J.-Y. Cavaillé

• PhD, Prof.
• Faculty Member at CNRS, Universite de Lyon, Tohoku University joint laboratory @Sendai, Japan

Polyurethanes have been extensively studied for their strong electromechanical response. Previous studies have mainly investigated the impact of electrical charges on these polymers' DC conductivity, which was measured on the order of 10⁻¹⁰ S/m. The movement of electric charges is responsible for the macroscopic deformation of polymer films under a...

Since 1998, our target of the projects has been the international active collaborations for Research for constructed and smart materials with original concepts. Excellent achievements were getting PhD (INSA Lyon) of master (Tokai U.) M. Kanda as well as more than 30 papers worked with three Research Unites in France.

Understanding the particle history during the cold spray process is primordial to better apprehend the particle's mechanical behavior during the impact. If the particle velocity can easily be measured using a high-speed camera, measuring the particle temperature remains a challenge. A solution is to perform numerical simulations of the process usin...

Previous work has shown that dielectrophoretic body forces resulting from permittivity and conductivity heterogeneities only partially contribute to the overall electromechanical deformation of segmented polyurethanes (PUs). In this work, we studied the experimental kinetics and electric current of PU thin films over a long time period (1–10⁵ s) fo...

High particle temperature and low particle velocity are required to successfully deposit polymer particles by cold spray process. To increase the particle temperature, a solution is to use a relatively long nozzle to increase the particle resident time inside the nozzle and limit the expansion of the supersonic flow. However, to do this, due to man...

This study reports the development of a magneto-rheological foam, which consists in a porous matrix filled by ferromagnetic particles. The porous matrix of such a composite being easily deformable, large magnetic properties changes are expected. The measurements of the magnetic properties of such a magneto-rheological foam submitted to a compressiv...

The electrostrictive response of soft elastomers with the same stiffness, strongly depends on their chemical nature and their typically multiphase microstructure. Moreover, some elastomers exhibit a strongly time dependent electrostriction over tens of minutes, and up to now, no theoretical approach has been proposed to analyze experimental data on...

Polyvinylidene difluoride (PVDF) is a ferroelectric polymer characterized by negative strain along the direction of the applied electric field. However, the electromechanical response mechanism of PVDF remains unclear due to the complexity of the hierarchical structure across the length scales. As described in this letter, we employ the Finsler geo...

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy convers...

Ultra-High Molecular Weight semi-crystalline polymers, such as Ultra-High Molecular Weight PolyEthylene (UHMWPE) exhibit strong wear and impact resistance, making them good candidates for structural applications in many industrial fields. At high strain rate and large strain, mechanisms of deformation are quite different from those involved in clas...

Monte Carlo simulations are performed to study the electromechanical properties of polyvinylidene difluoride (PVDF) because of its unusual deformation in response to an applied electric field. PVDF is a ferroelectric polymer characterized by a negative strain along the applied electric field direction. However, the mechanism of this electromechanic...

Recent works demonstrated the abilities of magneto rheological elastomers (MREs) for mechanical to electrical energy conversion. This class of materials consists of composites composed of a soft elastic matrix filled by ferromagnetic particles. In this work we focus primarily on anisotropic MREs featuring particles that are non-homogenously dispers...

Two-dimensional triangulated surface models for membranes and their three-dimensional (3D) extensions are proposed and studied to understand the strain-induced crystallization (SIC) of rubbers. It is well known that SIC is an origin of stress relaxation, which appears as a plateau in the intermediate strain region of stress–strain curves. However,...

The manufacture of polymer coatings via the cold-spray process remains challenging owing to the viscoelastic-viscoplastic behavior exhibited by polymers. One crucial step to improve cold-spray polymer coating is to determine the particles’ thermal history during their flight from inside the nozzle to their impact on the substrate. In this study, we...

We apply the Finsler geometry (FG) modeling technique to study the electric field-induced strain in ferroelectric polymers. Polyvinylidene difluoride (PVDF) has a negative longitudinal piezoelectric coefficient, which is unusual in ferroelectrics, and therefore the shape changes in this material are hard to predict. We find that the results of Mont...

