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Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Pollution, Déchets, Wastes, Déchets divers et constituants particuliers des déchets, Other wastes and particular components of wastes, Azote, Nitrogen, Nitrógeno, Cinétique, Kinetics, Cinética, Dioxyde de carbone, Carbon dioxide, Carbono dióxido, Hydrocarbure, Hydrocarbon, Hidrocarburo, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Polychlorobiphényles, Polychlorobiphenyls, Polichlorobifenilos, Pyrolyse, Pyrolysis, Pirólisis, Thermogravimétrie, Thermogravimetry, and Termogravimetría

Thermogravimetric (TG) analysis and infrared spectroscopy were used to analyze the pyrolysis characteristics of printed circuit board scraps (PCBs), coal powder and their mixtures under nitrogen atmosphere. The experimental results show that there is a large difference between waste PCBs and coal powder in pyrolysis processing. The pyrolysis properties of the mixing samples are the result of interaction of the PCBs and coal powder, which is influenced by the content of mixture. The degree of pyrolysis and pyrolysis properties of the mixture are much better than that of the single component. The TG and the differential thermogravimetric (DTG) curves of the PCBs mixed with coal powder move towards the high-temperature zone with increasing amount of coal powder and subsequently the DTG peak also becomes wider. The Coats-Redfern integral method was used to determine the kinetic parameters of pyrolysis reaction mechanism with the different proportion of mixture. The gas of pyrolysis mainly composes of CO2, CO, H2O and some hydrocarbon. The bromide characteristic absorption peak has been detected obviously in the pyrolysis gas of PCBs. On the contrary, the absorption peak of the bromide is not obvious in pyrolysis gas of the PCBs samples adding 40% coal powder.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Etudes théoriques. Données et constantes. Mesures, Theoretical studies. Data and constants. Metering, Combustion. Flammes, Combustion. Flame, Divers, Miscellaneous, Cinétique, Kinetics, Cinética, Dimension particule, Particle size, Dimensión partícula, Distribution dimension particule, Particle size distribution, Distribución dimensión partícula, Décane, Decane, Decano, Etude expérimentale, Experimental study, Estudio experimental, Flamme diffusion, Diffusion flame, Llama difusión, Flamme laminaire, Laminar flame, Llama laminar, Formation, Formación, Hydrocarbure, Hydrocarbon, Hidrocarburo, Kérosène, Kerosene, Queroseno, Modèle, Models, Modelo, Modélisation, Modeling, Modelización, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Mélange carburant, Fuel mixture, Mezcla carburante, Suie, Soot, Hollín, Jet A-1 surrogate, Kerosene chemical kinetic mechanism, Laminar coflow diffusion flame, Soot aggregate size distribution, Soot model, and Synthetic kerosene surrogate

A fully-coupled soot formation model is developed to predict the concentration, size, and aggregate structure of soot particles in the atmospheric pressure laminar coflow diffusion flames of a three-component surrogate for Jet A-1, a three-component surrogate for a Fischer-Tropsch Synthetic Paraffinic Kerosene (SPK), and n-decane. To model the chemical structure of the flames and soot precursor formation, a detailed chemical kinetic mechanism for fuel oxidation, with 2185 species and 8217 reactions, is reduced and combined with a Polycyclic Aromatic Hydrocarbon (PAH) formation and growth scheme. The mechanism is coupled to a highly detailed sectional particle dynamics model that predicts the volume fraction, structure, and size of soot particles by considering PAH-based nucleation, surface growth, PAH surface condensation, aggregation, surface oxidation, fragmentation, thermophoresis, and radiation. The simulation results are validated by comparing against experimental data measured for the flames of pre-vaporized fuels. The objectives of the present effort are to more accurately simulate the physical soot formation processes and to improve the predictions of our previously published jet fuel soot formation models, particularly for the size and aggregate structure of soot particles. To this end, the following improvements are considered: (1) addition of particle coalescence submodels to account for the loss of surface area, reduction of the number of primary particles, and increase of primary particle diameters upon collision, (2) consideration of a larger PAH molecule (benzopyrene instead of pyrene) for nucleation and surface growth to enhance the agreement between the soot model and the measured chemical composition of soot particles, and (3) implementation of a dimerization efficiency in the soot inception submodel to account for the collisions between PAH molecules that do not lead to dimerization. The results of two different particle coalescence submodels show that this process is too slow to account for the growth of primary particles, mainly because of the limited rate of particle collisions. Soot volume fraction predictions on the wings and at lower flame heights are considerably improved by using benzopyrene, due to the different distribution of the soot forming PAH molecule in the flame. The computed number of primary particles per aggregate and the diameters of primary particles agree very well with the experimentally measured values after implementing the dimerization efficiency for PAH collisions, because of the reduced rate of soot inception compared to growth by PAH condensation. Concentrations of major gaseous species and flame temperatures are also well predicted by the model. The underprediction of soot concentration on the flame centerline, observed in previous studies, still exists despite minor improvements.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Etudes théoriques. Données et constantes. Mesures, Theoretical studies. Data and constants. Metering, Combustion. Flammes, Combustion. Flame, Divers, Miscellaneous, Biocarburant, Biofuel, Biocarburante, Cinétique, Kinetics, Cinética, Ester, Jet gaz, Gas jet, Chorro gas, Liaison double, Double bond, Enlace doble, Modèle cinétique, Kinetic model, Modelo cinético, Modélisation, Modeling, Modelización, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Oxydation, Oxidation, Oxidación, Réacteur agité, Stirred tank reactor, Reactor agitado, Stéréoisomère trans, Trans stereoisomer, Estereoisómero trans, Hex-3-énoïque acide ester méthyle, Jet-stirred reactor, Mechanism, Methyl-3-hexenoate, and Unsaturated methyl ester

