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International audience; Chemical Product Engineering (CPE) is marked by numerous challenges, such as the complexity of the properties–structure–ingredients–process relationship of the different products and the necessity to discover and develop constantly and quickly new molecules and materials with tailor-made properties. In recent years, artificial intelligence (AI) and machine learning (ML) methods have gained increasing attention due to their performance in tackling particularly complex problems in various areas, such as computer vision and natural language processing. As such, they present a specific interest in addressing the complex challenges of CPE. This article provides an updated review of the state of the art regarding the implementation of ML techniques in different types of CPE problems with a particular focus on four specific domains, namely the design and discovery of new molecules and materials, the modeling of processes, the prediction of chemical reactions/retrosynthesis and the support for sensorial analysis. This review is further completed by general guidelines for the selection of an appropriate ML technique given the characteristics of each problem and by a critical discussion of several key issues associated with the development of ML modeling approaches. Accordingly, this paper may serve both the experienced researcher in the fieldas well as the newcomer.

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Рециклинг полимеров представляет собой способ снижения воздействия на окружающую среду накопленных материалов полимерных отходов. Однако часто наблюдается сниженные уровни рециклинга на традиционных установках для рециклинга, главным образом из-за проблемы сбора и транспортирования большого объема легковесных полимеров на обычных централизованных установках для рециклинга. Так как демократизация 3D-принтеров с открытым доступом1 продвигается благодаря таким инициативам как FabLab environments2, имеется растущий интерес к тому, как использовать эту технологию для повышения эффективности использования сырьевых материалов. Было предложено проведение исследований, для того чтобы осуществлять рециклинг полимеров с помощью 3D-принтера с программным обеспечением с открытым кодом. Была сделана оценка рециклинга полиэтилена высокой плотности (HDPE), полученного из использованной тары из-под молока с помощью использования системы для изготовления нитевидных материалов с открытым исходным кодом, называемой RecycleBot3. В данном исследовании проведена оценка возможности механического рециклинга полилактида (полимолочной кислоты) (PLA), материала, широко используемого для 3D-принтеров с открытым доступом, для того чтобы оценить жизнеспособность использования этого подвергнутого рециклинга материала в 3D-принтерах с открытым доступом. Сделана оценка ухудшения механических и реологических свойств материала после ряда циклов процессов экструзии и печатания. Определение характеристик подвергнутого рециклингу сырья для 3D-принтеров с открытым доступом подразумевает не только снижение воздействия полимерных отходов на окружающую среду, но также и позволит понять технические требования и проблемы для разработки машины/процесса рециклинга нити с открытым исходным кодом. Сочетание 3D-принтеров с открытым исходным кодом и экструдеров для получения нитей полилактида может служить основанием новой парадигмы рециклинга вторичных полимеров, которая отменяет традиционную парадигму централизованного рециклинга полимеров, который часто бывает неэкономичным и энергоемким из-за транспортировки, для которой требуется энергия. Более того, определение характеристик также позволит исследовать новый источник материалов и новые композиционные материалы для 3D-печати с открытым исходным кодом, чтобы улучшить качество продукции, изготовленной с помощью этой технологии.

The kinetics of the hydrolysis and polycondensation reactions of saccharides have made the subject of numerous studies, due to their importance in several industrial sectors. The present work, presents a novel kinetic modeling framework that is specifically well-suited to reacting systems under strict moisture control that favor the polycondensation reactions towards the formation of high-degree polysaccharides. The proposed model is based on an extended and generalized kinetic scheme, including also the presence of polyols, and is formulated using two different numerical approaches, namely a deterministic one in terms of the method of moments and a stochastic kinetic Monte Carlo approach. Accordingly, the most significant advantages and drawbacks of each technique are clearly demonstrated and the most fitted one (i.e., the Monte Carlo method) is implemented for the modeling of the system under different conditions, for which experimental data were available. Through these comparisons it is shown that the model can successfully follow the evolution of the reactions up to the formation of polysaccharides of very high degrees of polymerization.

