Solid-liquid phase equilibrium diagrams of binary mixtures containing fatty acids, fatty alcohol compounds, and tristearin

Fatty compounds have significant industrial applications as coatings, plastics, cleaning products, emulsifiers, structuring, and gelling agents. Due to these applications, it is important to understand their physical and chemical properties, such as melting behavior, crystallization processes, and phase transitions, all of them related to solid-liquid equilibrium (SLE). In this study, six binary mixtures composed of tristearin (SSS) plus fatty acids (capric acid, lauric acid, and myristic acid) and tristearin plus fatty alcohol compounds (1-decanol, 1-dodecanol, and 1-tetradecanol) were investigated using Differential Scanning Calorimetry (DSC) and optical microscopy analysis. The phase diagrams formed by tristearin + fatty acids presented a monotectic behavior and the phase diagrams formed by tristearin + fatty alcohol compounds, on the other hand, exhibited a solid solution formation on the entire composition range, although the liquidus line shape was very similar to that observed in the systems formed by fatty acids. The liquidus line of all systems were well-described by NRTL and three-suffix Margules models, and also by ideal assumption. The best result was observed for the three-suffix Margules model, with a root mean square deviation (RMSD) equal to 0.26.

Automated summary

Fatty compounds have significant industrial applications, and understanding their physical and chemical properties related to solid-liquid equilibrium is important. The phase behavior of binary mixtures composed of different components was studied, and it was found that the behavior could be well-described using the three-suffix Margules model.