The oxidation of trans-methyl-3-hexenoate (CAS Number 2396-78-3) under 3 different equivalence ratios of 0.6, 1.0 and 2.0 was investigated in a jet-stirred reactor over the temperature range of 560-1220 K at 10 atm and τ = 0.7 s. Mole fractions of 22 species were quantified as the function of temperature under each condition. Compared to the saturated ester methyl hexanoate, the absence of cool flame and negative temperature coefficient regions in the present work reflects the influence of C=C double bond to fuel oxidation. A mechanism based on previous work of methyl hexanoate was developed and validated against the experimental data with satisfactory agreement. Through analysis of the experimental and modeling results, the role of C=C double bond in the oxidation process and the resulting reaction pathways that feature the oxidation of methyl-3-hexenoate are discussed.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Etudes théoriques. Données et constantes. Mesures, Theoretical studies. Data and constants. Metering, Combustion. Flammes, Combustion. Flame, Biocarburant, Biofuel, Biocarburante, Butyle éther, Dibutylether, Butilo éter, Cinétique, Kinetics, Cinética, Combustion, Combustión, Délai inflammation, Ignition delay, Retardo encendido, Ecoulement laminaire, Laminar flow, Flujo laminar, Ether, Eter, Flamme laminaire, Laminar flame, Llama laminar, Lignocellulose, Lignocellulosics, Lignocelulosa, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Oxydation, Oxidation, Oxidación, Propagation flamme, Flame propagation, Propagación llama, Réacteur, Reactor, Temps retard, Delay time, Tiempo retardo, Di-n-butyl ether, Ethers, and Laminar flames

The combustion characteristics of promising alternative fuels have been studied extensively in the recent years. Nevertheless, the pyrolysis and oxidation kinetics for many oxygenated fuels are not well characterized compared to those of hydrocarbons. In the present investigation, the first chemical kinetic study of a long-chain linear symmetric ether, di-n-butyl ether (DBE), is presented and a detailed reaction model is developed. DBE has been identified recently as a candidate biofuel produced from lignocellulosic biomass. The model includes both high temperature and low temperature reaction pathways with reaction rates generated using appropriate rate rules. In addition, experimental studies on fundamental combustion characteristics, such as ignition delay times and laminar flame speeds have been performed. A laminar flow reactor was used to determine the ignition delay times of lean and stoichiometric DBE/air mixtures. The laminar flame speeds of DBE/air mixtures were measured in the stagnation flame configuration for a wide rage of equivalence ratios at atmospheric pressure and an unburned reactant temperature of 373 K. All experimental data were modeled using the present kinetic model. The agreement between measured and computed results is satisfactory, and the model was used to elucidate the oxidation pathways of DBE. The dissociation of keto-hydroperoxides, leading to radical chain branching was found to dominate the ignition of DBE in the low temperature regime. The results of the present numerical and experimental study of the oxidation of di-n-butyl ether provide a good basis for further investigation of long chain linear and branched ethers.

Energy, Énergie, Geology, Géologie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Combustibles, Fuels, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Brûleur, Burner, Quemador, Chaleur combustion, Heat of combustion, Calor combustión, Cinétique, Kinetics, Cinética, Dégagement chaleur, Heat liberation, Desprendimiento calor, Etude expérimentale, Experimental study, Estudio experimental, Flamme laminaire, Laminar flame, Llama laminar, Flamme prémélange, Premixed flame, Llama premezcla, Hydrogène, Hydrogen, Hidrógeno, Mesure, Measurement, Medida, Modélisation, Modeling, Modelización, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthane, Methane, Metano, Propagation flamme, Flame propagation, Propagación llama, Taux combustion, Combustion efficiency, Índice combustión, Température flamme, Flame temperature, Temperatura llama, Thermocouple, Termopar, Vitesse combustion, Combustion velocity, Velocidad combustión, Contributing reaction, Flame thickness, Rate of heat release, and Thickness of reaction zone

This paper presented an experimental study on the measurements of premixed laminar methane/air flames with and without hydrogen addition. The premixed flames were stabilized on a McKenna flat fame burner at atmospheric pressure. The traveling thermocouple approach was used to measure the axial flame temperature profiles over ranges of equivalence ratios and hydrogen enriching ratios. The measured temperatures, corrected by considering radiation loss, were analyzed to estimate the rate of flame heat release, by solving the continuity equations of mass, energy, and species which were applied to a flat flame. Some of important flame properties, such as the peak temperature, the average temperature, the flame thickness, the thickness of reaction zone and combustion efficiency, were presented to characterize the effect of hydrogen enrichment on laminar flame propagation. It is shown that the presence of hydrogen in laminar flame can promote flame reaction to some extent. With an increase of hydrogen addition fraction in fuel, the peak rate of heat release and combustion efficiency show increases, while the average temperature gives decrease. The analysis of the heat release profiles suggested that hydrogen addition has significant effect on the early part of flame heat release profile. The flames enriched by hydrogen show linear approximations in the plots of the logarithmic heat release rate against the reciprocal of flame temperature. A modeling for one dimensional premixed laminar burner-stabilized flame had been implemented with GRI-Mech 3.0 detailed kinetic reaction mechanism, based on the measured temperature profiles of these premixed flames. And then an analysis on the heat release was performed for each reaction. It suggested that the reaction OH + H2 ⇔ H + H2O gradually increases its contribution to the early heat release with the increase of hydrogen enrichment, which is due to the fact of hydrogen addition resulting in an increased concentration of radical H in flame. The promoted H formation accelerates the flame burning velocity, and then thins the thicknesses of flame and reaction zone to a great extent.

Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Sécurité, Safety, Pollution, Composé organique, Organic compounds, Compuesto orgánico, Carcinogène, Carcinogen, Carcinógeno, Champ température, Temperature distribution, Campo temperatura, Cinétique, Kinetics, Cinética, Explosif, Explosives, Explosivo, Explosion thermique, Thermal explosion, Explosión térmica, Hexogène, Hexogen, Hexogeno, Modélisation, Modeling, Modelización, Mutagène, Mutagen, Mutágeno, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthode analyse, Analysis method, Método análisis, Risque accidentel, Hazard, Riesgo accidente, Stockage, Storage, Almacenamiento, Sécurité, Safety, Seguridad, Isothermal, PBXs, RDX, and Reaction models

In this paper, the decomposition reaction models and thermal hazard properties of 1,3,5-trinitro-1,3,5-triazinane (RDX) and its PBXs bonded by Formex P1, Semtex 1A. C4. Viton A and Fluorel polymer matrices have been investigated based on isoconversional and combined kinetic analysis methods. The established kinetic triplets are used to predict the constant decomposition rate temperature profiles, the critical radius for thermal explosion and isothermal behavior at a temperature of 82 C. It has been found that the effect of the polymer matrices on the decomposition mechanism of RDX is significant resulting in very different reaction models. The Formex P1. Semtex and C4 could make decomposition process of RDX follow a phase boundary controlled reaction mechanism, whereas the Viton A and Fluorel make its reaction model shifts to a two dimensional Avrami-Erofeev nucleation and growth model. According to isothermal simulations, the threshold cook-off time until loss of functionality at 82 C for RDX-C4 and RDX-FM is less than 500 days, while it is more than 700 days for the others. Unlike simulated isothermal curves, when considering the charge properties and heat of decomposition, RDX-FM and RDX-C4 are better than RDX-SE in storage safety at arbitrary surrounding temperature.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polycondensation, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Méthodes. Procédés. Technologies, Methods. Procedures. Technologies, Bioconversions. Hémisynthèses, Bioconversions. Hemisynthesis, Alcanoate(hydroxy) polymère, Alkanoate(hydroxy) polymer, Alcanoato(hidroxi) polímero, Article synthèse, Review, Artículo síntesis, Biosynthèse, Biosynthesis, Biosíntesis, Cinétique, Kinetics, Cinética, Cristallinité, Crystallinity, Cristalinidad, Cristallisation, Crystallization, Cristalización, Culture microorganisme, Microorganism culture, Cultivo microorganismo, Ester polymère, Ester polymer, Ester polímero, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Origine microbienne, Microbial origin, Origen microbiano, Polymère aliphatique, Aliphatic polymer, Polímero alifático, Propriété mécanique, Mechanical properties, Propiedad mecánica, Structure cristalline, Crystalline structure, Estructura cristalina, Distribution composition chimique, Isodimorphisme, Biopolymer, Microbial polyesters, Poly((R)-3-hydroxybutyrate), Poly((R)-3-hydroxybutyrate-co-3-hydroxyvalerate), and Polyhydroxyalkanoates

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymérisation, Polymerization, Brome Composé organique, Bromine Organic compounds, Bromo Compuesto orgánico, Cinétique, Kinetics, Cinética, Cuivre Complexe, Copper Complexes, Cobre Complejo, Etude expérimentale, Experimental study, Estudio experimental, Groupe aminé, Amino group, Grupo aminado, Groupe terminal, End group, Grupo terminal, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Polymérisation transfert atome, Atom transfer polymerization, Polimerización transferencia atomo, Préparation, Preparation, Preparación, Structure moléculaire, Molecular structure, Estructura molecular, Styrène polymère, Styrene polymer, Estireno polímero, 1,1-bis(4-aminophenyl)ethylene, atom transfer radical polymerization, primary diamine functionalizing agent, primary-diamine-functionalized initiator, and α-bis(4-aminophenyl)- and α,ω-tetrakis(4-aminophenyl)-functionalized polystyrenes

The preparation of a symmetrically disubstituted 1,1-diphenylethylene derivative, 1,1-bis(4-aminophenyl)ethylene, by the Wittig reaction as well as the preparation of primary amine chain-end-functionalized polymers using that derivative in atom transfer radical polymerization (ATRP) reactions are reported. A new primary diamine initiator system was generated in situ by the atom transfer radical addition reaction of (1-bromoethyl)benzene with 1,1-bis(4-aminophenyl)ethylene in the presence of copper(I) bromide/2,2'-bipyridyl as the catalyst system and employed as the primary diamine-functionalized initiator for the polymerization of styrene by ATRP methods to produce well-defined α-bis(4-aminophenyl)-functionalized polystyrene. The polymerization kinetic data for the synthesis of α-bis(4-aminophenyl)-functionalized polystyrene shows that the polymerization process followed first-order rate kinetics with respect to monomer consumption. The number-average molecular weights (Mn = 1.1 x 103 to 13.14 x 103 gmol-1) of the α-bis(4-aminophenyl)-functionalized polymers increased linearly with percentage monomer conversion and polymers with narrow molecular weight distributions (Mw/Mn = 1.1 - 1.25) were obtained. The polymerization processes were monitored using gas chromatographic analyses to determine the extent of monomer consumption as a function of time. In addition, α,ω-tetrakis(4-aminophenyl)-functionalized polystyrene was prepared by a new, controlled/living, in situ post-ATRP chain-end functionalization reaction which involved the direct addition of 1,1-bis(4-aminophenyl)ethylene to the ω-terminus of α-bis(4-aminophenyl)-functionalized polystyrene, without the need for the isolation and purification of the polymeric precursor. The organic precursor compounds, the primary diamine-functionalized 1,1-diphenylethylene derivative and the functionalized polymers were characterized using 1H NMR, 13C NMR and Fourier transform infrared spectroscopy, size exclusion chromatography, thin-layer chromatography and non-aqueous titration measurements.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Copolymérisation, Copolymerization, Propriété surface, Surface properties, Propiedad superficie, Structure moléculaire, Molecular structure, Estructura molecular, Cinétique, Kinetics, Cinética, Copolymère fluor, Fluorine containing copolymer, Copolímero flúor, Copolymérisation radicalaire, Radical copolymerization, Copolimerización radical, Copolymérisation solution, Solution copolymerization, Copolimerización solución, Dégradation thermooxydante, Thermooxidative degradation, Degradación termooxidante, Etude expérimentale, Experimental study, Estudio experimental, Iode Composé organique, Iodine Organic compounds, Iodo Compuesto orgánico, Microstructure, Microestructura, Mouillabilité, Wettability, Remojabilidad, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthacrylate d'alkyle copolymère, Alkyl methacrylate copolymer, Metacrilato de alquilo copolímero, Préparation, Preparation, Preparación, Stabilité thermique, Thermal stability, Estabilidad térmica, Terminaison réaction, Termination reaction, Terminación reacción, Transfert chaîne, Chain transfer, Transferencia en cadena, Vinylidène fluorure copolymère, Vinylidene fluoride copolymer, Vinilideno fluoruro copolímero, Acrylate(alpha-trifluorométhyl) de 2-[perfluorooctyl]éthyle copolymère, and Chloroiodocarbone

