Search results for "CERAMICS"
showing 10 items of 1599 documents
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…
Lifetime predictions of non-ionic and ionic biopolymers: kinetic studies by non-isothermal thermogravimetric analysis
2021
AbstractIn this paper, films based on sustainable polymers with variable charge have been investigated by non-isothermal thermogravimetry in order to predict their lifetime, which is a key parameter for their potential use in numerous technological and biomedical applications. Specifically, chitosan has been selected as positively charged biopolymer, while alginate has been chosen as negatively charged biopolymer. Among non-ionic polymers, methylcellulose has been investigated. Thermogravimetric measurements at variable heating rates (5, 10, 15 and 20 °C min−1) have been performed for all the polymers to study their degradation kinetics by using isoconversional procedures combined with ‘Mas…
Effect of Plasma Treatment on Mechanical and Thermal Properties of Marble Powder/Epoxy Composites
2016
The aim of this work was to study the effect of the plasma treatment on the behavior of composite structures reinforced with marble powder, obtained as processing waste in the “Custonaci” basin. Moreover, different filler amounts (i.e. 10%wt, 20%, 30% in weight) were investigated. For the mechanical characterization, tensile and flexural quasi-static tests, Charpy impact test, and dynamic mechanical thermal analysis (DMTA) were performed. For the thermal stability, thermogravimetric analysis was carried out. Finally, real density and fraction of voids were measured. It was observed that untreated marble powder, on one hand, increases tensile and flexural stiffness and improves thermal stabi…
Incorporation of Silica Nanospherical Particles into Epoxy-Amine Crosslinked Materials
2008
Composites of silica nanospheres coated with crosslinked epoxy–amine were synthesised and examined by 29Si-magic-angle-spinning nuclear magnetic resonance spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. The most representative fact is that epoxy-modified nanospheres lost less weight at high temperatures. At temperatures greater than 300°C the loss of weight for epoxy-modified nanospheres was rather lower than for unmodified nanospheres. This helped them to retain their structures, as the loss of weight can have adverse effects on network defects, due to the loss of crosslinks by unit of volume.