A systematic study of the isothermal crystallization of the mono-alcohol n-butanol monitored by dielectric spectroscopy

Abstract

Isothermal crystallization of the mono-hydroxyl alcohol n-butanol was studied with dielectric spectroscopy in real time. The crystallization was carried out using two different sample cells at 15 temperatures between 120 K and 134 K. For all temperatures, a shift in relaxation times to shorter times was observed during the crystallization process, which is characterized by a drop in relaxation strength. The two different sample environments induced quite different crystallization behaviors, consistent and reproducible over all studied temperatures. An explanation for the difference was proposed on the background of an Avrami and a Maxwell-Wagner analysis. Both types analysis suggest that the morphology of the crystal growth changes at a point during the crystallization. The differences between the cells can be explained by this transition taking place at different times for the two cells.

Frustration of crystallisation by a liquid–crystal phase

“…This result can now be understood as coming from the partial ordering of the LC. The recently reported disappearance of the Debye process combined with the survival of the liquid-like β-process 26 during the transition is similarly fully consistent with the breakup of the hydrogen-bonded clusters in the isotropic liquid and formation of the LC.…”

“…The Raman spectrum of isotropic liquid in the OH-stretch region is very broad corresponding to the formation of 1 to 3 hydrogen bonds 23 and broadening caused by orientational disorder. Based on computer simulations of n -octanol 24 , small-angle x-ray scattering studies of n -alcohols 25 , and dielectric-relaxation studies 26 , it can be concluded that the isotropic liquid forms clusters with a polar hydrogen-bonded core and a nonpolar shell consisting of overlapping alkyl chains (see Fig. 5 ).…”

High-Pressure Dielectric Studies—a Way to Experimentally Determine the Solubility of a Drug in the Polymer Matrix at Low Temperatures

“…This difference was mainly due to the geometry of the container used in both experiments, as it is one of the factors affecting the beginning and progress of the crystallization process. 46 In the third step, the equilibrium concentration of the drug remaining in the polymer matrix after annealing is determined. This is done by determining the glass-transition temperature of the annealed material by DSC/BDS.…”

“…This difference was mainly due to the geometry of the container used in both experiments, as it is one of the factors affecting the beginning and progress of the crystallization process. 46 …”

“…In this work, this annealing time was up to 50 and 70 h for DSC and BDS measurements, respectively. This difference was mainly due to the geometry of the container used in both experiments, as it is one of the factors affecting the beginning and progress of the crystallization process In the third step, the equilibrium concentration of the drug remaining in the polymer matrix after annealing is determined.…”