A 2-trifluoromethacrylate monomer containing a C6F13 side chain, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 2-(trifluoromethyl)acrylate (MAF-C6F13) was synthesized and copolymerized with vinylidene fluoride (VDF). First, the preparation of MAF-C6F13 was achieved by two different routes: (i) transesterification of tert-butyl 2-trifluoromethacrylate (MAF-tBu) with C6F13C2H4OH (55% yield with ∼95% purity) and (ii) esterification of 2-trifluoromethacryloyl chloride with the same fluorinated alcohol, which gave higher yield (82%) and purity (99%). The radical copolymerization of MAF-C6F13 with VDF was initiated by three different systems (two peroxypivalates and one highly branched fluorinated persistent radical, PPFR), a chain transfer agent (CF3I), at various polymerization temperatures (65-90 °C) and in three types of solvents. The relative comonomer incorporation and number-average molecular weights (Mns) of the resulting random poly(VDF-co-MAF-C6F13) copolymers were assessed by NMR spectroscopy. Both features alongwith polymerization yields were influenced by the polymerization temperatures and the nature of solvents. The Mn values were further affected by the type of initiators and the use of chain transfer agent. When dimethyl carbonate was used as the solvent, lower (2-4 mol %) MAF-C6F13 comonomer was incorporated compared to those reactions that involved 1,1,1,3,3-pentafluorobutane (5-33 mol %). Surprisingly, Mns of these copolymers increased with polymerization temperatures when the reactions were initiated by PPFR. Thus, the copolymerization carried out at 65 °C and initiated by PPFR led to a Mn of 33 000 g mol-1, while those achieved at 90 °C yielded a Mn of 61 700 g mol-1. The thermostability of the obtained copolymers under air (the temperature for 10% weight loss, Td10% > 340 °C) was significantly improved compared to that of VDF copolymers containing 2-trifluoromethacrylic acid or MAF-tBu. Surface hydrophobicity of these copolymers was superior than that of PVDF homopolymer. For example, poly(VDF-co-MAF-C6F13) copolymer of 59,000 g mol-1 with 2 mol % MAF-C6F13 only, displayed a higher static water contact angle (114°) than that of PVDF homopolymer (ca. 94°).

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Copolymérisation, Copolymerization, Butyrate(hydroxy) copolymère, Butyrate(hydroxy) copolymer, Butirato(hidroxi) copolímero, Butyrate(hydroxy) polymère, Butyrate(hydroxy)polymer, Butirato(hidroxi) polímero, Cinétique, Kinetics, Cinética, Copolymère greffé, Graft copolymer, Copolímero injertado, Cristallisation, Crystallization, Cristalización, Ester copolymère, Ester copolymer, Ester copolímero, Ester polymère, Ester polymer, Ester polímero, Etude expérimentale, Experimental study, Estudio experimental, Greffage, Grafting, Injerto, Maléique anhydride copolymère, Maleic anhydride copolymer, Maleico anhídrido copolímero, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Polymère aliphatique, Aliphatic polymer, Polímero alifático, Propriété thermique, Thermal properties, Propiedad térmica, Relation composition propriété, Property composition relationship, Relación composición propiedad, Stabilité thermique, Thermal stability, Estabilidad térmica, Styrène copolymère, Styrene copolymer, Estireno copolímero, Butyrate(3-hydroxy) polymère, Maleic anhydride, Mechanism, Poly(β-hydroxybutyrate), Styrene, and Thermal behavior

