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Authors
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Ding, Q. ; Jehnichen, D. ; Gobel, M. ; Soccio, M. ; Lotti, N. ; Cavallo, D. ; Androsch, R.
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Title
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Smectic liquid crystal Schlieren texture in rapidly cooled poly(butylene naphthalate)
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Date
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01.04.2018
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Number
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54581
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Abstract
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The morphology of partially crystalline/ordered poly(butylene naphthalate) (PBN) forming on cooling the melt has been analyzed by polarized-light optical microscopy (POM) and microfocus-beam X-ray diffraction (XRD). Crystallization at rather low supercooling of the melt, at temperatures higher than about 200·°C, leads to slow and irregular spherulitic growth of ß´-crystals, with spherulites not showing a distinct Maltese cross in POM. At temperatures between approximately 200 and 160·°C, the melt partially converts directly to a-crystals, and the obtained spherulitic superstructure reveals an increasing nuclei density with decreasing crystallization temperature. At even lower temperature, a liquid crystalline (LC) phase develops. This mesophase may subsequently convert to a-crystals according to Ostwalds rule of stages. The transition of the LC-phase into a-crystals is suppressed at temperatures lower than about 120·°C or on cooling faster than about 200–500·K/s. X-ray analysis of PBN liquid crystals formed at well-defined cooling conditions in a fast scanning chip calorimeter revealed smectic periodicity while there is simultaneously observed a distinct Schlieren texture in POM.
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Publisher
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European Polymer Journal
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Wikidata
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Citation
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European Polymer Journal 101 (2018) 90-95
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DOI
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https://doi.org/10.1016/j.eurpolymj.2018.02.010
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Tags
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