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International audience; Additive manufacturing is a powerful tool to design materials with original properties. An innovative design of poly (Ethylene Vinyl Acetate) (EVA) containing 30 wt.-% of Aluminum TriHydroxide (ATH) was reported in a previous paper and liquids (water or potassium carbonate aqueous solution) were incorporated in the 3D printed structure. These multi-materials showing interesting properties, but stability, control and processing of these liquid-containing systems were an issue due to porosity of the polymeric matrix. To overcome this issue, the use of hydrogels is considered in this study: being either solid or highly viscous, hydrogels can retain water in the design, despite the high porosity of the EVA/ATH matrix. In this paper, the liquid phase was substituted by flame retardant hydrogels (based on agar, alginate or poly (vinyl alcohol) - PVA), containing in particular vermiculite platelets and for the hydrogel based on alginate, K2CO3 as flame retardant fillers. Excellent behavior under a 50 kW/m2 heat flux during a cone calorimeter test was obtained, with fast extinguishment of the flame and a low peak of Heat Release Rate (pHRR) and Total Heat Release (THR). The physical barrier formed by vermiculite platelets during the test, as well as the condensed phase mechanism of K2CO3 were found to be responsible for these excellent results, as found by confocal microscopy observations, electron probe micro analysis and X-Ray diffraction experiments.

This work aims at presenting and comparing the antifouling and antibacterial behaviour of three biomimetic surfaces targeting dairy fouling reduction, namely atmospheric plasma-sprayed silane-based thin films, lubricated slippery surfaces and femtosecond laser textured lotus-like surfaces. Fouling tests were conducted on a pilot-scale pasteurization plant fed with a model whey protein and calcium foulant solution and tested samples were placed in isothermal holding-like conditions. Detailed characterizations of the substrates before and after fouling test allowed connecting their surface properties to their antifouling performances. The best result was obtained with the nano-rough plasma coatings which led to a substantial fouling reduction for two consecutive pasteurisation runs. These surfaces were subsequently tested towards bacterial adhesion with three different foodborne pathogenic strains, again demonstrating better performances than bare stainless steel.

International audience; This paper reports the synthesis of novel hybrid poly(lactic acid) by use of a titanium oxo-cluster, acting both as a catalyst and crosslinking agent of the polymer matrix. The already reported oxo-cluster Ti16O16(OEt)32 ([Ti]16) was synthesized and screened at the lab-scale as catalyst for the bulk polymerization of L-lactide (L-LA). [Ti]16 was found to be highly active for this reaction as up to 90% conversion in 30 min was obtained, affording PLLAs with Mn up to 65 000 g·mol−1 and relatively narrow dispersities (1.2–1.6). These polymerization reactions were further transposed to reactive extrusion process in which [Ti]16 oxo-cluster kept its high activity, affording hybrid-PLLA materials with Mn close to 58 000 g·mol−1 (some PLLAs could not be dissolved). Electronic microprobe analysis of the resulting hybrid materials confirmed that the titanium oxo-cluster was well dispersed all over the PLLA matrix. Finally, it was shown that the hybrid PLLA containing [Ti]16 display superior dimensional stability under heat than commercial PLLA of same molar mass.

Whatever the dairy derived fluids that are heat processed, many studies have demonstrated the key role of beta-lactoglobulin (β-lg) denaturation in the initiation of a dairy fouling and mentioned that interactions between β-lg, phosphate and calcium ions are essential in fouling growth. However only few authors have reported the influence of the phosphate/calcium molar ratio on fouling mechanisms. To partly fill this gap, various whey protein solutions (composed mainly of β-lg) having different phosphate:calcium molar ratios were prepared by rehydrating a whey protein isolate powder and by adding calcium chloride and various amounts of soluble inorganic phosphate (noted Pi). Fouling experiments were carried out at pilot scale using a plate heat exchanger (PHE) at a fixed temperature profile and the deposited mass per channel was measured. Finally, the chemical composition and structure of the proteinaceous fouling layer were observed using an Electron Probe Micro Analyser. Results clearly demonstrated that the phosphate:calcium molar ratio modified the deposit structure and influenced substantially the amount of fouling. These results suggest that the relative proportion of calcium phosphate and calcium ions governs the mechanism of fouling build-up and also sets, to a certain extent, the fouling ability of the whey protein solutions.

