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In this study, polymeric/metallic yarns were fabricated by using the micrometric copper multifilament and the polymer multifilament to create electrically conductive, thin, flexible composite yarn structures. The main aim is to realize the circuit board by using fabricated conductive yarns in the needle position of the embroidery machine and to integrate electronic components on textile structures by the soldering process. In the embroidery machine, the usage of the yarn in the needle gives a chance to create a tailored design according to the specified application. Mechanical and electrical properties of fabricated yarns were investigated. Meanwhile, a benchmark test has been done by using other commercial conductive yarns. Their embroidery performances were tested by investigating the possible harms during the stitching process. Finally, several embroidered circuit boards have been realized to show the versatility of fabricated yarns for different circuit designs.

Poly(vinylidene fluoride) (PVDF)-electrosprayed nanofibers have been the subject of much research due to their flexibility and piezoelectric properties compared to other piezoelectrics, for example, ceramics or other polymeric materials. The piezoelectric performance of PVDF is mainly related to the presence of β-phase. This study aims to determine the influence of working and formulation parameters on the generation of β-phase, morphology, and crystal structure of PVDF nanofibers. In addition, this research innovatively analyzes the effect of the dispersion state of PVDF molecular chains in the solvent on the electrospinning results. The morphology and crystal structure of PVDF nanofibers were determined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Beadless nanofibers are obtained when the PVDF concentration reaches the semi-diluted regime entangled in dimethylformamide (DMF) or DMF/acetone solution. The optimization of the process parameters (static collector, tip to collector distance—25 cm, flow rate—1 mL/h, applied voltage—20 kV) allows the increase in the β-phase fraction from 68.3% ± 1.2% to 94.5% ± 0.6% for a PVDF concentration of 25 w/v% in a DMF/acetone mixture (2/3 v/v). With these same parameters applied to a rotating collector, it was observed that the piezoelectric performance is at maximum for a maximum β-phase fraction of 90.6% ± 1.1%, obtained for a rotational speed of 200 rpm. The effect of orientation of PVDF nanofibers on piezoelectric properties was quantitatively discussed for the first time; the piezoelectric properties are independent of the alignment of the nanofibers.

International audience; The piezoelectric behavior of poly(vinylidene fluoride), PVDF, has been known for several decades and is clearly related to its crystalline phases. Many works made on films or fibers have focused on the characterization of the phase transitions during various PVDF processing and on its electromechanical activity by combining several techniques. Piezo-force microscopy (PFM) is an interesting tool to underline the crystalline forms and piezoelectricity efficiency of PVDF at the local scale. However, this technique is little used on samples in the form of fibers and in this case, it is most often nanofibers. In this work, two conventional PVDF textile filaments, with different weak draw ratio, are produced and analyzed by FTIR, XRD, and PFM. We demonstrate that the PFM analysis can be relevant for specimens presenting low signals during other characterizations. Therefore, the local piezo-/ferroelectricity into the fiber is highlighted underlining the existence of the polar phases of PVDF. Then, the effective piezoelectric coefficient d33 of PVDF fiber drawn with a ratio of 1.5 is estimated at 12 pm/V.

International audience; Poly(vinylidene fluoride) (PVDF) fibres used to develop sensors or energy harvesters have great potential in the sector of portable electronic devices and especially in the development of smart textiles. This polymorphic polymer is known for several years for its excellent piezoelectric properties related to its different crystalline phases and more particularly to the polar β-phase is the subject of studies dedicated to the development, optimization, and characteri

Smart and e-textiles have nowadays an important increasing place in the garment industry. The rise of embedded telecommunications, especially smartphones in our pocket, enables us to provide a power source and a wireless link for smart textiles. The main issue is to develop garments able to receive power from smartphones and communicate with them without flexibility and comfort constraints bound to embedded solid-state electronic components. Consequently, this article aims to develop a fully textile NFC combiner to transfer data and power between a smartphone and sensors without any electronic components. It precisely describes textile NFC multiple combiners composed of textile NFC antennas linked by two-wire transmission lines. Also, theoretical analysis, simulations, and experiments have been conducted to adapt the resonant frequency of such structures to the NFC technology (13.56 MHz). Finally, our article generalizes textile NFC combiner resonant frequency equations for multiple combiners with any number of antennas.

