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Flax fibres progressively find their place in the composite sector. There are already largely used in the automotive sector and some semi-structural part starts to be built. Nevertheless, the biodegradation aspect of flax fibres is often neglected because of the non-biodegradable petrochemical resin used to make those composites. This study deals with the manufacturing parameters as well as the mechanical properties of biocompostables composites made of a flax non-woven and three biocompostables thermoplastic polymers: the poly-(hydroxyalkanoate) (PHA),the poly-(lactic acid)(PLA) and the poly-(butylene succinate) (PBS). Rheology and calorimetry studies were used to determine an optimal manufacturing temperature foreach polymers, aiming to work at a constant viscosity during the film-stacking process. Mechanical results highlight that non-woven flax/PLA shows the highest stiffness however, the flax/PBS has an important strain with an acceptable strength and stiffness regarding the poly-propylene as reference.These preliminary results show the possibility to develop new non-woven composites which are thermoplastic, recyclable, biocompostable, with configurable mechanical properties depending on the selected matrix, La place des fibres de lin dans le domaine des composites n’est plus à présenter. Ces dernières sont déjà couramment utilisées dans le domaine de l’automobile et des pièces structurelles se développent.Cependant, dans la réalisation des composites actuels,la capacité de biodégradation des fibres de lin est souvent délaissée en raison l’utilisation de résine non biodégradable. Cette étude s’intéresse aux paramètres de la mise en œuvre ainsi qu’aux propriétés mécaniques de composites biocompostables réalisés à partir d’un non-tissé de lin et de trois polymères thermoplastiques biocompostables: Le poly-(hydroxy-alcanoate) (PHA), le poly-(lactide) (PLA)et le Poly-(butylène-succinate) (PBS). Des études rhéologiques et calorimétriques ont permis de déterminer une température de mise en œuvre optimale pour chacun des composites afin de travailler à viscosité constante avec le procédé de film-stacking. Les résultats mécaniques montrent que le non-tissé PLA-lin possède la plus forte rigidité,mais que le PBS/lin permet d’atteindre un allongement important tout en conservant une rigidité, une contrainte et un allongement à rupture performants par rapport au poly-(propylène) (PP) de référence. Ces résultats préliminaires permettent d’envisager le développement de nouveaux composites non-tissés thermoplastiques, recyclables,biocompostables et aux performances mécaniques adaptables au cahier des charges en fonction de la matrice sélectionnée.

Two known tin-based polymers of formula {[R3Sn(CH3COO)]n} where R = n-Bu&ndash, (1) and R = Ph&ndash, (2),were evaluated for their in vitro biological properties. The compounds were characterized via their physical properties and FT-IR, 119Sn M&ouml, ssbauer, and 1H NMR spectroscopic data. The molecular structures were confirmed by single-crystal X-Ray diffraction crystallography. The geometry around the tin(IV) ion is trigonal bi-pyramidal. Variations in O&ndash, Sn&ndash, O&middot, &middot, Sn&prime, torsion angles lead to zig-zag and helical supramolecular assemblies for 1 and 2, respectively. The in vitro cell viability against human breast adenocarcinoma cancer cell lines: MCF-7 positive to estrogens receptors (ERs) and MDA-MB-231 negative to ERs upon their incubation with 1 and 2 was investigated. Their toxicity has been studied against normal human fetal lung fibroblast cells (MRC-5). Compounds 1 and 2 exhibit 134 and 223-fold respectively stronger antiproliferative activity against MDA-MB-231 than cisplatin. The type of the cell death caused by 1 or 2 was also determined using flow cytometry assay. The binding affinity of 1 and 2 towards the CT-DNA was suspected from the differentiation of the viscosity which occurred in the solution containing increasing amounts of 1 and 2. Changes in fluorescent emission light of Ethidium bromide (EB) in the presence of DNA confirmed the intercalation mode of interactions into DNA of both complexes 1 and 2 which have been ascertained from viscosity measurements. The corresponding apparent binding constants (Kapp) of 1 and 2 towards CT-DNA calculated through fluorescence spectra are 4.9 &times, 104 (1) and 7.3 &times, 104 (2) M&minus, 1 respectively. Finally, the type of DNA binding interactions with 1 and 2 was confirmed by docking studies.

The remarkable ability of polymeric additives to reduce the level of frictional drag significantly in turbulent flow, even under extremely low dilutions, is known as turbulent drag-reduction behavior. Several bio-polymers have been assessed as promising drag-reducing agents for the potential replacement of high molecular weight synthetic polymers to improve safety and ameliorate environmental concerns. This article reviews the recent advances regarding the impact of several bio-polymer additives on turbulent drag reduction in either pipe or rotating disk flow systems, and their potential applications in the petroleum, biomedical, and agricultural industries.

