Postnikov V. Crystallization Kinetics of Low-Molecular Organic Matters

With the help of the CTA and DTA the crysrtallization kinetics of benzene, phenol, resorcinol, pyrocatechol, hydroquinone, pyrogallol, naphthalene, a-naphtol, benzoic acid and binary mixtures in the system resorcinol-pyrocathehol and benzoic acid-naphthalene has been studied. We pioneered to fix a jump-like dependence of a pre-crystallization overcooling of the melt on the overheating about the melting temperature for benzene, phenol, resorcinol, pyrocatechol, hydroquinone, pyrogallol, naphthalene, a-naphtol, benzoic acid. There has been fixed that the physical overcooling depended neither one further melt overheating by 100 K higher than meltig temperature, nor on the isothermal holding time, nor on the cooling rate from 0,002 up to 8 K/c. There have been plotted the constitution diagrams of resorcinol-pyrocatechol and benzoic acid-naphthalene, pre-crystallization overcoolings being shown. On the base of the experimental data there has been carried out a mathematical analysis of a temperature curverun at a melt crystallization with regard to the cluster-coagulation mechanism of crystallization. An expression for a transformation degree at various kinds of crystallization has been obtained. The kinetic parameters of crystallization have been analyzed. There has been analyzed an influence of the electromagnetic fields on the quantity of Gibb's free energy change under nucleation. There has been suggested a scheme of calculating entropy changes as crystallization passes from a quasi-balance to a nonbalance-explosive one.