For environmentalists looking to replace petroleum-based food packaging, a group of researchers at Georgia Institute of Technology had a natural idea.
The team created a new kind of sustainable wrapping material, using two ingredients you might not expect in a snack machine: crab shells and tree fibers.
Plant-based cellulose is the most common natural biopolymer on Earth, followed next by chitin, which is found in shellfish, insects, and fungi.
The Georgia Tech formulation, described in the journal ACS Sustainable Chemistry and Engineering, is made by spraying multiple layers of chitin from crab shells and cellulose from trees to form a flexible film – one with similar properties to plastic packaging.
Once fully dried, the material is flexible, strong, transparent, and compostable.
The transparent packaging you see in vending machines is polyethylene terephthalate, or PET. Compared to some forms of PET, Georgia Tech’s crab-shell-and-cellulose innovation demonstrated a 67 percent reduction in oxygen permeability, said J. Carson Meredith, a lead researcher and professor in Georgia Tech’s School of Chemical and Biomolecular Engineering.
Meredith told Tech Briefs why he believes his material has the potential to replace plastic packaging.
Tech Briefs:What inspired you to create this material?
Professor J. Carson Meredith:About five years ago, we’d wanted to make renewable white pigmented coatings for paint. We developed a method to extract chitin nanofibers from crab shells and then found that not only could we make the bright, white materials, but transparent films as well. We thought it would be very cool to be able to make food packaging from a food waste (shellfish waste), and replace synthetic plastic with a more “circular” material, where “circular” means supplying materials by recycling or by using sustainable/renewable sources.
Tech Briefs:What is unique about your material?
Meredith:We are certainly not the only research group with this interest or who have put forward the idea of cellulose or chitin packaging. However, our idea of spraying the two in alternating layer fashion was unique. We succeeded in making the first combined cellulose nanocrystal – from trees, specifically pine trees – and chitin-nanofiber barrier films with commercially-relevant oxygen barrier properties, that were manufacturable by spray or other coating operations.
Tech Briefs:What kinds of applications do you envision for this material?
Meredith:I envision the material being used in the packaging of consumer products; packaging of pharmaceuticals; packaging of food (especially flexible packaging); and protective displays in electronic devices. This would be done by spraying the chitin and cellulose onto other materials to improve their barrier properties for oxygen.
Tech Briefs:What is it about the makeup of the material that enables oxygen permeability?
Meredith:The two natural materials – cellulose and chitin – are highly crystalline fibers. High crystallinity usually results in an ability to slow down the transport of gases like oxygen. It is much more difficult for a gas to diffuse through a crystal than a noncrystalline solid.
Tech Briefs:Why is the material a valuable and important one — especially from an environmental perspective?
Meredith:What is exciting to me is that this is a circular material innovation, where the two renewable sources work synergistically together in layers, to achieve remarkable properties. The circularity derives from the fact that food packaging is supplied renewably from sustainable forestry and from use of shellfish food waste that otherwise has few valuable uses and is often simply disposed into the sea.
The chitin and cellulose in the used packaging can be composted – even along with food waste – instead of accumulating in landfills or oceans. The compost products may even be able to serve as an amendment to soil (an additive that helps fertilizer work better), so it can contribute back to growing more food.
Tech Briefs:What’s next?
Meredith:This is at an early technology readiness, meaning it’s not ready to be commercialized yet, because we do not understand enough about the best methods to produce the chitin nanofibers at large volumes, or the costs for doing so. So, there is some process research and engineering to be done. We are working on a rudimentary process design now.
We are also interested in proving other properties, including water barrier and mechanical strength, so these would eventually be able to meet specifications for various types of packaging.
What do you think? Can crab shells and tree fibers replace plastic packaging? Share your comments and questions below.
Along with Meredith, the research team also included Meisha Shofner, an associate professor and interim executive director of the Renewable Bioproducts Institute. John R. Reynolds, a professor in the schools of Chemistry and Biochemistry and Materials Science and Engineering, and Chinmay Satam, a Georgia Tech graduate student who did much of the process engineering.