Lignin is an abundant polyphenol biopolymeric material. Due to its aromatic structure it develops a char under fire conditions. Lignin was used as flame retardant in acrylonitrile-butadiene-styrene (ABS). Enhancement of flame retardancy was observed, and the lignin was then phosphorylated to achieve highest performance. For the first time, characterization of FR phosphorylated lignin (P-LIG) was undertaken in detail. Grafting phosphorus onto lignin significantly increases the amount of residue from the polymer blend at high temperature. At 30 wt.%, P-LIG is well dispersed in ABS and leads to a significant reduction of the peak of heat release rate. It is shown that P-LIG promotes char formation by reacting with ABS during thermal decomposition. The char is therefore more cohesive and acts as a protective layer, such that less fuel from ABS degradation is released to the flame. Thus phosphorylated lignin is as a promising bio-based flame retardant for ABS.

Effect of accelerated ageing on neat and flame retarded (FR) polylactide (PLA) has been investigated. The influence of temperature and relative humidity on (i) the visual aspect, (ii) the fire performances, (iii) the molecular mass and (iv) the thermal properties of the formulations has been evaluated. The flame retardant (FR) properties of samples before and after ageing were compared using Limiting Oxygen Index (LOI) and Mass Loss Calorimetry (MLC). It was reported that degradation of PLA, mainly driven by hydrolysis phenomenon, is accelerated in presence of FR fillers (melamine and ammonium polyphosphate). This is even more pronounced when an organomodified montmorillonite is added. However the FR properties are enhanced after ageing due to the physicochemical of the flame retarded materials (e.g. migration of the flame retardants, decrease of the molecular mass…).

The aim of this work was to study the photocatalytic degradation of Methylene Blue and phenol by nano-particles coated on diatomite as a new nano-composite catalyst. Titanium dioxide (Degussa P25) was immobilized on diatomite powder at different compositions by a very simple and low cost technique. Diatomite powder (also called Kieselguhr) is an Algerian substance with a snow-white color and porosity greater than 72%. High porosity allowed the diatomite powder to float on the surface of water providing a means for the treatment process that enabled separation from water without any need for pumping as well as the exposure to solar radiation when supported beneath titanium dioxide (TiO2) during photocatalysis. The morphology characterization of the prepared catalysts was carried out by X-ray diffraction analysis, scanning electron microscopy and infrared spectroscopy (IR). Photocatalytic activity was initially tested in a single reactor followed by pH, conductivity and absorbance analyses. Photocat...

International audience; Self-stratification is an innovative one-step process used to design multi-functional coatings gathering simultaneously in a one-pot formulation the primer, the intermediate layer and the top coat properties. Many selfstratifying coatings contain oil-based epoxy resins but the literature is scarce in the development of “greener” solutions. In this work, silicone resins and bio-based epoxy resins were dissolved in various solvent blends, applied on a composite substrate and cured under different conditions to obtain stratified coatings. To reach aperfect stratification, the influence of various parameters including (i) the surface tension and the polarity of the resins, (ii) the solvents volatility, (iii) the curing temperature and (iv) the reactivity of the epoxy/amine reaction was studied by a systematic approach. In accordance with the literature, it was demonstrated that a large difference in surface energy and polarity favors resins separation. The volatility of the solvent blend was also shown to be a key factor in the stratification process. However, the predominant parameter, rarely taken into account, isthe curing temperature, which impacts the cross-linking reaction of the epoxy resin. The increase in molecular weight (MW) of epoxy resins due to the cross-linking reaction favors the incompatibility between resins by increasing the difference in MW between epoxy and silicone resins. Thus, optimization of process conditions allowed the design of perfectly stratified bio-based epoxy/silicone coatings. The mechanism of film stratification was also elucidated thanks to in-situ analyses.

International audience; This work aims at studying the impact of silane-based coatings, generated by atmospheric pressure plasma spraying (APPS) of a liquid precursor (hexamethydisiloxane – HMDSO), on dairy antifouling and antibacterial properties of food-grade 316L stainless steel. The influence of the manufacturing parameters (precursor flow rate, nozzle-to-substrate distance and scanning speed) on the coatings properties was investigated using a wide range of characterization techniques (drop shape analysis, X-Ray Mappings, Scanning Electron Microscopy, Fourier-Transformed Infrared Spectroscopy, Atomic Force Microscopy). Coating’s roughness in particular was shown to strongly increase when precursor flow rate increases. A pilot pasteurizer, fed with a model foulant solution (whey protein and calcium), allowed performing two consecutive industrial-like isothermal dairy fouling tests, revealing the promising anti-fouling properties of the HMDSO-coated steel. A fouling reduction of up to 90% compared to bare stainless steel was achieved after first cycle for all samples. The second fouling run allowed to select the best-performing sample, which kept the same antifouling properties as in the first test. Its mechanism of action was investigated, which revealed that a nanostructured, Si-O-Si rich surface was efficient to prevent isothermal dairy fouling. The adhesion of the pathogenic bacterium Staphylococcus aureus also proved to be impacted by this plasma coating, with a significant decrease of adhered cells (−30% compared to native stainless steel).