International audience; We present an experimental investigation of the mechanical properties of solid vitrimer samples obtained by incorporating a diepoxide into a commercial PBT in the presence of a Zn(II) catalyst using batch compounder and injection molding machines. Tensile experiments were carried out at different temperatures (80°C, 120°C, 160°C) below the melting point (220°C) and with various diepoxide concentrations (0, 1, 2wt%,). We found that vitrimer plastic deformation mechanisms differ drastically from those of the PBT precursor, and more generally from the regular behaviour of other semi-crystalline polymers. In PBT vitrimers, strain localization (necking) is very weak and can even be suppressed. This type of behaviour is due to the increase in strain hardening caused by vitrimer crosslinking. The creep resistance and stiffness of PBT vitrimers are significantly higher than that those of the pristine PBT. We found that vitrimer modification of PBT at moderate levels improves dimensional stability without inducing brittleness. These promising results highlight the need to find processes which enable significant

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In this study, a three-dimensional (3D) printing filament prepared from poly (lactic acid) (PLA) and acetylated tannin via a twin-screw extruder was reported. The impact of acetylated tannin loading content on the final properties of the resulting composite materials and their 3D printability were investigated. The experimental results indicate that PLA can be compounded with up to 20 wt% acetylated tannin without any obvious deterioration in the tensile property. The resulting composites acquired better degradation rate in aquatic system compared with neat PLA, especially in alkaline medium. Moreover, all composites are printable and showed generally good printing quality with brown color, however, this is limited to temperatures reasonably below 220°C to avoid printing defects, especially at high loadings of acetylated tannin.

International audience; The kinetic developments of the free-radical bulk polymerization of styrene in the presence of recycled rubber tire particles are studied by isothermal differential scanning calorimetry (DSC). Two different chemical initiators, namely benzoyl peroxide (BPO) and 2,2'-Azobis(2methylbutyronitrile) (AMBN), are tested in a series of variable-composition experiments, under three different polymerization temperatures, in order to selectively address the role of the different species on the evolution of the polymerization reaction. The variation of the overall effective kinetic rate constant and activation energy of the polymerization are also calculated to quantify the effect of the addition of the particulate filler. The results of the study demonstrate that the combination of the peroxide initiator agent with a composition of the reacting mixture in the order of 30 mass%, in terms of the rubber tire particles, results in a significant deviation of the evolution of the rate of polymerization and monomer conversion, with respect to that of the pure homopolymerization system in the absence of tire particles. The observed phenomena are consistent with previous studies reported in the literature and are mainly attributed to the chemical interactions taking place between the initiator agent and additives of the formulation of the tire particles.

International audience; This article focuses on reactors for radical polymerization in homogeneous medium. After defining structural characteristics of macromolecules as well as reactor models, kinetic scheme of radical polymerization is discussed in detail. The links between the type of reactor and the manufactured polymer are established following the method of moments combined with mass balances (reactants and macromolecules) and enthalpic balance. Dimensionless numbers characterizing reactor operation are defined.; Les réacteurs de polymérisation radicalaire en milieu homogène sont ici abordés. Après avoir défini les caractéristiques structurales des macromolécules et les modèles de réacteurs, le schéma cinétique d’une polymérisation radicalaire est détaillé. Les liens entre le réacteur de polymérisation et le polymère produit (quantité et qualité) sont établis par la méthode des moments associée aux bilans de matière (réactifs etmacromolécules) et au bilan enthalpique. Les nombres sans dimension décrivant le fonctionnement du réacteur sont déterminés.

The compatibility issue between poly(lactic acid) (PLA) and tannin is a big challenge for preparing PLA/tannin biocomposites with enhanced properties. In this work, composites with enhanced properties have been accomplished using an efficient one-step reactive extrusion method with the help of methylene diphenyl diisocyanate (p-MDI) or 3-aminopropytriethoxysilane (APS). The extent of compatibility achieved via the one-step was evaluated by tensile, morphological, rheological, and thermal properties. The obtained results indicated that the adhesion promoters, especially p-MDI, contributed efficiently to an improved tensile behavior of the resulting composites with a tough tensile-fracture surface compared with incompatibilized PLA/tannin composite. Moreover, these composites displayed a plateau-like rheological behavior, enhanced complex viscosity, higher melting and thermal degradation temperature. This approach can be potentially adapted to other PLA/biopolymers composite systems.

