Injection Molded Biocomposites from Lignin, Polylactide (PLA) and Poly(butylenes adiapate-co-terphthalate) (PBAT): Process Engineering and Performance

Recently, Lignin-based green composites have received scientific attention due to lignin’s availability as a byproduct of both paper and cellulosic ethanol industries, and its potential as a low-cost filler to reduce the cost of bioplastic production. Bioplastic-blends consisting of polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) were prepared with different weight ratios (70:30, 50:50 and 30:70). Lignin was then added as a reinforcing agent (20 wt.% fixed). The blends and biocomposites were processed using conventional melt extrusion and injection molding techniques. The characterization of the processed samples was performed through mechanical (tensile, flexural, and impact tests), thermal (differential scanning calorimetry (DSC), and heat deflection temperature (HDT)) properties of the materials, as well as morphological observations via scanning electron microscopy (SEM). Results of this study showed consistent flexural and tensile properties within the neat (PLA and PBAT) blends and lignin-based biocomposites. The notched Izod impact test showed a 50% decrease with incorporation of lignin. The morphological analysis showed lignin to have greater compatibility within the PLA matrix. The PLA70-PBAT30 blend with 20% lignin biocomposite was shown to have the greatest tensile and flexural strength, as well as strongest interfacial adhesion. However, the heterogeneity of the lignin particle size appears to generate agglomerates which weaken the interaction between the matrix and the filler. 

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Acknowledgements:

This research is financially supported by the Natural Sciences and Engineering Research Council (NSERC) Biomaterials and Chemicals Strategic Research Network.