2023 AIChE Annual Meeting
Assessing the Hydrolytic Degradability of Bio-Based Plastics from Birch Bark
The disposal of plastics in the environment harms global ecosystems and presents challenges to human health. Most commonly used plastics have slow degradation rates and are often improperly discarded into the environment, damaging ecosystems and food chains as well as releasing harmful chemicals into the environment. Thus, developing bio-based alternatives to petroleum-derived plastics is a promising approach to lessening the adverse environmental impacts of plastic use. This study focuses on the valorization of betulin, a pentacyclic triterpenol, which can be extracted in high quantities from birch bark. We incorporated betulin into a series of polyester networks with bio-based diacids of varying chain lengths using glycerol as a crosslinker. Dynamic mechanical analysis was used to examine thermomechanical properties and thermogravimetric analysis was used to determine degradative temperatures. We now extend this study to investigate the accelerated hydrolytic degradation of these thermoset polyesters. Results show that using shorter chain diacids as co-monomers lead to more crosslinked networks, which degrade slower in water. We used solid-state kinetic models to determine the rate constants describing the hydrolytic degradation. As a control experiment, negligible degradations of these samples are measured when tested at room temperature in deionized water. Overall, this work seeks to consider the viability of these biobased plastics from monomer selection, to polymer synthesis and properties, to end-of-life.