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About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts

Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temp...

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Autores principales: Weidner, Steffen M., Meyer, Andreas, Chatti, Saber, Kricheldorf, Hans R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8693987/
https://www.ncbi.nlm.nih.gov/pubmed/35424240
http://dx.doi.org/10.1039/d0ra10012a
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author Weidner, Steffen M.
Meyer, Andreas
Chatti, Saber
Kricheldorf, Hans R.
author_facet Weidner, Steffen M.
Meyer, Andreas
Chatti, Saber
Kricheldorf, Hans R.
author_sort Weidner, Steffen M.
collection PubMed
description Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temperatures (T(m)) < 180 °C into high melting (HT(m)) crystallites having T(m) values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HT(m) crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes thermal degradation with lowering of the molecular weights, a gradual transition of cyclic into linear chains and a moderate decrease of lamellar thickness. An unexpected result revealed by MALDI TOF mass spectrometry is a partial reorganization of the molecular weight distribution driven by a gain of crystallization enthalpy.
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spelling pubmed-86939872022-04-13 About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts Weidner, Steffen M. Meyer, Andreas Chatti, Saber Kricheldorf, Hans R. RSC Adv Chemistry Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temperatures (T(m)) < 180 °C into high melting (HT(m)) crystallites having T(m) values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HT(m) crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes thermal degradation with lowering of the molecular weights, a gradual transition of cyclic into linear chains and a moderate decrease of lamellar thickness. An unexpected result revealed by MALDI TOF mass spectrometry is a partial reorganization of the molecular weight distribution driven by a gain of crystallization enthalpy. The Royal Society of Chemistry 2021-01-12 /pmc/articles/PMC8693987/ /pubmed/35424240 http://dx.doi.org/10.1039/d0ra10012a Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/
spellingShingle Chemistry
Weidner, Steffen M.
Meyer, Andreas
Chatti, Saber
Kricheldorf, Hans R.
About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title_full About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title_fullStr About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title_full_unstemmed About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title_short About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
title_sort about the transformation of low t(m) into high t(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8693987/
https://www.ncbi.nlm.nih.gov/pubmed/35424240
http://dx.doi.org/10.1039/d0ra10012a
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