| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 104 === A model is developed in this work to determine the interfacial energy of various chiral forms of mandelic acid from the induction time data based on the classical nucleation theory. The induction time measurement is assumed to correspond to a point at which the total number density of accumulated crystals has reached a fixed (but unknown) value. By fitting the experimental induction time data with the developed model, the interfacial energy of S-mandelic acid, R-mandelic acid and RS-mandelic acid is determined. The results indicate that the interfacial energy is 2.82~3.23 mJ/m2 for R-mandelic acid, 2.93~3.41 mJ/m2 for S-mandelic acid, and 3.40~4.07 mJ/m2 for RS-mandelic acid. The interfacial energy of R-mandelic acid is similar to that of S-mandelic acid due to the similar crystal lattice between these two chiral forms. Compared to the formation of R-mandelic acid or S-mandelic acid crystal lattice, it is more difficult for the formation of RS-mandelic acid crystal lattice as R form and S form need to be incorporated into RS-mandelic acid crystal lattice in order. Thus, RS-mandelic acid has the largest interfacial energy
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