Biobased lignin represents one of the possible materials for next-generation flame retardant additives due to its sustainability, environmental benefits and comparable efficiency to other flame retardant (FR) additives. In this context, this study presents the development of FR polyamide 11 (PA11) multifilament yarns and fabric structures containing different industrial lignins (i.e., lignosulfonate lignin (LL), and Kraft lignin (KL)) and zinc phosphinate (ZnP). The combination of ZnP and lignin (KL or LL) at different weight ratios were used to prepare flame retarded PA11 blends by melt mixing using a twin-screw extruder. These blends were transformed into continuous multifilament yarns by the melt-spinning process even at a high concentration of additives as 20 wt%. The mechanical test results showed that the combination of KL and ZnP achieved higher strength and filaments showed regularity in structure as compared to the LL and ZnP filaments. Thermogravimetric (TG) analysis showed the incorporation of lignin induces the initial decomposition (T5%) at a lower temperature, at the same time, maximum decomposition (Tmax) shifts to a higher temperature region and a higher amount of char residue is reported at the end of the test. Further, the TGA-FTIR study revealed that the ternary blends (i.e., the combination of LL or KL, ZnP, and PA11) released mainly the phosphinate compound, hydrocarbon species, and a small amount of phosphinic acid during the initial decomposition stage (T5%), while hydrocarbons, carbonyls, and phenolic compounds along with CO2 are released during main decomposition stage (Tmax). The analysis of decomposition products suggests the stronger bonds formation in the condensed phase and the obtainment of a stable char layer. Cone calorimetry exploited to study the fire behavior on sheet samples (polymer bulk) showed an improvement in flame retardant properties with increasing lignin content in blends and most enhanced results were found when 10 wt% of LL and ZnP were combined such as a reduction in heat release rate (HRR) up to 64% and total heat release (THR) up to 22%. Besides, tests carried out on knitted fabric structure showed less influence on HRR and THR but the noticeable effect on postponing the time to ignition (TTI) and reduction in the maximum average rate of heat emission (MARHE) value during combustion.

International audience; In this article, it is shown how a smartphone can be used together with an e-textile structure, such as smart clothing, or any other smart home textile structure, smart composite, etc, to power it and to send and receive data generated by the e-textile by using the magnetic induction phenomenon through textile materials. This has been achieved using the NFC communication protocol and NFC compatible fully textile antennas without any electronic components such as resistors, inductors or capacitors. Our NFC antennas have been realized by embroidery and geometrical shapes using conductive threads. All the antennas realized have been tested to show their capacity to send the power and to send and receive data from sensors, in particular by testing their resonant frequencies, which are 13.7 MHz and 13.83 MHz, and their quality factor, which are 45 and 55, respectively. The approach used in this work facilitates the design and production of smart textiles and their reliability and washability, as they do not need any more to be equipped with power supplies such as batteries and data acquisition and interface cards, that are not laundering and cleaning friendly and are very difficult to be realized on flexible structures making them textile compatible. Therefore, we believe that in the future, a smartphone placed in specific locations in our clothing (pockets) equipped with our antennas will help the development and the market readiness of future generations of smart textile structures. The realized prototypes will enable to create a sensor network by acting as a current extension transmitting power and data.

This study investigates the thermal decomposition and fire behavior of zinc phosphinate (ZnP) in combination with low sulphonate content alkali lignin (LS) in a polyamide 11 (PA11) matrix. The influence of ZnP with LS on PA11 was assessed by using thermogravimetric analysis coupled with FTIR spectroscopy (TG-FTIR). Such decomposition products as hydrocarbons, amide and carbonyl units, phenolic and phosphinate compounds control the decomposition. The chemical structure of the condensed phase was evaluated by FTIR measurements carried out on the residues. The fire behavior was investigated using UL 94 vertical flame spread tests and cone calorimetry tests. In the ternary blends, the addition of LS promotes char formation as assessed by TG analyses; furthermore, ZnP contributes to flame inhibition mainly by radical trapping and partially by dilution of fuel, due to phosphinate ions and a small amount of phosphinic acid released in the gas phase. Besides, phosphate compounds are formed in the condensed phase. The combination of LS and ZnP enhanced flame-retardant properties due to the formation of a stable char layer with barrier features.

