New Algae Oil-based Degradable PU Foam for Completely Recyclable Flip-flops
Scientists at the University of California San Diego have formulated polyurethane foams, made from algae oil, to meet commercial specifications for midsole shoes and the foot-bed of flip-flops.
High Material Specifications for Shoes
In addition to devising the right formulation for the commercial-quality foams, the researchers worked with Algenesis to not only make the shoes, but to degrade them as well. Scientists have shown that commercial products like polyesters, bioplastics (PLA) and fossil-fuel plastics (PET) can biodegrade, but only in the context of lab tests or industrial composting.
“The paper shows that we have commercial-quality foams that biodegrade in the natural environment,” said Stephen Mayfield, a professor. “After hundreds of formulations, we finally achieved one that met commercial specifications. These foams are 52 percent biocontent—eventually we’ll get to 100 percent.”
“We redeveloped polyurethanes with bio-based monomers from scratch to meet the high material specifications for shoes, while keeping the chemistry suitable, in theory, so the shoes would be able to biodegrade,” Mayfield explained.
Testing of the Customized Foams
Putting their customized foams to the test by immersing them in traditional compost and soil, the team discovered the materials degraded after just 16 weeks. During the decomposition period, to account for any toxicity, a team of scientists led by UC San Diego’s Skip Pomeroy measured every molecule shed from the biodegradable materials. They also identified the organisms that degraded the foams.
Researchers took the enzymes from the organisms degrading the foams and showed that the organisms could be used to depolymerize these polyurethane products, and then identified the intermediate steps that take place in the process. The isolated, depolymerized products can be collected and can be used to synthesize new polyurethane monomers, completing a ‘bioloop.’
This full recyclability of commercial products is the next step in the scientist’s ongoing mission to address the current production and waste management problems we face with plastics.
“If you could turn back the clock and re-envision how you could make the petroleum polymer industry, would you do it the same today that we did it years ago? There’s a bunch of plastic floating in every ocean on this planet that suggests we shouldn’t have done it that way,” noted Skip Pomeroy.
Next Step: Commercial Scale Up
While commercially on track for production, doing so economically is a matter of scale that the scientists are working out with their manufacturing partners.
“People are coming around on plastic ocean pollution and starting to demand products that can address what has become an environmental disaster,” said Tom Cooke, president of Algenesis. “We happen to be at the right place at the right time.”
“The life of material should be proportional to the life of the product,” said Mayfield. “We don’t need material that sits around for 500 years on a product that you will only use for a year or two.”