ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760321721
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