International audience; A split ring resonator (SRR) antenna integrated in textile by embroidery is reported. The antenna was designed and produced by targeting two goals. First, a size reduction of the antenna was achieved by means of an SRR. Secondly, the connection loss was reduced by using a copper wire dipole fixed by embroidery. On the basis of numerical simulations, three operating modes are evidenced depending on the individual resonance frequency either of the dipole or resonator-related. Especially, a balanced mode is confirmed by experiments with two resonances measured at 1.8 GHz and 2.2 GHz with a return loss greater than 31 dB. Finally, the textile antenna exhibits a radiation pattern similar to the radiation pattern of a dipole antenna.

In this study, two different types of industrial lignin (i.e., lignosulphonate lignin (LL) and kraft lignin (DL)) were exploited as charring agents with phosphorus-based flame retardants for polyamide 11 (PA11). The effect of lignins on the thermal stability and fire behavior of PA11 combined with phosphinate additives (namely, aluminum phosphinate (AlP) and zinc phosphinate (ZnP)) has been studied by thermogravimetric analysis (TGA), UL 94 vertical flame spread, and cone calorimetry tests. Various blends of flame retarded PA11 were prepared by melt process using a twin-screw extruder. Thermogravimetric analyses showed that the LL containing ternary blends are able to provide higher thermal stability, as well as a developed char residue. The decomposition of the phosphinates led to the formation of phosphate compounds in the condensed phase, which promotes the formation of a stable char. Flammability tests showed that LL/ZnP ternary blends were able to achieve self-extinction and V-1 classification, the other formulations showed a strong melt dripping and higher burning. In addition to this, cone calorimetry results showed that the most enhanced behavior was found when 10 wt % of LL and AlP were combined, which strongly reduced PHRR (&minus, 74%) and THR (&minus, 22%), due to the interaction between LL and AlP, which not only promotes char formation but also confers the stability to char in the condensed phase.

Bicomponent fibers were melt spun to investigate the effect of individual component viscosity on the cross section morphology. Two couples were tested, polypropylene MFI 18 (PP18) with polyamide 6 (PA6) and, polypropylene MFI 25 (PP25) with polyamide 6 (PA6). Viscosity versus shear rates was evaluated by both rotational and capillary rheometers to cover a large range of shear rates. Higher viscosity of PA6 compared to PP25 and PP18 at the theoretical shear rate resulted in the encapsulation of PA6 by PP25 and PP18 at the periphery of the bicomponent fiber cross section. Interfacial instability from the center to the periphery fiber was explained as a result of non-uniformity of shear rates across the fiber cross section. Interface shape dependency on the viscosity ratio of the two polymers has been clearly demonstrated: lower viscosity component wrapping around the higher viscosity one whatever the initial configuration, that is, side-by-side or segmented pie structure.

Microfibers can be obtained by bicomponent spinning, followed by subsequent mechanical splitting. During process, two materials are coextruded in a die to form a unique complex morphology. Many factors affect these morphologies: melt viscosity and difference of crystallization temperature combined with polymers position. Consequently, fiber splitting can be improved by choosing an association of polymers with a stable interface and a poor adhesion. The aim of this study is to understand which intrinsic parameters of polymers allow to enhance bicomponent fiber's splitting. Bicomponent fibers (side-by-side and sheath/core) have been made with two grades of polypropylene and polyamide 6. Instable interface happens when a low-viscosity polymer flows around and encapsulates a high-viscosity material. Possible mechanism responsible of interface deformation is variation of shear rates through the morphology (highest shear rate is at the fiber periphery). DMA analysis reveals that fiber with polyamide as core exceeds the strength of fiber with polyamide as sheath. This increase of strength can be attributed to a better adhesion than fibers with PA6 in sheath. From experimental results, the position combined with the difference crystallization temperature shows poor or strong interface.

We present a new class of wearable textile antenna and analyse their performances through an electrical study. The developed prototypes have been realized by an embroidery process and are made of conductive twisted copper/polyester yarns on a cotton substrate. These antennas aim to transfer power and data thanks to the NFC technology, so the operating frequency is 13.56MHz and the maximal reading distance is around 10cm. The strong resistance of the yarn (4.20Ω/m) make us overlap three yarns to reach satisfactory electrical characteristics. Antennas are composed of a textile plan circular coil to which we add a usual capacitor. The study of coils electrical characteristics highlights a linear evolution of coil resistance and inductance in function of embroidery geometrical parameters. Also, these data show the feasibility of such antennas, especially through quality factor values reaching 45.

