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International audience; Standardless Energy dispersive spectroscopy (EDS) on polished samples of Portland cement clinker is routinely performed both for unhydrated phases as well as in cement pastes. Typically, the calcium to silica ratio is investigated. EDS analyses are highly dependent on the polishing quality of the sample. It is thus worth studying the Ca/Si ratios of cement phases in a clinker since they can be used as a reference. Indeed, alite (Ca3SiO5 or C3S in cement chemistry notation) and belite (Ca2SiO4 or C2S) should have an atomic Ca/Si ratio of 3 and 2, respectively. EDS carried out under the scanning electron microscope (SEM) is routinely used on polished samples to assess the composition of such phases. In the present study, Ca/Si ratios are investigated on a commercial clinker polished at various steps (6, 3, 1 and 0.25 µm diamond pastes, 0.05 µm alumina). All along the polishing process, ratios are coherent with theoretical ones and with the reference ones obtained by electron probe microanalysis (EMPA) in the present study.

International audience; Dairy fouling is a ubiquitous problem in food processing, however, the fouling mechanism is not fully understood and investigations arose mainly from experiments with model systems that contained only whey proteins, typically reconstituted from whey protein isolate powder (WPI). The effect of casein on fouling has been rarely considered despite it is the major component of milk proteins. To fill this gap, whey protein-based model fluids containing different casein concentrations and fixed content of added calcium were prepared, leading to various Casein/WPI mass ratios. The effect of Casein/WPI on β-lactoglobulin (BLG) denaturation at molecular level and subsequent fouling behavior in the pilot-scale plate heat exchanger during pasteurization treatment was investigated. It was shown that Casein/WPI significantly affects the fouling behavior: at low Casein/WPI, fouling mass dropped dramatically until a minimum value was reached located at Casein/WPI of 0.2. While at higher Casein/ WPI, fouling mass increased with elevated Casein/WPI. Element mapping of the fouling layer also reveals that different structures and fouling mechanisms occur depending on Casein/WPI ratio. Finally, it was established that contrary to WPI solutions, BLG thermal denaturation is poorly correlated to decrease/extent of fouling for casein protein-based solutions showing that the presence of casein deeply modifies mineral and protein interactions and fouling build-up.

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.

International audience; Radiative heat transfer dominates in medium- to large-scale fires, with infrared ray absorption causing the rapid ignition of combustible materials. In an attempt to hinder this phenomenon, low-emissivity coatings consisting of an aluminum layer topped by alumina have been deposited on polypropylene (PP) and polyamide 6 (PA6) substrates by pulsed DC magnetron sputtering. Emissivity measurements have confirmed the decrease in the emissivity of both surfaces. The samples were tested with a mass loss cone (MLC) calorimeter at 50 kW/m(2) to mimic the radiative thermal constraint of the last stages of a developing fire. The evolution of the temperature was monitored by a thermocouple to confirm the radiative barrier effect. With this setup, it was evidenced that the presence of low-emissivity coatings reduced the heat absorption, effectively increasing the time to ignition of both substrates. Indeed, coated PP ignited after 7 min, whereas a neat PP ignited in 1 min, and PA6 had a time to ignition of as long as 1 h, as opposed to the neat polymer igniting in only 75 s. However, the effect of the coating on flammability parameters such as the peak heat release rate (PkHRR) and the total heat release (THR) was found to be very low. To counterbalance this downside and to take advantage of the reduction of heat absorption, Al/Al2O3 coatings were deposited on PP and PA6 filled with thermally triggered fire-retardant additives, respectively, expandable graphite and a commercial mixture of melamine polyphosphate and aluminum diethylphosphate. Without surface treatment, the presence of the additives caused a shorter time to ignition, but a reduction in the PkHRR of similar to 50%. The combination of the Al/Al2O3 coating with flame retardants in the bulk led to both a long time to ignition and a reduction in the PkHRR and the THR under MLC testing.