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International audience; Nowadays, the low recycling rate of polymers is still a challenge to humankind due to energy, economic and logistical issues. In the context of additive manufacturing, there is an exponential use of thermoplastic materials in the industrial and public open-source additive manufacturing sector, leading to an increase in global polymer consumption and waste generation. However, the coupling of the open-source 3D printers with polymer processing could potentially offer the basis for a new paradigm of distributed recycling process. It could be a complementary alternative to the traditional paradigm of centralized recycling of polymers, which is often uneconomical and energy intensive due to transportation embodied energy. In order to achieve this goal, a first step is to prove the technical feasibility to recycle thermoplastic material intended for open-source 3D printing feedstock. The contribution of the present study is twofold: first, a general methodology to evaluate the recycla-bility of thermoplastics used as feedstock in open-source 3D printing machines is proposed. Then, the proposed methodology is applied to the recycling study of polylactic acid (PLA) material addressed to the fused filament fabrication (FFF) technique, which is currently the most widely used. The main results of this application contribute to the understanding of the influence of the material's physico-chemical degradation on its mechanical properties as well as its potential distributed recyclability.

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The elaboration of new hybrid polymer/metal composite materials depends on the development of innovative polymer matrices with improved mechanical properties and high effective adhesion behaviour with metal surfaces. This way, a new type of polyolefin was developed based on a peculiar crosslinking reaction. For this elaboration, an iPP-g-MAH with 1 wt% of MAH was crosslinked with polyether triamine molecules by twin screw reactive extrusion. The evolution of the crosslinking reaction, the microstructure and the mechanical behaviour of the different materials were studied as a function of the NH2:MAH molar ratio in the range of 0:1 and 1.5:1. Gel content determination and FTIR analysis were performed to characterise the material at the molecular scale, when differential scanning calorimetry, wide angle X-rays scattering and self-successive auto-nucleation techniques were used for a deep microstructure analysis. Brillouin spectroscopy showed an interesting evolution of the elastic constants at the microscopic scale and results were in good agreement with those obtained at the macroscopic scale by a video-controlled uniaxial tensile test. Moreover, it was demonstrated that the true mechanical behaviours switch from brittle to ductile illustrating an important improvement of the resilience ability of the synthetized materials as a function of the NH2:MAH molar ratio even for molar ratio other than an equimolar ratio, with remaining MAH or NH2 chemical groups for further chemical reaction.

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International audience; A fully bio-sourced and biodegradable composite material has been developed based on polyhydroxybutyrate and hemp fibres (20 wt% content). Improvements of the final performances of composite materials were shown to depend highly on the filler dispersion state and on the polar filler/apolar matrix interface. Those two parameters were tuned by playing around with the processing conditions (screw profile and speed) and the formulation (possible recourse to a green compatibiliser). The so-prepared biocomposites exhibited homogeneous structures, a controlled matrix–fibre interface and suitable thermal properties. Even if the materials also suffered some matrix degradation from identified sources, their mechanical properties were maintained and their water vapour sensitivity could be tuned by the processing conditions and formulation. The strong nucleating effect provided by the fibres has been highlighted, and a clear fibre–matrix load transfer confirmed the effectiveness of the prepared compatibiliser. Concerning the end of life, the high biodegradability of the fully bio-based composites in compost was also confirmed.

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International audience

Ductile functionalized polypropylene is of great interest in multi-layer composites development. A capped-end triblock polyether diamine (H2N-PO2-TMO9-PO3-NH2) was used as a linker of two different maleated isotactic polypropylenes (iPP-g-MAH, at 1 and 3 wt%) by twin-screw reactive extrusion. The molecular architecture, the semi-crystalline microstructure and the mechanical properties of the resulting polymers were analysed as a function of the molar ratio of NH2:MAH (0:1, 0.33:1, 0.5:1, 0.66:1, 1:1, 1.5:1, 2:1). At the molecular scale, the chemically modified polymers were characterized by FTIR and by the determination of gel content following the ASTM D2765-84 standard method. Differential Scanning Calorimetry, Wide Angle X-rays Scattering and Self Successive Auto-nucleation techniques showed the impact of the crosslinking: a decrease of the melting temperature as compared with the unmodified iPP-g-MAH polymer, as well as a decrease of the crystallinity ratio for the iPP-g-MAH at 3 wt% of MAH. Interestingly, Dynamic Mechanical Analysis and video-controlled uniaxial tensile tests showed that the polymers obtained in stoichiometric NH2:MAH molar ratio exhibit the best mechanical properties enlightened by a switch from brittle to ductile mechanical behaviour with few differences between the two iPP-g-MAH.

