Valorisation des déchets ligno-cellulosiques pour la préparation d’un nouveau matériau composite PVC/farine des noyaux de dattes

Afin de limiter l’utilisation des énergies fossiles et de valoriser les déchets ligno-cellulosiques, les composites à fibres naturelles s’inscrivent dans un contexte favorable qui permettra de répondre à des enjeux environnementaux, économiques et sociaux grâce à leurs propriétés de faible coût, faible densité, renouvelables et de biodégradabilité. L’objectif de cette étude est de développer un nouveau matériau composite constitué d’une matrice thermoplastique, le polychlorure de vinyle (PVC), renforcée par des fibres naturelles à base des noyaux de dattes (FND) avec des taux de charge allant de 10 à 40 % massique. Différentes techniques d’analyses ont été utilisées pour étudier les propriétés mécaniques, morphologiques et la perméabilité d’eau des échantillons obtenus. Les résultats enregistrés indiquent que la contrainte à la rupture diminue avec l’augmentation du taux de charge en FND tandis que la rigidité augmente. L’analyse morphologique par microscopie électronique à balayage (MEB) montre une meilleure dispersion pour de faible taux de charge en FND. Une très faible absorption d’eau a été enregistrée

Thermomechanical and acidic treatments to improve plasticization and properties of chitosan films A comparative study of acid types and glycerol effects

Plasticized and unplasticized chitosan films were successfully prepared by thermomechanical treatment, as a possible alternative route to solvent casting method. Acetic acid and lactic acid were used as solvents and glycerol was used as plasticizer with a fixed concentration of 25 wt.-%. The properties of the prepared samples were investigated demonstrating the effects of acid type and the addition of glycerol. Microstructure analysis results revealed a homogeneous and cohesive matrix, indicating a smooth surface without pores, cracks and irregularities. Unplasticized samples with lactic acid showed lower stiffness, higher elongation at break, more thermal stability, higher water uptake and water vapor permeability compared to the samples prepared with acetic acid. The introduction of glycerol affected all properties of the samples, but the samples prepared with lactic acid were more influenced. The rheological and mechanical properties (tensile strength and elongation at break) were improved when glycerol was added, resulting in a ductile behavior with a small plastic deformation and higher elongation at break compared to unplasticized films. On the other side, thermal properties were negatively affected by a decrease in the thermal stability. The water uptake and WVP measurements verified that the hydrophilic character of the material was enhanced by the addition of glycerol

Effects Of Acetylation Process And Cellulose Content On The Mechanical, Thermal, Morphological And Rheological Properties Of Poly (Vinyl Chloride)/Cellulose Composites

International audienceThe aim of the present work is the chemical modification of microcrystalline cellulose (MCC) by acetic anhydride and using it as reinforcement in poly (vinyl chloride) (PVC). The treatment efficiency was assessed by Fourier Transform Infrared Spectroscopy (FTIR) analysis and contact angle measurements. Likewise, the morphological, mechanical, thermal and viscoelastic properties of the composites were studied. The different changes in the FTIR spectra and contact angle measurements corroborate the occurrence of chemical modification. The acetylation has improved the compatibility between the PVC and MCC by diminishing the surface energy of the fiber. This contributes to the amelioration of the interfacial adhesion, which appears in the SEM images. The treated and untreated cellulose has decreased the mechanical properties of PVC. The modulus and the thermal stability of PVC were improved by the introduction of both untreated and treated cellulose

Different compatibility approaches to improve the thermal and mechanical properties of EVA/starch composites

Biocompostable composites based of ethylene‐co‐vinyl acetate (EVA) copolymer were prepared by using a twin‐screw extruder. The compatibility between EVA/starch composites were improved either by addition of polyethylene‐grafted maleic anhydride (PE‐g‐MA), or by reactive extrusion with maleic anhydride (MA) and benzoyl peroxide. The crystallinity of the non‐compatibilized composites increased with the starch content. The addition of PE‐g‐MA increased the crystallinity of the composites made with up to 20 wt% of starch. The thermal stability of EVA/starch composites decreased with increasing the starch content, and the addition of PE‐g‐MA compatibilizer enhanced the thermal stability of the composite. The in‐situ grafting with MA and PBO led to an increase in the thermal stability of the composites containing higher amounts of starch. Further, the mechanical properties of the compatibilized EVA/starch composites were improved with increasing the starch content and this was ascribed to the improved interfacial interactions between starch and EVA

Comportement mécanique et propriétés thermique des composites polyéthyènes renforcés par des fibres lignocellolusiques

