Search results for "Ceramic"
showing 10 items of 2129 documents
Biphasic dimerisation of methylacrylate--immobilisation and stabilisation of cationic Pd-catalysts in ionic liquids by an ammoniumphosphine ligand.
2002
The first continuous, biphasic, Pd-catalysed dimerisation of methylacrylate is described. The biphasic system has been realised by using a tetrafluoroborate ionic liquid as catalyst medium and an ammoniumphosphine ligand to immobilise and stabilise the Pd-catalyst.
Synthesis and Characterization of Iron-Doped ZrSiO4 Solid Solutions from Gels
2011
The mechanism of formation and the structural features of tetragonal Fe–ZrO2-amorphous silica composites and particulated Fe-doped ZrSiO4 solid solutions were studied. A series of specimens with compositions Fex–ZrSiO4, 0 ≤ x ≤ 0.10 were prepared by sol–gel techniques and thermally annealed over the range of temperature between 400°C and 1600°C. Results confirmed the formation of tetragonal Fe–ZrO2 solid solution as first crystalline phase on the whole process leading to Fe-doped ZrSiO4 solid solution. The annealing temperature for the preparation of Fe-containing ZrSiO4 solid solutions was dependent on the nominal amount of iron. The Fex–ZrSiO4 solid solutions, with 0.02 < x < 0.08, were a…
A 2,3-dialkoxynaphthalene-based naphthocage
2019
A 2,3-dialkoxynaphthalene-based naphthocage has been synthesized. This naphthocage prefers to bind small organic cations with its low-symmetry conformation, which is in contrast to 2,6-dialkoxynaphthalene-based naphthocages. Self-sorting of these two naphthocages with two structurally similar guests tetramethylammonium and tetraethylammonium was achieved as well. peerReviewed
Novel method for functionalising and patterning textile composites:Liquid resin print
2016
Abstract The paper reports a novel method of integrating resin into continuous textile reinforcement. The method presents a print of liquid reactive resin into textile preforms. A series of targeted injections forms a patch which upon consolidation and curing transforms into a stiff region continuously spanning through preform thickness. Enhancing the injected resin with conductive phase allows creating a pattern of patches with controlled dimensions and added functionalities. Patterned composites reveal features which are not typical for conventional composites such as fibre bridged interfaces, regular thickness variation, and gradient matrix properties. The presented study explores the ro…
Strength prediction of a triaxially braided composite
2011
The architecture of textile reinforcement affects the deformation and failure behavior of the textile reinforced composites. This paper presents an approximate method that incorporates the in-plane periodic meso structure of the textile composite in finite element models. In this approach, the representative unit cell (RUC) of a textile composite is divided into sub-cells. Instead of obtaining a homogeneous equivalent, these sub-cells are idealized and represented with laminates of different layups using shell elements. In this way, an RUC can be constructed with a small number of elements. This method holds the promise of creating a textile composite FE model with an improved accuracy with…
Active colloidal suspensions: Clustering and phase behavior
2014
We review recent experimental, numerical, and analytical results on active suspensions of self-propelled colloidal beads moving in (quasi) two dimensions. Active colloids form part of the larger theme of active matter, which is noted for the emergence of collective dynamic phenomena away from thermal equilibrium. Both in experiments and computer simulations, a separation into dense aggregates, i.e., clusters, and a dilute gas phase has been reported even when attractive interactions and an alignment mechanism are absent. Here, we describe three experimental setups, discuss the different propelling mechanisms, and summarize the evidence for phase separation. We then compare experimental obse…
Aging effects in simple models for glassy relaxation
2006
Aging effects in the two-time correlation function and the response function after a quench from a high temperature to some low temperature are considered for a simple kinetic random energy model exhibiting stretched exponential relaxation. Because the system reaches thermal equilibrium for long times after the quench, all aging effect are of a transient nature. In particular, the violations of the fluctuation-dissipation theorem are considered and it is found that the relation between the response and the two-time correlation function depends on another function, the so-called asymmetry. This asymmetry vanishes in equilibrium but cannot be neglected in the aging regime. It is found that pl…
Rapid synthesis of tin (IV) oxide nanoparticles by microwave induced thermohydrolysis
2008
Abstract Tin oxide nanopowders, with an average size of 5 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in aqueous solutions of tin tetrachloride and hydrochloric acid using a microwave autoclave (RAMO system) specially designed by the authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, nitrogen adsorption isotherm analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), were used to characterize these nanoparticles. Compared with conventional synthesis, nanopow…
Preparation and characterization of gels with garnet structure: A3B2C3O12, using ‘non-classical’ solvents
1992
Abstract Synthesis and characterization of some crystalline garnets by sol-gel techniques is described. The effects of emthanol, dimethyl sulfoxide (DMSO), CH2Cl2 and toluene solvents on gelation of TEOS are considered. Multicomponent gel formation in systems with stoichiometries 3CaO·Cr2O3·3SiO2 and 3CaO·Al2O2 was studied using DMSO, a polar solvent, and toluene, an apolar solvent. The dried gel was thermally treated and the powder was characterized by X-ray diffraction, differential thermal analysis/thermogravimetric analysis and scanning electron microscopy.
Effect of plasma treatment on the properties of Arundo Donax L. leaf fibres and its bio-based epoxy composites: A preliminary study
2016
Abstract A preliminary investigation about the effect of plasma treatment on the properties of natural fibres extracted from the leaf of the giant reed Arundo Donax L. and their compatibility with a bio-based epoxy resin is performed. To this aim, the influence of plasma treatment on the functional groups and on the thermal behaviour of fibre were investigated using Fourier transform infrared spectroscopy and thermogravimetric analysis. Moreover, the mechanical characterization of fibres was performed through fibre tensile tests. Short randomly oriented fibres/bio-based epoxy composites were manufactured by hand lay-up method followed by compression moulding, varying both fibres weight cont…