Hydroxyapatite composites are the main biomaterials used for metal implant coatings. Their in vitro study is very important. That is why their behavior was monitored in simulated body fluid (SBF), which is a solution with ion concentrations and pH value similar to those of human blood plasma. Silica, chitosan and gelatin-doped hydroxyapatite-based biomaterials were studied in SBF; the samples were characterized pre-, during and post-SBF immersion using infra-red, scanning and transmission electron spectroscopy and X-ray diffraction methods. The solubility of materials in SBF was determined, and the variation of Ca2+ and phosphorus concentration was also recorded during SBF experiments. The results were compared and their in vitro biological activity was determined.

In this study, we simulate the electrophoretic motion of a bio-polymer through a synthetic nanopore in the presence of an external bias voltage by considering the hydrodynamic interactions between the polymer and the fluid explicitly. The motion of the polymer is simulated by 3D Langevin dynamics technique by modeling the polymer as a worm-like-chain, while the hydrodynamic interactions are incorporated by the lattice Boltzmann equation. We report the simulation results for three different lengths of the nanopore. The translocation time increases with the pore length even though the electrophoretic force on the polymer is the same irrespective of the pore length. This is attributed to the fact that the translocation velocity of each bead inside the nanopore decreases with the pore length due to the increased fluid resistance force caused by the increase in the straightened portion of the polymer. We confirmed this using a theoretical formula.

Silks have a great potential as sustainable, ecologically benign commercial polymers. Here we discuss this fascinating bio-material by merging the biologist's with the polymer scientist's views i.e. combine insights into the characterisation and understanding of evolved structure, property and function in natural silk proteins with the broad scope of applied disciplines ranging from molecular modelling to rheology and mechanical testing. We conclude that silk cannot be defined simply by only its origin or material composition but any meaningful designation must include the key feature of formation by extrusion spinning. We further conclude that silk 'spinning' largely depends on a highly specific denaturation process dependent on competing molecular-level interactions of hydrogen bonding between water and main chain amide groups in the silk protein chains. Finally we conclude that silks have a bright future not only as archetype models to guide our understanding of highly adapted and energy efficient bio-polymers but also as prototype models to guide the design of totally novel polymer systems. © 2009 Elsevier Ltd. All rights reserved.

Composites from petroleum based polymers and synthetical or mineral fibers can be advantageously replaced by biomaterials from biopolymers and vegetal fibrous reinforcements, allowing recycling and /or biodegradation at the end of their lifecycle. In this purpose, we prepared a wood / lactic acid biopolymer based bio composite. Wood vacuum / pressure impregnation by lactic acid oligomers containing chemical catalyst or not, was followed by a heating process in a drying kiln. The aim of this study was to induce oligomers polymerization into the wood cells, and a potential grafting on the free hydroxyls wood groups, in order to improve wood properties. We showed an effective in-situ polymerization, and a strong interaction between wood and biopolymers chains, however not grafted. The biopolymer impact on the lignocellulosic structure is shown by a significant softening of wood, occurring at an intermediate level of the heating process, probably due to a reaction between lactic acid oligomers and the lignin mainly contained into the middle lamella. The material darkening suggests a probable reaction between chemical catalysts and cellulose. Once the heating process has been completed, the composite gets stiff. The treatment imparts an excellent dimensional stability to the wood composite : an anti swelling efficiency approaching 70%. A good antifungal resistance is also noticed. As for mechanical properties, bending and compression resistances are slightly influenced, while hardness is significantly improved, and shearing resistance altered, due to the middle lamella degradation. Therefore, high density and hardness, plus a good material stability could be valorized by industrial uses such as flooring. In the intermediate state, moulding applications are also conceivable.; La substitution des matériaux composites à base de polymères d'origine fossile renforcés de fibres minérales ou synthétiques, par des bio-matériaux conçus par association de bio-polymères et de renforts fibreux végétaux, permet d'envisager un recyclage et/ou une bio-dégradation en fin de vie. Dans cet objectif, nous avons élaboré un bio-composite à base de bois et de bio-polymère d'acide lactique, par imprégnation vide / pression d'acide lactique oligomérisé, contenant ou non un catalyseur chimique de polymérisation, dans les cellules de bois, suivie d'un chauffage en étuve. L'objectif de ce travail était de provoquer la polymérisation des oligomères d'acide lactique in-situ, et d'induire éventuellement un greffage de ces molécules sur les sites hydroxyles libres du bois, dans le but d'améliorer les propriétés du matériau. Nous avons démontré une polymérisation in-situ effective, et une forte interaction entre le bois et les chaînes d'acide lactique, toutefois non greffées. L'action du bio-polymère sur la structure lignocellulosique est également mise en évidence par un « ramollissement » important du bois, apparaissant à un stade intermédiaire de l'étape de chauffage, vraisemblablement dû à une réaction entre les oligomères d'acide lactique et la lignine contenue principalement dans la lamelle mitoyenne. Une forte coloration traduit d'autre part une probable réaction entre les catalyseurs chimiques et la cellulose. Le cycle de chauffage achevé, le matériau se trouve dans un état final rigide dont les performances ont été étudiées. Il s'avère que le traitement confère une excellente stabilité dimensionnelle au bois : environ 70% d'efficacité anti-gonflement. Une amélioration de la résistance à l'attaque fongique a été observée. En ce qui concerne les propriétés mécaniques, les résistances à la flexion et la compression sont peu influencées, alors que l'on note une forte augmentation de la dureté de surface, et une diminution de la résistance au cisaillement, due à la fragilisation de la lamelle mitoyenne. Ainsi, les densité et dureté élevées, ainsi que la stabilité du matériau laissent envisager des applications dans certains domaines industriels comme la parqueterie. Dans l'état intermédiaire « ramolli », des applications de mise en forme, telles que le matriçage ou le cintrage sont également concevables.

