Vieillissement environnemental accéléré et propriétés mécaniques des fibres issues du chanvre

International audience; Ce travail a pour objectif de caractériser l’influence d’un vieillissement environnemental accéléré sur les propriétés mécaniques de fibres extra-xylémiennes issues du chanvre. Le protocole de vieillissement accéléré proposé dans cette étude consiste en des cycles de 24h comprenant une phase d’immersion de 12h dans une eau distillée à 70°C et une phase de séchage de 12h dans une étuve contrôlée à 50°C. Les résultats montrent une perte de masse significative et une diminution des propriétés de rigidité et de résistance en traction de l’ordre de 50% après 30 cycles de vieillissement.

Effect of moisture uptake on flax-reinforced composite laminates: influence on dynamic and quasi-static properties

International audience; This study proposes to investigate the effect of moisture uptake on a wide spectrum of mechanical behaviours of unidirectional flax fibre-reinforced epoxy laminates. It includes tensile monotonic and fatigue testing. Results show that UD flax-epoxy composites, whenexposed to hygrothermal conditioning at 70°C and 85% RH, exhibit a diffusion kinetic which follows a one dimensional Fickian behaviour. The mass uptake at equilibrium is approximately 3.3 % and the diffusion coefficient 6.5 10-6 m2.s-1. Water vapour sorption is shown to induce a significant change in the shape of the tensile stress-strain curve. Contrary to all expectations, water saturation does not degrad…

Hydrothermal ageing of fibre metal laminates made of flax fibres

International audience; In the past two decades, fibre metal laminates (FMLs) have been widely used to manufacture aircraft and aerospace components. FMLs are hybrid composite structures based on thin sheets of metal alloys reinforced by organic matrix composites (Sinmazçelik et al., 2011). When compared to mono-material solutions, FMLs provide added functionalities such as high specific bending strength, fatigue resistance, acoustical absorption, vibration transmissibility and damping characteristics. They overcome most of the limitations of metal and polymeric reinforced composites. The first generation of FMLs was based on thermoset resins. To shorten the process cycle times, lower the p…

Microstructure et vieillissement hygrothermique de composites renforcés de fibres de lin unidirectionnelles

The current production of structural composite materials relies mainly on non-renewable fossil resources. Many regulations encourage the industry to move towards eco-friendly solutions. Within that general background, vegetal fibers appear to be an interesting alternative to synthetic fibers due to their good mechanical properties and their low density. However, using these fibers for structural composites is still limited because of their hydrophilic behavior which impacts processing, in-service properties and durability. The aim of this work is to study the effect of hygrothermal ageing, based on a sorption-desorption sequence, on the mechanical properties of flax fibers reinforced epoxy …

Design and development of 100 % bio-based high-grade hemp/epoxy composites

International audience; In order to develop 100% bio-based high-grade epoxy composites, in this study, bio-based epoxy thermosets and hemp slivers are processed and characterized by different technologies. Epoxy resins are synthesized from the diglycidylether of Eugenol, extracted from cloves. They are cured with bio-based acid anhydrides. The physicochemical properties of the resulting epoxy resins are characterized using thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), and nanoindentation. The mechanical properties of hemp fibres extracted from the slivers are also determined using tensile tests. After their processing and characterization, these bio-based consti…

Multicatalytic Transformation of (Meth)acrylic Acids: a One-Pot Approach to Biobased Poly(meth)acrylates

International audience; Shifting from petrochemical feedstocks to renewable resources can address some of the environmental issues associated with petrochemical extraction and make plastics production sustainable. Therefore, there is a growing interest in selective methods for transforming abundant renewable feedstocks into monomers suitable for polymer production. Reported herein are one-pot catalytic systems, that are active,<br&gtproductive, and selective under mild conditions for the synthesis of copolymers from renewable materials. Each system allows for anhydride formation, alcohol acylation and/or acid esterification, as well as polymerization of the formed (meth)- acrylates, providi…

Fabrication De Matériaux Composites À Fibres De Lin En Vue D’une Application De Mobilier Urbain Ultraléger Et Mobile

