Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation
The influence of temperature on the formation of high molecular weight poly(lactic acid) (PLA) stereocomplex was studied by evaluation of the precipitates from dioxane solutions of PLA enantiomers (PLLA and PDLA). The racemic mixtures were characterized by Gel Permeation Chromatography, Infrared Spe...
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Budapest University of Technology
2019-02-01
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doaj-b1717da451394547963ba7ab633be4ee2020-11-25T02:32:52ZengBudapest University of Technology eXPRESS Polymer Letters1788-618X2019-02-0113212313410.3144/expresspolymlett.2019.12Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formationM. HortosM. VinasS. EspinoJ. J. BouThe influence of temperature on the formation of high molecular weight poly(lactic acid) (PLA) stereocomplex was studied by evaluation of the precipitates from dioxane solutions of PLA enantiomers (PLLA and PDLA). The racemic mixtures were characterized by Gel Permeation Chromatography, Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electronic Microscopy, Wide-Angle X-ray Scattering and Vicat Softening Temperature. Precipitation was carried out under different solution temperatures, keeping constant the mixing ratio (XD), the molecular weight, the optical purity of both PLA enantiomers and the stirring rate. It was found that the precipitates contained only pure stereocomplex crystallites (racemic crystallites), without observing crystal phase separation between both homocrystals. The kinetics of the insoluble phase formation could be adjusted with the Avrami model, classically used for polymer crystallization in molten state. It was observed that the maximum PLA stereocomplex production rate was at about 40 °C. However, more thermally stable racemic crystallites were formed at high solution temperatures. It was found that all the precipitates were sphere-like at 10 g・dl–1 at the solution temperature of 25, 40, 60 and 80 °C.http://www.expresspolymlett.com/letolt.php?file=EPL-0009365&mi=cdBiodegradable polymerscrystall growingcapillary rheometrypolylactideracemic mixture |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
M. Hortos M. Vinas S. Espino J. J. Bou |
spellingShingle |
M. Hortos M. Vinas S. Espino J. J. Bou Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation eXPRESS Polymer Letters Biodegradable polymers crystall growing capillary rheometry polylactide racemic mixture |
author_facet |
M. Hortos M. Vinas S. Espino J. J. Bou |
author_sort |
M. Hortos |
title |
Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
title_short |
Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
title_full |
Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
title_fullStr |
Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
title_full_unstemmed |
Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
title_sort |
influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation |
publisher |
Budapest University of Technology |
series |
eXPRESS Polymer Letters |
issn |
1788-618X |
publishDate |
2019-02-01 |
description |
The influence of temperature on the formation of high molecular weight poly(lactic acid) (PLA) stereocomplex was studied by evaluation of the precipitates from dioxane solutions of PLA enantiomers (PLLA and PDLA). The racemic mixtures were characterized by Gel Permeation Chromatography, Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electronic Microscopy, Wide-Angle X-ray Scattering and Vicat Softening Temperature. Precipitation was carried out under different solution temperatures, keeping constant the mixing ratio (XD), the molecular weight, the optical purity of both PLA enantiomers and the stirring rate. It was found that the precipitates contained only pure stereocomplex crystallites (racemic crystallites), without observing crystal phase separation between both homocrystals. The kinetics of the insoluble phase formation could be adjusted with the Avrami model, classically used for polymer crystallization in molten state. It was observed that the maximum PLA stereocomplex production rate was at about 40 °C. However, more thermally stable racemic crystallites were formed at high solution temperatures. It was found that all the precipitates were sphere-like at 10 g・dl–1 at the solution temperature of 25, 40, 60 and 80 °C. |
topic |
Biodegradable polymers crystall growing capillary rheometry polylactide racemic mixture |
url |
http://www.expresspolymlett.com/letolt.php?file=EPL-0009365&mi=cd |
work_keys_str_mv |
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1724817085993844736 |