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Vegetable oils are more and more used in industry for the production of biodiesel, biolubricant, or polymer. In this context, production of polyurethane by nonisocyanate routes involves the production of epoxidized and carbonated vegetable oils. The determination of the optimum operating conditions and the scale-up of these processes require the knowledge of different physicochemical properties such as viscosity, density, refractive index, or specific heat capacity. These data are rare for the epoxidized and carbonated vegetable oils, and the evolution of these data with the temperature is absent in the literature. This article proposes to study the evolution of these properties with temperature and composition in double bond, epoxide, and carbonated groups. It was demonstrated that density and refractive index of these oils vary linearly with temperature. Viscosity of these oils, which were found to be Newtonian fluids, is an exponential function of temperature. The ratio of specific heat capacity at a t...

Biomass valorization processes are being used more frequently in industry. These processes are greener because they use some renewable and biodegradable raw materials, but are they safer? We propose to study the thermal stability of different epoxidized and carbonated vegetable oils. The severity of the thermal risk, i.e., adiabatic temperature rise, was determined by using differential scanning calorimetry tools. The probability of the thermal risk, i.e., time-to-maximum rate under adiabatic conditions, was determined by using an accelerating rate calorimeter. By analyzing these safety criteria, we have found that the thermal risk, essentially during storage and reactor loading, can be assumed to be negligible.

International audience; This study describes the numerical implementation of accurate and fully coupled physical models in order to investigate the sensitivity of Surface Acoustic Wave (SAW) devices using the magnetoelas-tic interaction with an external magnetic field. The model was first validated using experimental data previously published by Kadota et al. obtained with SAW resonators based on quartz substrates and nickel Inter Digital Transducers (IDTs). The model was then used to optimize the geometry of a new magnetostrictive-piezoelectric layered structure (Ni/ZnO/IDT/LiNbO 3), regarding its sensitivity to the magnetic field intensity. The optimized structure was designed and fabricated and experimental results show a good correlation with the numerical modeling. Simulations also show that if alumina is used instead of ZnO, the Ni/Al 2 O 3 /IDT/LiNbO 3 structure exhibits a sensitivity that is 9 times higher than the one based on ZnO.

International audience; Aluminum nitride on sapphire is a promising substrate for SAW sensors operating at high temperatures and high frequencies. To get a measure of the suitability and temperature stability of such devices, an experimental relationship between the SAW performance and the structural properties of the AlN thin films was investigated in the temperature range between the ambient temperature and 1000°C. The crystalline structure of the AlN films was examined in situ versus temperature by X-ray diffraction. The results reveal that the AlN films remain (002) oriented even at high temperatures. A gradual increase of the tensile stress in the film due to the thermal expansion mismatch with the substrate has been observed. This increase accelerates around 600°C as the AlN film crystalline quality improves. This phenomenon could explain the amelioration in the SAW performance of AlN/sapphire devices observed previously between 600°C and 850°C. At higher temperatures, surface oxidation of the AlN films reduces the SAW performance. The potential of ZnO thin films as protective layers was finally examined.