Contribution to the formulation of green lubrificants using local biomass

International audienceFriction and wear are the first causes of the decrease of the performances and the durability in mechanical systems. The role of lubrication is to minimize friction between the sliding surfaces to protect them from wear. Conventional liquid lubricants are constituted of a base oil and solid additives particles presenting specific properties, such as friction reduction and antiwear performances. The role of friction reducers is to ensure the lubricating performances in boundary lubrication regime. Commercial lubricants generally use graphite and petroleum-based oils because of their recognized lubricating properties, their stability and low cost. However, such lubricants induce health and environmental hazards due to their life cycle.The aim of this work is to investigate the possibility to use local biomass in order to produce environmentally-friendly lubricants. Local vegetable oils are interesting candidates because of their inherent qualities like renewability, bio-degradability, non-toxicity. This work shows that such natural oils present better friction performances than petroleum-based ones. Then considering friction reduction additives, the tribological behaviour of activated carbons synthetized from biomass is evaluated and special attention is paid to the role of the carbon structure, in terms of morphology, size, porosity of the carbon particles on the friction properties of the additives. The tested activated carbons are obtained from either terrestrial (sugar cane bagasse, banana tree, etc.) or alga (sargassum alga) precursors. Very good friction performances are observed by selecting the adequate precursor and tunning the activation experimental conditions. Finally, the determination of the tribological properties of activated carbons/natural oils mixtures results in the first formulation step of our lubricant made from local biomass

Friction Properties of Fluorinated Graphitized Carbon Blacks

International audienceThe tribologic properties of graphitized carbon blacks and their fluorinated derivatives are investigated as a function of the fluorination rate. Very low intrinsic friction coefficients are obtained for highly fluorinated compounds. The correlation of the tribologic results and structural investigations of the initial compounds by TEM strongly suggests that the friction mechanisms involve surface effects in the early stage of friction. Long-term tribologic experiments and Raman analyses point out an evolution of the structure and composition of the tribofilms during the friction process leading to similar friction properties of the tribofilms. Wear studies revealed that highly fluorinated derivatives appear less efficient than pristine and weakly fluorinated compounds

Analytical Transmission Electron Microscopy Investigation of the Fluorination Process of Carbon Nanoparticles.

International audienc

Fluorinated Nanocarbons for Lubrication.

International audienc

G.P.357 - Early expression of ΔCH1 dystrophin isoform reverses or prevents muscular dystrophy in the Dup2 mouse

International audienceno abstrac

Utilisation des (nano)carbones pour la mise au point de nouvelles générations de lubrifiants.

International audienc

Molecular clues about the dystrophin-neuronal nitric oxide synthase interaction: a theoretical approach.

International audienceDystrophin is a large skeletal muscle protein located at the internal face of the plasma membrane and interacting with membrane phospholipids and a number of cytosolic proteins. Binding of neuronal nitric oxide synthase (nNOS) to dystrophin appears to be crucial for exercise-induced increases in blood supply in muscle cells. By contrast, utrophin, the developmental homologous protein of dystrophin, does not display nNOS interaction. Recent in vitro and in vivo experiments showed that the dystrophin region involved in nNOS binding is located in spectrin-like repeats R16 and R17 of its filamentous central domain. Using homology modeling and atomistic molecular dynamics simulation, we compared the structural organization and surface potentials of dystrophin, utrophin, and chimeric fragments, thus revisiting the dystrophin-nNOS binding region. Our simulation results are in good agreement with experimental data. They provide a three-dimensional representation of the repeats and give insight into the molecular organization of the regions involved in dystrophin-nNOS interaction. This study also further elucidates the physical properties crucial for this interaction, particularly the presence of a large hydrophobic patch. These results will be helpful to improving our understanding of the phenotypic features of patients bearing mutations in the nNOS-binding region of dystrophin