Heating-induced phase transition of bupropion hydrobromide polymorphs
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Updated: May 27, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Guoqing Zhang1, Liping Gao, Zhaoxia Zhang
1Engineering Research Center for Eco-Dyeing and Finishing of Textiles, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, People's Republic of China. zgq@zstu.edu.cn
Abstract:
Crystal phase transition and isothermal crystallization kinetics of bupropion hydrobromide is studied by thermal analysis, X-ray powder diffractometry, and scanning electron microscopy. As well known, bupropion hydrobromide has two stable polymorphic forms, form I and form II, during the production. Here it is found that form II will convert into form I with thermal treatment. Avrami exponent n is evaluated to be around 2.0 in the range 170°C-190°C, which indicates that the phase transition is a process of one-dimensional nucleation growth. This viewpoint is also confirmed by microscope morphology study. In addition, phase-transition active energy is calculated to be 239.4 kJ/mol, which means that a high energy barrier needs to be overcome to start up the phase transition.
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