Microwaves; a promising solution for the in-melt elaboration of innovative materials

International audienceMicrowaves; a very promising solution for the in-melt elaboration of innovative materials. Kedafi Belkhir, Fréderic BecquartUniversité de Lyon, Ingénierie des Matériaux Polymères, UMR CNRS 5223, Université de Saint-Etienne, Jean Monnet, F-42023 Saint-Etienne, France Microwaves have gained a growing interest these last decades due to their ability to interact directly with materials having “good” dielectric properties i.e. polar or ionic systems. Then, microwave technology found major and very efficient applications in ceramics elaboration, drying and cooking in food industry. In chemistry and polymer chemistry, microwaves find more and more applications thanks to their direct wave-matter interaction leading to rapid heating and faster reactions. Their higher selectivity also favors reactions without solvent, with higher yields and limited side reactions. These promising advantages explain the dramatic growth of academic scientific production in chemistry and polymer chemistry under microwaves. [1]In polymer chemistry, microwaves are used for polymerization, chemical modification, grafting, depolymerization, pyrolysis and other processes. Both synthetic polymers, biosourced ones like polyesters and a majority of natural polymers from biomass are involved. This potential of application is very high and real with the additional possibilities to achieve reactions with less amounts of, or without, catalysts (atom economy) and lower energy consumption than the conventional conductive heating. Thus, microwaves are naturally an attractive way to face the current societal challenges. [2]However, one major counterpart exists, due to its selective interaction with the most polar bonds at the molecular scale in a reactive system, some heterogeneous heating with hot spots, may appear (Figure 1) [3]. So, we propose to present conceptually how it could be possible to take advantage from both this selectivity and this heterogeneity in the specific polymer reactive systems which could be biphasic. Biphasic polymer systems are very common in polymer blends or filled polymers, especially reactive systems are performed without solvent, at high temperature in the molten state and ideally under shear. In this way, microwaves offer the exclusive possibility to innovate in polymer science. Some concrete examples will illustrate the presented concepts. Figure 1. Microwave-generated hot spots in dispersed Pd/AC catalyst during Suzuki-Myaura reaction with different stirring rates.[1] A. Loupy; Microwave in Organic Synthesis; 2008;2nd Ed;WILEY-VCH[2] L. Zong et al. J. Microw. Power. Electromagn. Energy. 2003, 38, 49-74.[3] S. Horikoshi et al. Ind. Eng. Chem. Res. 2014, 53, 14941-14947

Microwaves; a promising solution for the in-melt elaboration of innovative materials

International audienceMicrowaves; a very promising solution for the in-melt elaboration of innovative materials. Kedafi Belkhir, Fréderic BecquartUniversité de Lyon, Ingénierie des Matériaux Polymères, UMR CNRS 5223, Université de Saint-Etienne, Jean Monnet, F-42023 Saint-Etienne, France Microwaves have gained a growing interest these last decades due to their ability to interact directly with materials having “good” dielectric properties i.e. polar or ionic systems. Then, microwave technology found major and very efficient applications in ceramics elaboration, drying and cooking in food industry. In chemistry and polymer chemistry, microwaves find more and more applications thanks to their direct wave-matter interaction leading to rapid heating and faster reactions. Their higher selectivity also favors reactions without solvent, with higher yields and limited side reactions. These promising advantages explain the dramatic growth of academic scientific production in chemistry and polymer chemistry under microwaves. [1]In polymer chemistry, microwaves are used for polymerization, chemical modification, grafting, depolymerization, pyrolysis and other processes. Both synthetic polymers, biosourced ones like polyesters and a majority of natural polymers from biomass are involved. This potential of application is very high and real with the additional possibilities to achieve reactions with less amounts of, or without, catalysts (atom economy) and lower energy consumption than the conventional conductive heating. Thus, microwaves are naturally an attractive way to face the current societal challenges. [2]However, one major counterpart exists, due to its selective interaction with the most polar bonds at the molecular scale in a reactive system, some heterogeneous heating with hot spots, may appear (Figure 1) [3]. So, we propose to present conceptually how it could be possible to take advantage from both this selectivity and this heterogeneity in the specific polymer reactive systems which could be biphasic. Biphasic polymer systems are very common in polymer blends or filled polymers, especially reactive systems are performed without solvent, at high temperature in the molten state and ideally under shear. In this way, microwaves offer the exclusive possibility to innovate in polymer science. Some concrete examples will illustrate the presented concepts. Figure 1. Microwave-generated hot spots in dispersed Pd/AC catalyst during Suzuki-Myaura reaction with different stirring rates.[1] A. Loupy; Microwave in Organic Synthesis; 2008;2nd Ed;WILEY-VCH[2] L. Zong et al. J. Microw. Power. Electromagn. Energy. 2003, 38, 49-74.[3] S. Horikoshi et al. Ind. Eng. Chem. Res. 2014, 53, 14941-14947