Configurations of the polymer state in rubbers, such as so-called isotropic (random) and anisotropic (almost aligned) states, are symmetric/asymmetric under space rotations. In this paper, we present numerical data obtained by Monte Carlo simulations of a model for rubber formulations to compare these predictions with the reported experimental stre...

Nanoceramic interlayers at the polymer-polymer interfaces have been demonstrated to be extremely vital for the coating buildup (up to 4 mm thickness) during cold-spray consolidation of Ultra-High Molecular Weight Polyethylene (UHMWPE). This paper investigates the polymer-polymer interface formation and strength as a function of the compressive stat...

A new method to fabricate linear connected joints of Ti (titanium) to Epoxy polymer connected by CF-plug designated here as [Ti/CFW-CFRP] was innovated to enhance safety level of airplanes, since fine carbon fibers (CFs, 6-7/1000 mm) generate extremely large friction force by their broad interface between Ti and Epoxy [Ti/Epoxy] giving strong adhes...

The influence of the chemical microstructure on the secondary mechanical relaxations of PB and SBR has been studied by varying the content of vinyl, cis, trans butadiene and styrene groups. Two relaxational mechanisms are involved in their β mechanical relaxations with two distinct activation energies. The fitting by the summation of two Havriliak...

A model of structured Magneto-rheological Elastomer made of a soft matrix filled by magnetic particles was studied for energy harvesting, in pure shear condition. The particles were supposed to be aligned in a chain along which the magnetic field is applied and considering a shear strain applied in a plane perpendicularly to the chain. As the strai...

Electroactive devices are developed for energy conversion purposes. In particular, polyurethanes (PU) are lightweight and flexible materials, which have demonstrated their ability to convert electrical energy into mechanical energy (actuation by electrostriction) and vice-versa (energy harvesting). It has been shown that energy conversion efficienc...

A mathematical modeling, the Finsler geometry (FG) technique, is applied to study the rubber elasticity. Existing experimental data of stress-strain (SS) diagrams, which are highly non-linear, are numerically reproduced. Moreover, the strain induced crystallization (SIC), typical of some rubbers like Natural Rubber (NR), which is known to play an i...

Electroactive polymers (EAPs) are promising materials for actuation and energy harvesting applications. Among the EAPs, polyurethane (PU) material is of considerable interest given its high values of deformation under an electric field. The electromechanical properties were found to be dependent on the processing technique and the thickness of the...

The cold spray deposition mechanism of Ultra-High Molecular Weight Polyethylene (UHMWPE) requires a detailed understanding of strain rate sensitivity of UHMWPE. The yield and flow in UHMWPE are complex and sophisticated compared to metals due to their dependency on time, temperature, strain, strain-rate and the history of the processing. In this re...

Cold-spray process (CS) showed suitable properties to weld together compatible and incompatible materials. Since it has been intensively studied as additive technique using metallic powders on metallic surfaces, and only recently with polymeric powders, we compare, in a very preliminary attempt, simulated data of the impact of an aluminum particle...

The cold spray has been shown to be one of the promising additive manufacturing technologies to process Ultra High Molecular Weight Polyethylene (UHMWPE)-metal integrated systems by successfully being able to coat UHMWPE on metals using fumed nano-alumina (FNA) as UHMWPE particle surface modifiers. However, the exact mechanism of UHMWPE deposition...

Semi-crystalline polymers, and more particularly high molecular weight semi-crystalline polymers, exhibits interesting properties such as wear and impact resistance which contributes to their spreading into several industries and applications. However, because they have very long chains and exhibit high viscoelastic mechanical behavior, they are di...

Magneto-rheological (MR) elastomers contain micro-/nano-sized ferromagnetic particles dispersed in a soft elastomer matrix, and their rheological properties (storage and loss moduli) exhibit a significant dependence on the application of a magnetic field (namely MR effect). Conversely, it is reported in this work that this multiphysics coupling is...

