Polycarbonate reinforced with silica nanoparticles (original) (raw)
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Composites Science and Technology, 2012
Polycarbonate/silica nanocomposites with different silica quantities were prepared by a melt compounding method. The effect of silica amount, in the range 1-5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of polycarbonate (PC) was investigated. Clusters of silica nanoparticles were well dispersed in the polycarbonate whose structure remained amorphous. NMR results showed intermolecular interactions involving the carbonyl groups of different polymeric chains which did not affect the intramolecular rotational motions. The presence of the lowest silica content showed a decrease in the storage and loss moduli below the glass transition temperature, probably due to a plasticization effect. However, an increase in the amount of silica increased the moduli. The presence of silica in PC slightly increased the thermal stability, except for the highest silica content which showed a decrease. The activation energies of thermal degradation for the nanocomposites depended on the amount of silica and on the degree of conversion.
Polymer-layered silicate nanocomposites: an overview
Applied Clay Science, 1999
An overview of polymer-clay hybrid nanocomposites is provided with emphasis placed on the use of alkylammonium exchanged smectite clays as the reinforcement phase in selected polymer matrices. A few weight percent loading of organoclay in nylon 6 boosts the heat distortion temperature by 808C, making possible structural applications under conditions where the pristine polymer would normally fail. A similar loading of clay nanolayers in elastomeric epoxy and polyurethane matrices dramatically improves both the toughness and the tensile properties of these thermoset systems. Glassy epoxy nanocomposites exhibit substantial improvement in yield strength and modulus under compressive stress-strain conditions. The latest development in polypropylene hybrids have yielded nanocomposites with improved storage moduli. Polyimide hybrids in thin-film form display a 10-fold decrease in permeability toward water vapor at 2 wt.% clay loading. In situ and melt intercalation processing methods are effective in producing reinforced polystyrene hybrids. Nitrile rubber hybrids show improved storage moduli and reduced Ž . permeabilities even toward gases as small as hydrogen. Poly´-caprolactone -clay nanocomposites prepared by in situ polymerization of´-caprolactone in organoclay galleries show a Ž substantial reduction in water adsorption. Polysiloxane nanocomposites produced from poly di-. methylsiloxane and organoclay mixtures have improved in tensile properties, thermal stability and Ž . resistance to swelling solvents. Organoclay-poly l-lactide composite film was obtained by solvent casting technique. Clay nanolayers dispersed in liquid crystals act as structure directors and form hybrids composites that can be switched from being highly opaque to highly transparent by applying an electric field of short duration. q 1999 Published by Elsevier Science B.V.
Polymer Layered Silicate Nanocomposites: A Review
Materials, 2009
This review aims to present recent advances in the synthesis and structure characterization as well as the properties of polymer layered silicate nanocomposites. The advent of polymer layered silicate nanocomposites has revolutionized research into polymer composite materials. Nanocomposites are organic-inorganic hybrid materials in which at least one dimension of the filler is less than 100 nm. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or pre-polymers from solution, in-situ polymerization, melt intercalation etc. The nanocomposites where the filler platelets can be dispersed in the polymer at the nanometer scale owing to the specific filler surface modifications, exhibit significant improvement in the composite properties, which include enhanced mechanical strength, gas barrier, thermal stability, flame retardancy etc. Only a small amount of filler is generally required for the enhancement in the properties, which helps the composite materials retain transparency and low density.
Porous polymeric nanocomposites filled with chemically modified fumed silicas
Surface Chemistry in Biomedical and …, 2006
Porous copolymers have been prepared by suspension-emulsion polymerization of divinylbenzene with styrene or some methacrylic monomers: di(methacryloyloxymethyl)naphthalene, methacrylic ester of p,p′ -dihydroxydiphenylpropane diglycidyl ether, and dimethacrylglycolethylene in the presence and absence of chemically modified fillers (fumed silicas with grafted methyl and silicon hydride groups). The results of investigations of the unfilled and filled polymeric systems by IR and 13 C NMR spectroscopies combined with AFM are presented.
A review on polymer–layered silicate nanocomposites
This review reports recent advances in the field of polymer-layered silicate nanocomposites. These materials have attracted both academic and industrial attention because they exhibit dramatic improvement in properties at very low filler contents. Herein, the structure, preparation and properties of polymer-layered silicate nanocomposites are discussed in general, and detailed examples are also drawn from the scientific literature.
