Chiara Vianello

Microwave-assisted synthesis of isosorbide-derived diols for the preparation of thermally stable thermoplastic polyurethane

Abstract In order to prepare thermally stable isosorbide-derived thermoplastic polyurethane, the synthesis of two new chiral exo–exo configured diols, prepared from isosorbide, and two types of diphenols (bisphenol A and thiodiphenol) was described. The synthesis conditions were optimized under conventional heating and microwave irradiations. To prove their suitability in polymerization, these monomers were successfully polymerized using 4,4′-diphenylmethane diisocyanate (MDI) and hexamethylene diisocyanate (HDI). Both monomers and polymers have been studied by NMR, FT-IR, TGA, DSC; intrinsic viscosity of polymers has also been determined. The results showed the effectiveness of the synthetic strategy proposed; moreover, a dramatic reduction of the reaction time and an important improvement of the monomers yield using microwave irradiation have been demonstrated. The monomers, as well as the polymers, showed excellent thermal stability both in air and nitrogen. It was also shown that the introduction of sulphur in the polyurethane backbone was effective in delaying the onset of degradation as well as the degradation rate.

Preliminary study of epoxidation of soybean oil in stirred tank reactor: The effect of the mixing program

Epoxidated vegetable oils are largely employed as plasticizer instead of harmful phthalates and they represent a sustainable choice to produce lubricants and intermediates. In this work, the epoxidation of soybean oil is carried using hydrogen peroxide (H2O2) 32wt.% and acetic acid instead of the commonly used H2O2 at 60wt.% and formic acid to reduce the risk of detonation and corrosion. The efficacy of an acid catalyst (sulfuric acid) is tested. Particular attention is focussed on a proper mixing program.

A complete approach for the determination of the heat exchange coefficient of a calorimetric reactor

The study of heat exchange is fundamental to perform an accurate thermal study in a calorimetric, jacketed, stirred tank reactor. Moreover, since cooling or heating in a jacketed stirred reactor is an indispensable operation to control a process, the knowledge of the rate of the heat exchange is needed. In this way, the heat exchange coefficient should be determined with a good precision. In the literature, a theoretical semi-empirical approach is provided by Sinnot (2005), who provides a set of correlations by mean the heat exchange coefficient can be calculated. Each correlation is valid for only a kind of impeller. Several articles deal with the empirical determination of the heat exchange coefficient, as the case of Raguraman et al. (2012), Dostàl et al. (2010) or Debab et al. (2010). Essentially, all the methods are obviously based on the enthalpy balance as Eq(1):

Structural Behaviour of Multi-storey Buildings Subjected to Internal Explosions

Structural Behaviour of Multi-Storey Buildings Subjected to Internal Explosion Michael Andreotti, Paolo Mocellin, Mariano Angelo Zanini, Chiara Vianello, Carlo Pellegrino, Claudio Modena, Giuseppe Maschio Department of Civil, Envirnmental and Architectural Engineering, University of Padua, Via Marzolo 9, Padova (Italy) Department of Industrial Engineering, University of Padua, Via Marzolo 9, Padova (Italy) michael.andreotti@studenti.unipd.it