Degradation of PLA in Soil

Plastic pollution is currently one of the most pressing environmental issues since most plastics take hundreds of years to decompose. Bioplastics, such as PLA, are often derived from organic sources, and are able to degrade much faster than traditional plastics. However, these alternative plastics perform worse than traditional plastics in some areas due to their weaker physical properties, such as having a lower glass transition temperature. Cellulose nanofibers can be used as an additive filler with PLA to form a stronger composite that has a higher stiffness and tensile strength, comparable to other commodity polymers, but there is still little known on the effect that adding these nanofibers has on the length of degradation of PLA. This study investigates how the addition of cellulose nanofibers changes the rate of degradation of PLA in soil. PLA samples with a range of weight percentages of cellulose nanofibers were compared. Different techniques for forming samples were also utilized to compare solid-state shear pulverization (SSSP), solid-state/melt extrusion (SSME), and twin screw extrusion (TSE), and to see if the method of forming samples has an effect on the length of degradation. Following ASTM D5338 standards, we built a custom setup to simulate controlled composting settings to conduct our tests and obtain our results.