Search results for "composites"

Application of time–stress superposition to nonlinear creep of polyamide 66 filled with nanoparticles of various sizes

2007

The long-term tensile creep of polyamide 66 and its nanocomposites filled with 1 vol.% TiO2 nanoparticles 21 and 300 nm in diameter is studied. It is assumed that the dominant mechanisms of creep deformation are of viscoelastic nature, while the contribution of plastic strains is not essential in the stress (< 0.6 of the ultimate stress) and time (about 100 hours) ranges considered. The creep isochrones obtained show that the materials exhibit a nonlinear viscoelastic behaviour and the degree of nonlinearity is reduced significantly by incorporation of the nanoparticles. The evolution of viscoelastic strains is less pronounced for the nanocomposite filled with smaller nanoparticles. Smooth …

Luminescence of localized states in silicon dioxide glass. A short review

2011

Abstract The target is the description of the properties of localized states in silica glass, which relate to aspects of short-to-intermediate-range order. It has been observed that laser light interaction with localized states of silica glass leads to the creation of luminescence centers. Created luminescence centers, excited with laser light, provide intra-center luminescence of oxygen deficient centers (ODC) comprising a blue band at 2.7 eV and a UV band at 4.4 eV. Structurally, these ODCs are understood to comprise twofold-coordinated silicons that are commonly part of some larger local structure, and their luminescence bands can be suppressed by reaction with chlorine or hydrogen. Besi…

Biomaterials coated by dental pulp cells as substrate for neural stem cell differentiation

2011

[EN] This study is focused on the development of an in vitro hybrid system, consisting in a polymeric biomaterial covered by a dental pulp cellular stroma that acts as a scaffold offering a neurotrophic support for the subsequent survival and differentiation of neural stem Cells. In the first place, the behavior of dental pulp stroma on the polymeric biomaterial based on ethyl acrylate and hydroxy ethyl acrylate copolymer was studied. For this purpose, cells from normal human third molars were grown onto 0.5-mm-diameter biomaterial discs. After cell culture, quantification of neurotrophic factors generated by the stromal cells was performed by means of an ELISA assay. In the second place, s…

STRONTIUM CONCENTRATION DEPENDENCE OF SELECTED STRUCTURAL AND MECHANICAL PROPERTIES OF POLYCRYSTALLINE Ba1−XSrXTiO3

2009

ABSTRACT Microstructure and material constants such as Young modulus E, shear modulus G, Poisson ratioν of polycrystalline ferroelectric materials Ba1-xSrxTiO3 for 0≤x≤0.4 were investigated to determine their dependence on strontium concentration. The performed investigations showed that the material is chemically homogeneous. It was found that the strontium concentration had no significant influence on the grain size. The highest value of Young's modulus is observed for Ba0.6Sr0.4TiO3 sample. The performed investigations of mechanical properties made it possible to evaluate the usability of this material for manufacturing transducers and sensors which could work under load.

Erratum to “Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates”

2008

Optimization of laminated composites plates using glowworm algorithm

2010

Dielectric and Elastic Parameters of LixNa1-xTa0.1Nb0.9O3 Ferroelectric Solid Solution Ceramics

2011

Results of the studies of electric and elastic parameters as functions of concentration in ferroelectric LiхNa1-хTa0.1Nb0.9O3 (x = 0–0.16) solid solutions and comparative studies of the elastic properties by acoustic and contact probe techniques are reported. The electric and elastic properties of LiхNa1-хTa0.1Nb0.9O3 solid solutions are shown to be rather sensitive to structural distortion at concentration-induced structural phase transitions. The values of elastic modules obtained from acoustic measurements are found to be in good agreement with those obtained by contact probe techniques.

Materials Communicating with the BIM: Aims and First Results of the McBIM Project

2019

This paper introduces McBIM, a French national research project working on on-line monitoring on concrete structure. This project gathers 3 french laboratories (the CRAN, LAAS and LIB) associated with one company (360SmartConnect/FINAO SAS) that are working together from 2018 to 2021. It proposes 1) to design a “communicating concrete”, made of concrete equipped with embedded low-energy wireless microsensor network, able to manage and exchange data using BIM standards, and 2) to demonstrate the usefulness of this approach across several building lifecycle phases, namely the manufacturing, construction and exploitation phases for structural health monitoring. The paper will first start by in…

Mechanical and acoustical behavior of sugarcane and flax fibres reinforced biocomposite

2017

For reasons of comfort, modern constructions require acoustic and thermal insulating materials, offering good mechanical performances. In this context, the valorization of plant fibres from the agro-food industry presents economic and environmental benefits. Thus, the aim of the present study is to develop a multifunctional sugarcane fibres reinforced epoxy porous composite combining good acoustic and mechanical properties.The study of the bagasse fibres geometry has shown that fibres’ length and diameter distribution can be fitted by lognormal laws. Composites manufactured by thermocompression process with an epoxy matrix were characterized using an experimental design whose parameters wer…

Isolation, dynamic NMR study and X-ray characterisation of a bis sulfonium zirconocene-ate dimer.

2004

The novel dimer [Cp(2)Zr[upper bond start]([minus sign in circle])S([plus sign in circle])CH(Ph)CH[double bond]C[upper bond end]PPh(2)](2), the first example of a structurally characterised sulfur-bridged binuclear zirconathiolane complex, was prepared, characterised by NMR spectroscopy and X-ray crystallography, and some aspects of its solution behaviour were studied.