A Useful Biomass Component for Simple Fabrication of the Honeycomb Poly(L-lactide) Film

This concept is the development of useful material based on biomass such as a poly(L--lactide)[PLLA] with new added-value to extend applications. PLLA, which is an attractive raw material produced from renewable resources, has received much attention for applications in bioabsorbable and biodegradable materials. However, PLLA is not utilized well for practical use. This paper has explored an additive compound, which is a biocompatible, to facilitate a regular patterned porous film from PLLA to provide a valuable material. The method we adopted was to form a regular pattern on polymer film containing a surfactant in order to help the amphiphilic polymer to migrate at the interface between the organic solvent and the water droplets as the water-assisted formation method. To give the regular patterned porous film, some compounds from biomass were used for the water-assisted formation method. As surfactants in PLLA solutions, the experimental results showed the effectiveness of soy-bean oil. The pore size and surface morphology on the film can be controlled through the moisture condition, the PLLA concentration, and the molecular weight of PLLA

Suivi de l’infiltration d’une zone de rejet végétalisée par un système d’observation de la qualité de l’eau en continu, cas de Coutières (Deux-Sèvres)

Les zones de rejet végétalisées sont des espaces aménagés entre la station d’épuration et le milieu récepteur, censés contribuer à la réduction de l’impact des rejets sur le milieu naturel. Des incertitudes subsistent toutefois quant à leur capacité réelle à épurer les eaux usées traitées. Ici, les auteurs étudient le fonctionnement de la station de Coutières depuis le procédé de traitement jusqu’au milieu récepteur pour mieux comprendre les phénomènes d’infiltrations et proposer des règles de dimensionnement

Étude de la microstructure et du comportement mécanique de la fibre de soie

Natural polymers seem to be more and more a credible alternative for many applications such as technical or biomedical applications. They have evident qualities such as modularity, durability, and usually biocompatibility. Nevertheless a detailed understanding of the mechanisms governing the behaviour of these materials is difficult and usually incomplete. This study deals with the understanding of the relationship between the mechanical behaviour and microstructure of silk fibres. Precise mechanical characterization has been carried out, sometimes with original experiments such as the association of a mechanical testing machine and electronic microscopy. Hence, it has been shown that silk presents a composite behaviour and all its constituents are important explaining the mechanical behaviour of industrial silk yarns. This behaviour has been described under different atmospheric conditions of temperature and humidity. This characterization has been linked with a microstructural description using X-ray diffraction and Raman spectroscopy techniques. Notably, Raman spectrometry has been associated with an in situ mechanical tester machine. This has permitted a discussion about the link between microstructure and mechanical behaviour. In this way, it has been proved that it is possible to control microstructure and mechanical behaviour using biotechnologic methods at the genetic level. This opens new ways for promising improvements for such material. Finally, a model has been developed, which is simple but effective, based on a physical description of the material. This has validated the advances, made in this study, into the understanding of silk. These results are expected to encourage other numerical studies on assemblies, in order to bring a new point of view about industrial products.Les polymères naturels présentent de plus en plus une alternative crédible pour de nombreuses applications techniques et biomédicales. Ils possèdent des qualités de modularité, de durabilité, souvent de biocompatibilité, qui leurs sont propres. Mais la compréhension détaillée des mécanismes qui gouvernent le comportement de tels matériaux est difficile et reste souvent incomplète. Cette étude a cherché à mieux comprendre le lien qui existe entre le comportement mécanique et la microstructure pour la fibre de soie. Une caractérisation minutieuse du comportement mécanique a donc été effectuée par des moyens parfois originaux comme l'association entre une machine de traction et une observation en microscopie électronique. Il a ainsi été montré l'aspect composite du fil de soie industriel et l'importance des différents éléments constitutifs de la soie. Le comportement de la fibre a également été décrit dans différentes conditions atmosphériques d'humidité et de température. Cette caractérisation s'est accompagnée d'une description de la microstructure en utilisant des techniques telles que la diffraction aux rayons X et la spectrométrie Raman. Notamment, la spectrométrie Raman a pu être associée à une traction in situ. Ceci a permis d'établir des liens entre mécanique et microstructure. Il a ainsi été prouvé notre capacité à modifier la microstructure et le comportement mécanique de la soie par voie biotechnologique en modifiant le génome du Bombyx mori. Ce qui ouvre une nouvelle voie d'innovation prometteuse pour améliorer ce type de matériau. Enfin, une modélisation simple mais robuste basée sur une description physique du matériau a permis de valider les avancées faites quant à la compréhension de ce polymère. Le comportement en environnement contrôlé a été étudié. Ces résultats pourraient alimenter des études numériques sur des assemblages, plus proches du produit fini

Silk: fibres, films and composites – Processing, Structure and Mechanics (ch. 5)

International audienceSilk fibres are produced by a variety of animals but the most widely used silk is made from the cocoon of the Bombyx mori larvae. Silk from spiders has been seen to possess greater strength and elongation to failure and this has prompted research into improving the properties of traditional silk for textile applications and also for more technical uses. The fibre is protein based, i.e. a polyamide, and the possibility of creating regenerated fibres or films, and composites, for technical applications is appealing but requires a detailed knowledge of the fibre micro/nanostructure. Techniques such as FTIR, X-ray diffraction, NMR and Raman spectroscopy coupled to tensile tests are amongst the techniques used for such analyses

Étude de la microstructure et du comportement mécanique de la fibre de soie

PARIS-MINES ParisTech (751062310) / SudocSudocFranceF

Bio-composite aspects of silk : the sericin sheath acting as a matrix

International audienceIndustrial Bombyx mori silk yarns have been degummed and mechanically tested. The principal mechanical characteristics of these yarns have been obtained and compared, before and after degumming. It has been observed that the sericin sheath surrounding the silk fibres plays a bigger part in determining behaviour than had been expected. The initial gradients of the force/strain curves were reduced by 21% when the sericin were removed and this was associated with a 20% fall in the failure forces obtained. The force/strain curves up to failure of the yarns were completely modified with the removal of the sericin and showed a multi-level fracture surface rather than a net failure. This variation was not due to the treatment involved in removing the sericin. The role of the sericin sheath has been studied using scanning electron microscopy with in situ tensile testing. The sericin have been seen to act like a matrix, as in a fibre composite with the silk fibres as the reinforcements. As in a composite, the force transfer between the sericin sheath and the inner fibre is controlled by shear forces at the interface between the two and result in the modified fracture morphology and physical properties

Origin of the variability of the mechanical properties of silk fibres: 3. Order and macromolecule orientation in Bombyx mori bave, hand-stretched strings and Nephila madagascarensis spider fibres

International audienceThe comparison of the low wavenumber of polarized Raman spectra (50–300 cm–1) from Bombyx mori (fresh cocoons fibres, hand-stretched ‘Crins de Florence’ strings from the gland content, dried gland, regenerated silk films) and Nephila madagascarensis silks reveals the high polarisation of fibre modes and the absence of polarisation for dried gland and regenerated silk films. This is consistent with X-ray diffraction measurements. The orientation of the fibroin/spidroin chains is due to the stretching during production, as for advanced synthetic fibres. The bandwidth of the ‘ordered chains’ signature is almost the same for the different fibres. However, the degree of polarisation seems to be higher in the case of spider fibre. The huge bandwidth of low wavenumber components of regenerated films indicates high disorder. Measurements along the fibre point out conformation changes with a periodicity (~20 mm) related to the silkworm head motion during the fabrication of the cocoon

LCA Case Study: Tertiary treatment process options for wastewater reuse

International audienc

LCA Case Study: Tertiary treatment process options for wastewater reuse

International audienc