This paper aims at developing an innovative approach to characterize the char residue of an intumescent coating obtained after a UL1709 furnace test. The intumescent formulation is based on an epoxy resin and contains numerous additives including zinc borate, ammonium polyphosphate and silicate fibers. The purpose is to characterize the numerous reactions that can occur upon burning using crossed methods including Electron Probe Micro-Analysis (EPMA), X-ray diffraction (XRD) and 1D/2D solid state Nuclear Magnetic Resonance (NMR). In particular, it emphasizes the potential of the advanced NMR technique namely two-dimensional Dipolar Heteronuclear Multiple Quantum Correlation (2D D-HMQC) NMR. As a result, EPMA evidenced that B/P and B/Si are located in the same domain suggesting the formation of boron-phosphorus and/or boron-silicone containing compounds on the sample surface. H3BO3 was identified by XRD as a main crystalline specie, additional species (e.g. SiO2, Zn4O(BO2)6) were also identified. The borate, silicate and phosphate chemical species were then characterized using 1D NMR but no definitive assignments could be given. To specify those assignments, 2D D-HMQC NMR was performed and the formation of amorphous borophosphates and borosilicates was evidenced emphasizing the chemical reactivity between the ingredients of the formulation. It was suggested that these species allow reinforcing the char and improving the fire protective properties of the coatings. This work highlights the particular interest of advanced NMR technique, which provides unique information on the characterization of intumescent char.

A new, efficient and fast process was developed to coat poly(ethylene terephthalate) (PET) fabrics with acrylic acid (AA) and this novel eco-friendly material was designed to be used as a filtration medium for complexing heavy metals from aqueous media. PET is impregnated with acrylic acid, and directly polymerized using a KrF excimer laser. The conditions of irradiation were optimized using the experimental design technique: a 40 mm × 3.5 mm surface was irradiated per pulse, and 24 mJ/cm 2 and 700 pulses were necessary to obtain a good coating without degrading the textile structure. For industrial purpose, these conditions were extended to treat larger surfaces (40 mm × 11.5 mm pulse) using a fluence of 24 mJ/cm 2 and 700 pulses. Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) were carried out to characterize the functionalized surfaces. A thick coating, resistant to low-temperature-washing was obtained. Finally, the efficiency of this coated textile was evaluated with copper sulfate solutions: 0.131 mg copper was trapped per cm 2 of PET, which is a promising result.

This paper investigates the flame retardant (FR) mechanism of action of a flexible PU foam, flame retarded with a sol-gel coating made of a mixture of tetraethoxysilane (TEOS), methyl triethoxysilane (MTES), 3-amino propyl triethoxysilane (APTES) and diethyl phosphite (DEP) in an ethanol/water solution. To build a mechanism of action, the coating as well as the residues obtained after fire testing were analyzed using solid state nuclear magnetic resonance (NMR), rheology, thermogravimetric analyses coupled with infrared detection (TGA-FTIR), microcalorimetry of combustion (MCC), smoke box and Pyrolysis Gas chromatography coupled with mass spectrometry (Py-GCMS). The coating shows an intumescent behavior upon burning exhibiting significant expansion and bubbling. The expansion occurs in two steps: a first step around 190 °C, related to the release of ethanol, and a second one around 380 °C, related to the release of non-degraded DEP, ammonia and propylene during degradation of the PU matrix. The flame retardant effect occurs (i) in the condensed phase by intumescence, which yields a thermal insulating layer made of a SiO2 and Si-O-P network mixed with orthophosphate at the surface of the PU foam, but also (ii) in the gas phase by the release of non-degraded DEP, which acts as free radical scavenger. The coating allows the protection of the underlying PU foam during burning as well as the reduction of the amount of smoke released.