Microwaves; a promising solution for the in-melt elaboration of innovative materials

International audienceMicrowaves; a very promising solution for the in-melt elaboration of innovative materials. Kedafi Belkhir, Fréderic BecquartUniversité de Lyon, Ingénierie des Matériaux Polymères, UMR CNRS 5223, Université de Saint-Etienne, Jean Monnet, F-42023 Saint-Etienne, France Microwaves have gained a growing interest these last decades due to their ability to interact directly with materials having “good” dielectric properties i.e. polar or ionic systems. Then, microwave technology found major and very efficient applications in ceramics elaboration, drying and cooking in food industry. In chemistry and polymer chemistry, microwaves find more and more applications thanks to their direct wave-matter interaction leading to rapid heating and faster reactions. Their higher selectivity also favors reactions without solvent, with higher yields and limited side reactions. These promising advantages explain the dramatic growth of academic scientific production in chemistry and polymer chemistry under microwaves. [1]In polymer chemistry, microwaves are used for polymerization, chemical modification, grafting, depolymerization, pyrolysis and other processes. Both synthetic polymers, biosourced ones like polyesters and a majority of natural polymers from biomass are involved. This potential of application is very high and real with the additional possibilities to achieve reactions with less amounts of, or without, catalysts (atom economy) and lower energy consumption than the conventional conductive heating. Thus, microwaves are naturally an attractive way to face the current societal challenges. [2]However, one major counterpart exists, due to its selective interaction with the most polar bonds at the molecular scale in a reactive system, some heterogeneous heating with hot spots, may appear (Figure 1) [3]. So, we propose to present conceptually how it could be possible to take advantage from both this selectivity and this heterogeneity in the specific polymer reactive systems which could be biphasic. Biphasic polymer systems are very common in polymer blends or filled polymers, especially reactive systems are performed without solvent, at high temperature in the molten state and ideally under shear. In this way, microwaves offer the exclusive possibility to innovate in polymer science. Some concrete examples will illustrate the presented concepts. Figure 1. Microwave-generated hot spots in dispersed Pd/AC catalyst during Suzuki-Myaura reaction with different stirring rates.[1] A. Loupy; Microwave in Organic Synthesis; 2008;2nd Ed;WILEY-VCH[2] L. Zong et al. J. Microw. Power. Electromagn. Energy. 2003, 38, 49-74.[3] S. Horikoshi et al. Ind. Eng. Chem. Res. 2014, 53, 14941-14947

Méthode de dimensionnement des structures de chaussées : quelle(s) adaptabilité(s) pour les matériaux granulaires alternatifs ?

International audienceDans le cadre du développement durable, les enjeux de préservation des ressources naturelles non renouvelables et de protection de l'environnement conduisent à considérer à part entière les matières premières secondaires granulaires comme un gisement alternatif à l'utilisation des agrégats naturels, notamment en technique routière. La diffusion de ces matériaux alternatifs dans ce domaine reste fondamentalement dépendante de leur niveau de performance technico-environnementale, par référence à celui des matériaux standards classiquement utilisés. On s'intéresse spécifiquement dans ce papier aux critères mécaniques en lien avec le dimensionnement des structures de chaussées. Dans une démarche d'optimisation et de diffusion des granulaires alternatifs en technique routière, une prise en compte effective du comportement mécanique réel (et des sollicitations réelles par ailleurs) s'avère essentielle. Dans ce contexte, cette contribution concoure à démontrer, à l'appui d'une étude de sensibilité spécifique, la nécessité de disposer de modèles en fatigue propres aux matériaux alternatifs, identifiés expérimentalement et permettant de s'affranchir des hypothèses réductrices concernant l'association des paramètres mécaniques des matériaux standards aux granulaires alternatifs. L'étude de sensibilité sur les paramètres empiriques des modèles d'accumulation des déformations permanentes (spécifique aux graves naturelles non liées) et de fatigue (spécifique aux graves naturelles traitées au liant hydraulique) permet d'évaluer leurs influences sur les contraintes admissibles et sur les variations associées d'épaisseur de couche de la structure de chaussée

Méthode de dimensionnement des structures de chaussées : quelle(s) adaptabilité(s) pour les matériaux granulaires alternatifs ?