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; Soot is one of the degradation products of material burning, having the fingerprints of the conditions in which it is formed. In this work, in-flame soot was probed from flaming combustion of balsa core and its sandwich composite at different heat flux scenarios during mass loss cone calorimeter tests. Soot probing was performed by thermophoresis. Electron microscopy was performed to analyze the size of the particulate media at multiscale. The size of the aggregates and the primary particles were found to be inherent to scenarios, i.e. materials specifications and heat flux rates. Nanoscale structure of in-flame soot was consistent with the results of thermogravimetric analysis of emitted-deposited soot. This semi-quantitative study contributes to soot observations in fire scenarios and constitutes the first application of soot probing by thermophoresis in a bench-scale fire scenario simulated by cone calorimetry. Technique shall be used in future to support emitted soot and smoke data.

International audience; A small-scale single burning item test has been developed to allow quicker, easier and less costly development studies of building materials presenting high performance. The test is fully described including the dimensions of the equipment, the procedure used to perform the test, but also the methodology used for the calibration of the heat release rate (HRR) and smoke production. To study the efficiency of the test, different rigid polyurethane and rigid polyisocyanurate foams, with and without flame retardants, are used as case studies and their fire behavior evaluated. The small-scale single burning item test allowed discriminating the different foams in terms of HRR and flame spread, but also in terms of FIGRA and SMOGRA index. It also permits an easy use of additional sensors (thermocouples) leading to a better understanding of the fire behavior. The results were compared to data obtained from the mass loss cone (ISO13927). The results in terms of HRR and smoke lead to similar conclusion but compared to mass loss cone, the small-scale single burning item test makes it possible to access the flame spread behavior of the materials, which is a crucial parameter and leads to an additional discrimination of the performance of the materials.

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.

Lowering fire hazard raised by combustible materials such as plastics may be achieved by the use of suitable flame retardant treatments, like fire protective coatings. However, exposure to long-term environmental conditions can cause loss of their functional properties, thus reducing their effectiveness over time. This is why two or three different layers with specific properties (e.g. adhesive, fire retardant and hydrophobic) are generally needed to provide durable fire retardancy. Effective and economical self-layering coatings can be developed to reduce the number of layers without compromising the advantages of the actual system. In this work, the efficiency of applying a silicone based coating to fire retard polycarbonate and the modification of the behaviors of the system, using a mixture of epoxy/silicone resins, a curing agent and either iron oxide or calcium carbonate as fire retardant filler is investigated. Self-stratification and fillers dispersion were evidenced by microscopic analyses coupled with chemical detection, the flame retardant properties using Limiting Oxygen Index (LOI), UL-94, Mass Loss Calorimetry (MLC), Thermogravimetric analyses (TGA) and a tubular furnace, and aging resistance by accelerated thermal, humidity and UV exposure. It appears that the selected fillers have no negative effect on the layering process when introduced from 2.5 to 10 vol.%: perfect stratification is obtained, with the silicone layer being the top layer. The best improvements in terms of fire retardant properties, adhesion and fillers dispersion were obtained by incorporating 2.5 vol.%: V0 rating at UL-94 and 33 and 35 vol.% at LOI with Fe2O3 and CaCO3 respectively were measured when a 200 μm wet thick coating was applied. The coating containing iron oxide was unaffected by weathering conditions. Finally, the application of those coatings on polycarbonate allows the formation of a protective barrier which limits substrate/flame mass transfers. It therefore results in (i) a delay of the time to ignition, (ii) the inhibition of the flame spread and of dripping when submitted to a flame, and (iii) a reduction of the combustibility of polycarbonate. A modification of the structure of the silica network formed by the particles which enhances the barrier effect of the silicone-based layer would be the most probable assumption to explain these excellent results.