Maleic anhydride (MA) was grafted onto poly(β-hydroxybutyrate) (PHB) chains by using styrene (St) as co-monomer and dicumyl peroxide (DCP) as free-radical initiator. The grafting degree of MA was increased from 0.2 wt% to 0.9 wt% with the St/MA ratio up to 2/1. The St-assisted grafting mechanisms are revealed based on titration, thermogravimetric analysis and infrared analysis, i.e. MA is grafted onto PHB chains by way of single monomers and charge-transfer-complex (CTC) at the St/MA ratios of ≤ 1/1. while St-co-MA oligomers are the dominating grafting pendants when the St/MA ratios ≥ 2/1. The decomposition temperature (Td-5%) of PHB is raised by approx. 35 °C after grafting of the MA and/or short St/MA pendants, meanwhile higher molecular weight of the PHB is obtained. In addition, the crystallization of PHB is promoted by grafting of the MA or MA-co-St oligomers. The crystallization mechanism of maleated PHB is proposed as well.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères d'origine naturelle, Natural polymers, Cellulose et dérivés, Cellulose and derivatives, Cellulose copolymère greffé, Cellulose graft copolymer, Celulosa copolímero injertado, Cinétique, Kinetics, Cinética, Dégradation thermique, Thermal degradation, Degradación térmica, Dérivé de la cellulose, Cellulose derivatives, Celulosa derivado, Effet température, Temperature effect, Efecto temperatura, Energie activation, Activation energy, Energía activación, Etude expérimentale, Experimental study, Estudio experimental, Lactique acide copolymère, Lactic acid copolymer, Láctico ácido copolímero, Modèle cinétique, Kinetic model, Modelo cinético, Modélisation, Modeling, Modelización, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Propriété thermique, Thermal properties, Propiedad térmica, Relation composition propriété, Property composition relationship, Relación composición propiedad, Stabilité thermique, Thermal stability, Estabilidad térmica, Température transition vitreuse, Glass transition temperature, Temperatura transición vítrosa, Thermogravimétrie, Thermogravimetry, Termogravimetría, Cellulose, Degradation mechanism, Kinetic parameter, Poly(L-lactic acid), and Thermogravimetric analysis

The thermal degradation of cellulose-gra/t-poly(L-lactic acid) at different heating rates in nitrogen was studied by thermogravimetric analysis (TGA) in the temperature range 20-550 °C. Nuclear magnetic resonance (NMR), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) analyses were utilized to determine the microstructure and glass transition temperature of cellulose-graft-poly(L-lactic acid). The kinetic parameters were determined by using Friedman, Flynn-Wall -Ozawa, and Kissinger methods. Coats-Redfern method was used to investigate the probable degradation mechanism. The results indicated that the trend of activation energy of cellulose-graft-poly(L-lactic acid) increases with increasing the content of the poly(L-lactic acid) and the process of the non-spontaneous degradation stage, goes to a random nucleation with two nuclei on the individual particle mechanism, whose rate-controlling process could be described by conversion rate (α) (integral form 1/(1 - α)).

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Traitement des déchets, Waste treatment, Cinétique, Kinetics, Cinética, Déchet plastique, Plastic waste, Residuo plástico, Dégradation thermique, Thermal degradation, Degradación térmica, Ethylène haute densité polymère, High density ethylene polymer, Etileno alta densidad polímero, Etude théorique, Theoretical study, Estudio teórico, Modèle cinétique, Kinetic model, Modelo cinético, Modélisation, Modeling, Modelización, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthode dynamique moléculaire, Molecular dynamics method, Método dinámico molecular, Oléfine polymère, Olefin polymer, Olefina polímero, Produit dégradation, Degradation product, Producto degradación, Propriété thermique, Thermal properties, Propiedad térmica, Pyrolyse, Pyrolysis, Pirólisis, Simulation ordinateur, Computer simulation, Simulación computadora, Stabilité thermique, Thermal stability, Estabilidad térmica, Vérification expérimentale, Experimental test, Verificación experimental, Chemical reaction mechanism, HDPE pyrolysis, Reactive molecular dynamics, ReaxFF MD, and VARMD

PE pyrolysis is considered as an important process for converting plastic solid waste into fuel or other valuable chemicals to alleviate the environmental burdens. A computational approach can be of help for fully understanding the mechanisms and reaction pathways during PE pyrolysis in various industrial applications. In this paper, ReaxFF molecular dynamics was for the first time applied in simulating the pyrolysis of a High Density Polyethylene (HDPE) model system with 7216 atoms. Detailed reaction mechanisms and generation pathways of primary gas molecules were obtained by further analysis of the trajectories within a total of 250 ps simulation in NVT ensemble at 2000-3000 K using a newly created program, VARMD. The product profile and primary gas products evolution tendencies with temperature agree reasonably with the observations in Py-GC/MS experiments and literature data. The overall kinetics of ~ C31 were analyzed and used to predict the reaction time for 90% weight loss of HDPE thermolysis that falls in around the reported time observed experimentally in the literatures. The reaction mechanisms based on the detailed reactions from the simulation trajectories are in broad agreement with what reported in literatures. The work presented here validates that ReaxFF MD is a promising method to help building a systematic understanding of the detailed chemical reactions in pyrolytic process for polymers.

Energy, Énergie, Geology, Géologie, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie organique, Organic chemistry, Réactivité et mécanismes, Reactivity and mechanisms, Cinétique et mécanisme des réactions, Kinetics and mechanisms, Analyse thermodynamique, Thermodynamic analysis, Análisis termodinámico, Cinétique, Kinetics, Cinética, Composé modèle, Model compound, Compuesto modelo, Etude théorique, Theoretical study, Estudio teórico, Guaiacol, Lignine, Lignin, Lignina, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthode fonctionnelle densité, Density functional method, Pyrolyse, Pyrolysis, Pirólisis, Density functional theory (DFT), and Lignin model compound

