Publications de Yves Leterrier

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The increase of the elongational viscosity of recycled poly(ethylene terephthalate) (PET) is investigated with the aim of producing closed-cell foams by means of a cost-effective reactive extrusion technique. A recycled PET grade containing controlled contamination levels of polyvinyl chloride (PVC) and poylethylene (PE) is selected, and compared with virgin bottle-grade PET as a reference. Reactive processing with a tetrafunctional epoxy additive induces randomly branched molecules with a lower degree of b

Organic-inorganic hybrid coatings are becoming increasingly important due to their unique property combination [1, 2], including high optical transparency, improved scratch and abrasion resistance and excellent weathering, thanks to the synergism between t ...

The invention relates to a process for increasing the melt viscosities of polyester resins. This process comprises a step of heating the polyester resin in the temperature range comprised between the melting temperature of the polyester resin and the degradation temperature of the polyester resin with the addition of at least one modifier compound which has at least three glycidyl side chains. The improved polyester resins, having such improved properties, are used for the production of polyester foamed mat

Nanoindentation tests were carried out on the surface of polymer nanocomposites exhibiting either graded or homogeneous distributions of Fe3O4@silica core-shell nanoparticles in a photocurable polymeric matrix. The results reveal a complex interplay between graded morphology, indentation depth, and calculated modulus and hardness values, which was elucidated through numerical simulations. First, it was experimentally shown how for small (1 μm) indentations, large increases in modulus (up to +40%) and hardne

Flexible and soft bioelectronics display conflicting demands on miniaturization, compliance, and reliability. Here, the authors investigate the design and performance of thin encapsulation multilayers against hermeticity and mechanical integrity. Partially ...

Barrier film for encapsulation of oxygen and moisture sensitive devices comprising a base polymer substrate and applied onto the base substrate, a barrier layer comprising an inorganic coating deposited by a vapour deposition method, characterised in that ...

Probabilistic model of coating fragmentation under uniaxial tensile loading is developed. Analytical expressions of the crack spacing evolution are obtained for small-strain and large-strain fragmentation regimes. The model is applied for coating and inter ...

Organic–inorganic hybrid materials were prepared using the sol–gel process in order to improve the scratch resistance of poly(methyl methacrylate) (PMMA) substrates. Sol–gel solutions based on tetraethoxysilane and α,ω-triethoxysilane terminated polycaprol ...

Materials exhibiting a gradient in permittivity are synthesized through the application of an external magnetic field to a suspension of Fe3O4@TiO2 nanoparticles in an epoxy matrix. It is shown how the application of the magnetic field not only induces the magnetophoretic motion of the particles, but causes also their alignment in high aspect ratio structures. The combination of these two effects gives rise to graded nanocomposites exhibiting gradients in permittivity that go beyond the ones predicted for n

Among the main challenges of our century, the climate change and the need of diversification of the energy sources are of most importance. Renewable energies undoubtedly have an important role to play, photovoltaic (PV) electricity being especially well suited to face these energy challenges. However, the current integration of PV panels often comes without architectural consideration. In this context, the Archinsolar project [1] aims to develop a new generation of photovoltaic elements based on silicon thi

A difunctional cycloaliphatic epoxy monomer was cationically photo-polymerized in the presence of a diaryliodonium salt photoinitiator and an isopropyl thioxanthone photosensitizer at different temperatures and UV intensities. The photo-polymerization kine ...

The fragmentation behaviour of a thin brittle coating attached to a ductile substrate subjected to equibiaxial quasi-static in-plane tension is studied. The experimentally observed cracking patterns are related to repetitively branching coating cracks. The ...

Nanocomposites based on polyvinylidene fluoride– trifluoroethylene copolymer and up to 4 vol % of hydrophobized clay nanoparticles are investigated. The structure, piezoelectric properties, and oxygen permeability of solvent cast films are analyzed before ...

The interplay between residual stress state, cohesive and adhesive properties of coatings on substrates is reviewed in this article. Attention is paid to thin inorganic coatings on polymers, characterized by a very high hygro-thermo-mechanical contrast between the brittle and stiff coating and the compliant and soft substrate. An approach to determine the intrinsic, thermal and hygroscopic contributions to the coating residual stress is detailed. The critical strain for coating failure, coating toughness an

The formation of resin fillet between honeycomb core cell walls and skin in light sandwich structures was studied to gain a better understanding of the bonding process. A method was developed for tailoring the amount of adhesive between 8 and 80 g/m2. The ...

A theoretical modeling framework is proposed to follow shape and residual stress evolutions of layered flexible display structures with respect to deposition, ambient temperature and relative humidity conditions. This model couples the mechanical equilibri ...

Flexible displays present a challenging problem in terms of mechanical integrity, a result of the considerable hygro-thermomechanical contrast between the inorganic, brittle device layers and the compliant polymer substrates. This paper reviews the main ap ...

Crack patterns of 100-nm thick silicon oxide coatings on poly(ethylene terephthalate), polypropylene and polyamide films are analyzed under equibiaxial stress loading. The loading is achieved by means of a bulging cell mounted under an optical microscope with stepwise pressurization of film specimens. The evolution of the coating fragment area distribution in the early stages of the fragmentation process is modeled using Weibull statistics to describe the coating strength. Fragment areas are found to follow

Recent studies investigated the hydrolysis of Magnesium (Mg) thin films, highlighting their potential use in biodegradable devices. Quantitatively monitoring the degradation rate and morphological changes of Mg through optical methods and light-delivery de ...

To improve temperature durability for autoclaving of SiOx diffusion barrier coatings on polypropylene, plasma polymerized hexamethyldisiloxane (pp-HMDSO) is applied by plasma enhanced chemical vapour deposition as interlayer material and compared with resu ...

Yves Leterrier

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Recycling of poly(ethylene terephthalate) into closed-cell foams

Interface interactions in hybrid organosilane-nitride films on polymer substrates

Increasing the melt viscosities of a polyester resin

Nanoindentation of Functionally Graded Polymer Nanocomposites: Assessment of the Strengthening Parameters through Experiments and Modeling

Extended Barrier Lifetime of Partially Cracked Organic/Inorganic Multilayers for Compliant Implantable Electronics

Diffusion-barrier coating for protection of moisture and oxygen sensitive devices

Evaluation of interfacial stress transfer efficiency by coating fragmentation test

Cohesive and adhesive properties of polycaprolactone/silica hybrid coatings on poly(methyl methacrylate) substrates

Graded-permittivity polymer nanocomposites as superior dielectrics

Innovative Solution for Building Integrated Photovoltaics

UV-intensity, temperature and dark-curing effects in cationic photo-polymerization of a cycloaliphatic epoxy resin

Coating fragmentation by branching cracks at large biaxial strain

High diffusion barrier and piezoelectric nanocomposites based on polyvinylidene fluoride-trifluoroethylene copolymer and hydrophobized clay

Mechanical integrity of thin inorganic coatings on polymer substrates under quasi-static, thermal and fatigue loadings

Prediction of the adhesive fillet size for skin to honeycomb core bonding in ultra-light sandwich structures

Residual stresses in diffusion barrier films on polymer substrates for flexible displays

Models and Experiments of Mechanical Integrity for Flexible Displays

Analysis of the initial fragmentation stage of oxide coatings on polymer substrates under biaxial tension

Magnesium Optrodes for Real-Time Optical Monitoring of Water Transport in Ultrathin Encapsulations for Bioelectronics

Oxygen permeation, mechanical and structural properties of multilayer diffusion barrier coatings on polypropylene