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首页> 外文期刊>Crystal growth & design >Kinetics of Cold Crystallization of 4-Cyano-3-fluorophenyl 4-Butylbenzoate (4CFPB) Glass Forming Liquid Crystal. I. Nonisothermal Process As Studied by Microscopic, Calorimetric, and Dielectric Methods
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Kinetics of Cold Crystallization of 4-Cyano-3-fluorophenyl 4-Butylbenzoate (4CFPB) Glass Forming Liquid Crystal. I. Nonisothermal Process As Studied by Microscopic, Calorimetric, and Dielectric Methods

机译：4-氰基-3-氟苯基4-丁苯甲酸酯（4CFPB）玻璃形成液晶的冷结晶动力学。 I.非等温过程，通过微观，量热和介电方法研究

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For 4-cyano-3-fluorophenyl 4-butylbenzoate (4CFPB), the process of the crystallization of the CrII phase was Studied in microscopic (POM), calorimetric (DSC), and dielectric (BDS) nonisothermal experiments with various (0.5-50 K/min) heating of the metastable nematic phase obtained from its glass: Growth of areas of crystal CrII in the microscopic texture of nematic phase during heating allows estimation of degree of crystallinity D(T) vs temperature curves similar to these obtained basing on DSC heat flow curves and for slow heating with help of dielectric relaxation (BPS) method. Two types of CrII crystallization mechanisms seem to be identified: (1) strong phi dependence On temperature of full crystallization T-c(phi) and half time of crystallization t(1/2)(phi) on slow heating up to 5 K/min points to diffusion-controlled mechanism with the energy barrier 57 kJ/mol, and (2) small effect of faster heating on T-c(phi) and tau(1/2)(phi) seems to illustrate thermodynamic mechanism with energy barrier 180 kJ/mol. The scenario of two mechanisms of CrII crystallization is results of new method proposed by Mo et al., using combination of Avrami and Ozawa equations for description nonisothermal crystallization. In addition to crystallization of CrII of 4CFPB, at higher temperature range CrII-CrI transformation to a stable CrI crystal was digitalized based on microscopic and DCS results for heating at 1 K/min.
机译：对于4-氰基-3-氟苯基4-丁基苯甲酸酯（4CFPB），CrII相的结晶过程在微观（POM），量热（DSC）和电介质（BDS）非等温实验中进行了研究，其中各种实验（0.5-50 K / min）加热从其玻璃获得的亚稳态向列相：加热期间向列相微观结构中CrII晶体区域的生长允许估算结晶度D（T）随温度变化的曲线，类似于基于DSC获得的曲线热流曲线，并借助介电弛豫（BPS）方法进行缓慢加热。似乎确定了两种类型的CrII结晶机理：（1）强烈的phi依赖性对缓慢升温至5 K / min点时全结晶温度Tc（phi）和半结晶时间t（1/2）（phi）的依赖性（57）（2）快速加热对Tc（phi）和tau（1/2）（phi）产生的小影响似乎说明了能级为180 kJ / mol的热力学机理。 CrII结晶的两种机理的情景是Mo等人提出的使用Avrami和Ozawa方程的组合描述非等温结晶的新方法的结果。除了4CFPB的CrII结晶外，在更高的温度范围内，基于显微镜和DCS结果以1 K / min的加热速率，将CrII-CrI转变为稳定的CrI晶体的过程也进行了数字化。

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