A wholly bio-composite based on poly (lactic acid) (PLA) and tannin acetate was successfully prepared via in situ reactive extrusion using dicumyl peroxide (DCP) to improve interfacial adhesion. The composites based on PLA and tannin acetate with high acetylation degree exhibited increased molecular weight as compared with reactive extruded PLA, together with the improvement of Young’s modulus and tensile strength. The rheology results showed that reactive extruded PLA/tannin acetate composites exhibited increased complex viscosity and modulus storage, indicating the strong interfacial adhesion of PLA and tannin acetate. Besides, Glass transition temperature, thermal stability, and crystallinity degree were all enhanced as a result of better interaction by radical initiated polymerization. From contact angle data, free radical extruded composites had a more hydrophobic characteristic compared with PLA, which might be interesting for food packaging application. This approach opens up a pathway to diversify the applications of tannin as a component for bio-composite preparation.

International audience; A continuous pilot-scale tubular reactor is designed for the polymerization of acrylic acid in aqueous solution. The reactor is equipped with CSE-X static mixers from Fluitec which strongly increase heat and mass transfer despite laminar flow. A mathematical model of the reactor is proposed assuming that it is a perfect plug-flow reactor and using kinetic and rheological equations previously established using a lab-scale rheo-Raman device. Calculated values of temperature and polymer concentration profile along the reactor as well as outlet average molar masses and viscosity are in good agreement with experimental results. Provided that the outlet viscosity of reaction medium does not exceed 0.5 Pa s, no reactor fouling occurred. On the contrary, fouling is detected after 6 to 8 h running with higher viscosities. This work is the first demonstration of applicability of CSE-X static mixer elements in a continuous polymerization process producing high molar mass water-soluble polymer. In addition, successful scale-up of polymerization reactor is reported up to pilot-scale as well as batch to continuous transposition, only on the basis of lab-scale rheo-Raman data. The interest of rheo-Raman device for the acquisition of primary data is established.

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Ground tire rubber (GTR) was devulcanized in a system comprised of a conventional microwave oven adapted with a motorized stirring system with speed control by 5.5 minutes. Blends composed of GTR/high density polyethylene (HDPE) were prepared in a twin-screw extruder with two feeders at 180°C. The blends were produced in different concentrations, and both the effect of devulcanization and the dynamic revulcanization of GTR phase in the dynamic mechanical properties of the blends were analyzed. As main results, the devulcanization of GTR phase changed the crystallinity of HDPE phase of some blends, possibly because of changes in sizes of particles of devulcanized GTR and its distribution in the matrix. Concerning the revulcanization of the elastomeric phase, generally, it was observed the shift of the glass transition temperature (Tg) peak of the GTR to higher temperatures, and reduction in the area under the peak of tan δ for the Tg of the same phase, as a result of the restriction on the mobility of the GTR by dynamic revulcanization.Ground tire rubber (GTR) was devulcanized in a system comprised of a conventional microwave oven adapted with a motorized stirring system with speed control by 5.5 minutes. Blends composed of GTR/high density polyethylene (HDPE) were prepared in a twin-screw extruder with two feeders at 180°C. The blends were produced in different concentrations, and both the effect of devulcanization and the dynamic revulcanization of GTR phase in the dynamic mechanical properties of the blends were analyzed. As main results, the devulcanization of GTR phase changed the crystallinity of HDPE phase of some blends, possibly because of changes in sizes of particles of devulcanized GTR and its distribution in the matrix. Concerning the revulcanization of the elastomeric phase, generally, it was observed the shift of the glass transition temperature (Tg) peak of the GTR to higher temperatures, and reduction in the area under the peak of tan δ for the Tg of the same phase, as a result of the restriction on the mobility of the ...

