Photooxidation of polylactide/calcium sulphate composites |
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Authors: | Mé lanie Gardette,Sandrine Thé rias,Jean-Luc Gardette,Marius MurariuPhilippe Dubois |
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Affiliation: | a Clermont Université, Université Blaise Pascal, Laboratoire de Photochimie Moléculaire et Macromoléculaire, BP 10448, F-63000 Clermont-Ferrand, France b CNRS, UMR 6505, LPMM, F-63173 Aubière, France c Centre of Innovation and Research in Materials & Polymers (CIRMAP), Laboratory of Polymeric and Composite Materials (LPCM), University of Mons - UMONS & Materia Nova Research Centre, Place du Parc 20, 7000 Mons, Belgium |
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Abstract: | Stable CaSO4 β-anhydrite II (AII), a specific type of dehydrated gypsum and a by-product of the lactic acid (LA) production process, was melt-blended with bio-sourced polylactide (PLA) to produce highly filled composites. Samples containing different amounts of filler (10-40 wt.%) with various granulometries were used for preparation of films by compression moulding. The influence of adding filler (calcium sulphate) on the photochemical behaviour of PLA-AII composites was studied by irradiation under photo-oxidative conditions (λ > 300 nm, temperature of 60 °C and in the presence of oxygen). Several analytical methods were used to characterise the polymer degradation. Oxidation of the polymer matrix was evaluated by infrared and UV-visible spectroscopies, differential scanning calorimetry (DSC) and size exclusion chromatography (SEC). The main photoproducts formed upon UV-light irradiation of the PLA were identified along with the influence of filler content and its particle size on the rate of oxidation. It was shown that oxidation of PLA and PLA-AII composites occurred without any induction time and that the presence of the CaSO4 filler (AII) increased the oxidation rate of the polymer. Moreover, a faster degradation rate of PLA was observed in composites containing natural anhydrite of lower particle size (4 μm). |
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Keywords: | Biodegradable polyesters Polylactide Calcium sulphate anhydrite Composites Degradation UV irradiation |
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