Five possible pyrolytic pathways of guaiacol were proposed with an emphasis on the reactivity of the methoxy group. Pathway 1 is about the homolysis of O-CH3. Pathways 2-4 focus on the demethoxylation of guaiacol. Pathway 5 concerns the O-CH3 rearrangement. Standard thermodynamic and kinetic parameters of each reaction pathway were calculated at different temperatures based on density functional theory methods by using Gaussian 03 package at B3LYP/6-31G++ (d,p) level. According to the calculation results, the five reaction pathways were ranked as Path 3, Path 1, Path 4, Path 2 and Path 5, in descending order of reactivity. Kinetic analyses results of the three demethoxylation reaction pathways (Path 2, Path 3 and Path 4) indicate that coupling a hydrogen radical to the carbon atom to which the methoxyl group bond can effectively lower the reaction energy barrier that existed in the process of demethoxylation. Pathway 5 demonstrates the possible formation mechanism of o-quinonemethide which is the key polymerization intermediate during lignin pyrolysis process.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Ecology, Ecologie, Environment, Environnement, Pollution, Toxicology, Toxicologie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Pollution, Traitement et pollution des eaux, Water treatment and pollution, Eaux usées, Wastewaters, Procédés généraux d'épuration, General purification processes, Métal transition, Transition metal, Metal transición, Platinoïde, Platinoid, Platinoide, Anode, Anodo, Bore, Boron, Boro, Carbone organique total, Total organic carbon, Carbono orgánico total, Chromatographie HPLC, HPLC chromatography, Cromatografía HPLC, Cinétique, Kinetics, Cinética, Diamant, Diamond, Diamante, Dégradation, Degradation, Degradación, Eau souterraine, Ground water, Agua subterránea, Epuration eau usée, Waste water purification, Depuración aguas servidas, Epuration physicochimique, Physicochemical purification, Depuración fisicoquímica, Etude comparative, Comparative study, Estudio comparativo, Iridium, Iridio, Matériau dopé, Doped materials, Matériau électrode, Electrode material, Material electrodo, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthode couplée, Coupled method, Método acoplado, Oxydation, Oxidation, Oxidación, Pesticide, Pesticides, Plaguicida, Platine, Platinum, Platino, Polluant, Pollutant, Contaminante, Pollution eau, Water pollution, Contaminación agua, Produit dégradation, Degradation product, Producto degradación, Réaction électrochimique, Electrochemical reaction, Reacción electroquímica, Résidu, Residue, Resíduo, Spectrométrie UV, Ultraviolet spectrometry, Espectrometría UV, Spectrométrie masse, Mass spectrometry, Espectrometría masa, Benzamide(2,6-dichloro), LC MS, 2,6-Dichlorobenzamide, Degradation intermediates, Electrochemical oxidation, Groundwater, and Pesticide pollution

Electrochemical oxidation is a promising technique for degradation of otherwise recalcitrant organic micropollutants in waters. In this study, the applicability of electrochemical oxidation was investigated concerning the degradation of the groundwater pollutant 2,6-dichlorobenzamide (BAM) through the electrochemical oxygen transfer process with two anode materials: Ti/Pt90-Ir10 and boron doped diamond (Si/BDD). Besides the efficiency of the degradation of the main pollutant, it is also of outmost importance to control the formation and fate of stable degradation intermediates. These were investigated quantitatively with HPLC-MS and TOC measurements and qualitatively with a combined HPLC-UV and HPLC-MS protocol. 2,6-Dichlorobenzamide was found to be degraded most efficiently by the BDD cell, which also resulted in significantly lower amounts of intermediates formed during the process. The anodic degradation pathway was found to occur via substitution of hydroxyl groups until ring cleavage leading to carboxylic acids. For the BDD cell, there was a parallel cathodic degradation pathway that occurred via dechlorination. The combination of TOC with the combined HPLC-UV/MS was found to be a powerful method for determining the amount and nature of degradation intermediates.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Constituants de formulation, Compounding ingredients, Stabilisants (antioxygènes, antiozones, etc.), Stabilizers (antioxydants, antiozonants, etc.), Propriétés et essais, Properties and testing, Propriétés physiques, Physical properties, Vieillissement, Ageing, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Acide gallique, Gallic acid, Gálico ácido, Additif, Additive, Aditivo, Antioxydant, Antioxidant, Antioxidante, Biomatériau, Biomaterial, Cinétique, Kinetics, Cinética, Dose rayonnement, Radiation dose, Dosis irradiación, Dérivé de l'acide gallique, Gallic acid derivatives, Gálico ácido derivado, Effet concentration, Concentration effect, Efecto concentración, Ethylène ultra haute masse moléculaire polymère, Ultra high molecular weight ethylene polymer, Etileno ultra altro peso molecular polímero, Etude expérimentale, Experimental study, Estudio experimental, Faisceau électronique, Electron beam, Haz electrónico, Moulage compression, Compression molding, Moldeo por compresión, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Mélange polymère, Polymer blends, Oléfine polymère, Olefin polymer, Olefina polímero, Phénols, Phenols, Fenoles, Polymère réticulé, Crosslinked polymer, Polímero reticulado, Polyphénol, Polyphenol, Polifenol, Propriété chimique, Chemical properties, Propiedad química, Résistance oxydation, Oxidation resistance, Resistencia a la oxidación, Stabilisant, Stabilizer agent, Estabilizante, Stabilité stockage, Storage stability, Estabilidad al almacenamiento, Stérilisation, Sterilization, Esterilización, Vitamine E, Vitamin E, Vitamina E, Stérilisation radiochimique, Ageing, Crosslinking, FTlR, Oxidation, Polyphenols, and UHMWPE