Un intéret particulier a été porté au grignons dʼolive, qui est un sous produit des rejets des différentes huileries. Chaque année, des milliers de tonnes de ce produit sont incinérés ou carrément rejetés dans la nature. Ce dernier, dont les caractéristiques restent à valoriser, est mis à profit par son incorporation comme charge dans lʼélaboration des matériaux composites à matrice polyéthylène haute densité (PEHD). Pour réduire le caractère hydrophile de la farine, un agent compatibilisant (polyéthylène greffé anhydride maléique) commercialisé sous le nom XA255 a été utilisé. Les échantillons obtenus par extrusion et injection seront ensuite caractérisés par différentes techniques dʼanalyse à savoir, le test de traction, lʼanalyse thermogravimétrique (ATG/DTG), lʼanalyse enthalpique différentielle (DSC) et lʼanalyse microscopique électronique à balayage (MEB). Avec lʼincorporation de la farine de grignon dʼolive (FGO) dans la matrice PEHD, la contrainte à la rupture diminue, tandis que la rigidité du matériau et le taux de cristallinité augmentent. Après traitement, on enregistre une amélioration, à la fois de la contrainte à la rupture et du module de Young, due principalement à une meilleure adhésion fibre/matrice, confirmée par lʼanalyse MEB. Lʼanalyse thermogravimétrique a montré une meilleure stabilité thermique des formulations F30 traitée, qui se manifeste par la diminution de la vitesse maximale de décomposition

Characterization of polylactic acid green composites and its biodegradation in a bacterial environment

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Effect of alfa fiber loading on the mechanical, physical and dielectric properties of epoxy-amine composite

International audienceIn this work, a varied content of alfa fiber was used as reinforcement and epoxy resin as matrix material. In order to eliminate the amorphous part of the alfa fiber, the fibers are treated with 5% of sodium hydroxide solution and their weight fraction is varied between 10% and 30%. Dielectric and water characteristics of different content of untreated and alkali treated alfa reinforced epoxy matrix is carried out in order to determine the role of cellulosic fibers in electrical field. Then, the Fourier transform infrared (FTIR) is employed to analyze the chemical structure of epoxy resin before and after curing with amine hardener. FTIR and Differential Scanning Calorimetry analysis confirm that epoxy resin is completely cured with amine hardener at room temperature. For composites loaded with 30% treated and untreated alfa fiber, a decrease in tensile and dielectric properties has been obtained, this may be related to the random distribution of alfa fiber in the epoxy matrix. Scanning electron microscopy analysis highlight the microstructure of epoxy matrix and its composites. The bio composites elaborated on the basis of alfa fiber and epoxy matrix have good physical and dielectric properties can be applied in different fields

Effects of MAPP Compatibilization and Acetylation Treatment Followed by Hydrothermal Aging on Polypropylene Alfa Fiber Composites

This work investigates the effect of hydrothermal aging on the properties of polypropylene/alfa fiber composites. Hydrothermal aging was induced in an environmental testing chamber at 65 degrees C and 75% relative humidity (RH) over a 1000 h period. At the beginning (t = 0h), the results showed that Young's moduli of the untreated alfa fibers and the acetylation-treated fibers increased by 21% and 36%, respectively, compared with the virgin polypropylene (PP). Additionally, Young's moduli decreased by 7% for the compatibilized composites composed of maleic anhydride grafted polypropylene (MAPP). After 1000 h of aging, Young's moduli decreased by 36% for untreated alfa fibers and 29% for the acetylation-treated alfa fibers and the compatibilized composites. Significant degradation was observed in the untreated alfa fiber samples. The Fourier transformed infrared (FTIR) allows us to distinguish the characteristic absorption bands of the main chemical functions present in the composite material before and after aging. The thermal properties showed that the thermal stability and the degree of crystallinity of the composites decreased after hydrothermal aging; this result was corroborated by the dynamical mechanical analysis (DMA) results

Morphology and mechanical and viscoelastic properties of rubbery epoxy-organoclay montmorillonite nanocomposites

International audienceThe morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite (MMT) nanocomposites were investigated with wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis. An ultrasonicator was used to apply external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling MMT in a curing agent, that is, an aliphatic diamine based on a polyoxypropylene backbone with a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added to the mixture. Better dispersion and intercalation of the nanoclay in the matrix were expected. The organic modification of MMT with octadecylammonium ions led to an increase in the initial d-spacing (the [d001] peak) from 14.4 to 28.5 Å, as determined by WAXS; this indicated the occurrence of an intercalation. The addition of 5 phr MMTC18 (MMT after the modification) to the epoxy matrix resulted in a finer dispersion, as evidenced by the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MMT and MMTC18 nanocomposites, but they were more pronounced for the modified ones