MagnetoRheological Elastomers (MREs) have been widely used for actuation purposes in numerous applications (e.g., vibration damping), thanks to their magnetic-field controllable shear modulus. Nevertheless, the converse effect, namely, the modification of the magnetic properties through the application of a shear strain or stress has been barely st...

Recent advances has made possible to obtain Ultra High Molecular Weight Polyethylene (UHMWPE) coatings by cold spray technique with nano-ceramic additives with the feedstock. However, the exact role of nano particles is largely not understood. In this work, isolated depositions of UHMWPE particles with 0%, 2%, 4%, 10% of fumed nano alumina (FNA) on...

2-layer laminated sheets (PE/PET) with Polyethylene (PE) and Polyethylene Terephthalate (PET) were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (≦1.30 MGy) homogeneous low energy electron beam irradiation (HLEBI) prior to hot-press under 5 MPa and 403 K. Although the weak hot-press adhesion of the PE/PE...

Among the key parameters, which must be taken into account for the choice of actuators used as electrical to mechanical energy converters, the response to a step function and/or the frequency dependence of this response is extremely important. For polymeric actuators and more generally for electroactive polymers, three mechanisms can be at the orig...

Evaluation of the Tensile Strength of Electron Beam Irradiated Powdered Ultra High Molecular Weight-Polyethylene Prior to Sintering [1] The variation in tensile strength (σb), fracture strain (εf) and Young modulus (dσ/dε) of low voltage electron beam irradiation (HLEBI) on powdered ultra-high molecular weight-polyethylene from 0.043 to 0.43 MGy p...

2-layer laminated sheets (PE/18-8) with Polyethylene (PE) and austenitic 18-8 stainless steels (18-8) were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (≦0.43 MGy) homogeneous low energy electron beam irradiation (HLEBI) prior to hot-press under 5 MPa and 343 K. Although the weak hot-press adhesion o...

Powder for cold spray containing a mixture of powder of a macromolecule and nanoparticles of a ceramic. Macromolecular coating film containing a mixture of powder of a macromolecule and nanoparticles of a ceramic.

The cold spray deposition of ultra-high molecular weight polyethylene (UHMWPE) powder mixed with nano-alumina, fumed nano-alumina, and fumed nano-silica was attempted on two different substrates namely polypropylene and aluminum. The coatings with UHMWPE mixed with nano-alumina, fumed nano-alumina, and fumed nano-silica were very contrasting in ter...

Polyurethanes (PU) have demonstrated their ability to convert electrical energy into mechanical energy and vice versa. The incorporation into a PU matrix of nanofillers, such as carbon nanotubes (CNT), can even enhance the actuation and the harvested energy performances. However, it is well known that CNTs are hardly dispersed in a polymeric matrix...

We have studied the variation in tensile strength (σb), fracture strain (εf ) and Young modulus (dσ/dε) of low voltage electron beam irradiation (HLEBI) on powdered ultra-high molecular weight-polyethylene from 0.043 to 0.43MGy prior to sintering. The low dose of 0.043MGy-HLEBI enhanced the σb, εf and dσ/dε, as well as increased the crystallinity r...

Ultra-high molecular weight polyethylene or UHMWPE is an extremely difficult material to coat with, as it is rubbery and chemically very inert. The Cold Spray process appears to be a promising alternative processing technique but polymers are in general difficult to deposit using this method. So, attempts to develop UHMWPE coatings were made using...

The cold spray deposition of ultra-high molecular weight polyethylene (UHMWPE) powder mixed with nano-alumina, fumed nano-alumina, and fumed nano-silica was attempted on two different substrates namely polypropylene and aluminum. The coatings with UHMWPE mixed with nano-alumina, fumed nano-alumina, and fumed nano-silica were very contrasting in ter...

The cold spray deposition of ultra high molecular weight polyethylene (UHMWPE) powder mixed with nano alumina, fumed nano alumina and fumed nano silica was attempted on two different substrates namely polypropylene (PP) and aluminum (Al). Approximately 4mm and 1mm thick coating were observed on Al and PP substrates respectively with UHMWPE and fume...

