Reactive extrusion of poly(lactide) with low molecular weight acryl-functionalized poly(ethylene glycol).An original and effective methodology to toughen poly(lactide)Georgio Kfoury1, 2, Fatima Hassouna1, Valérie Toniazzo1, Jean-Marie Raquez2, David Ruch1, Philippe Dubois21Department of Advanced Materials and Structures (DAMS), Centre de Recherche Public Henri Tudor, rue Bommel 5 (ZAE Robert Steichen), 4940 Hautcharage, LUXEMBOURG2UMons Research Institut for Materials Science and Engineering, Laboratory of Polymeric and Composite Materials, University of Mons (UMONS), Place du Parc 23, 7000 Mons, BELGIUM
State of the art
Poly(lactide) (PLA) is one of the mostextensivelystudiedbiodegradablethermoplasticsderivedfromrenewableresources. One of the main drawbacks of PLA isitsinherentbrittleness,whichlimitsits applications. Plasticization of PLA withlowmolecularweight poly(ethylene glycol) (PEG) iscurrentlycarried out to sustainthis issue, but itresults the migration of plasticizerat high PEG loadings.
In situpolymerization and free-radical grafting of acryl-
functionalized PEG onto PLA backbone via reactive
extrusion aims to reduce the migration of the plasticizer.
grafted on PLA
Reactive extrusion (REx)
Soft domains (after cryofracture) made of poly(acrylPEG) (core) surrounded with an immiscibility gradient are observed due to the grafting of acrylPEG on PLA (shell)
AcrylPEG + L101
Drying PLA under vacuum at 60°C over night
REx under N2co-rotating twin-screw extruder DSM Xplore (15cc):
Tmelt ~ 175°C; scew speed = 100 rpm; REx time = 5 min
Core-shell microdomains played a stress concentrator role and impact energy dissipation fracture inhibitors
Formation of a low AcrylPEG oligomers (DP~7) fraction (extracted by Soxhlet)
Formation of a highly grafted fraction of poly(AcrylPEG) in PLA (not extracted by Soxhlet in methanol)
Efficient plasticization resulting in improved ductility and impact resistance with increasing L101 amount
In the absence of L101, AcrylPEG migrated to the surface of the specimen after DMA, while it was not the case in the presence of L101
Thanks to the AMS Department of CRP Henri Tudor and the Laboratory of Polymeric and Composite Materials (LPMC) for the technical and scientific supports and the Fond National de la Recherche (FNR) for the financial support.