Relations structures-propriétés dans les composites 100 % naturels, bio-sourcés, renforcés par des fibres végétales

Le devenir des matières plastiques issues de la production pétrolière est de plus en plus remis en cause et en conséquence de nouvelles matières plus repectueuses de l'environnement sont proposées. Parmi ces nouvelles matières, les plastiques issus de bio-ressources en général, et l'amidon en particulier, semblent être capables de remplacer les matières plastiques issues de la pétrochimie. Ainsi, le premier objectif de ce travail est d'étudier l'influence des différents constituants utilisés pour la mise en oeuvre d'une matrice thermoplastique à base de farine de blé sur les propriétés physiques des films obtenu. Nous avons réalisé des films de compositions différentes et comparé les structures, les morphologies, les propriétés thermiques, mécaniques et vibro-acoustiques obtenues. Puis, nous nous sommes intéressés à la valorisation des fibres naturelles (coton, lin et bambou) par leur incorporation dans notre matrice. Ces fibres n'ont pas été choisies par hasard. En effet, le coton est issu du recyclage de découpe de tissus, la fibre de lin courte est un sous-produit de la production des fibres longues et enfin le bambou a l'avantage de croître très rapidement. Nous avons pu montrer dans un premier temps, que la composition de la matrice initialement établie dans un brevet peut être simplifiée et améliorée par la suppression de certains constituants comme la silice, le stéarate de magnésium et le sorbitol en partie. Dans un deuxième temps, des composites 100 % naturels "low-tech" ou à courte durée de vie ont été réalisés en variant la nature du renfort utilisé. A l'avenir, les performances observées peuvent permettre de cibler des marchés bien spécifiques.Over the last decades the consumption of synthetic polymers and their products increased rapidly and the problems concerning the plastic wastages are now one of the most important limiting factors for its extensive usages. The research efforts are being harnessed in the development of fully biodegradable "green" materials. Among these new materials , plastics resulting from bio-resources in general, and starch in particular, seem to be able to replace polymers resulting from petro chemistry. Thus, the primary goal of this work was to study the effect of the composition of a wheat flour based matrix on the physical properties. By the mean of an extrusion process, we carried out films with different compositions and compared the structures, morphologies, the thermal and mechanical properties obtained. Then, we focused on the valorisation of natural fibres (cotton, flax and bamboo) by their incorporation in our matrix. These fibres were not chosen by hazard, indeed, cotton is resulting from the recycling of fabric cutting, the short flax fibres are a by-product of the production of long fibres and finally the bamboo because this plant can present very fast growths. We could show initially that the matrix composition initially established in a patent can be simplified and improved by the suppresion of certain components like silica, stearate of magnesium and partly the sorbitol. Then, "low-tech" 100 % natural composites (short life time) were carried out by varying the nature of the reinforcement used. In the future, these performances will make it possible to target quite specific markets.ROUEN-BU Sciences Madrillet (765752101) / SudocSudocFranceF

Are 100% Green Composites and Green Thermoplastics the New Materials for the Future?

A review of the history of the evolution of material science and material technology shows us that one tendency for the future could be the use of agriculture resources. In this work, we review the performances of one of these resources, that is, wheat flour. We show that it is possible to get thermoplastic films with properties quasiequivalent to what is obtained for expensive pure starch. By adding natural fibres, composites are also obtained. These composites exhibit performances which allow their use only for short duration

Agromatériaux à base de farine de blé renforcés par des fibres de coton

International audienc

Synthetic Polymer Composites Reinforced by Bamboo Fibers

International audienc

Vibro-Acoustic Behaviour in Biosourced Composites

International audienc

Studies on the physico-mechanical, thermal, and morphological behaviors of high density polyethylene/coleus spent green composites

This study is aimed at utilizing nutraceutical industrial waste and reducing carbon footprints of plastics. Eco-friendly ``green composites'' of high density polyethylene (HDPE) were fabricated using coleus spent (CS)-a nutraceutical industrial waste as reinforcing filler and maleic anhydride-graft-polyethylene (MA-g-PE) as compatibilizer. Composites were fabricated with 5, 10, 15, and 20% (w/w) of CS by extrusion method. The fabricated HDPE/CS composites were evaluated for mechanical and thermal behavior. A slight improvement of about 5% in tensile strength and marked improvement of about 25% in tensile modulus for 20 wt % CS filled HDPE composites was noticed. The effect of CS content on rheological behavior was also studied. Thermal characteristics were performed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA thermogram indicated increased thermal stability of CS-filled composites. From TGA curves the thermal degradation kinetic parameters of the composites have been calculated using Broido's method. The enthalpy of melting (Delta H(m)) obtained from DSC curves was reduced with increase in CS content in HDPE matrix, due to decrease in HDPE content in composite systems. An increase in CS loading increased the water absorption behavior of the composites slightly. Morphological behavior of cryo-fractured composites has been studied using scanning electron microscopy. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1889-1895, 201

Investigation of the Interactions Involved in the Formation of Nanotubes from Organogelators

Investigations into the formation of nanosized structures, particularly nanotubes, by a diamide ester compound are reported. Two aspects are concurrently examined: the role of the solvent and the role of the alkyl chain. The former is addressed by using a benzene derivative (<i>o</i>-xylene) and a totally saturated double ring (<i>trans</i>-decahydronaphthalene) whereas the latter is achieved by replacing the hydrogenous alkyl chain with its fluorinated counterpart while keeping the overall architecture the same. The thermodynamic behavior by differential scanning calorimetry, the morphology by transmission electron microscopy, and the structure by X-ray scattering and small-angle neutron scattering are studied. Despite the identical architecture, the fluorinated molecule does not produce any nanotubes, unlike its totally hydrogenous counterpart. Also, <i>o</i>-xylene prevents the hydrogenous molecule from forming nanotubes, while nanotapes are produced instead. Conversely, the fluorinated molecule produces regularly twisted protostructures in either solvent. Neutron scattering experiments show that the fluorinated alky chain is located within the core of this structure. This suggests that the prerequisite for forming nanotubes relies on the necessity of the alkyl group to point outward