Renewable and biodegradable materials are a key element to a sustainable planet. Ecovative Design, LLC (Ecovative) has created new compostable mycelium-based (fungus) bioplastic/biocomposite materials. The material is grown at room temperature in the dark (thus requiring little energy for processing) and heated/dried to drive off water and inactivate the fungus. These new biodegradable and renewable materials are being sold commercially as replacements for expanded polystyrene and polyethylene foams that are petroleum-based and difficult to recycle or reuse. These fungus-based biopolymers have the potential to be used in additional markets such as transportation and recreation that currently use petroleum-based plastics. To meet that potential, however, the structure/property/processing relationships need to be understood. This award supports fundamental research to provide needed knowledge on how to optimize and tailor the properties of these new materials. The impact of this project, which is a collaboration between Rensselaer Polytechnic Institute, Union College, and Ecovative, will be to expand the range of applications where highly renewable, compostable, and inexpensive materials can replace petroleum-derived products.
Ecovative's bioplastic / biocomposite materials are created from a mixture of agricultural waste, feedstock, nutrients, and fungal inoculant. The resulting biopolymer/biocomposites consist of a self-assembled filamentous mass of hyphae (the filament cellular building block of mycelium fungi) grown around and securely anchoring the agriwaste. Thus, the biopolymer/biocomposite properties are strongly dependent on the agriwaste morphology, the hyphae alignment, density of the biocomposites, and degree of colonization. As in all materials development, structure/property/processing relationships are key to optimizing physical performance. To tailor the structure, we will explore processing techniques (electrospinning of model growth substrate, aligned cellulose fiber substrate, growth of hyphae under pressure, and freeze drying) that can potentially control hyphae alignment and hyphae strength as well as biopolymer density. We will use imaging techniques and image analysis to characterize the morphologies that develop. A range of mechanical properties will be measured from the scale of individual hyphae and progressing up through the bulk. The results will be compared to continuum level composite models as a starting point to evaluate the applicability of current models.
