Isothermal and Non-isothermal Crystallization in Liquid Crystals …
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manifested by Vogel−Fulcher−Tammann (VFT)-type temperature dependence of
structural relaxation time τ (T ).
6.1 Non-isothermal Melt Crystallization Process in SmB cr
DSC curves of BBOA for various cooling/heating rates are shown in Fig. 13. Upon
cooling, the isotropic phases found at higher temperatures are followed by four
mesophases: N-SmA-SmB hex -SmB cr as identified also by POM textures. In the next
phase transition, parts of SmB cr crystallize and the remainder vitrifies. Crystallization
is completed after the glass softens during subsequent heating. At heating rates of φ
≥ 5, complex cold crystallization in SmB cr was found, as indicated by the presence
of a broad exothermal peak with three maxima at around 241, 249 and 261 K. These
findings are in agreement with adiabatic calorimetry studies, which found that two
metastable crystalline states undergo transformation to a stable crystalline phase [48].
Fig. 13 Thermograms of BBOA measured at various rates of cooling a and heating b. c POM
textures of various liquid crystalline states as indicated. Adapted with permission from [15]
(according to an open access Creative Commons CC BY license)
139
manifested by Vogel−Fulcher−Tammann (VFT)-type temperature dependence of
structural relaxation time τ (T ).
6.1 Non-isothermal Melt Crystallization Process in SmB cr
DSC curves of BBOA for various cooling/heating rates are shown in Fig. 13. Upon
cooling, the isotropic phases found at higher temperatures are followed by four
mesophases: N-SmA-SmB hex -SmB cr as identified also by POM textures. In the next
phase transition, parts of SmB cr crystallize and the remainder vitrifies. Crystallization
is completed after the glass softens during subsequent heating. At heating rates of φ
≥ 5, complex cold crystallization in SmB cr was found, as indicated by the presence
of a broad exothermal peak with three maxima at around 241, 249 and 261 K. These
findings are in agreement with adiabatic calorimetry studies, which found that two
metastable crystalline states undergo transformation to a stable crystalline phase [48].
Fig. 13 Thermograms of BBOA measured at various rates of cooling a and heating b. c POM
textures of various liquid crystalline states as indicated. Adapted with permission from [15]
(according to an open access Creative Commons CC BY license)