Maria A. Krähenbühl

The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids

For the first time, the solid-liquid phase diagrams of five binary mixtures of saturated fatty acids are here presented. These mixtures are formed of caprylic acid (C(8:0))+capric acid (C(10:0)), capric acid (C(10:0))+lauric acid (C(12:0)), lauric acid (C(12:0))+myristic acid (C(14:0)), myristic acid (C(14:0))+palmitic acid (C(16:0)) and palmitic acid (C(16:0))+stearic acid (C(18:0)). The information used in these phase diagrams was obtained by differential scanning calorimetry (DSC), X-ray diffraction (XRD), FT-Raman spectrometry and polarized light microscopy, aiming at a complete understanding of the phase diagrams of the fatty acid mixtures. All of the phase diagrams reported here presented the same global behavior and it was shown that this was far more complex than previously imagined. They presented not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules, with implications in various industrial applications.

The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids: differing by four carbon atoms

The complete solid-liquid phase diagrams for four binary mixtures of saturated fatty acids are presented, for the first time, in this work. These mixtures are formed by caprylic acid (C(8:0))+lauric acid (C(12:0)), capric acid (C(10:0))+myristic acid (C(14:0)), lauric acid (C(12:0))+palmitic acid (C(16:0)) and myristic acid (C(14:0))+stearic acid (C(18:0)). The phase diagrams were obtained by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FT-Raman spectrometry and polarized light microscopy were used to complement the characterization for a complete understanding of the phase diagram. All of the phase diagrams here reported show the same global behavior that is far more complex than previously accepted. They present not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids, and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules with implications in various industrial applications.

Artificial neural networks associated to calorimetry to preview polymer composition of high solid content emulsion copolymerizations

Artificial neural networks (ANN) have demonstrated to be powerful tools to model nonlinear systems, such as high solid content latexes produced by emulsion polymerisation. This system has a great importance in the polymeric industry, essentially for environmental reasons, since they usually have water as continuous phase. In order to propose technical and economically feasible alternatives to control polymeric structure, this work is aimed to develop a new methodology based on artificial neural networks associated with calorimetry to preview polymeric structure. The designed artificial neural networks presented excellent results when tested with process condition variations as well as when they were submitted to test concerning to the variation on the proportion of monomers in the latex formulation. Hence, it was possible to conclude that artificial neural networks, associated to calorimetry, lead to an efficient method to preview the polymer composition in emulsion copolymerizations.

EXCESS MOLAR ENTHALPIES OF 1-OCTENE + DIMETHYLCARBONATE OR DIETHYLCARBONATE OR 1,2-PROPYLCARBONATE AT 363.15 K AND 413.15 K

The excess molar enthalpies of 1-octene + dimethylcarbonate or diethylcarbonate or 1,2-propylcarbonate have been measured at two high temperatures 363.15 K and 413.15 K and for pressures varying from 18 to 20 bar with an isothermal flow-calorimeter. All these mixtures have exhibited positive HEm.