Plastic alternative formed from crab shells and plants

Researchers at the Georgia Institute of Technology have developed a flexible bioplastic by combining the biological properties from plant fibres and crab shells. The flexible bioplastic — which behaves similar to conventional PET-based plastic — is a breakthrough material as it prevents oxygen from penetrating its surface, which when used as packaging, maintains food’s freshness.

To construct the bioplastic, the Georgia-based team extracted the chitin from waste crab shells and the cellulose from plant tissue. Cellulose and chitin are natural biopolymers: polymeric biomolecules produced by living organisms. After cellulose, chitin is the second most abundant biopolymer in the world and is found in insects, fungi, molluscs and crustaceans. In the seafood industry, current food processing methods result in large volumes of wastage —  in fish scales and skin— each of which holds large qualities of chitin, and when extracted, has excellent material qualities including biodegradability.

At the nanolevel, chitin fibres are positively charged and cellulose is negatively charged; when combined, the materials have a strong interface which gives the bioplastic a resilient and flexible plastic-like characteristic.  To develop the material, the researchers crushed crab shells into a powder which was deproteinised, disrupting the chemicals bonds within the material. After this, the chitin was biologically extracted using enzymes — a far more sustainable practice than conventional methods of extraction involving chemicals and high temperatures.

After the cellulose and chitin extraction, both chemicals’ nanofibers were suspended in water, then sprayed on top of each other,  layer by layer, increasing its strength. The researchers then dried the material, resulting in a usable bioplastic which is compostable when broken down with hot water. When comparing the bioplastic material to PET plastic, there was a 67% reduction in oxygen permeability, which means that the bioplastic kept food fresher for longer.

As researchers continue to successfully utilize biopolymers such as cellulose and chitin as alternatives to PET plastic, this creates the huge potential to meet consumer needs in various commercial sectors such as the food and design industries. To view more about this research click here.

 

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