Composites from petroleum based polymers and synthetical or mineral fibers can be advantageously replaced by biomaterials from biopolymers and vegetal fibrous reinforcements, allowing recycling and /or biodegradation at the end of their lifecycle. In this purpose, we prepared a wood / lactic acid biopolymer based bio composite. Wood vacuum / pressure impregnation by lactic acid oligomers containing chemical catalyst or not, was followed by a heating process in a drying kiln. The aim of this study was to induce oligomers polymerization into the wood cells, and a potential grafting on the free hydroxyls wood groups, in order to improve wood properties. We showed an effective in-situ polymerization, and a strong interaction between wood and biopolymers chains, however not grafted. The biopolymer impact on the lignocellulosic structure is shown by a significant softening of wood, occurring at an intermediate level of the heating process, probably due to a reaction between lactic acid oligomers and the lignin mainly contained into the middle lamella. The material darkening suggests a probable reaction between chemical catalysts and cellulose. Once the heating process has been completed, the composite gets stiff. The treatment imparts an excellent dimensional stability to the wood composite : an anti swelling efficiency approaching 70%. A good antifungal resistance is also noticed. As for mechanical properties, bending and compression resistances are slightly influenced, while hardness is significantly improved, and shearing resistance altered, due to the middle lamella degradation. Therefore, high density and hardness, plus a good material stability could be valorized by industrial uses such as flooring. In the intermediate state, moulding applications are also conceivable.; La substitution des matériaux composites à base de polymères d'origine fossile renforcés de fibres minérales ou synthétiques, par des bio-matériaux conçus par association de bio-polymères et de renforts fibreux végétaux, permet d'envisager un recyclage et/ou une bio-dégradation en fin de vie. Dans cet objectif, nous avons élaboré un bio-composite à base de bois et de bio-polymère d'acide lactique, par imprégnation vide / pression d'acide lactique oligomérisé, contenant ou non un catalyseur chimique de polymérisation, dans les cellules de bois, suivie d'un chauffage en étuve. L'objectif de ce travail était de provoquer la polymérisation des oligomères d'acide lactique in-situ, et d'induire éventuellement un greffage de ces molécules sur les sites hydroxyles libres du bois, dans le but d'améliorer les propriétés du matériau. Nous avons démontré une polymérisation in-situ effective, et une forte interaction entre le bois et les chaînes d'acide lactique, toutefois non greffées. L'action du bio-polymère sur la structure lignocellulosique est également mise en évidence par un « ramollissement » important du bois, apparaissant à un stade intermédiaire de l'étape de chauffage, vraisemblablement dû à une réaction entre les oligomères d'acide lactique et la lignine contenue principalement dans la lamelle mitoyenne. Une forte coloration traduit d'autre part une probable réaction entre les catalyseurs chimiques et la cellulose. Le cycle de chauffage achevé, le matériau se trouve dans un état final rigide dont les performances ont été étudiées. Il s'avère que le traitement confère une excellente stabilité dimensionnelle au bois : environ 70% d'efficacité anti-gonflement. Une amélioration de la résistance à l'attaque fongique a été observée. En ce qui concerne les propriétés mécaniques, les résistances à la flexion et la compression sont peu influencées, alors que l'on note une forte augmentation de la dureté de surface, et une diminution de la résistance au cisaillement, due à la fragilisation de la lamelle mitoyenne. Ainsi, les densité et dureté élevées, ainsi que la stabilité du matériau laissent envisager des applications dans certains domaines industriels comme la parqueterie. Dans l'état intermédiaire « ramolli », des applications de mise en forme, telles que le matriçage ou le cintrage sont également concevables.