With a final view to prototyping a textile energy harvesting system, piezoelectric textile structures based on 100% poly(vinylidene fluoride) (PVDF) were developed and characterized. Multifilaments of 246 tex were produced by melt spinning. The mechanical stretching during the process provides PVDF fibers with an optimal β-phase ratio (97%). Some studies have already been carried out on piezoelectric PVDF-based structures as films or textiles. The goal of the study is the investigation of the differences between 2D and 3D woven fabrics structures from piezoelectric PVDF multifilament yarns. The textile structures were poled after the weaving process, and a maximum output voltage of 2.3 V was observed on an angle - through-the-thickness interlock (interlock 3D structure) under compression by DMA tests. Energy harvesting is optimized in a 3D interlock thanks to the stresses of the multifilaments in the thickness. This finding has led to the design of an inner sole prototype from a knitting structure and another structure with piezoelectric fibers outside the plane of the fabric. The prototype is able to harvest energy and the results are consistent with the measurement realized with DMA under dynamic compression close to walking.

International audience; A multiresonant split ring resonator (SRR) composed of two circular-shaped meandered strips is presented. Resonances are first analyzed by means of eigenmodes computation and field mapping. It is shown that a resonance can emerge from a standing wave taking place in each slot produced by a meandered strip. A slot operates as a two-wire transmission line section short-circuited at one termination and loaded by an open-circuit at the other end. Consecutively, a resonance occurs approximately when a quarter-wavelength matches the length of the slot. A resonance frequency shift is observed, and it is related to a transverse magnetic coupling between a first antisymmetric mode and a second symmetric mode. Finally, multiple resonances in an SRR are experimentally evidenced by spectroscopy of the input impedance of an SRR resonator antenna. Experimental results are favorably compared with simulation.

International audience; Textile metamaterials produced by a weaving of metallic and dielectric yarns are considered for filtering operations in the sub-millimeter hand. A woven metamaterial was designed by parametric simulations aimed at producing a high-pass filter with a cutoff frequency at around 500 GHz above a high-reflective band and a strong rejection. The woven metamaterial is analyzed by means of an equivalent circuit formed by two resonant impedances, which are responsible of the rejection and high-pass features. A textile metamaterial was produced by an automatic weaving loom in a semi-industrial environment and it was electromagnetically characterized in free space. Experimental results are in good agreement compared with simulation and a phase-advance in transmission is evidenced. The phase of the reflection coefficient is also experimentally investigated thanks to a de-embedding process using a double-sided reflective mirror as a reference. Finally, the equivalent circuit of the fabricated textile is computed from the complex experimental reflection and transmission coefficients.

This study investigates the influence of various lignins and their content on the thermal stability and fire retardancy of biobased polyamide 11 (PA). Microcomposites based on PA and containing 5, 10, 15, and 20 wt % different lignins were prepared with a twin-screw extruder. Morphological analysis showed good interfacial interaction and uniform distribution of lignin particles within the resulting microcomposites. Further, thermogravimetric analyses carried out in inert atmosphere indicated that, unlike kraft lignin, which is able to give rise to the formation of lower char residue (41–48 wt % at 600 °C), the sulfonated counterpart provides a higher thermal stability as well as a higher char residue (55–58 wt %). Furthermore, vertical flame spread tests clearly showed that 15 wt % is the optimum of kraft or sulfonated lignin loading to achieve improved flame retardant properties and a V1 rating. In addition, a cone calorimeter was exploited to study forced combustion behavior; in particular the microcomp...

Microencapsulated flame retardant, bisphenol-A bis (diphenyl phosphate) (BDP), with a silane shell was prepared by sol–gel process with the goal of incorporating them in polymeric matrices by melt blending to improve the flame retardancy of isotactic polypropylene (iPP) and polyethylene terephtalate (PET). The influence of the loading content on thermal transitions has been studied by differential scanning calorimetry (DSC), the thermal stability of the polymer/microcapsules composites has been assessed by thermogravimetric analysis (TGA) and cone calorimetry has been used to study the fire reaction. It was noticed that the microcapsules have a limited influence on the thermal transitions of iPP matrix, but a decrease of the melting and glass transition temperatures was detected for the PET microcomposites. TGA results showed that the addition of microcapsules could improve char formation of the PET systems both in nitrogen and in air atmospheres, whereas only a small improvement of the thermal stability was detected in oxidative atmosphere for the iPP samples. Furthermore, cone calorimeter experiments show that the incorporation of microcapsules in the iPP gives almost no improvement in the iPP fire reaction. However, the microcapsules act as flame retardant in PET reducing the heat release rate during the combustion and the total heat evolved. Therefore, microcapsules can act as a char promoter agent to enhance the fire resistance in the case of PET.