Advances in Polymer Technology, 2013
The nanocomposites are materials, which involve fillers in the nanometer scale, yielding substantial improvements. Polymer-layered silicate nanocomposites have received much attention during the past decade and have great interest both in the academic field and in industry, since they often give more attractive improvement to material properties than both micro-and macrocomposite materials. This extensive review presents recent studies in polymer nanocomposites based on layered silicate. The background, morphology, preparations, and properties of these materials are discussed. The review covers and discusses various modern methods and equipments in the preparation of nanocomposites, deeply focusing on the morphology of nanocomposites and its effects on the overall properties.
Journal of Applied Polymer Science, 2012
Polycarbonate nanocomposite containing silicon oxide nanoparticles average size of 5 nm at different weight ratio has been prepared by solution mixing method. The dispersion of nanoparticles in polymer matrix was studied by transmission electron microscopy (TEM). The optical and thermally stimulated behavior of nanocomposites were analyzed by energy dispersive X-ray spectra (EDX), X-ray diffraction pattern (XRD), UV-vis spectroscopy, differential scanning calorimetry (DSC), and thermally stimulated discharge current (TSDC). TEM images show the dispersion and size of the nanoparticles, however, EDX indicate the presence of SiO 2 on the surface of the nanocomposite film. An XRD result reveals that the crystallinity increases with increase in concentration of SiO 2 nanoparticles in polymer matrix. The direct and indirect optical energy band gaps decreased and number of carbon atom increased with concentration of SiO 2 nanoparticles. We have observed that the increase of SiO 2 nanoparticles in PC significantly reduces the refractive index. DSC and TSDC show that glass transition temperature increases according to SiO 2 weight ratio. The TSDC of nanocomposites samples could be understand in terms of non-Debye theory of charge relaxation and co-tunneling mechanism of charge transport. V
Polymer layered silicate nanocomposites
Macromolecular Materials and Engineering, 2000
Polymer nanocomposites with layered silicates as the inorganic phase (reinforcement) are discussed. The materials design and synthesis rely on the ability of layered silicates to intercalate in the galleries between their layers a wide range of monomers and polymers. Special emphasis is placed on a new, versatile and environmentally benign synthesis approach by polymer melt intercalation. I0 contrast to in-situ polymerization and solution intercalation, melt intercalation involves mixing the layered silicate with the polymer and heating the mixture above the softening point of the polymer. Compatibility with various polymers is accomplished by derivatizing the silicates with alkyl ammonium cations via an ion exchange reaction. By hetuning the surface characteristics nanodispersion (i.e. intercalation or delamination) can be accomplished. The resulting polymer layered silicate (PLS) nanocomposites exhibit properties dramatically different from their more conventional counterparts. For example, PLS nanocomposites can attain a particular degree of stiffoesr, strength and barrier properties with far less inorganic content than comparable glass-or mineral reinforced polymers and, therefore, they are far lighter i n weight. In addition, PLS nanocomposites exhibit significant increase in thermal stability as well as self-extinguishing characteristics. The combination of improved properties, convenient processing and low cost has already led to a few commercial applications with more currently under development.
Polymer/layered silicate nanocomposites: a review from preparation to processing
Progress in Polymer Science, 2003
A review is given of the academic and industrial aspects of the preparation, characterization, materials properties, crystallization behavior, melt rheology, and processing of polymer/layered silicate nanocomposites. These materials are attracting considerable interest in polymer science research. Hectorite and montmorillonite are among the most commonly used smectite-type layered silicates for the preparation of nanocomposites. Smectites are a valuable mineral class for industrial applications because of their high cation exchange capacities, surface area, surface reactivity, adsorptive properties, and, in the case of hectorite, high viscosity and transparency in solution. In their pristine form they are hydrophilic in nature, and this property makes them very difficult to disperse into a polymer matrix. The most common way to remove this difficulty is to replace interlayer cations with quarternized ammonium or phosphonium cations, preferably with long alkyl chains.
Polymer-layered silicate nanocomposites, preparation and properties
This review aims at reporting on very recent developments in syntheses, properties and (future) applications of polymer-layered silicate nanocomposites. This new type of materials, based on smectite clays usually rendered hydrophobic through ionic exchange of the sodium interlayer cation with an onium cation, may be prepared via various synthetic routes comprising exfoliation adsorption, in situ intercalative polymerization and melt intercalation. The whole range of polymer matrices is covered, i.e. thermoplastics, thermosets and elastomers. Two types of structure may be obtained, namely intercalated nanocomposites where the polymer chains are sandwiched in between silicate layers and exfoliated nanocomposites where the separated, individual silicate layers are more or less uniformly dispersed in the polymer matrix. This new family of materials exhibits enhanced properties at very low filler level, usually inferior to 5 wt.%, such as increased Young's modulus and storage modulus, increase in thermal stability and gas barrier properties and good flame retardancy.