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Artificial neural network (ANN) modeling was applied to study the photocatalytic degradation of bisphenol-A. The operating conditions of the Ag/ZnO photocatalyst synthesis and its performance were simultaneously modeled and subsequently optimized to target the highest efficiency in terms of the degradation reaction rate. Two ANN models were developed to simulate the stages of the photocatalyst synthesis and photodegradation performance, respectively. A direct dependence between the two networks was also established, thus making it possible to directly relate the degradation rate of the contaminant, not only to the photodegradation conditions, but also to the photocatalyst synthesis conditions. In this respect, an optimization study was carried out, by means of an evolutionary algorithm, in order to identify the optimal synthesis and photodegradation conditions that would result in the degradation of a maximal amount of the contaminant. Through this integrated approach it was demonstrated that neural network models can be proven valuable tools in the evaluation, simulation and, ultimately, the optimization of different stages of complex photocatalytic processes towards the maximization of the efficiency of the synthesized photocatalyst.

International audience; The disposal of urban solid residues is an enormous problem, especially in the case of vulcanized rubbers like tires. The old practice of landfilling is out of use due to the rising land costs, environmental concerns, fire risks and the possibility of proliferation of mosquitoes and other disease-carrying vectors. Devul-canization is shown to be an effective technique for making rubbers to flow and to be remolded. However, this process not only breaks down sulphur links, but also creates new other bonds, modifying the structure of the material as a whole. In order to help understand structural modifications of ground tire rubbers (GTR) as a result of devulcanization by microwaves, this work proposes an in-depth study of the chemical modifications, flow and thermo-oxidative degradation behavior as a function of the exposure time of the GTR to microwaves. An important conclusion is that the final temperature reached by the sample is the primary factor responsible for the success of the process. Depending on the final temperature of the sample, different types of sulphur bonds can be broken. During the treatment, there is a balance between break down and formation of new bonds. Therefore, it is important to control the process carefully in order to avoid degradation of the main chains. Tires usually are composed of a mixture of synthetic and natural rubbers, wherein natural rubbers could be more degraded by microwaves because carbon black is mainly found on this phase.

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The understanding of lignin softening and pyrolysis is important for developing lignocellulosic biorefinery in order to produce carbon fibers, polymers additives, green aromatics, or biofuels. Protobind lignin (produced by soda pulping of a wheat straw) was characterized by thermogravimetry, calorimetry (for glass transition temperature and heat of pyrolysis reactions), in situ 1H NMR (for the analysis of the mobility of protons upon lignin thermal conversion), and solution-state 13C and 31P NMR (determination of functional groups in lignin). In situ rheology reveals the real-time viscoelastic behavior of lignin as a function of temperature. Upon heating, lignin undergoes softening, through glass transition overlapped with depolymerization, and is followed by the solidification of the softened material by cross-linking reactions. The lignin residues were quenched within the rheometer at the midpoint temperatures of softening and solidification regions and were further analyzed by elemental analysis, GPC-U...

The thermal and mechanical properties of cassava starch films are analyzed in relation to the starch–kaolinite interactions. The kaolinite filler induces a lowering of the crystallinity in accordance with an increase plasticization of the starch matrix. The increase of plasticization induces a decrease of the elastic modulus and an increase of the elongation at break. A retardant effect to the starch matrix decomposition is observed. The filler–matrix interface at which the plasticizer infiltration is enhanced and the reduction of starch chain–chain interactions appears as keys of the observed properties changes. POLYM. COMPOS., 36:184–191, 2015. © 2014 Society of Plastics Engineers

Tannins were used as reinforcing components for polypropylene with anti-UV properties via dynamic curing extrusion. The influence of cross-linked tannins in different weight fraction and their anti-UV capacity on morphological, mechanical, rheological, crystallize and thermal properties were studied. The experimental results indicated that the cross-linked tannins improve Young&rsquo, s modulus, crystallinity, and thermal stability and reinforce the internal network of polypropylene. After UV accelerated weathering, polypropylene had fewer surface cracks, lower carbonyl index, fewer crystallinity decreases and less mechanical properties loss with increasing tannin content.

Free radical polymerization of styrene was monitored in situ by combining Raman spectroscopy to other experimental techniques (gravimetry and rheology). Three different processes were investigated: bulk, emulsion and miniemulsion polymerization. A complete analysis of the evolution of Raman spectrum during the course of reaction showed that a lot of information about molecular dynamics could be extracted and related to chemical phenomena. In addition, we report for the first time the coupling of Raman spectroscopy to a rheometer in order to monitor styrene bulk polymerization both at the scale of chemical bonds and at the scale of macroscopic phenomena (viscosity variation). Copyright © 2013 John Wiley & Sons, Ltd.