In the present work, dodecyl gallate (DG) and gallic acid (GA) were blended with UHMWPE and consolidated by compression moulding prior to e-beam irradiation. Stabilisation of highly crosslinked UHMWPE with these polyphenols was examined by tracing post-irradiation oxidation kinetics of UHMWPE at room temperature with Fourier transform infrared (FTIR) spectroscopy, in comparison to highly crosslinked vitamin E (VE)-blended and virgin UHMWPE. Phenol loss upon e-beam irradiation depended on the polyphenol chemistry and compatibility with the polyethylene matrix: the oleophilic DG and VE showed higher phenol loss than GA. Nevertheless, all the antioxidant-containing materials exhibit improved oxidation stability compared to virgin material. The formation kinetics of ketones, hydroperoxides, carboxylic acids, esters, and ketoacids were analysed in detail over time in order to understand the effect of polyphenols on the oxidation mechanism of highly crosslinked UHMWPE. Our results suggest that these polyphenols show limited phenol loss and are protective for highly crosslinked UHMWPE, which may be promising alternative for UHMWPE biomaterials with improved stability.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Bois. Papiers. Non tissés, Wood. Paper. Non wovens, Bois, Wood, Dégradation et protection, Degradation and preservation, Analyse chimique, Chemical analysis, Análisis químico, Bois feuillu, Hardwood, Madera de frondosas, Bois résineux, Softwood, Madera de coníferas, Cinétique, Kinetics, Cinética, Composition chimique, Chemical composition, Composición química, Dégradation biologique, Biodegradation, Degradación biológica, Engorgement sol, Waterlogging (soil), Anegamiento suelo, Etude expérimentale, Experimental study, Estudio experimental, Fluorescence RX, X ray fluorescence, Fluorescencia RX, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Méthode non destructive, Non destructive method, Método no destructivo, Propriété optique, Optical properties, Propiedad óptica, Spectrométrie IR proche, Near infrared spectrometry, Espectrometría IR próximo, Spectrométrie UV visible, Ultraviolet visible spectrometry, Espectrometría UV visible, Tourbe, Peat, Turba, Cellulose, Degradation stage, Hemicellulose, Lignin, Spectroscopy, and Waterlogged wood

Non-destructive spectroscopic methods (UV-Vis, FT-NIR and XRF) were utilized to evaluate the degradation state of natural polymers of contemporary wood exposed to short-term (eight years) waterlogging. Experimental samples included both softwood (Scots pine) and hardwood (Penduculate oak) degraded in two differing environments (peat and water). The species investigated exhibited diverse mechanisms of degradation. Differing sites also seem to have influenced degradation kinetics. Samples of both species placed in trenches filled with water show slightly more intense degradation. However, interpretation of FT-NIR spectra revealed that different woody polymers (functional groups) were degraded in waterlogged pine and oak respectively. Characteristic darker color was observed in oak wood with progressive waterlogging. XRF analysis identified deposition of iron in the external zone of oak samples. Partial Least Square prediction models for exposure time of wood decomposed in wet environment were also developed. The degradation stage of the short-term waterlogged samples was compared to archaeological oak dated at 13th century, and to pine dated at 17th century. Archaeological pine wood exhibits more intense degradation relative to the oak, even though the latter was 400 years older. Spectral analysis in the near-infrared range confirmed that amorphous and semi-crystalline regions of cellulose, hemicelluloses and lignin changed due to waterlogging. Conversely, the crystalline regions of cellulose seem not to be degraded.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Biotechnology, Biotechnologies, Energy, Énergie, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Energie, Energy, Combustibles, Fuels, Bois. Tourbe. Lignite, Wood. Peat. Brown coal, Bois, Wood, Arbre forestier résineux, Softwood forest tree, Arbol forestal resinoso, Coniferales, Gymnospermae, Spermatophyta, Analyse thermique, Thermal analysis, Análisis térmico, Bois de feu, Fuelwood, Leña para fuego, Chromatographie pyrolytique, Pyrolytic chromatography, Cromatografía pirolítica, Cinétique, Kinetics, Cinética, Lignine, Lignin, Lignina, Microscope platine chauffante, Hot stage microscope, Microscopio platina caliente, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Produit réaction, Reaction product, Producto reacción, Pseudotsuga menziesii, Pyrolyse éclair, Flash pyrolysis, Pirolisis rápida, Pyrolyse, Pyrolysis, Pirólisis, Réacteur, Reactor, Hot stage, Liquid intermediate, and Wire mesh reactor

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir (Pseudotsuga menziesii) wood was extracted using the milled wood enzyme lignin isolation method. Slow pyrolysis using a microscope with hot-stage captured the liquid formation (>150 °C), shrinking, swelling (foaming), and evaporation behavior of lignin intermediates. The activation energy (Ea) for 5―80% conversions was 213 kJ mol-1, and the pre-exponential factor (log A) was 24.34. Fast pyrolysis tests in a wire mesh reactor were conducted (300―650 °C). The formation of the liquid intermediate was visualized with a fast speed camera (250 Hz), showing the existence of three well defined steps: formation of lignin liquid intermediates, foaming and liquid intermediate swelling, and evaporation and droplet shrinking. GC/MS and UV-Fluorescence of the mesh reactor condensate revealed lignin oligomer formation but no mono-phenols were seen. An increase in pyrolytic lignin yield was observed as temperature increased. The molar mass determined by ESI-MS was not affected by pyrolysis temperature. SEM of the char showed a smooth surface with holes, evidence of a liquid intermediate with foaming; bursting from these foams could be responsible for the removal of lignin oligomers. Py-GC/MS studies showed the highest yield of guaiacol compounds at 450―550 °C. .