International audience; Because of its widespread use in furniture upholstery, buildings, and transportation, the flame retardancy of flexible polyurethane foam is a matter of great concern. In an effort to impart fire resistance in an environmentally benign manner, hexagonal boron nitride (h-BN) nanosheets were dispersed by an aqueous route and deposited as a single bilayer with polyethylenimine (PEI) on flexible polyurethane foam by using layer-by-layer assembly. Butane torch exposure and cone calorimetry show that the nanocoating performs similarly to vermiculite clay (VMT), while in situ quantitative gas phase analysis reveals that carbon monoxide emissions are lower with h-BN. The PEI/h-BN system also maintains foam flexibility and protects against weathering, preventing yellowing. These combined properties make the use of h-BN nanoplatelets an interesting alternative for the protection of polyurethane foam (and perhaps other flammable substrates).

Epoxy-based intumescent coatings are effective solutions for protecting steel against fire. To design a successful product, it is, however, of primary importance to investigate its long-term durability. Some of these coatings do not resist accelerated aging conditions such as contact with salted water. One solution to overcome this drawback consists of applying a specific topcoat. In this work, various topcoats were applied on a model intumescent coating. Topcoats were shown to impact, under heating, the char expansion, char morphology, and char strength. The general trend is that the topcoats, before any aging exposure, improve the fire resistance behavior of the intumescent coatings. Most topcoats, however, do not limit penetration of salted water into the coating, thus affecting the intumescent properties. Only a silane-based topcoat was reported to trap or limit the diffusion of sodium and chlorine ions, thus protecting the underlying intumescent coating.

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.

Flexible polyurethane foam is one of the most versatile materials used in upholstered products; however, untreated polyurethane flexible foams are prone to rapid fire growth. In order to overcome issues encountered by the addition of flame retardant additives during the manufacturing process, the sol–gel process was evaluated to make flexible polyurethane foams flame retardant. Various formulations using different catalysts and monomers were prepared and deposited on flexible polyurethane foams by an impregnation process. Coating morphology was assessed by scanning electron microscopy analyses to optimize the formulation and to obtain a homogenous crack-free coating. Flame retardant properties were measured by mass loss calorimeter and UL 94, and thermal degradation was evaluated by thermogravimetric analysis. Chemical and structural analyses were carried out using attenuated total reflectance Fourier transformed infra-red spectroscopy and electron probe microanalysis. It appears that when a mixture of an appropriate ratio of 3-amino propyl triethoxysilane and diethyl phosphate is prepared in association with tetraethoxysilicate and methyltriethoxysilicate and deposited on flexible polyurethane foam, the coating shows an intumescent behavior when exposed to a flame. The foam also self-extinguishes after 30 seconds of flame application during UL94 test and a 60% reduction of the peak of heat release rate is obtained under mass loss calorimeter conditions.

The electron probe microanalyzer is a device often used in the field of geology or in the glass and steel industries. However, it is barely known or used in the polymer field. Thus, in this paper, we investigate the use of electron probe microanalyzer for polymer microanalyses and compared it with a scanning electron microscope equipped with an energy dispersive spectrometer. To show the unique potential of this technique only develop in our lab for polymer application, three different samples were studied: (i) a fire protective epoxy-based coating submitted to aging in salt water, (ii) the distribution of organometallic catalysts into a thermal isolative silicone polymer, and (iii) the fouling growth of milk protein (biopolymer) on a stainless steel surface. Compared to an energy dispersive spectrometer, with an electron probe microanalyzer it is possible to quickly create X-ray mappings of low concentration elements at a good resolution, as well as allowing the interpretation of the mechanism of action for the three samples which was impossible using only an energy dispersive spectrometer because of its too low detection resolution. Copyright © 2015 John Wiley & Sons, Ltd.

