Abstract
The melting curves of the diphenyl – n-geneucosane and diphenyl – n-tricosane systems were calculated using the Schroeder equation and using the UNIFAC and UNIFAC Dortmund methods. The results obtained by calculation methods showed that both systems are eutectic. The use of a differential scanning microcalorimeter made it possible to experimentally confirm the presence of phase equilibrium in these alloys. Experimentally, for each system, individual substances and compositions within each of the studied systems were studied. Based on the data obtained, phase diagrams were constructed for two systems diphenyl – n-geneucosane and diphenyl – n-tricosane. In each system, at temperatures of 29.94 °C and 40.6 °C, polymorphic transformations are observed for n-geneicosane and n-tricosane, respectively, which coincide with the literature data. The UNIFAC Dortmund method for both systems showed the smallest deviation of the composition of the eutectic alloy from the experimental data at relatively close calculated values of the melting temperature of the eutectic with the UNIFAC method. These methods can be used to preliminary estimate the coordinates of eutectics in organic systems before planning an experiment. Calculations were made of the specific enthalpy of melting, molar values of entropy and enthalpy of melting, volumetric specific enthalpy of melting and density under standard conditions for each eutectic composition. The study of the fusibility of diphenyl – n-heneicosane and diphenyl – n-tricosane systems is important for understanding its physical properties and possibilities of application in various technological processes. Eutectic mixtures can be used as coolants and heat-storing substances. Eutectic melts of diphenyl – n-heneicosane and diphenyl – n-tricosane systems are safe to use.
Publisher
Ivanovo State University of Chemistry and Technology