2023 AIChE Annual Meeting
Sustainable Polylactic Acid / Cellulose Nanofiber Composites: Mechanical and Thermal Properties
Plastics have been an integral part of society for decades.Today's sustainability goal call for these plastics to be more biobased and biodegradable. Polylactic acid (PLA) is a major contender in this field since it replicates many of the properties of its non-biodegradable counterparts. However, commercial PLA loses its stiffness and strength at higher temperatures. Even for simple applications like packaging, neat PLA cannot withstand 65oC without deforming. Thus we developed a composite of PLA with cellulose nanofibers (CNF) to improve its physical performance . The methods of combining PLA and CNF under investigation are solid-state shear pulverization (SSSP), solid-state/melt extrusion (SSME), twin screw extrusion (TSE), and melt mixing (MM). SSSP and SSME yield higher, more consistent strength at higher temperatures when compared to TSE and MM. We also tested the PLA and CNF composites with a range of neat PLA to 10% CNF to determine the optimal amount of CNF. We measured the heat deflection temperature (HDT), performed a creep test, and used X-ray diffraction (XRD) to determine the optimal amount of CNF as well as the optimal process to manufacture the composites.