(636e) New supertough biocomposites from poly(lactic acid) and lignin:  Fabrication and performance evaluation

Poly(lactic acid) (PLA) is a biobased aliphatic thermoplastic polymer that can be used in a broad range of applications as a potential alternative to petroleum-based plastics. Yet, PLA is currently being hindered by its low impact strength and brittleness. Similarly, the inherent brittleness of lignin regularly poses limitations for its applications. Therefore, using PLA’s carbonyl groups from their ester functionalities to create hydrogen bonds with the hydroxyl groups of lignin, potential composites may be formed that benefits both materials. In this study, a new flexible elastomer was made from PLA and organosolv lignin by melt reactive extrusion to make tough PLA biocomposites for replacement of traditional thermoplastic elastomer such as ethylene-propylene-diene terpolymer (EPDM). To improve the mechanical properties of the biocomposites, poly(vinyl acetate) (PVAc) and glycidyl methacrylate (GMA) were selected as a compatibilizer and toughening agent, respectively. The chemical interactions between the polymers were studied by using FTIR analysis. Synergistic effects in elongation at break and impact strength were detected in PLA quaternary biocomposites. Elongation at break of the PLA quaternary biocomposites was enhanced by over 340%, while the impact strength was increased by over 900 J/m. Morphological characterization displayed good miscibility between PLA and lignin in the presence of PVAc and GMA. Thermal behaviour and miscibility of the binary, ternary and quaternary biocomposites were also studied through dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC).

Acknowledgements

The authors are thankful to (i) the Ontario Research Fund, Research Excellence Program; Round-7 (ORF-RE07) from the Ontario Ministry of Research, Innovation and Science (MRIS) (Project # 052849 and 052850); and ii) The financial support from the Natural Sciences and Engineering Research Council (NSERC), Canada Lignoworks Project # 400470 to carry out this research is gratefully acknowledged. Authors also acknowledge Lignol Innovations (BC, Canada) for providing the organosolv lignin samples for this research.