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International audience; The influences of selected catalysts on the structures and properties of polyurethane prepolymers and networks are investigated to adjust the catalyst/structure/properties relationship to a targeted application. This study highlights the necessity of catalysis for polyurethane synthesis, both at the prepolymer and at the crosslinking stages, and emphasizes on the catalyst-dependency of each stage. We also suggest some tin-free and overall metal-free alternatives to ubiquitous tinbased catalysts with metals such as Bi, Ti, Zn and organic catalysts such as DABCO, DMDEE. In polyurethane formulations without fillers, the strong interwoven urethane-and urea-devired H-bonding network is mainly responsible for the mechanical properties of the material and tends to overshadow the catalyst effects. Nonetheless, in presence of fillers such as those used in industrial polyurethane formulations, tensile test evidenced that mechanical properties are affected and can be tailored by the choice of catalyst.

An hypothetical 220 MW pumped storage power plant to be incorporated in Uruguayan grid was considered. System operation modelling and an operation along 20-year simulation in order to estimate whole system supply cost savings was made applying the SimSEE tool. As outstanding results total cost much lower than the estimated without the system and some of projects main specifications should change in order to make it economically feasible. In addition, to have a better visualization how this technology might operate, simulations where run for several random weeks, including one during 2020 pandemic period.