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; Heat-induced fouling is a financial and environmental burden for food and dairy industries and its control is therefore desperately needed. A better understanding of the fouling mechanisms and their relation to stainless steel surface properties is thus of considerable interest. This work aims at studying the impact of stainless steel's surface morphology and surface free energy on fouling by a model dairy solution by a close examination of the deposit's growth and adhesion at the substrate-fluid interface. Pristine model surfaces of controlled roughness and surface energy, i.e. native, mirror polished and biomimetic femtosecond laser textured stainless steel surfaces, fluorosilanized or not, were tested under isothermal conditions in a pilot pasteurization facility fed with a model dairy fluid (whey protein and calcium solution). Multi-scale characterizations of those surfaces before and after fouling, using a wide range of analytical tools (goniometry, SEM, ToF-SIMS, EPMA X-Ray mappings) allowed for a better comprehension of the impact of surface energy and morphology modifications on the fouling behavior while highlighting their complex interactions in fouling governance. Lower surface energy was shown to be an asset against deposit growth, as fluorosilanization of native stainless steel allowed to reduce fouling by 72% (wt.%). The relative sizes of surface relief versus fouling agents has been found crucial, as it impacts interlocking phenomena. Textured surfaces have shown a tremendous increase in fouling (+391% for textured, +86% for fluorosilanized textured). However, interesting fouling performances were obtained on smooth, hydrophobic surfaces, as a reduction by 83% of fouling weight was achieved with fluorosilanized polished samples. Crown Copyright (C) 2018 Published by Elsevier Ltd. All rights reserved.

International audience; Dairy industries are burdened by fouling phenomena that increase costs and environmental impacts of thermal processes. One remedial solution could be to replace stainless-steel equipment by other materials less prone to fouling. This work studied the fouling behaviour and hygienic features of two hydrophobic and non-polar commercial graphite-based composites (Graphilor (R) XC and XTH) that were exposed to isothermal whey protein fouling in an industrial pasteurisation unit and to foodborne pathogenic bacterial strains, namely Staphylococcus aureus, Listeria monocytogenes and Salmonella enterica. Both composites exhibited impressive fouling-release properties: a simple 20 min water rinse was enough to remove all dairy deposit after 1.5 h of pasteurisation, as opposed to usual heavy clean-in-place procedures. The composites also showed a significant effect on bacterial adhesion, exhibiting lower cell counts than stainless-steel surfaces. These results suggest that graphite-based materials might successfully replace stainless steel as equipment material to reduce fouling in dairy fouling industries.

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.

A classical Schiff base N,N′-bis(4-hydroxysalicylidene)ethylenediamine (L2), a member of the Salen group that has been introduced as a non-phosphorus and non-halogen flame retardant in thermoplastic polyurethane (TPU) is found to operate in an intriguing way to fire retard the material. L2 blended with TPU significantly improves the inherent flammability of TPU without a synergist. A plausible mechanism including intermediates in the reinforcement of this elastomer towards flame retardancy is elaborated in line with the char forming abilities of this β-resorcylaldehyde based Schiff base. Conclusions were drawn based on the input from thermal, spectroscopic, microscopic and operando spectroscopic techniques. While its un-substituted counterpart, N,N′-bis(salicylidene)ethylenediamine (L1) lags behind in performance, its structural isomer N,N′-bis(5-hydroxysalicylidene)ethylenediamine (L3) is equally efficient but exhibits another mechanism of action. The performance of L2-TPU is found to be mainly in a condensed phase and is due to decoding of intrinsic cross-linking ability of the key building block of the additive i.e. resorcinol via structural transformation over a range of temperature. This results in the methylene bridged phenolic resin type material having high temperature stability. The process is also found to interfere with TPU unzipping process delaying its thermal degradation and favoring extensive cross-linking promoting char formation with insulative properties.

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.

