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Renewable material from plants and crabs could replace plastic

A team of researchers at the Georgia Institute of Technology have transformed crab shells and tree fibers into a material that could potentially replace flexible plastic film packaging.

The new material is made by spraying multiple layers of chitin from crab shells and cellulose from trees to create a flexible film similar to the plastic film that is used to keep food fresh.

Study co-author J. Carson Meredith is a professor in Georgia Tech’s School of Chemical and Biomolecular Engineering.

“The main benchmark that we compare it to is PET, or polyethylene terephthalate, one of the most common petroleum-based materials in the transparent packaging you see in vending machines and soft drink bottles,” said Professor Meredith.

“Our material showed up to a 67 percent reduction in oxygen permeability over some forms of PET, which means it could in theory keep foods fresher longer.”

Cellulose and chitin are the most abundant natural biopolymers on the planet. The team devised a way to suspend cellulose and chitin nanofibers in water while spraying them onto a surface in alternating layers. Once the material has dried, it is strong, flexible, transparent, and compostable.

“We had been looking at cellulose nanocrystals for several years and exploring ways to improve those for use in lightweight composites as well as food packaging, because of the huge market opportunity for renewable and compostable packaging, and how important food packaging overall is going to be as the population continues to grow,” said Professor Meredith.

The new material will improve upon the effectiveness of conventional plastic packaging because of its crystalline structure, which will keep oxygen from passing through and keep food fresher.

“It’s difficult for a gas molecule to penetrate a solid crystal, because it has to disrupt the crystal structure,” explained Professor Meredith. “Something like PET on the other hand has a significant amount of amorphous or non-crystalline content, so there are more paths easier for a small gas molecule to find its way through.”

With the amount of cellulose and chitin-rich byproducts already available, there is probably enough material to make this flexible packaging alternative a reality, according to Professor Meredith.

But first, a cost effective manufacturing process needs to be developed, as well as methods to mass produce chitin. Additionally, more research is needed to improve the material’s ability to block water vapor.

The study is published in the journal ACS Sustainable Chemistry and Engineering.

By Chrissy Sexton, Staff Writer

Image Credit: Allison Carter, Georgia Tech

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