm to less than 10 µm. This heat-resistant polymer foam can be produced by, for example, impregnating a heat-resistant polymer under pressure with an non-reactive gas such as carbon dioxide, which is in, e.g., a supercritical state, reducing the pressure, and then heating the polymer at a temperature exceeding 120°C to foam the polymer.

Polymer-Layered Silicate Nanocomposites: Emerging Scientific and Commercial Opportunities

Abstract: Polymer nanocomposites represent a radical alternative to conventionally (macroscopically) filled polymers. Because of their nanometer-size dispersion the nanocomposites exhibit markedly improved properties when compared to the pure polymers or conventional composites. These include increased modulus and strength, outstanding barrier properties, increased solvent and heat resistance and decreased flammability. In this paper the physical and mechanical properties of nanocomposites are reviewed and discussed in terms of their static and dynamic properties.

Research on dispersed states of the bulking and strengthening agents in the rubber matrix

Abstract: The dispersed states of ZnO, CaCO 3, argil, clay, carbon black and carbon white in SBR matrix were characterized by electronic microscope TEM and SEM. To make a comparison with the above, the dispersed states of clay/rubber nanocomposites were studied and compared with that of clay/PMMA nanocomposite. According to TEM and SEM photos, there are several levels of dispersed structure with different dimension. Mechanical intermix of rubber contributes to the further fragmentation of the dispersed particles. The further fragmentation of the dispersed particles depends on the cohesion and structural feature of the dispersed phase. Especially, just direct mechanical intermix can in some degree induce fragmentation of clay particles to form some nanodimension dispersed particles. There, however, is no way to form ideally uniformly dispersed nanocomposite. In most nanocomposites besides nanocomposites prepared by in situ polymerization, there are some congeries. The more the loading amount of dispersed phase leads to the more amount of congeries. The definition of the dispersed phase depends on the resolution of the instrument. A new definition of nanocomposite, therefore, was put forward. If in certain resolution, the dimension of dispersed particles which was less than 100nm and these particles have more than 80 percent by weight or by volume of all the dispersed phase, this materials is nanocomposite. From the point of this view, the rubber strengthened by either carbon black or carbon white involved in this paper was nanocomposites.

Method of manufacturing polymer films having second order non-linear optical properties, polymer films, and non-linear optical element

Abstract: A method of manufacturing a polymer film having second order non-linear optical properties which has excellent stability of orientated molecules and does not become disorientated, and a polymer film and a non-linear optical element are provided. A polymer solution is placed between two substrates, which are disposed substantially perpendicular with respect to a rotating stand and substantially symmetrical with respect to a rotation axis of the rotating stand, and the rotating stand is rotated. A polymer film having second order non-linear optical properties is formed by the centrifugal force generated at the polymer solution. The polymer solution is a solution formed by dissolving, in an organic solvent, at least one of (1) a host-guest polymer in which low molecular weight compounds are dispersed in polymers, (2) a modified polymer in which regions which exhibit a function of second order non-linear optical properties are chemically modified in polymer side chains and/or a polymer main chain, and (3) a crosslinked polymer. Among these, modified polymers are particularly preferable.

Femtosecond Z-scan investigation of third-order optical nonlinearity in PbS-polymer nanocomposite

Abstract: Summary form only given. There is much current interest in the nonlinear optical properties of quantum confined semiconductor nanocrystals, particularly for their potential use in nonlinear photonic devices. Recently we have successfully synthesized an optically homogenous PbS-polymer nanocomposite by in-situ polymerization of bicontinuous microemulsions. The PbS nanocrystals with an average size of 5 nm were formed in aqueous domains randomly embedded in the methyl methacrylate (MMA)/acronitrile (AN)//spl omega/-methoxy poly(ethylene oxide)/sub 40/ undecyl-/spl alpha/-methacrylate (C/sub 1/-PEO-R-MA-40) copolymer network. We present an experimental study of third-order optical nonlinearity in the PbS-polymer nanocomposite, using the Z-scan technique with linear polarized 120-fs laser pulses at 780-nm wavelength. The mechanisms responsible for the observed optical nonlinearity are also discussed.

Laminated carrier material with controllable release characteristics for PVC films

Abstract: A support material with release properties for vinyl films and improved aging characteristics comprising a support comprising a base paper, a polymer layer formed from a thermoplastic resin and applied to the base paper and a release layer wherein the release layer comprises a polymer or a copolymer selected from the group consisting of styrene contains / butadiene copolymer, polyvinyl acetate, polyvinyl acetate copolymer, acrylic polymer, styrene / acrylic polymer, acrylonitrile polymer, and mixtures thereof.