Understanding the mechanism of whey protein fouling along a plate heat exchanger is a challenging issue in the dairy industry. The influence of the calcium/protein molar ratio on β-lactoglobulin (β-LG) denaturation and its consequence both on fouling mass along the plate heat exchanger and the structure of the fouling layer were studied. The experimental design was defined by varying the calcium/protein molar ratio from 2.3 to 22.9 and fixing the total concentration of calcium at 100 ppm. Results established that both the β-LG denaturation rate constants and the distribution of fouling in the plate heat exchanger were strongly impacted by the calcium/protein molar ratio. Structural analysis provided evidence that the fouling layer evolved from a thin and dense structure at low calcium/protein molar ratio towards a thicker and more open structure at higher calcium/protein molar ratio.

International audience; In this report, indium-tin-oxide (ITO)-layer extraction from end-of-life (EOL) Liquid Crystal Displays (LCDs) was discussed by sulfuric acid leaching with simultaneous application of ultrasonication on the ITO-side of glass/ITO panels, exhibiting various dimensions. Applying this technique presents several advantages compared to the traditional leaching process such as fast and controllable kinetics, high extraction yield of indium and tin, selective recovery of these two metals possible, and the opportunity to recycle the neat glass separately avoiding additional separation processes. ITO-dissolution kinetics from EOL LCD panels were investigated as function of leaching time and acidity of sulfuric acid. At a temperature of 60°C, a nearly quantitative indium yield was obtained using an acid concentration of 18 mol/L by simultaneous application of ultrasonication, whereas only 70 % were recovered in the absence of ultrasound. Results from ICP-AES agreed well with SEM/BSE observations demonstrating the high efficiency of the ultrasound assisted process since only 3-4 min were required to obtain maximum ITO recovery.

Pasteurization of dairy products is plagued by fouling, which induces significant economic, environmental and microbiological safety concerns. Herein, an amphiphilic silicone coating was evaluated for its efficacy against fouling by a model dairy fluid in a pilot pasteurizer and against foodborne bacterial adhesion. The coating was formed by modifying an RTV silicone with a PEO-silane amphiphile comprised of a PEO segment and flexible siloxane tether ([(EtO)3Si-(CH2)2-oligodimethylsiloxanem-block-(OCH2CH2)n-OCH3]). Contact angle analysis of the coating revealed that the PEO segments were able to migrate to the aqueous interface. The PEO-modified silicone coating applied to pretreated stainless steel was exceptionally resistant to fouling. After five cycles of pasteurization, these coated substrata were subjected to a standard clean-in-place process and exhibited a minor reduction in fouling resistance in subsequent tests. However, the lack of fouling prior to cleaning indicates that harsh cleaning is not necessary. PEO-modified silicone coatings also showed exceptional resistance to adhesion by foodborne pathogenic bacteria.

Flame retardancy of flexible polyurethane foams has become an issue due to very severe regulations. To overcome the challenge of incorporating flame retardant (FR) additives during the foaming process without altering the foam properties, a plasma surface treatment was used for the first time in this work: a cold plasma induced graft-polymerization of phosphonate containing precursors (diethylvinylphosphonate-DEVP) with or without a crosslinking agent (1,4 butanedioldiacrylate) was applied on open cell flexible polyurethane foams (PUF). The flame retardant properties of these foams, before and after further rinsing, were evaluated using horizontal UL-94 test for 10 s and 60 s. One of the tested systems (DEVP + crosslinker), even after sonication, completely stops the melt dripping of the foams when exposed to the flame of the butane torch and charring occurs. This efficient surface treatment was characterized before and after burning by Scanning Electron Microscopy (SEM), electron probe microanalysis (EPMA), 31P solid state NMR and X-ray Photoelectron Spectroscopy (XPS). Its FR mechanism of action was then further investigated using microscale combustion calorimetry (MCC), thermogravimetric analyses coupled with infrared Fourier transform spectroscopy (TGA-FTIR), pyrolysis gas-chromatography coupled with mass spectrometry (GC-MS pyrolysis) and 31P solid state NMR. The results obtained show that it is necessary (i) to use the crosslinking agent, as DEVP mainly reacts with this crosslinker and (ii) to activate the PU foam before graft-polymerization to promote further reaction with the crosslinker. The characterizations also proved that before sonication, non-reacted DEVP precursors mainly act in the gas phase, preventing ignition, whereas after sonication the covalently grafted phosphorus containing species mainly act in the condensed phase to form phosphonic acid which will promote charring and thus will limit dripping and flame spread.