Polyurethane (PU) exhibit very high electromechanical activity, and has a great interest for a wide range of transducer and actuator applications. It has been recently pointed out that this strong electrostriction may result from the phase separation. In the present work, a model taking account the PU nanostructure is presented. In order to validat...

The structure of styrene-butadiene rubbers (SBRs) consists of chains attached to cross-links of relatively small number density. These rubbers show an α-relaxation process that is attributed to segmental motions of the attached chains. To investigate how an SBR's rubber-like behavior would change when free chains interpenetrate its structure, we pr...

The incorporation of carbon nanotubes into polymer matrices is justified because of their unique intrinsic properties combined with their high aspect ratios. Nevertheless, the understanding of the nanocomposites macroscopic properties requires a detailed characterization of several microstructural parameters, among which are the nanotubes' dispersi...

In the present study organic–inorganic hybrid nanocomposites of cross-linked polyethylene (XLPE) with 0, 2, 5 and 10 wt% of trimethoxyoctyl-silane surface treated ZnO nanoparticles were prepared by melt mixing. Non-isothermal crystallization kinetics is examined in detail to reveal the crystallization characteristics of the cross-linked system (XLP...

Composites based on a polyurethane polymer matrix filled with various amounts of different types of nano-objects (carbon black, carbon nanotubes and graphene) were prepared and characterized. Such semi-crystalline polymers are very attractive for electromechanical applications as they can generate high strain levels under moderate electrical fieds....

The impact of small amounts of carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH) added into a polyether-based thermoplastic polyurethane elastomer (TPU) was studied considering mainly on the morphological, mechanical, electrical and electrostrictive properties. The electrostrictive properties were measured by the analysis of the de...

Some polyurethanes have demonstrated their ability to convert electrical energy into mechanical energy and vice versa. Furthermore, these materials are lightweight, very flexible, presenting low manufacturing costs, and can be readily molded into any desirable shape. It has been recently pointed out that this strong electrostriction results mainly...

Some polymers exhibit very high electromechanical activity, and there is a lack of physical understanding of the mechanisms at the origin of this behavior. In amorphous or slightly crystalline polymers, piezoelectric effect is negligible and the contributions to electrostriction are quadratic function of the applied electric field. These contributi...

The biaxial sequential stretching process of poly(ethylene terephthalate) produces films with a fibrillar microstructure in which fibrils are parallel to the transverse extrusion direction. The mechanical properties of such films are strongly anisotropic due to both the orientation of crystallites and the properties of the intrafibrillar and interf...

In this work poly(hydroxybutyrate/poly(vinyl butyral)- co-(vinyl alcohol)-co(vinyl acetate) (or ethylene propylene diene monomer rubber) blends were prepared by conventional processing techniques (extrusion and injection moulding). A droplet type morphology was obtained for P(3HB)/PVB blends whereas P(3HB)/EPDM blends presented some extent of co-co...

The magnetostriction of composites consisting of a non-magnetic matrix, randomly filled by ferromagnetic particles is measured as a function of temperature. The magnetic property of the particles and the mechanical property of the matrix are both dependent on temperature. Extracting the thermal expression of the magnetic stress and recording the co...

The electrostrictive properties of a polyether-based polyurethane elastomer and its corresponding composites filled with conductive carbon black (CB) were studied by measuring the thickness strain SZ induced by external electric fields E. For films with thicknesses of approximately 50 μm, the apparent electrostrictive coefficient M was measured at...

RESUME : Former des ingénieurs, des scientifiques et des cadres : a) généralistes, de haut niveau scientifique et technologiques, b) experts dans la gestion de projets innovants, c) « ouverts » sur le monde, et d) aptes à répondre aux enjeux de la complexité,-telle est l'une des ambitions de l'INSA de Lyon dans un contexte où la plupart des fonctio...

a b s t r a c t This review intends to present different aspects concerning clay/polymer nanocomposites produced by heterophase polymerization in aqueous media. This paper highlights the ability of miniemulsion poly-merization to produce clay/polymer nanoparticles with tailored nanostructures. Indeed, this polymeri-zation route enables the synthesi...