Self-stratifying coatings are promising coating systems based on incompatible polymer blends which can produce polymer/polymer laminate. A complex multi-layer or gradient coating structure is formed from one single coat, providing an undercoat and finishing coating. The preferential distribution of concentration through the film thickness greatly eliminates the interfacial adhesion failure without compromising the advantages of a multi-layer system, and thus favors an industrial eco-efficient process. Powder, waterborne and solventborne coating systems are able to stratify: the most well-known and effective systems are described in this review. Finally, this concept constitutes a great possible versatile process for a broad range of applications and could thus favor the development of new products, taking into account the reduction of solvent and labor cost

The self-stratification is an eco-efficient process since it reduces solvent emission, time of implementation and labor cost. Moreover it could lead to the development of a large range of new products for extensive application fields. For self-stratification to occur, liquid coatings must contain at least two incompatible resins, giving rise in “one pot” to a two-phases mixture after the formation of the solid film. In this work, an innovative self-stratifying coating, based on an epoxy/silicone blend, has been developed and applied on a plastic substrate (Polycarbonate). The perfect self-stratification of this system was evidenced by microscopic analysis coupled with X-ray mappings. The influence of solvents and a curing agent on the stratification process has been investigated. It is shown that the system diluted in butylacetate:xylene (at a 1:1 ratio) leads to the best stratification pattern, with the silicone phase located on the top of the coating. Three pigments (red iron oxide, calcium carbonate and zinc phosphate) were also incorporated in this epoxy/silicone system. They do not affect stratification, whereas visual appearance and adhesion are strongly dependent on the phase in which pigments are dispersed, as well as on the solvent used.

Nowadays, before setting up an industrial process, special attention has to be paid to its environmental footprint. This new way of thinking allows evaluating the hotspots so as to propose solutions to conceive more eco-friendly processes. Thus, the coating industry is increasingly preoccupied by the environmental impacts of newly designed paints. That is why innovation tries to take into consideration both the formulation composition and the application and drying methods. Following a Life Cycle Assessment (LCA) approach, the present study aims to compare the environmental impacts of self-stratifying coatings (with three process steps), either oil-based or bio-based, to those of an oil-based multilayered coating (with six process steps). The concept of the self-stratifying coating is to bring the primer, the intermediate and the top coat properties together in a one-pot formulation to produce a multi-functional coating through a less laborious process. The total environmental impact of each process can be characterized by four main categories of impacts: Climate Change Human Health (CCHH), Human Toxicity (HT), Climate Change Ecosystem (CCE) and Fossil Depletion (FD), which together represent approximately 86% of the global impact for each system. The results obtained show that the self-stratifying oil-based coating process is more energy efficient compared to the currently used multilayered oil-based coating process, with a 15% decrease of CCHH, HT and CCE indicators and a 14% decrease of FD indicator, corresponding to a 13.6% decrease of the total environmental impact. However, as this decrease was lower than expected, particular attention was then paid to the chemicals used (resins, solvents) and to the process conditions. The substitution of the oil-based epoxy resin by a bio-based one and the use of less harmful solvents allow reducing the total environmental impact by 32.4% compared to the multilayered oil-based system (with 30% decrease of CCHH indicator, 50% of HT indicator, 31% of CCE indicator and 34% of FD indicator). In a global way, electricity consumption control and the nature of chemicals used were reported to contribute in a significant way to the improvement of the process environmental impact.

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 aim of this work was to prepare a nonwoven polypropylene (PP) textile functionalized with bioactive molecules in order to improve simultaneously anticoagulation and antibacterial properties. The immobilization of either heparin (anticoagulation agent) or gentamicin (aminoglycoside class antibiotic) alone has already been proven to be effective on PP nonwoven textiles. In this work, we managed to go further, by immobilizing both heparin and gentamicin at the same time on one unique textile. A successive immersion in different heparin and gentamicin bathes successfully led to a dual drug coated textile, as confirmed by several characterization techniques (Fourier transform infrared-attenuated total reflectance, X-ray photoelectron spectroscopy, and scanning electron microscopy). The immobilization times were varied in order to determine the best compromise between cytocompatibility, anticoagulant effect, and antimicrobial activity. Short immersion times in gentamicin solutions confer very good antimicrobial activity to the textile and avoid cytotoxicity, whereas long immersion times in heparin solution were necessary to observe a significant anticoagulant effect.