International audience; L’effet de massification automobile qui accompagne les besoins croissants de mobilité terrestre et l’offre de nouvelles infrastructures routières qui soutient de nouvelles demandes rendent les modèles de mobilité actuels de plus en plus difficilement acceptables. En effet, les personnes souffrent de l’inconfort des villes engorgées (nuisances), de l’insécurité lors de transports du fait de défaillances techniques ou humaines, de la très grande difficulté d’optimiser ses itinéraires en fonction des horaires ou circonstances exceptionnelles (accident par exemple). Par ailleurs, la mobilité se heurte toujours aux contraintes liées aux rigidités des infrastructures compo…

Influence du chargement thermohydrique sur le comportement mécanique statique, cyclique et dynamique des composites renforcés de fibres de lin

International audience; Ce travail porte sur la caractérisation de l’influence d’un chargement thermohydrique sur le comportement en traction quasi-statique, en fatigue et vibratoire d’un matériau composite lin/époxy unidirectionnel. Les résultats montrent que lorsque ces composites sont exposés à ces conditions hygrothermiques (70°C et 85% d’humidité relative), ils absorbent de l’eau suivant une loi de Fick 1D. L’absorption d’eau induit un changement de l’allure de la réponse en traction, diminue le module élastique d’environ 20% et augmente le coefficient d’amortissement d’approximativement 50%. La résistance sous chargement monotone n’est pas significativement affectée par l’absorption d…

Industrial Hemp Transformation for Composite Applications: Influence of Processing Parameters on the Fibre Properties

The main objective of this collaborative work is to characterize the influence of the processing stages of industrial hemp on the fibre properties. Transformation processes well suited for composite reinforcing textiles are considered. The work focuses on the different stages along the transformation chain of hemp, from the straw retting to the preform manufacturing. The main highlight is the predominant influence of retting on the tensile properties of individual fibres after their mechanical extraction from the stalks. Regarding the secondary processing, different technologies such as spinning, and use of natural binder systems are also proposed to produce yarns and woven fabrics. The eff…

Bio-composites for structural urban outdoor applications - A study of the impact of fiber content on the durability of flax fiber-reinforced epoxy composites

International audience

Design and synthesis of biobased epoxy thermosets from biorenewable resources

International audience; Biobased diepoxy synthons derived from isoeugenol, eugenol or resorcinol (DGE-isoEu, DGE-Eu and DGER, respectively) have been used as epoxy monomers in replacement of the diglycidyl ether of bisphenol A (DGEBA). Their curing with six different biobased anhydride hardeners leads to fully biobased epoxy thermosets. These materials exhibit interesting thermal and mechanical properties comparable to those obtained with conventional petrosourced DGEBA-based epoxy resins cured in similar conditions. In particular, a high Tg in the range of 90–130 °C and instantaneous moduli higher than 4.3 GPa have been recorded. These good performances are very encouraging, making these n…

Metals in aqueous solutions and real effluents: biosorption behavior of a hemp-based felt

In this study, a hemp-based material in the form of a felt is used to adsorb metals in individual aqueous solutions and in polycontaminated effluents using the batch method. The factors affecting the biosorption process were initial metal concentration, biosorbent dosage, contact time and pH. In controlled conditions, results showed that: (i) the felt exhibited high adsorption capacities towards metals in the following order: Pb g (ii) no significant differences were observed for the three salts used (sulfate, chloride and nitrate); (iii) the process was rapid: 10 min were sufficient to attain equilibrium ; iv) the biosorption efficiency increased considerably with the increase of the bioso…

Development and characterization of a bio-based epoxy matrix for high-grade bio-based composites

This study aims to develop 100% bio-based hemp/epoxy composites for semi-structural and structural applications. The thermal and mechanical performances of a 100% bio-based matrix derived from biomassare evaluated and reveal properties in the same order of magnitude as those obtained for polyepoxides based on DGEBA, that means a glass transition temperature of approximately 150°C and mechanical properties in the order of 120MPa for the maximum stress and 3.2 GPa for the tangent apparent modulus. This natural origin matrix is then used for the manufacture of composites reinforced with hemp rovings. The bending properties of these 100% bio-based materials are equivalent to those determined fo…

Mechanical characterization of bio-based composite/metal laminates for an application in street furniture

In this work, it is proposed to study the influence of three manufacturing parameters in the development of bio-basedcomposite/steel hybrids. These parameters arethe methodof assembly between composite and metal, the distribution of composite and steellayers throughthe thicknessof the hybrid,and the stacking sequence of the composite part of the hybrid. The study was conducted through impact tests at different energies and quasi-static three-point bending tests. For each of these parameters, the influenceon the mechanical properties of the hybrid is evaluated.The results show that these properties depend essentially on the relative distribution of steel and composite through the thickness.