We investigate the blow up points of the one--dimensional parabolic Burgers' equation $$\partial_t u=\partial_x^2 u-u\partial_xu+u^p $$ under a dissipative dynamical boundary condition $\sigma \partial_t u+\partial_\nu u=0$ for one bump initial data. A numerical example of a solution pertaining exactly two bumps stemming from its initial data is presented. Moreover, we discuss the growth order of the $L^\infty$--norm of the solutions when approaching the blow up time.

Using bio-based polymers to replace of polymers from petrochemicals in the manufacture of textile fibers is a possible way to improve sustainable development for the textile industry. Polylactic acid (PLA) is one of the available bio-based polymers. One way to improve the fire behavior of this bio-based polymer is to add an intumescent formulation mainly composed of acid and carbon sources. In order to optimize the amount of bio-based product in the final material composition, lignin from wood waste was selected as the carbon source. Different formulations of and/or ammonium polyphosphate (AP) were prepared by melt extrusion and then hot-pressed into sheets. The thermal properties (thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC)) and fire properties (UL-94) were measured. The spinnability of the various composites was evaluated. The mechanical properties and physical aspect (microscopy) of PLA multifilaments with lignin (LK) were checked. A PLA multifilament with up to 10 wt % of intumescent formulation was processed, and the fire behavior of PLA fabrics with lignin/AP formulation was studied by cone calorimeter.

There is a growing interest in the supply of autonomous electronic devices, particularly in the field of smart textiles. Energy harvesting is considered as a clean and renewable alternative technology to reach this objective. One of the methods explored is scavenging the energy from ambient mechanical vibrations by using piezoelectric materials. Due to textile requirements, the development of PVDF based fibers appears to be an interesting solution. However, the amount of its β crystalline form should be as high as possible. PVDF/clay components (modified or unmodified clay as well as organic modifier) containing up to 5 wt % additive are prepared by melt spinning. FTIR and XRD experiments show that the most important factor for obtaining high levels of β crystalline form is to increase the drawing ratio. The results indicate also that an organic modifier (quaternary ammonium salt) influences the crystalline forms and leads to a high ratio of β phases. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43244.

A microencapsulated flame retardant with a melamine-formaldehyde shell was prepared by in situ polymerization, then incorporated into an iPP matrix with a coupling agent to manufacture multifilament yarns by melt spinning. The influence of the post-treatment on the resulted microcapsules with an alcoholic solution was also studied. The spinnability of these formulations based on the interface characterization from contact angle measurements, tensile test and thermal characterizations was explored to determine the maximum draw ratio (DR) to apply. Finally, knitted fabrics were processed from multifilaments, and their flame-retardant properties were evaluated by performing fire tests according to the FMVSS 302 and Din 4102 part B experiments. The different mechanical and thermal behaviors were discussed in terms of the influence of the DR and the post-treatment applied on fibers during the spinning process and during the recovery of the microcapsules, respectively. The results showed that it was possible to obtain multifilament yarns with a DR of 4, but the best properties were obtained with a DR of 3 and for un-treated microcapsules. Furthermore, the samples containing un-treated microcapsules reach a B rating at the FMVSS test with a fast flame progression and a very low duration of burning. Copyright © 2012 John Wiley & Sons, Ltd.