Glass-fiber reinforced polyamide 66 is flame retarded with a mixture of melamine-poly(zinc phosphate), (Safire®400) and diethyl aluminium phosphinate. The performance of this synergistic combination of additives is multi-modal and a comprehensive investigation is undertaken to elucidate the underlying flame retardancy mechanism. The strategy was to characterize the different chemical species responsible for flame retardancy that are generated in gas and condensed phases under different fire scenarios. Following heat release rate (HRR) curve of flame retarded polyamide formulations obtained by mass loss calorimeter, samples in different stages of degradation are collected and investigated. Further flame retardants and formulations were degraded in tubular furnace whose temperature protocol relied on thermal degradation profile obtained from thermogravimetric analysis (TGA). In either case, species generated in condensed phase were studied by solid state nuclear magnetic resonance spectroscopy (magic angle spinning (MAS) NMR; 27Al, 31P and 13C), Fourier transform Infra-red spectroscopy (FTIR), X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and optical microscopy, whereas TGA coupled FTIR, and pyrolysis gas chromatography mass spectrometry (Py/GC/MS) were utilised to investigate species released in gas phase. Flame retardancy mechanism is elaborated based on the identification of the chemical species in both gas and condensed phases and their specific contributing role.

A higher analogue in the melamine polyphosphate family, melamine-poly(aluminium phosphate) (Safire®200), that has shown flame retardancy along with aluminium phosphinate in glass-fibre reinforced polyamide 66 was investigated to elucidate their mode of action. The mechanistic investigation is based on examining the chemical species formed in the condensed and gas phase under different fire scenarios. Samples at different stages of degradation were collected based on the heat release rate (HRR) curve of cone calorimetry and further analysed. Additionally, formulations and flame retardants were also pyrolysed at characteristic temperatures in a tubular furnace based on their thermogravimetric analysis (TGA) profile and investigated. A fire retardancy-quenching mechanism is mapped out on the basis of input from solid state nuclear magnetic resonance spectroscopy (MAS NMR; 27Al, 31P and 13C), Fourier transform Infra-red spectroscopy (FTIR), X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and optical microscopy on degraded samples. Gas phase analysis was studied by TGA coupled FTIR.

The present study assesses the formation of an interfacial oxide layer on aluminum alloys concomitant to the electrodeposition of an anaphoretic coating. The morphology, size, chemical composition and corrosion resistance properties are investigated for 2024-T3 clad aluminum substrate. The morphology and thickness of the oxide layer was examined using TEM. On the other hand, a ToF-SIMS method combining depth profiling and high resolution imaging has been developed as a new approach to determine simultaneously the chemical composition, the thickness and the homogeneity of the oxide layer. The results obtained with this method are validated through comparison with those from the TEM standard approach. Finally the two complementary methods have been used to investigate the growing mechanism of the oxide layer.

Functionalized polypropylene nonwoven (PP) geotextiles can be used as a new eco-friendly way to trap heavy metals in sediments. Chitosan was chosen as sorbent because of its ability to trap heavy metals, its natural origin (from shells) and its low cost. PP was first functionalized with acrylic acid using a low pressure cold plasma process, in order to bring reactive carboxylic functions onto the surface. Chitosan was then covalently grafted on the acrylic acid modified PP. The functionalized surfaces were characterized by Fourier Transform Infrared Spectroscopy–Attenuated Total Reflectance (FTIR–ATR) and X-ray Photoelectron Spectroscopy (XPS) and evidence of chitosan grafting was given. The ability of the functionalized geotextile to trap heavy metals was then investigated. Copper was chosen as a model heavy metal, and artificial solutions of CuSO 4 were prepared for the experiments. Sorption studies were carried out at 20 °C with Polypropylene-grafted-Acrylic acid-Chitosan (PP-g-AA-chitosan) varying the concentration of copper in polluted solutions to evaluate the maximum of adsorption of the surface: the textile can chelate copper increasingly as a function of the initial copper concentration until 830 ppm. At this concentration, it reaches a plateau at about 30 mg of trapped copper per gram of geotextile. The effects of pH and of the ionic strength (adsorption in a NaCl containing solution) were finally investigated. The trapping of Cu 2+ decreases slowly when the ionic strength increases. When there are 30 g/L NaCl in the artificial polluted solution (like in seawater), only 20 mg of Cu 2+ can be trapped per g of geotextile. Finally, the optimum pH to trap the maximum amount of copper was determined to be 4.8, which corresponds to the optimum pH for the chitosan solubility.