Biomass-derived phenylpropenes as precursors of thermosetting epoxy resins : from synthesis to materials

International audience; As demonstrated by the current international awareness, and supported by several independent studies, the replacement of fossil fuels and the need to find competitive alternatives are crucial issues to reduce global warming, and to limit the consequences for life on Earth [1]. As part of this challenge, the biomass and molecules from the living can be considered as providential pools of renewable building blocks dedicated to the chemistry of the future. This is particularly true in polymer science, where the use of renewable resources for the synthesis of fully or partially biobased materials arouses a great deal of interest, in academia and industry [2].

Caractérisation mécanique de matériaux hybrides composites biosourcés/métal pour le mobilier urbain

Towards Fully Bio-Based Thermosets: From Prepolymers Synthesis to Composite Applications

International audience

New reactive isoeugenol based phosphate flame retardant : toward green epoxy resins

A biobased reactive phosphate flame retardant derived from isoeugenol was synthesized and fully characterized (1H, 13C, 31P NMR, FTIR, MS) with the aim of improving flame retardancy behavior of bio...

Development and characterization of a bio-based epoxy matrix for high-grade bio-based composites

This study aims to develop 100% bio-based hemp/epoxy composites for semi-structural and structural applications. The thermal and mechanical performances of a 100% bio-based matrix derived from biomassare evaluated and reveal properties in the same order of magnitude as those obtained for polyepoxides based on DGEBA, that means a glass transition temperature of approximately 150°C and mechanical properties in the order of 120MPa for the maximum stress and 3.2 GPa for the tangent apparent modulus. This natural origin matrix is then used for the manufacture of composites reinforced with hemp rovings. The bending properties of these 100% bio-based materials are equivalent to those determined fo…

Étude d'un procédé de traitement innovant des fibres de chanvre sous condition de fluide supercritique et propriétés induites

International audience

Vieillissement accéléré et propriétés mécaniques des fibres issues du chanvre

International audience; L’objectif de ce colloque est de regrouper les personnes du monde académique et de l’industrie intéressées par le comportement en fatigue et la durabilité des composites biosourcés et de leurs constituants. Ce colloque permettra de faire un état des lieux sur les connaissances actuelles, de partager les dernières avancées effectuées dans le domaine et d’échanger sur les principaux verrous à lever pour accéder à une utilisation pérenne des composites biosourcés dans les applications structurales.

Crystal structure of the diglycidyl ether of eugenol

The diep­oxy monomer (DGE-Eu) was synthesized from eugenol by a three-step reaction. It consists of a 1,2,4-tris­ubstituted benzene ring substituted by diglycidyl ether, a meth­oxy group and a methyl­oxirane group. The three-membered oxirane rings are inclined to the benzene ring by 61.0 (3) and 27.9 (3)°. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to the ab plane.

Fibre extraction from oleaginous flax for technical textile applications: influence of pre-processing parameters on fibre extraction yield, size distribution and mechanical properties

International audience; Cultivated primarily for its seeds, oleaginous flax could also be valued for the different fractions that can be extracted from the straw. However, as the straws are not harvested with the same technique and care than for the textile flax, the classical scutching technique cannot be used. As a consequence, an “all fibre” device was used to perform the separation of the different constituents of the oleaginous flax straws. The different fractions were quantified for two retting levels and for two degrees of rewetting of the stems. The physical and mechanical properties of fibres were then evaluated. It appears that the relative amount of fibres extracted from oleagino…

Etude du comportement en fatigue d’un composite lin-époxy soumis à un vieillissement hydro-thermique.

International audience