We consider the generalized Burgers' equation \begin{eqnarray*} \left\{ \begin{array}{ll} \partial_t u = \partial_x^2u - u \partial_x u + u^p - \lambda u &\textrm{ in } \overline{\Omega} \textrm{ for } t>0, \\ \mathcal{B}(u)=0 & \textrm{ on } \partial \Omega \textrm{ for } t>0, \\ u(\cdot,0) = \varphi \geq 0 & \textrm{ in } \overline{\Omega}, \end{array} \right. \end{eqnarray*} with $p>1$, $\lambda \in \mathbb{R}$, $\Omega$ a subdomain of $\mathbb{R}$, and where $\mathcal{B}(u)=0$ denotes some boundary conditions. First, using some phase plane arguments, we study the existence of stationary solutions under the Dirichlet or the Neumann boundary conditions and prove a bifurcation depending on the parameter $\lambda$. Then, we compare positive solutions of the parabolic equation with appropriate stationary solutions to prove that global existence can occur when $\mathcal{B}(u)=0$ stands for the Dirichlet, the Neumann or the dissipative dynamical boundary conditions $\sigma \partial_t u + \partial _\nu u=0$. Finally, for many boundary conditions, global existence and blow up phenomena for solutions of the nonlinear parabolic problem in an unbounded domain $\Omega$ are investigated by using some standard super-solutions and some weighted $L^1-$norms.

Whether for health reasons or for comfort, the reduction of noise in our living spaces is a crucial issue. Nowadays, porous materials such as polyurethane foams or glass wool are still widely used to reduce the noise levels emitted in the fields of building and transport. However, these materials show a certain number of limits. Beyond the general renewed interest in the use of natural materials, some materials such as bast fibers show performance often unknown and unexploited, particularly in the acoustic and vibration field. This paper focus in particular on the potential of thin nonwoven fibrous materials (less than 10 mm) with a mono or bilayer structure and made from natural vegetable fibers (scutched flax tow, cottonized flax, hemp, kenaf and recycled jute), bonded with a thermoplastic fiber which is polypropylene in our case. In this study, the differences of performance between the selected vegetable fibers as well as the interest of the hydroentangled (spunlaced) nonwovens compared to needlepunched nonwovens are pointed out. The interest of bilayer structures is also highlighted.

Polypropylene and polypropylene grafted maleic anhydride based composites with modified and non-modified carbon nanotubes and sepiolite were prepared by melt extrusion. Their thermal, rheological, and dynamic mechanical properties were evaluated. Multifilament yarns were obtained from the composites by spin-drawing process and their mechanical properties were measured. Knitted fabrics from the multifilament yarns were characterized by cone calorimetry. The best interaction was obtained for polypropylene/carbon nanotubes and polypropylene/polypropylene grafted maleic anhydride/sepiolite composites, as was confirmed by the increasing on the elastic modulus and thermal resistance. Nanofillers changed the thermal decomposition profiles compared to bare polypropylene. Knitted structures containing sepiolite decrease the maximum of heat release rate in comparison with unfilled samples.

Piezoelectric textile structures based on 100% poly(vinylidene fluoride) (PVDF) were developed and characterised. Multifilaments of 246 tex were produced by melt spinning. The mechanical stretching during the process provides PVDF fibres with a piezoelectric β-phase of up to 97% has been measured by FTIR experiments. Several studies have been carried out on piezoelectric PVDF-based flexible structures (films or textiles), the aim of the study being the investigation of the differences between 2D and 3D woven fabrics from 100% optimised (by optimising piezoelectric crystalline phase) piezoelectric PVDF multifilament yarns. The textile structures were poled after the weaving process, and a maximum output voltage of 2.3 V was observed on 3D woven under compression by DMA tests. Energy harvesting is optimised in a 3D interlock thanks to the stresses of the multifilaments in the thickness. The addition of a resistor makes it possible to measure energy of 10.5 μJ.m−2 during 10 cycles of stress in compression of 5 s each.

Polypropylene filled with 10 wt% of inorganic nanoparticles has been prepared by melt blending. The fillers investigated were manganese oxides (MnO and Mn 2 O 3 ) and manganese oxalate (MnC 2 O 4 ). The morphology and thermal stability of these nanocomposites have been studied by transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The experimental results reveal that the addition of 10 wt% manganese oxides improves the thermal stability in air of polypropylene by about 70–80 °C. In a second step, these nanocomposites have been processed by melt spinning in order to produce multifilament yarn. The mechanical properties of these filaments have then been characterized. It is shown that just the addition of Mn 2 O 3 improves the mechanical properties of polypropylene filaments. The flammability of these nanocomposites used as knitted fabrics has finally been evaluated with a mass loss calorimeter at 35 kW/m 2 . This kind of experiment has not revealed a real improvement of fire properties.

