Efforts to shift from petrochemical plastics to renewable and biodegradable plastics have proven tricky — the production process can require toxic chemicals and is expensive, and the mechanical strength and water stability is often insufficient. Now, researchers have used wood byproducts to produce more durable and sustainable bioplastics.
The process deconstructs the porous matrix of natural wood into a slurry. The resulting material shows a high mechanical strength, stability when holding liquids, and UV-light resistance. It can also be recycled or safely biodegraded in the natural environment and has a lower life-cycle environmental impact when compared with petroleum-based plastics and other biodegradable plastics.
To create the slurry mixture, the researchers used a wood powder — a processing residue usually discarded as waste in lumber mills — and deconstructed the loose, porous structure of the powder with a biodegradable and recyclable deep eutectic solvent (DES). The resulting mixture — which features nanoscale entanglement and hydrogen bonding between the regenerated lignin and cellulose micro/nanofibrils — has a high solid content and high viscosity that can be casted and rolled without breaking.
A comprehensive lifecycle assessment tested the environmental impacts of the bioplastic against common plastics. Sheets of the bioplastic were buried in soil, fracturing after two weeks and completely degrading after three months; additionally, researchers say the bioplastic can be broken back down into the slurry by mechanical stirring, which also allows for the DES to be recovered and reused.
The bioplastic can be molded into a film that can be used in plastic bags and packaging — one of the major uses of plastic and causes of waste production. Because the bioplastic can be molded into different shapes, it has potential for use in automobile manufacturing as well. The team has begun working with a forest ecologist to create forest simulation models, linking the growth cycle of forests with the manufacturing process.