A thermal, rheological and mechanical material characterization of an aeronautic epoxy resin from commercial prepreg is reported in this article. The kinetic of the crosslinking reaction of the resin ...is characterized and modeled. The specific heat, the glass transition temperature, the thermal expansion coefficients, the chemical shrinkage coefficients and the thermo-mechanical properties have been investigated as a function of temperature and degree of cure. Dynamic mechanical measurements are used to determine the gel point. Finally, the residual stresses developed during the curing process are calculated using a finite element simulation, taking into account the material properties evolutions according to proposed models. The results highlight the importance of the characterization accuracy and the associated models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the era of limited energy resources, researchers and scientists are highlighting bioenergy or biomass energy as a sustainable form of renewable and upgradable energy source. Hydrothermal ...liquefaction, known as HTL, is a thermochemical conversion process which produces mainly biocrude, from several biomass types: microalgae, waste water, crops, etc. Commercializing HTL and upscaling it for industrial applications needs intensive studies for building continuous systems. This work defines the HTL of biomass, including the major components of a continuous system: feeding system, heating system, reactor and separator. Many previous studies are compared to investigate the effect of operating parameters; residence time, temperature, pressure, flow rate, catalyst and co-solvent types on the products’ qualities and quantities. In addition, using data from previous HTL studies, a new analytic study concerning the effect of the biomass composition on the optimum temperature of liquefaction and the maximum yield of biocrude is presented and the results show the effect of the biomass used on these values. Although, using previous works of continuous HTL systems, this work presents all the aspects of continuous processing, including the hardware used and the parameters involved in the hydrothermal processing of biomass. In addition, a transition phase from batch to continuous processing, re-defining the variables needed for the design, is proposed. The analysis of the biomass components and the operating parameters effects, and, the proposed transition phase will be used to select and calibrate the suitable conditions for designing and constructing a large scale continuous HTL system.
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•State of the art is set on continuous hydrothermal processes design.•Construction materials and heating modes are discussed.•Operating parameters effects on products of continuous systems discussed.•Effects of feeding characteristics on products discussed.•Effects of catalysts and solvents are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An extensive material study of an aeronautic epoxy resin from commercial prepregs is reported in this article. The kinetics of the chemical reaction and the heat capacity are characterized by ...differential scanning calorimetry (DSC). The thermal conductivity, the thermal expansion coefficient, crosslinking heat flux and associated degree of cure, the volumetric shrinkage, the effective chemical shrinkage coefficient have been identified using a specific mold (named PVTα mold). Dynamic mechanical measurements are used to determine the rheological properties. The gel times at different curing temperatures are estimated. The degree of polymerization at the gel point is found to be independent of temperature. Finally, the residual stresses in a composite part are calculated using a finite element simulation and taking into account the evolution of the material properties, the temperature and degree of cure gradients during the curing process.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