The efficiency of new phosphinates, in combination with melamine cyanurate, was studied using different polypropylene textile structures. The influence of different ratios up to a total amount of 6 wt% in the polypropylene fiber was investigated using the limiting oxygen index (LOI) and cone calorimeter method for research purposes, while the performances were correlated to the standards FMVSS 302 (Federal Motor Vehicle Safety Standards) and DIN 4102-l (Deutsches Institut für Normung) used more specifically for automotive and building sector.

Due to the increasing consideration in nanotechnology during the past decade, numerous studies were undertaken in improving the flame retardancy properties of natural, artificial and synthetic fibers as well as fabrics by applying nanocomposite approach. This chapter considers key issues concerning traditional and novel approaches or processes to develop nanocomposites coating, nanocoatings on textile as well as the incorporation of nanoparticles into fibers. The incorporation of nanocomposite to form flame retardant coatings onto the surface of textiles or to functionalize fibers by melt spinning which can be subsequently woven or knitted are mainly related for application fields required high performance such as automotive, protective clothing, etc.

This study investigates new intumescent formulations based on lignin and phosphinates to improve the flame retardant properties of Polyamide 11, while preserving the bio-based characteristics of this latter. Lignin has the advantage of being a bio-based compound and can be effectively used as carbon source for the design of intumescent systems in combination with other flame retardant additives. Metal phosphinates belong to a novel class of phosphorus flame retardants. Despite their increasing use, there is lack of scientific understanding as far as their fire retardancy mechanism is considered, especially in char forming polymeric materials. In this context, Polyamide 11 was melt blended with lignin and metal phosphinates. The possibility of melt spinning the prepared blends were assessed through melt flow index (MFI) tests; thermogravimetric (TG) analyses and cone calorimetry tests were exploited for investigating the thermal stability and the combustion behaviour of the obtained products, respectively. MFI results indicate that some formulations are suitable for melt spinning processes to generate flame retardant multifilament. Furthermore, the combination of lignin and phosphinates provides charring properties to polyamide 11. Finally, cone calorimetry data confirmed that the designed intumescent formulations could remarkably reduce PHRR through formation of protective char layer, hence slowing down the combustion process.

A first study focused on the realization of a 100% Polyvinylidene fluoride woven fabric. The multi-filaments produced by melt spinning and studied by FTIR, X-Ray and DSC, were optimized in the β-phase, 97%, thanks drawing ratio of λ=5, and the processing temperature, 90°C. When the polar β-phase achieves a certain level in PVDF, the woven material is poling with fields up to about 6kV. DMA tests coupled to a Keithley voltmeter allow the solicitation of PVDF fabrics. A variation of voltage is obtained in compression, with a maximum output voltage of up to 2,3V. The other part of the study explains premises of a tricomponent fibre development, PEHD/PVDF/PA12. Two layers of conductive polymers acting as electrodes are placed on either side of the PVDF layer. The interfacial adhesion between the three different layers is analysed by SEM. The maximum stretch on melt spinning was fixed at 2.5 and the β-phase of the PVDF measured by X-Ray.

This study deals with the development of a large woven metamaterial surface for applications in the submillimeter frequency band. Before weaving, design of the metamaterial textile is investigated to obtain a phase-advance near 500 GHz. Then, a large sample is produced by semi-industrial machine and characterized in terms of dimensional homogeneity and electromagnetic behaviours in the frequency band [325 – 700 GHz]. Dimensional heterogeneity is measured to be less than 2% and shows that weaving process is well controlled. A phase-advance and high-pass filter behaviors are experimentally evidenced by electromagnetic characterizations with potential applications for selective shielding and phase manipulation of the wave.

We are interested in the existence of travelling waves for the Benjamin-Bona-Mahony equation on a network. First we construct an explicit wave, defined in $\mathbb{R}$. Then, we use this wave to derive some conditions on the coefficients appearing in the equations and on the geometry of the network to ensure the existence of travelling waves on the network., Comment: 18 pages, 7 figures

Transmission with phase advance is experimentally evidenced in a woven metasurface made of metallic wires and dielectric yarns. Similar to the negative refraction in metamaterials, phase advance is analyzed with a retrieval procedure of effective medium parameters. It is shown that a quasi-unitary transmission level can be achieved below the magnetic plasma frequency with a phase advance in a propagation regime for which both effective permittivity and permeability exhibit negative values. By stacking two metasurfaces with metallic wires woven in orthogonal directions, the phase advance is maintained and a polarization insensitive woven metamaterial is achieved.