Polylactide (PLA) and Highly Filled PLA - Calcium Sulfate Composites with Improved Impact Properties |
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Authors: | M Murariu A Da Silva Ferreira E Duquesne L Bonnaud Ph Dubois |
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Institution: | Center of Innovation and Research in Materials & Polymers (CIRMAP), Laboratory of Polymeric and Composite Materials, University of Mons-Hainaut & Materia Nova Research Center, Place du Parc 20, 7000- Mons, Belgium |
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Abstract: | Summary: Starting from gypsum as by-product of lactic acid fabrication process, novel high performance composites have been produced by melt-blending PLA and this filler after a previous specific dehydration performed at 500 °C for min. 1h. Due to PLA sensitivity towards hydrolysis, the utilization of β-anhydrite II (AII) as filler is a prerequisite. Characterized by attractive mechanical and thermal properties due to good filler dispersion throughout the polyester matrix, these composites are interesting in biodegradable rigid packaging or technical applications. Interestingly, tensile strength of PLA – AII composites proved remarkably high, e.g. higher than 35 MPa at 50 wt-% filler content. However a decrease of impact properties has been recorded. To increase the toughness of these composites while preserving high stiffness an impact modifier based on ethylene copolymer has been mixed with both the polymer matrix and AII by melt-compounding. The effectiveness of the impact modifier was confirmed in both neat PLA and AII-based composites. Addition of 5-10 wt-% impact modifier into highly filled composites (30 to 40 wt-% filler) leads to an attractively threefold increase of impact strength with respect to the compositions without modifier, remarkable thermo-mechanical performances and good filler dispersion. |
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Keywords: | calcium sulfate anhydrite composites compounding impact resistance poly(lactic acid) |
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