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Oxidation of trichloroethylene and derivatives of phenol, which are toxic compounds present in water, to harmless species has been carried out in the presence of modified clays such as HDTMA-immobilized-interlayer-Mn(VII) (surfactant immobilized manganate clay) and Mn+-bent-Mn (VII) (metal cations like Al, Cr, Fe, Cu, Ni, Mn & Zn impregnated on manganate clays), by treating the toxic compounds...
Silicon carbide based fibers are generally prepared by the melt spinning of ceramic material precursors like polycarbosilane (PCS) and the hetero-metal substituted derivatives (M-PCS). Therefore, the rheological behaviour of PCS in the melt with respect to time, temperature, atmosphere, molecular weight and polydispersity becomes very important for successful processing and for preparing green fibres...
The effect of sterically hindered carbosilane moieties, situated as end groups in telechelic oligodimethylsiloxanes, was investigated with respect to the mobility of silicon atoms in the main chain. The relaxation phenomena in such crowded systems were studied by DSC and NMR methods. Spin–lattice relaxation times T1 (29Si NMR) of silicon atoms in the oligomer chain were estimated and related to the...
The effects of precursor structure and polycondensation conditions on the properties of hybrid nanoparticles synthesized from organo-trimethoxysilanes were studied. Hybrid nanoparticles containing groups capable of forming hydrogen bonds were synthesized from functional derivatives of 3-aminopropyltrimethoxysilane. For the synthesis of phenylurea-functionalized organosilica nanoparticles different...
A study was made in the present investigation on siloxane containing tetraglycidyl epoxy nanocomposites in order to determine their suitability for use in high performance applications. The synthesis of the siloxane tetraglycidyl epoxy resin denoted as ‘E’ was done and it was characterized by Fourier Transform Infrared (FT-IR) spectra and 1H, 13C Nuclear Magnetic Resonance (NMR) spectra. Nanoclay...
High molecular weight copolymers, referred to as polysilalkylene siloxanes or hybrid silicones, were prepared using anionic ROP of 1,1,3,3,14,14,16,16-octamethyl-2,15-dioxa-1,3,14,16-tetrasilacyclohexacosane (II) and octamethylcyclotetrasiloxane (D4) mixtures. The resultant gum-like polymers were characterized by 1H NMR, 13C NMR, 29Si NMR, FTIR, GPC, TGA and FTIR. It was determined that the resultant...
We report the synthesis of highly porous hybrid silica-polyacrylamide aerogels where the inorganic network was obtained through the hydrolysis and poly-condensation of tetramethoxysilane via a two-step sol–gel process while the polyacrylamide polymer was made by photo-copolymerization of two organic monomers, the acrylamide and the bis-acrylamide. These aerogels were obtained after a carbon dioxide...
Infrared absorption spectroscopy measurements for a number of Na-borosilicate glasses containing AgBr and Cu2O were carried out in order to elucidate the structure of these glasses and the forms in which the transition metal ions exist in it. The raw materials used were of chemically pure grade and were finely pulverized. The temperature of the melting was 1,450 °C for 2 h and the samples were then...
The conjugation of nanoparticles to carbon nanotubes (CNTs) involves various steps including premodification of the nanotubes, which is known to be a very tedious process and sometimes leads to a mixture of products. In this regard, a direct route to generate such conjugates is a worthwhile endeavor. In this paper, we report a novel, mild, one-pot, approach to a controlled and direct coordination...
Comparison between the two main sol–gel/emulsion methods to prepare microparticles made of organosilica doped with a lipophilic molecule shows that entrapment only takes place starting from O/W emulsions. In this case, however, formation of spherical microcapsules, observed when the sol–gel polycondensation is carried out in a W/O microemulsion, does not take place.
The effect of silyl ether substitution on the physical and electrochemical properties of single and two-nitrogen centered arylamines was explored. It was found that this substitution can significantly lower the Tg and suppress crystallization of these compounds. This resulted in arylamines that were isolated as liquids, waxes, glasses, and in some cases crystalline solids at ambient conditions. Additionally,...
The purpose of surface treatment (conditioning) methods on dental ceramics is to improve the retention and bonding between the enamel or the dentin and ceramic veneer, with the help of resin composite luting cements. These types of surface treatments include chemically altering the surface of ceramics with some specific acidic etchants followed by applying a silane coupling agent (silane). The silane...
The growth of SiOx nanowires and nanocakes on an Au-coated n-type-Silicon (100) substrate was achieved via carbothermal evaporation. The effects of the Au layer thickness and the rapid heating rate on the morphology of obtained SiOx nanowires were investigated. A broad emission band from 290 to 600 nm was observed in the photoluminescence (PL) spectrum of these nanowires. There are four PL peaks:...
Large-pore mesoporous silica particles were synthesized through a solvent evaporation process using hydrophobic fumed silica particles and tetraethyl orthosilicate (TEOS) as silica sources. The solvent evaporation of an ethanol solution of fumed silica particles, TEOS, HCl and triblock copolymer (F127) resulted in mesoporous silica particles with pores with sizes of about 7 nm. In addition, the interplanar...
Ceramics are widely used biomaterials in prosthetic dentistry due to their attractive clinical properties. They are aesthetically pleasing with their color, shade and luster, and they are chemically stable. The main constituents of dental ceramic are Si-based inorganic materials, such as feldspar, quartz, and silica. Traditional feldspar-based ceramics are also referred to as “Porcelain”. The crucial...
The formation of glass-ceramics based on Na2O–CaO-silicates containing P2O5 with minor additives of some trivalent oxides (e.g. La, In, Ga, and Al), has been investigated. Different crystalline phases including sodium-orthosilicate containing lanthanum, or aluminum were formed together with Na2Ca2Si3O9, NaInSi2O6, and Na3Ga2Si3O10. The nature and mechanism of HA formed in the glass-ceramics are considered...
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