The fire performance of a curable-silicone based coatings containing expandable graphite (EG) and an organoclay is evaluated in hydrocarbon fire scenario (standard UL1709) using a lab-scale furnace test. It is shown that the use of organoclay allows achieving better performance. The influence of the clay as additional filler is investigated on the fire performance and on the mechanical properties of the char. It is shown that the clay increases significantly the mechanical properties of the char and hence, the fire performance of the silicone based coating. In a next part, the silicone/clay material was characterized by electron microscopy, wide-angle X-ray scattering and solid state 29 Si nuclear magnetic resonance (NMR). It evidences the nanodispersion of the clay into the silicone matrix and two main interactions: (i) intercalation of some silicate layers and (ii) chemical reactions between the hydroxyl groups of the clay and the silicone matrix. Finally, X-ray fluorescence of the residue after fire testing shows the organoclay is present uniformly throughout the thickness of the char, due to the previous interaction, and hence increasing the cohesion of the char.

The fire performance of two curable-silicone based coatings containing 25% expandable graphite (EG) are evaluated in hydrocarbon fire scenario (standard UL1709) using a lab-scale furnace test. In this paper, the influence of the catalyst on the fire performance are investigated. Two organometallic titanium based- and tin based catalyst are used to make the curable silicone crosslink. When titanium based catalyst is used, the fire performance are higher and the mechanical properties of the char is better than that when tin is used as catalyst. To explain this surprising different fire behavior, the two residues after the furnace test were analyzed by X-ray photospectroscopy. It has been demonstrated that in the case of titanium based catalyst, the char is composed of graphite embedded by crosslinked silicone structure compare to linear silicone structure in the case of tin based catalyst. The two silicone resins were characterized by Fourier Transform Infrared spectroscopy, 29Si NMR, thermogravimetric analyses, EPMA (electron probe microanalyses). It was highlighted that the tin migrates into the surface during the crosslinking of the matrix leading to a low thermal stability and, thus, low fire performances. Whereas, when titanium based catalyst is used, it participates to the silicone network with the formation of Si–O–Ti bounds increasing the thermal stability of the matrix and so enhancing the fire performance of the silicone/EG based coating.

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.

The self-stratifying approach is a one step process allowing the formation of a complex laminated coating structure at the surface of plastics or other substrates, combining optimized surface and adhesion properties. These coatings have already been developed for various application fields but have never been considered for fire retardant purposes, whatever the substrate involved. In this work, the self-layering concept has been used to make polycarbonate fire retardant, using a mixture of epoxy and fluoropolymer resins, and iron oxide as flame retardant additive (10 wt%). Self-stratification was evidenced by microscopic analyses. The flame retardant properties were evaluated according to Limiting Oxygen Index (LOI), UL-94 and Mass Loss Calorimetry (MLC). Weathering resistance by accelerated UV, thermal and humidity exposure was also considered. In the first part, the effect of solvent on the self-layering process was investigated. It was shown that the system diluted in a blend of butylacetate : xylene (1 : 1 ratio) exhibits a perfect stratification and excellent adhesion onto polycarbonate. In such a system, an outstanding improvement of the fire retardant properties (V0 rating at UL-94 and 32 vol% at LOI), unaffected by weathering (both UV and temperature/humidity exposure), was observed when a 200 μm wet thick coating was applied. The coating allows the formation of a protective barrier and the presence of metal particles avoids dripping and promotes a charring effect.

