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Preparation and characterization of silica nanoparticles through sol-gel processing using sodium silicate as a precursor were carried out. Amorphous silica was synthesized using sodium silicate and hydrochloric acid by precipitation according to Stőber method. A system of chemical reactions has been developed using two different polymeric anionic surfactants, namely poly(methacrylic acid) (PMAA) and...
Polymers filled with inorganic nanoparticles have been extensively investigated in recent years because of their improved mechanical and electrical properties compared with the unfilled polymers. The most commonly used inorganic particles are oxides, particularly silica, because of their good properties and low cost. However, oxides have a hydrophilic nature, which leads to presence of water at the...
The functional characteristics depend strongly on the chemical structure of polymer and on the formulation of material, as well. In the present work, the effects of gamma irradiation at different doses on the resistivity and on the absorption currents in nanocomposites of thermoplastic polymers, such as low density polyethylene (LDPE), polypropylene (PP) and ethylene-propylene-diene monomer rubber...
Study of the experimental literature regarding nanodielectrics indicates numerous inconsistencies in the results obtained. In many cases, the likely cause is due to a lack of quality control during nanocomposite processing. By examining examples from the literature along with an alumina/polyamideimide nanocomposite and silica/crosslinked polyethylene nanocomposite, this contribution seeks to shed...
Nanomaterials have attracted considerable attention due to their unique physicochemical properties. However, agglomerations of nanofillers in nanocomposites have hindered the potential improvements to their properties. A novel technique of infusing nanosilica into silicone rubber with reduced agglomeration is reported in this paper. The technique involves electrospinning of silicone fibers, embedded...
Various epoxy-based samples were prepared with different content of micro- and nanosized silica filer. In the case of a constant %-weight content of filler amounting to 65%, the microphase was replaced by a nanophase consisting of 2.5% and 5% weight. Three research teams used dielectric spectroscopy to compare the dielectric behaviour of the different composites. Microstructure analyses of the various...
Epoxy polymers reinforced with a premixed epoxy/nano-silica masterbatch or dry non-surface-treated nano-silica and ground micro-silica flour were compared. Cured plates of epoxy containing both nano-particles (up to 15 %wt) and micro-particles (up to 51 %wt) of silica were produced and tested. The glass transition temperature, Tg, of the epoxy was measured using differential scanning calorimetry (DSC),...
Electron paramagnetic resonance (EPR) investigations were carried out on hybrid Core-Shell nanomaterials associating silicon carbide nanoparticles and conducting polyaniline. The performed experiments compare the paramagnetic centres, the electronic transport features and the interface effects in two classes of materials, bare polymers and core-shell nanocomposites. By EPR, large doping rates were...
It has been shown that in many cases, the addition of nanoscale metal oxide fillers to polymers leads to an improvement in dielectric breakdown strength at room temperature. However, in some cases electrical insulation is exposed to elevated temperatures. A thermally stable polymer material, such as polyamideimide (PAI), is desired for these applications. For this reason, breakdown strength measured...
Quality control has demanded methods to quantify the mixing state of nanoparticles imbedded in polymeric materials. Several quantification methods are reviewed based on the analysis of images from electron microscopy. This includes the quadrat-based skewness, nearest neighbor distance, the k-function and Monte Carlo method. A novel method in which the dispersion and distribution are evaluated respectively...
Dielectric characteristics of LDPE filled with micro- and nano-sized particles of SiO2 were studied in this paper. The dependence of the loss factor and dielectric constant of composites on frequency was investigated in a relatively wide frequency range, and the roles of the size and loading level of the filler are discussed. Compared with additive-free LDPE, incorporating nano-sized SiO2 can effectively...
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