International audience; Particular coating compositions based on incompatible polymer blends can produce coatings having complex layered structures after film formation. The most traditional approaches to their structural modification are the introduction of additives (extenders, inorganic pigments, surface active agents, etc.). As minor additives, some are capable of substantially accelerating the phase separation process with a moderate or negligible influence on the composition equilibrium of solutions. In contrast, in order to be effective, some have to be introduced in significant amounts, thereby substantially changing the resulting distribution of components through the film. Up to now, most of the liquid additives that have been tested destabilized the solutions while impacting the layering process. In this work, two phosphorus based liquid fillers have been introduced (at 2.5 and 5 wt.%) in a partially incompatible polymer blend based on a silicone resin and a curable epoxy resin to fire retard a polycarbonate matrix. Self-stratification was evidenced by microscopic and chemical analyses, flammability by Limiting Oxygen Index (LOI) and UL-94 tests, fire performances by Mass Loss Calorimetry and thermal stability by using a tubular furnace and ThermoGravimetric Analysis. The ternary compositions including 5 wt.% of additives exhibit the best stratification and excellent adhesion onto polycarbonate. Improvements of the fire resistant properties were observed (+7% for the LOI compared to the virgin matrix) when a 200 µm wet thick coating was applied, due to reduced flame propagation and dripping.

In this work, we have investigated the intumescent behaviour of linear low-density polyethylene (LLDPE) containing calcium carbonate (chalk) treated by stearic acid. This system swells during burning and creates a protective layer when exposed to an external heat flux of 50 kW/m 2 in a mass loss calorimeter. This system has been fully characterized by FTIR, XRD, TGA and SEM. The carbonation/decarbonation temperatures, the swelling phenomenon and the effect of the thermal stress on the swelling have been examined. The residue is composed of a smooth surface made of chalk and CaO and a bulk of only chalk. Stearic acid allows a good dispersion of chalk particles into the LLDPE matrix, and contributes to form a cohesive network during burning when the thermal stress is high enough. A governing parameter of the intumescent effect is the particle size, which permits the formation of an insulating and cohesive mineral network during burning.

International audience; Using XRD, impedance spectroscopy, and XPS, it was shown that both Bi2Ru2O7 and Pb2Ru2O6.5, generally announced as attractive electrode materials for IT-SOFCs, chemically react with CGO. In addition, a never-mentioned time-instability under electrochemical measurements with YZS as electrolyte mediates the polarization tests. For Pb2Ru2O6.5, long time experiments (stabilization time > 900 h, previously to complementary electrochemical tests), yields strong increasing of the resistance polarization. Concerning Bi2Ru2O7, a partial transformation into Bi3Ru3O11 is observed after impedance measurements. The investigation of the Bi2−xMxRu2O7−δ (M = Sr, Pb) solid solutions was performed with the aim to improve the catalytic/electric properties. For low x values, it shows a time and chemical stabilization of the electrode/electrolyte cells, able to preserve high electrode performances of these materials. For higher substitution, the chemical/electrochemical instability reappears. According to our polarization measurements versus oxygen pressure and temperature in the so-called “stabilized” samples, the electrode performance appears limited by the diffusion of adsorbed oxygen on the triple point boundary. It is fully compatible with the metallic behavior checked in all the series.

Silk is one of the most desirable textile fibers due to its unprecedented flexibility, strength, and chemical resistance. Recent work has shown that ionic liquids possess great potential for dissolving and processing silk. Furthermore, ionic liquids have been shown to improve dispersion of nanoparticles throughout conventional polymer networks. In our current work, we have used imidazolium based ionic liquids to dissolve silk and disperse clay, carbon nanotubes, and chitin using film casting, wet spinning, and electrospinning techniques. The structural characteristics and morphology were determined using x-ray diffraction, Raman spectroscopy, laser scanning confocal microscopy, and scanning electron microscopy. Thermogravimetric analysis and differential scanning calorimetry were used to assess the potential benefits of adding nanocomposites to silk fibers and films. It was determined that carbon nanotubes offer the best potential for improving the thermal properties of silk.

