Properties and Morphology of Ternary Blends of PLA/PBAT/ Fractionated Lignin

Lignin is an abundant natural resource that meets every aspect of sustainability since it is highly renewable, low cost, and an industrial by-product of the paper and bioethanol industries. The blending of lignin as a component in a thermoplastic blend poses a challenge in the form of dispersion and compatibility. Polyesters such as poly(lactic acid) and poly(butylene adipate-co-terephthalate) offer the best opportunity of compatibility in melt blending with lignin due to their ability to form hydrogen bonds. The fractionation of lignin into more homogeneous fractions offers better dispersion and more consistent properties. The resulting blend of methanol fractionated lignin, PLA, and PBAT shows highly dispersed lignin particles with particle size of < 5 µm in addition to the presence of lignin between the PLA/PBAT interface inducing improved stress transfer between the two polymer phases. Mechanical properties of the blend showed retention of elongation with slight reduction in strength and modulus for blends containing 30% lignin by weight. 

Acknowledgements:

The authors would like to acknowledge the NSERC Biomaterials and Chemicals Research Network for the financial support necessary for this project, along with MeadWestvaco for supplying the lignin used in this project.