The magnetostriction of composite consisting of a soft matrix, non-magnetic, randomly filled by ferromagnetic particles is measured. The measured elongation on cylinder-shaped samples displays shape dependence. A model based on the demagnetizing field and the effective Young’s modulus is provided. Both calculation and measurement show a positive ma...

This article is devoted to the effects of the presence of modified clays during in-situ polymerization. Such synthesis routes require clay modifications in order to render the clay surface compatible with the monomer-polymer and/or reactive during polymerization. In addition, the use of nanometric clays (laponite) induces a large surface area which...

The main goal in material science is to provide behaviour laws, i.e. to be able to predict the material properties under given conditions (mechanical, electrical, environmental conditions, temperature, etc.). This requires relating microscopic parameters and local mechanisms to macroscopic behaviours, as there is no other way to express such behavi...

Poly(3-hydroxybutyrate) (PHB) is a very promising biopolymer. In order to improve its processability and decrease its brittleness, PHB/elastomer blends can be prepared. In the work reported, the effect of the addition of a rubbery phase, i.e. ethylene-propylene-diene terpolymer (EPDM) or poly(vinyl butyral) (PVB), on the properties of PHB was studi...

In this work, the microstructure and the rheology of a glass-fibre-reinforced fresh mortar were studied. Various fibre contents and aspect ratios and two types of fibrous reinforcement, i.e. slender fibre bundles and fibres, were tested. The microstructure was analysed by using X-ray microtomography. It is shown that the non-deformed mortar is a po...

A range of polymer–nanotube nanocomposites were produced using different processing routes. Both polymer-grafted and as-grown nanotubes were used and latex and polystyrene matrices investigated. The microstructures of the nanocomposites were studied, mainly by electron microscopy, in terms of the dispersion state of the nanotubes and the polymer–na...

Among other uses, latexes are a successful alternative to solvent-borne binders for coatings. Efforts are made to produce hybrid nanostructured latexes containing an acrylic phase and an alkyd phase. However, after the film-forming process, the surfactant used to stabilize these latexes remains in the film, and its location can have a drastic effec...

La caractérisation des propriétés mécaniques de composites cimentaires minces renforcés par des fibres de verre a été réalisée par l'intermédiaire de deux types d'essais de traction : un chargement simple à rupture et un essai de fissuration sur éprouvettes entaillées. Deux types de fibres de verre et trois longueurs ( L_f = 6, 12, 24 mm)...

The magnetostriction of a soft matrix, nonmagnetic, randomly filled by ferromagnetic particles is measured and calculated. Dipolar forces between particles have been calculated using a simple model of particles with the same permanent magnetic moment. Forces are injected in an FEM software to evaluate the strain of the composite. The longitudinal s...

This study is concerned with the improvement of interfacial adhesion in polystyrene – carbon nanotubes composites by grafting polystyrene chains onto the nanotube surface. Based upon a previously described method (Fragneaud B, Masenelli-Varlot K, Gonzalez-Montiel A, Terrones M, Cavaille JY. Efficient coating of N-doped carbon nanotubes with polysty...

Thermoplastic elastomers (TPEs) are block copolymers made up of “hard” (glassy or crystalline) and “soft” (rubbery) blocks that self-organize into “domain” structures at a length scale of a few tens of nanometers. Under typical processing conditions, TPEs also develop a “polydomain” structure at the micron level that is similar to that of metal pol...

The relationships between the microstructure and the fracture behavior of three polymer/clay nanocomposites were studied. Two different polymer matrices were chosen, namely polyamide-6 and polyethylene (compatibilized with PE-g-MA or PE-g-PEo), to reach very different clay dispersion states. The microstructure was characterized in terms of polymer...