Ecology, Ecologie, Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Pollution, Traitement et pollution des eaux, Water treatment and pollution, Eaux usées, Wastewaters, Procédés généraux d'épuration, General purification processes, Eaux usées industrielles, Industrial wastewaters, Métal transition, Transition metal, Metal transición, Phosphore Composé, Phosphorus Compounds, Fósforo Compuesto, Anion minéral, Inorganic anion, Anión inorgánico, Cinétique, Kinetics, Cinética, Composé de l'azote, Nitrogen compounds, Compuesto nitrogenado, Eau usée industrielle, Industrial waste water, Agua servida industrial, Eau usée, Waste water, Agua residual, Enlèvement, Removal, Toma, Epuration eau usée, Waste water purification, Depuración aguas servidas, Epuration physicochimique, Physicochemical purification, Depuración fisicoquímica, Fer, Iron, Hierro, Industrie électronique, Electronics industry, Industria electrónica, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Métal zérovalent, Zerovalent metal, Metal cerovalente, Nitrate, Nitrates, Nitrato, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Phosphate, Phosphates, Fosfato, Réaction simultanée, Simultaneous reaction, Reacción simultánea, Semiconducteur, Semiconductor materials, Semiconductor(material), Zero-valent iron, hydrogen peroxide, nitrate, phosphate, and semiconductor acidic wastewater

The zero-valent iron (ZVI) wastewater treatment has been applied to simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewaters. The simultaneous removal occurs by the reactions performed due to the sequential transformation of ZVI under the acidic condition. Fortunately the solution pH of semiconductor acidic wastewaters is low which is effective for the sequential transformation of ZVI. Firstly the reduction of nitrate is taken place by electrons generated by the corrosion of ZVI under acidic conditions. Secondly the ferrous ion generated by the corrosion of ZVI reacts with hydrogen peroxide and generates ·OH radical (Fenton reaction). The Fenton reaction consists of the degradation of hydrogen peroxide and the generation of ferric ion. Finally phosphate precipitates out with iron ions. In the simultaneous removal process, 1.6 mM nitrate, 9.0 mM hydrogen peroxide and 1.0 mM phosphate were completely removed by ZVI within 100, 15 and 15 min, respectively. The synergy among the reactions for the removal of nitrate, hydrogen peroxide and phosphate was found. In the individual pollutant removal experiment, the removal of phosphate by ZVI was limited to 80% after 300 min. Its removal rate was considerably improved in the presence of hydrogen peroxide and the complete removal of phosphate was achieved after 15 min.

Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Genie chimique, Chemical engineering, Réacteurs, Reactors, Pollution, Traitement et pollution des eaux, Water treatment and pollution, Eaux usées, Wastewaters, Procédés généraux d'épuration, General purification processes, Ammoniac, Ammonia, Amoníaco, Azote, Nitrogen, Nitrógeno, Cinétique, Kinetics, Cinética, Dioxyde de carbone, Carbon dioxide, Carbono dióxido, Eau usée industrielle, Industrial waste water, Agua servida industrial, En semi continu, Semicontinuous, En semicontinuo, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Oxydation, Oxidation, Oxidación, Polluant, Pollutant, Contaminante, Pollution, Polución, Produit réaction, Reaction product, Producto reacción, Réacteur, Reactor, Réaction parallèle, Parallel reaction, Reacción paralela, Sulfate, Sulfates, Sulfato, Synergie, Synergism, Sinergia, Cyanide, Reaction pathway, Synergistic phenomena, and Thiocyanate

Thiocyanate and cyanide are important contaminants that frequently appear mixed in industrial effluents. In this work the wet oxidation of mixtures of both compounds, simulating real compositions, was carried out in a semi-batch reactor at temperature between 393 K and 483 K and pressure in the range of 2.0-8.0 MPa. The presence of cyanide (3.85 mM) increased the kinetic constant of thiocyanate degradation by a factor of 1.6, in comparison to the value obtained for the individual degradation of thiocyanate, (5.95 ± 0.05) × 10-5 s-1. On the other hand, the addition of thiocyanate (0.98 mM) decreased the degradation rate of cyanide by 16%. This revealed the existence of synergistic and inhibitory phenomena between these two species. Additionally, cyanide was identified as an intermediate in the oxidation of thiocyanate, and formate, ammonia and sulfate were found to be the main reaction products. Taking into account the experimental data, a reaction pathway for the simultaneous wet oxidation of both pollutants was proposed. Two parallel reactions beginning from cyanate as intermediate were considered, one yielding ammonia and formate and the other giving carbon dioxide and nitrogen as final products.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Propriétés et essais, Properties and testing, Propriétés physiques, Physical properties, Vieillissement, Ageing, Butyrate(hydroxy) copolymère, Butyrate(hydroxy) copolymer, Butirato(hidroxi) copolímero, Cinétique, Kinetics, Cinética, Dégradation enzymatique, Enzymatic digestion, Degradación enzimática, Eau mer, Seawater, Agua mar, Effet température, Temperature effect, Efecto temperatura, Ester copolymère, Ester copolymer, Ester copolímero, Etude expérimentale, Experimental study, Estudio experimental, Morphologie, Morphology, Morfología, Mécanisme réaction, Reaction mechanism, Mecanismo reacción, Propriété chimique, Chemical properties, Propiedad química, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Résistance hydrolyse, Hydrolysis resistance, Resistencia hidrólisis, Temps exposition, Exposure time, Tiempo exposición, Valérate(hydroxy) copolymère, Valerate(hydroxy) copolymer, Valerato(hidroxi) copolímero, Vieillissement accéléré, Artificial ageing, Envejecimiento acelerado, Butyrate(3-hydroxy) copolymère, Valérate(3-hydroxy) copolymère, Vieillissement marin, Accelerated ageing, Hydrothermal degradation, and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The aim of this study is to establish a baseline for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) lifetime prediction in a marine environment, by means of mechanical and physico-chemical characterization of specimens immersed in continuously renewed and filtered natural seawater in the laboratory at different temperatures (4, 25 and 40 °C). Samples were also aged at sea in Lorient harbour in order to compare laboratory and natural degradation mechanisms and kinetics. Due to its morphology, hydrolysis of PHBV in natural seawater is quite slow, and samples were observed to undergo preferentially an enzymatic surface degradation. Increasing the aging temperature in the laboratory promotes the water uptake and causes hydrolysis. As two degradation mechanisms occur in parallel, the choice of test conditions is critical, and the lifetime of PHBV in a marine environment is difficult to predict accurately.