Three different films, poly(acrylonitrile-co-methylacrylate)/single wall carbon nanotubes (PAN-MA/SWCNT), poly(acrylonitrile-co-methylacrylate)/carbon black (PAN-MA/CB) and pure functionalized SWCNT, are analyzed. The diffuse reflectance and transmittance of the films from 2 μm to 18 μm are characterized with an integrating-sphere Fourier transform spectrophotometer system. The SWCNT film shows high reflectance and low emissivity. Surface roughness characterization by laser scanning confocal microscopy confirms that the low emissivity is not due to a highly polished surface and is therefore more likely due to the metallic behavior of the SWCNTs. Characterization using infra red thermography highlighted the thermal protective behavior of the SWCNT film; the maximum temperature obtained from a 5.2 kW/m 2 heat flux exposure was 50 °C lower than that for the two (SWCNT, CB) PAN-MA based films.

A broad spectrum of applications of "Salen"-based Schiff bases tagged them as versatile multifunctional materials. However, their applicability is often bounded by a temperature threshold and, thus, they have rarely been used for high temperature applications. Our investigation of a classical Schiff base, N,N'-bis(4-hydroxysalicylidene)ethylenediamine (L2), reveals that it displays an intriguingly combative response to an elevated temperature/fire scenario. L2 resists and regulates thermal degradation by forming an ablative surface, and acts as a thermal shield. A polycondensation via covalent cross-linking, which forms a hyperbranched cross-linked resin is found to constitute the origin of the ablative surface. This is a unique example of a resin formation produced with a Schiff base, that mimicks the operational strategy of a high-heat resistant phenolic resin. Further applicability of L2, as a flame retardant, was tested in an engineering polymer, polyamide-6. It was found that it reinforces the polymer against fire risks by the formation of an intumescent coating. This paves the way for a new strategic avenue in safeguarding polymeric materials toward fire risks. Further, this material represents a promising start for thermal protective applications.

Considerable research has been conducted in improving the performance characteristics of nanocomposites, however, relatively few attempts have been made to address the thermal stability of nanocomposites. An attempt is being made to improve the thermal properties of nanocomposites by synthesizing imidazolium salts from 2-methyl imidazole and ion exchanging the salts with clay minerals. This study focuses on the role of the chemistry of imidazolium salt(s) used in functionalizing clay and processing conditions in the formulation of epoxy nanocomposites. The nanodispersion of clay in an epoxy matrix is evaluated qualitatively by X-ray diffraction (XRD), transmission electronic microscopy (TEM), and laser scanning confocal microscopy (LSCM). We demonstrate the use of LCSM for quantitative image analysis and to study the dispersion of clay layers, tagged with a fluorescent dye in the epoxy matrix. XRD and TEM results reveal that the hand mixed nanocomposite has tactoid morphology, while ultrasonicated organoclay (without hydroxyl group) epoxy nanocomposite exhibits a mixed morphology, and an ultrasonicated organoclay (with hydroxyl group) epoxy nanocomposite had well dispersed clay distribution in the epoxy matrix. Results from the three complimentary techniques enable the characterization of the clay platelets over several length scales ranging from the micrometer to the nanometer scale.

A simple nonaqueous sol−gel processing led to ionogels, resulting in the confinement of an ionic liquid within a silica-like network. In the case of a non-water-soluble ionic liquid, ionogels were made stable toward water immersion by the presence of hydrophobic methyl groups in the solid network. A set of ionogels with different ionic liquid content was studied by DSC and 1H NMR spectroscopy. The nanometric level of the confinement of the ionic liquid turned out to significantly modify the phase transitions, while still allowing some molecular mobility. Moreover, ionogels were found to keep the high conducting performances of the ionic liquid.

Summary: Laser-induced fluorescence spectroscopy of the optical probe Nile Blue A in polymer clay nanocomposites is described. Concentration quenching of the fluorescence dominates the probe behavior until the clay platelets are physically separated by polymer intercalation. Further separation into an exfoliated structure results in an intense increase in probe fluorescence. Preliminary results indicate the ability to discriminate between intercalated and exfoliated structures in nanocomposites formed by melt processing. Polyamide 6 nanocomposites: Purple, 1 minute processing (left). Red, 7 minute processing (right).