International audienceDans le cadre du développement durable, les enjeux de préservation des ressources naturelles non renouvelables et de protection de l'environnement conduisent à considérer à part entière les matières premières secondaires granulaires comme un gisement alternatif à l'utilisation des agrégats naturels, notamment en technique routière. La diffusion de ces matériaux alternatifs dans ce domaine reste fondamentalement dépendante de leur niveau de performance technico-environnementale, par référence à celui des matériaux standards classiquement utilisés. On s'intéresse spécifiquement dans ce papier aux critères mécaniques en lien avec le dimensionnement des structures de chaussées. Dans une démarche d'optimisation et de diffusion des granulaires alternatifs en technique routière, une prise en compte effective du comportement mécanique réel (et des sollicitations réelles par ailleurs) s'avère essentielle. Dans ce contexte, cette contribution concoure à démontrer, à l'appui d'une étude de sensibilité spécifique, la nécessité de disposer de modèles en fatigue propres aux matériaux alternatifs, identifiés expérimentalement et permettant de s'affranchir des hypothèses réductrices concernant l'association des paramètres mécaniques des matériaux standards aux granulaires alternatifs. L'étude de sensibilité sur les paramètres empiriques des modèles d'accumulation des déformations permanentes (spécifique aux graves naturelles non liées) et de fatigue (spécifique aux graves naturelles traitées au liant hydraulique) permet d'évaluer leurs influences sur les contraintes admissibles et sur les variations associées d'épaisseur de couche de la structure de chaussée

Monotonic aspects of the mechanical behaviour of bottom ash from municipal solid waste incineration and its potential use for road construction

Municipal solid waste incineration (MSWI) bottom ash is an atypical granular material because it may include industrial by-products that result from the incineration of domestic waste. The prospects for the beneficial use of this particular material mainly lie in the field of road construction, as a substitute for the traditional natural aggregates. However, its mechanical properties are still little known, particularly in term of stiffness and deformability, characteristics that are essential to the construction of a durable roadway. The purpose of this paper is to describe better the mechanical behaviour of this recycled material.In order to reach this objective, a large experimental campaign is presented. The first part of this paper presents and comments in detail on the results obtained from static monotonic tests.Oedometric and triaxial shear tests were performed on MSWI bottom ash both before and after treatment with a specific hydraulic binder. These tests allow specification of the mechanical characteristics of the MSWI bottom ash, such as the initial Young's modulus, Poisson's ratio, the compressibility index, the friction angle, and the contracting or dilating behaviour of the material. The results reveal a mechanical behaviour similar to that of initially dense standard materials (sands, unbound granular materials) and a dependence on the applied average pressure, characteristic of the mechanical behaviour of granular media. More laboratory data on other samples of MSWI bottom ash are required to ensure that this comparison is statistically valid

Vapothermal curing of hemp shives: Influence on some chemical and physical properties

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Properties of new vegetal concretes from an IAQ point of view

The need to build a more sustainable future leads us to reduce human greenhouse gas emissions and energy consumption. The building sector is one of the biggest emitters of greenhouse gases (over 120 million tons CO2eq/year in France). Besides, requirements in terms of comfort and air quality continuously increase to achieve the target of healthy and sustainable buildings. Therefore, there is no denying the urgent need to develop new bio-based materials with the smallest ecological footprint and at the same time complying with Indoor Air Quality (IAQ) standards. Bio-based construction materials produced through more energy efficient and less CO2eq emissive process, vapothermal curing, are good candidates to address this challenge. Nevertheless, they have to be validated from an IAQ point of view. Fungi development on their surfaces, a source of microbial volatile organic compounds (mVOC) may deteriorate the air quality and induce odour nuisances. Fungi might be more likely to colonize bio-based materials as their high organic content presents sources of nutrients. This work assesses the impact on IAQ of two new hemp and flax based construction bio-materials. Each of these is evaluated in an emission chamber for 28 days at three relative humidities (50, 75 and 95%) and at 20°C. VOC emissions from these materials are analysed by GC-MS and HPLC-UV methods and linked to odour assessments. The fungal growth on the material and fungal spore emissions in the air are jointly evaluated (quantification and speciation). This way, the relationships between fungal growth, odour and VOC emissions are examined