International audience; Three different accelerated ageing scenarios were applied on flame retarded polylactic acid (FR-PLA). The influence of (i) Temperature and UV-light exposure (T/UV), (ii) Temperature and relative humidity exposure (T/RH) and (iii) combined Temperature, UV-light and relative humidity (T/UV/RH) exposure on (i) the morphology, (ii) the physico-chemical properties and (iii) the fire performances of FR-PLA were evaluated. The influence of FR fillers (melamine, ammonium polyphosphate and organomodified montmorillonite) as well as the associated mechanisms of degradation (i.e. photo-degradation under T/UV, hydrolysis under T/RH and a combination of both phenomena under T/UV/RH) were explained. The flame retardant properties of FR-PLA before and after ageing were compared using Limiting Oxygen Index (LOI) and Mass Loss Calorimetry (MLC). It was reported that FR-PLA aged under T/UV/RH conditions is more degraded compared to FR-PLA exposed to T/RH or T/UV. Surprisingly, the FR properties are enhanced after ageing, even if the degradation of the samples is observed.

International audience; Fouling is a widespread and costly issue, faced by all food-processing industries. Particularly, in the dairy sector, where thermal treatments are mandatory to ensure product safety, heat-induced fouling represents up to 80% of the total production costs. Significant environmental impacts, due the massive consumption of water and energy, are also to deplore. Fouling control solutions are thus desperately needed, as they would lead to substantial financial gains as well as tremendous progress toward eco-responsible processes. This work aims at presenting a novel and very promising dairy fouling-mitigation strategy, inspired by nature, and to test its antifouling performances in real industrial conditions. Slippery liquid-infused surfaces were successfully designed directly on food grade stainless steel, via femtosecond laser ablation, followed by fluorosilanization and impregnation with an inert perfluorinated oil. Resulting hydrophobic surfaces (water contact angle of 112 degrees) exhibited an extremely slippery nature (contact angle hysteresis of 0.6 degrees). Outstanding fouling-release performances were obtained for these liquid-infused surfaces as absolutely no trace of dairy deposit was found after 90 min of pasteurization test in pilot-scale equipment followed by a short water rinse.

Lignin is an abundant polyphenol biopolymeric material. Lignin was phosphorylated thanks to the presence of reactive hydroxyl groups in its structure. A detailed characterization allowed us to prove that phosphate groups are covalently bonded to the lignin's structure. The thermal stability of lignin was improved with the presence of phosphorus and was evaluated at 3% w/w. The thermal decomposition of lignin was deeply investigated through gas and condensed phases analyzes. The phosphorus was found to promote dehydration and decarboxylation reactions, thus increasing the amount of carbonaceous residue which was more stable at high temperature. The combustibility of lignin was also lowered when phosphorylated. Finally, even if half of the initial amount was released in the gas phase, the phosphorus mainly acts in the condensed phase by forming different species, which prevents the residue from oxidation.

Intumescent coatings, mainly composed of ammonium polyphosphate, pentaerythritol and melamine, are widely used in the field of fire protection of steel structures. The objective of this study was to investigate how the presence of two different inorganic fillers (titanium dioxide and mineral fibres) will affect the fire performance of an acrylic-based intumescent coating. In both cases, it was observed that the inorganic filler enabled improvement of the fire-protective behaviour of intumescent paints, maintaining their performance for a longer time. The mode of action was attributed to reinforcement of the char due to the presence of the fillers.

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

Layer-by-layer (LbL) assembly of nanocoatings on fabric substrates has been very successful in terms of reduction of flammability. In particular, an LbL system comprised ammonium polyphosphate as the polyanion and chitosan as the polycation, applied to cotton fabric, dramatically reduced cotton flammability. At this point, the fire-retardant (FR) mechanism of action of this system has never been fully elucidated. Sonicated and nonsonicated coated cotton fabrics were evaluated using a vertical flame test and mass loss calorimeter. Coating morphology was investigated before and after burning. Thermal analyses and chemical analyses in the condensed phase (and in the gas phase) were conducted to reveal the FR mechanism of action. At the cotton surface, a combination of both condensed (formation of aromatic char) and gas phase (release of water and highly flammable gases) mechanisms impart the FR behavior, promoting a kind of “microintumescence” phenomenon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43783.