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Thermal properties, phase transitions, and morphology of a conjugated polymer
Author(s) -
Cheng Stephen Z. D.,
Wu Xiao Xin,
Zhang Anqiu,
Meador Michael A.
Publication year - 1992
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760321721
Subject(s) - materials science , phase transition , glass transition , crystallization , polymer , crystal (programming language) , crystallography , thermodynamics , composite material , chemistry , physics , computer science , programming language
A highly conjugated polymer was synthesized from α,α′‐dibromo‐p‐xylene, 1,4‐bis(2‐hydroxy‐benzoyl)benzene, and benzyl bromide via a modified Williamson ether synthesis under phase transfer conditions. Based on thermal analysis, polarized light microscopy, electron diffraction, and wide angle X‐ray diffraction experiments, the heat capacities in the solid and liquid states have been determined. The glass transition temperature is at 358 K with a heat capacity increase of 164 J/(K mol). Two different ordered crystal forms with different crystal unit cells were observed. The more ordered crystal shows a low transition temperature and the less ordered one a high transition temperature. This is mainly due to the effect of entropy change. These crystals exhibit various crystal morphologies with different birefringences. Transition kinetics are expressed by an Avrami equation. Two crystals show different Avrami exponents with crystallization temperature, which corrspond to the morphological change. Competition between crystal growths is also discussed.