Scientists from Canada’s Memorial University of Newfoundland have proposed a safer and biodegradable plastic alternative derived from fish waste.
This waste – consisting of fish heads, bones, skin and guts that is otherwise discarded – could help replace polyurethanes, a type of plastic derived from crude oil and found in shoes, clothes, refrigerators and construction materials.
The scientists led by principal investigator Francesca Kerton will present their findings on April 5, 2021, at the spring meeting of the American Chemical Society (ACS).
If developed successfully, a fish-oil based polyurethane could help meet the immense need for more sustainable plastics, says Kerton.
Salmon farming is a major industry for coastal Newfoundland, where Kerton’s university is located.
After the fish are processed, leftover parts are often discarded, but sometimes oil is extracted from them.
Kerton and her colleagues developed a process for converting this fish oil into a polyurethane-like polymer.
First, they add oxygen to the unsaturated oil in a controlled way to form epoxides, molecules similar to those in epoxy resin.
After reacting these epoxides with carbon dioxide, they link the resulting molecules together with nitrogen-containing amines to form the new material which is odourless.
Kerton and her team described this method in a paper last August, and since then, Wheeler has been tweaking it.
She has recently had some success swapping out the amine for amino acids, which simplifies the chemistry involved.
And while the amine they used previously had to be derived from cashew nut shells, the amino acids already exist in nature.
According to graduate student Mikhailey Wheeler, preliminary results suggest that histidine and asparagine could fill in for the amine by linking together the polymer’s components.
Kerton and Wheeler plan to continue testing the effects of using an amino acid in the synthesis and studying how amenable the material is to the microbial growth that could hasten its breakdown.
They also intend to study its physical properties to see how it might potentially be used in real world applications, such as in packaging or fibers for clothing.
Image and content: Shutterstock/ACS