This work aims at preparing and characterizing poly(butyl acrylate) (PBA)—laponite (LRD) nanocomposite nanoparticles and nanocomposite core (PBA-LRD)-shell poly(methyl methacrylate) (PMMA) nanoparticles, on the one hand, and the morphology and properties of poly(lactic acid) (PLA)-based blends containing PBA-LRD nanocomposite nanoparticles or (PBA-LRD)/PMMA core-shell nanoparticles as the dispersed phase, on the other hand. The PBA and (PBA-LRD)/PMMA nanoparticles were synthesized by miniemulsion or emulsion polymerization using LRD platelets modified by 3-methacryloxypropyltrimethoxysilane (MPTMS). The grafting of MPTMS onto the LRD surfaces was characterized qualitatively using FTIR and quantitatively using thermogravimetric analysis (TGA). The amounts of LRD in the PBA-LRD nanocomposites were characterized by TGA. The PBA/PMMA core-shell par- ticles were analyzed by 1 H-NMR. Their morphology was confirmed by SEM and TEM. Mechanical properties of (PBA-LRD)/PLA blends and (PBA-LRD)/PMMA/PLA ones were tested and compared with those of the pure PLA, showing that core-shell particles allowed increasing impact strength of the PLA while minimizing loss in Young modulus and tensile strength. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 129: 2580-2590, 2013

International audience; Polymer nanocomposites are multiphase materials in which particles are dispersed in a polymer matrix at a nanometer scale. This chapter shows how rheology can be used as a tool for studying the kinetics of polymerization in the presence of nanoparticles such as carbon nanotubes (CNTs), on the one hand, and rheological properties of the resulting polymer nanocomposites, on the other hand. It is based on the Couette analogy that consists in determining the dimensions of a virtual Couette, which are equivalent to those of a real stirred tank in terms of torque versus rotational speed relationship. The usefulness of rheokinetics is shown with the example of the activated anionic polymerization of e‐caprolactam (AAPCL) in the presence of multi‐walled carbon nanotubes (MWCNTs). The rheology is also a useful tool to the percolation threshold of rheological properties of polymer nanocomposites. This is shown with the example of MWCNT/polystyrene nanocomposites

International audience; A pilot-scale tubular reactor containing static mixers is equipped with several Raman probes in order to perform online monitoring of radical copolymerization of acrylic acid in aqueous solution. This setup allows determination of residence time distribution while polymerization reaction occurs, using sodium nitrate as a tracer. These results prove that the use of convenient static mixers allows obtaining a nearly perfect plug-flow reactor in all explored conditions (reactive and nonreactive medium, between 0.001 and 1 Pa s viscosity). Furthermore, the dynamics of the pilot-scale reactor is characterized. Experimental transient and steady-state values are compared to predictions based both on residence time distribution and model of polymerization kinetics. The applicability of Raman spectroscopy to online monitoring of pilot-scale reactors is demonstrated.

International audience; A complete mathematical model of the free-radical copolymerization of acrylic acid in an aqueous solution, taking place in a pilot-scale tubular reactor equipped with static mixers, is presented. The developed kinetic/reactor model is numerically integrated in terms of a coupled deterministic-stochastic numerical approach that combines the advantages of speed, efficiency, and increased predictive capabilities. A series of experimental measurements on the monomer conversion and the molecular weight characteristics of the produced copolymer, under a wide range of process conditions, are used for the identification of the kinetic model parameters while a thorough analysis of the compositional characteristics of the produced copolymers is also carried out in terms of a series of bivariate distributed properties

Raman spectroscopy was used for in-situ monitoring of styrene emulsion polymerization with sodium dodecyl sulfate and potassium persulfate as the surfactant and initiator, respectively. A new method for analyzing Raman data and calculating monomer conversion was proposed on the basis of the shift of peak corresponding to aromatic ring breathing. It was demonstrated that monomer conversion calculated with this method was similar to the one calculated using the area of vinylic bond as well as to off-line gravimetric determination. Moreover, the kinetic intervals were detected. The conversion measured at the transitions was similar to the literature data.

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