Polymer grafting of polystyrene (PS) on nitrogen-doped multiwall carbon nanotubes (CNx) was successfully obtained by a "grafting from" technique. The production method involves the immobilization of initiators, using wet chemistry, onto the nanotube surface, followed by an in situ surface-initiated polymerization. The polymer-grafting carbon nanotu...

We describe the fabrication of nanocomposites and study their electrical properties using two different types of polymers: polystyrene (PS) and poly(butadiene-co-styrene) (PSBS), in conjunction with N-doped multi-walled carbon nanotubes (CNx MWNTs). The N-doped tubes were embedded in the polymer matrix in two ways: as produced and PS-grafted using...

Montmorillonite and other lamellar materials are very promising for reinforcing semicrystalline thermoplastics, especially if exfoliation is achieved. To understand the macroscopic properties of polymers filled with lamellar materials, it is unavoidable to characterize their structures. Parameters have to be determined such as the clay dispersion s...

Two different types of high aspect ratio flexible nanofibers, cellulose nanofibrils and carbon nanotubes, were dispersed in an amorphous thermoplastic polymer matrix. The mechanical and (in the case of carbon nanotubes filled composites) electrical properties of these composites were investigated. Dynamic mechanical analysis highlighted the influen...

Structure de double paroi mince avec isolation acoustique, caractérisée en ce que dans la cavité, située entre les deux plaques de la double paroi, est placé un matériau granulaire léger, dont les grains ne sont liés ni entre eux, ni auxdites plaques.

This article presents the mechanical behaviour of rigid polyurethane foams with relative density (ρf/ρs) above 0,3. The parameter taken into account is the density, which controls the foam architecture. The mechanical properties of the foams, characterised by large deformation compression tests and dynamic mechanical analyses, were compared to two...

This article presents the mechanical behaviour of rigid polyurethane reinforced by mineral fillers, for a density range (ρf/ρs) > 0.27. The influence of the particle size on the foam microstructure and its mechanical behaviour has been studied using calcium carbonate with two different sizes (with average diameter of 1 and 30 μm, respectively) and...

Nanocomposite films of isotactic polypropylene reinforced with cellulose whiskers highly dispersed with surfactant were prepared for the first time and compared with either bare or grafted aggregated whiskers. Films obtained by solvent casting from toluene were investigated by means of X-ray diffraction, differential scanning calorimetry, dynamic m...

A new modeling approach is presented to simulate direct current electrical conductivity in entangled fibrous networks. Isotropic three-dimensional structures, made up of high aspect ratio non-straight conductive fibers, are generated using a spline calculation; the corresponding volume conductivity is determined by integration using finite element...

In the present work, the large deformation behavior of high aspect ratio flexible nanofiber reinforced polymer composites is investigated. Simple or successive tensile tests are performed at room temperature, i.e. in the rubbery state. By studying two different types of fibers, namely cellulose nanofibrils and carbon nanotubes, with two processing...

We describe an efficient and novel route to graft covalently polystyrene (PS) on the external layers of nitrogen-doped multi-walled carbon nanotubes (CNx MWNTs) using atomic transfer radical polymerization (ATRP). The doped tubes did not require any acid treatment prior to the ATRP reaction. Samples were characterized using FTIR, thermogravimetric...

Polymer brushes consisting of polystyrene (PS) chains bonded covalently to N-doped multiwalled carbon nanotubes (CNx) were synthesized by a "grafting from" route using nitroxide mediated radical polymerization (NMRP).

New nanocomposite films were prepared with atactic polypropylene as the matrix and either of three types of cellulose whiskers, with various surface and dispersion characteristics, as the reinforcing phase: aggregated without surface modification, aggregated and grafted with maleated polypropylene or individualized and finely dispersed with a surfa...

This paper reports in situ measurements of electrical resistivity during mechanical solicitation of insulator-conductor composite. Electrical and mechanical behaviors will be discussed on 3 examples namely (i) unidirectional carbon fiber reinforced polymers (CFRP), (ii) stick-like whiskers reinforced soft thermoplastics and (iii) carbon nanotubes r...