The microstructures of two dairy fouling deposits obtained at a stainless steel surface after different processing times in a pilot plate heat exchanger were investigated at different scales. Electron-Probe Micro Analysis, Time-of-Flight Secondary Ion Mass Spectrometry, Atomic Force Microscopy, and X-Ray Photoelectron Spectroscopy techniques were used for this purpose. The two model fouling solutions were made by rehydrating whey protein in water containing calcium or not. Results on samples collected after 2 h processing show that the microstructure of the fouling layers is completely different depending on calcium content: the layer is thin, smooth, and homogeneous in absence of calcium and on the contrary very thick and rough in presence of calcium. Analyses on substrates submitted to 1 min fouling reveal that fouling mechanisms are initiated by the deposit of unfolded proteins on the substrate and start immediately till the first seconds of exposure with no lag time. In presence of calcium, amorphous calcium carbonate nuclei are detected in addition to unfolded proteins at the interface, and it is shown that the protein precedes the deposit of calcium on the substrate. Moreover, it is evidenced that amorphous calcium carbonate particles are stabilized by the unfolded protein. They are thus more easily trapped in the steel roughnesses and contribute to accelerate the deposit buildup, offering due to their larger characteristic dimension more roughness and favorable conditions for the subsequent unfolded protein to depose. (C) 2013 Elsevier Inc. All rights reserved.

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Using XRD, impedance spectroscopy, and XPS, it was shown that both Bi2Ru2O7 and Pb2Ru2O6.5, generally announced as attractive electrode materials for IT-SOFCs, chemically react with CGO. In addition, a never-mentioned time-instability under electrochemical measurements with YZS as electrolyte mediates the polarization tests. For Pb2Ru2O6.5, long time experiments (stabilization time > 900 h, previously to complementary electrochemical tests), yields strong increasing of the resistance polarization. Concerning Bi2Ru2O7, a partial transformation into Bi3Ru3O11 is observed after impedance measurements. The investigation of the Bi2−xMxRu2O7−δ (M = Sr, Pb) solid solutions was performed with the aim to improve the catalytic/electric properties. For low x values, it shows a time and chemical stabilization of the electrode/electrolyte cells, able to preserve high electrode performances of these materials. For higher substitution, the chemical/electrochemical instability reappears. According to our polarization mea...

International audience; SnO2 translucent monolith ionogels were obtained by a sol-gel processing using bis(2-methylbutan-2-oxy)di(pentan-2,4-dionato)tin as a precursor in the presence of various ionic liquids: [BMI][Br], [BMI][TFSI], [BMI][BF4]. The confinement of ionic liquids within the gels was evidenced by Differential Scanning Calorimetry, FTIR and FT-Raman spectroscopy. The ionic liquids could be efficiently washed off, which resulted in supermicroporous solids. Calcination in air at 550 degrees C of the dried monoliths resulted in nanoporous nanocrystalline cassiterite tin dioxide particles with crystallite sizes of about 8-12 nm and mean pore sizes around 5 nm.

Layered double hydroxides (LDH) are a class of readily synthesizable layered crystals that can be used as an alternative to the commonly used silicate crystals for the preparation of polymeric nanocomposites. In this work layered double hydroxide/polyamide 6 nanocomposites (LDH/PA6) were prepared from organo-modified LDH by melt processing. The anionic exchange capacity of LDH was varied in order to investigate its influence on the degree of exfoliation. LDH were dispersed by a twin screw micro-extruder at a variety of processing conditions. The nanocomposites were characterized by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), transmission electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis. It was found that exfoliated nanocomposites were successfully prepared by melt processing with a low exchange capacity LDH, whereas residue tactoids were observed with a high exchange capacity LDH. Shear, together with the exchange capacity, seems to be the key factor for the delamination in LDH/PA6. No major change in the crystalline phase or in the rate of crystallization was observed in the nanocomposite as compared to the neat polymer. A reduction in the onset of thermal decomposition temperature was observed in PA6/LDH compared to neat PA6, likely due to a nucleophilic attack mechanism. The properties of this nanocomposite system are discussed with connections to the current understanding within the broader nanocomposite field.

In this work, the reaction to fire of polymer nanocomposites (thermoplastic polyurethane, polylactide and polyamide-6) containing different nanofillers (organoclay, polyhedral silsesquioxanes or POSS and carbon nanotube) is investigated. When high level of nanodispersion is achieved (shown by transmission electron microscopy (TEM)), they exhibit good flame retardancy in specific scenarii (high heat flux), but fail to flammability tests (LOI, UL-94). The mechanism of protection is the formation of mineral layer associated to char promotion but the protective coating is not efficient enough to provide the highest standard of protection. It is shown that this technology gives the best results combined with conventional flame retardants and leads to synergistic effects. The aspects of nanodispersion of the filler with the flame retardant are also fully commented in the paper using TEM and electron microprobe.