8-12 July 2019
Cité des Congrès
Europe/Paris timezone

Effect of Molecular Weights on the Physical Properties and Microstructure of Poly(lactic acid)

10 Jul 2019, 15:30
15m
Salle GH (Cité des Congrès)

Salle GH

Cité des Congrès

Speaker

Dr Yoga Sugama Salim (Normandie Univ, ENSICAEN, UNICAEN, CNRS, LCMT)

Description

A three-phase microstructure involving crystalline, rigid and mobile amorphous regions has been successfully used to describe the macromolecular arrangements in poly(lactic acid) (PLA). The establishment of a rigid amorphous fraction, in particular, is dependent on the molecular motions of polymer chains during crystallization; Our aim is to understand the contribution of the size of the polymer chains (related to their number average molar mass, Mn) on its molecular structure during crystallization. To achieve this, a commercial grade of PLA was hydrolyzed by extrusion in controlled conditions of time, temperature and water content. The glass transition temperatures of these fractions obey the Flory-Fox model and reach a plateau beyond ~20000 g/mol. Preliminary measurements performed by Differential Scanning Calorimeter (DSC) showed that, as Mn decreases and reaches values lower than ~40000 g/mol, cold crystallization starts to occur. As Mn further decreases, the melting peaks associated to cold-crystallized domains gradually shifts towards lower temperatures. PLA crystallizes easier when the polymer chains are shorter, which was confirmed by optical polarizing microscopy. Further characterizations by temperature-modulated DSC were performed to determine whether Mn affects the specific heat capacities at the glass transition and how the rigid amorphous fraction evolves with Mn.

Choix de session parallèle 4.2 Physique des polymères: de la molécule au matériau

Primary authors

Dr Yoga Sugama Salim (Normandie Univ, ENSICAEN, UNICAEN, CNRS, LCMT) Dr Estève Ernault (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Dr Nicolas Delpouve (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Prof. Benoît Vieille (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Dr Laurent Delbreilh (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Prof. Eric Dargent (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Dr Antonella Esposito (Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux) Prof. Loïc Le Pluart (Normandie Univ, ENSICAEN, UNICAEN, CNRS, LCMT)

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