At five sites in the world’s oceans, plastic waste accumulates in large swirling gyres, the largest of which is three times the size of France. Millions of tons of plastic enters the oceans every year, damaging marine ecosystems, harming ocean animals and entering the human food chain.
Japanese researchers have developed a new kind of biodegradable plastic that could help. The material, reported in the journal Carbohydrate Polymers, is made from starch and cellulose, and could be a step towards a low-cost biodegradable plastic that can be mass-produced.
At the G20 Summit in Osaka last summer, member countries agreed to a framework called Osaka Blue Ocean Vision initiated by Japan, which plans to lead global efforts to reduce ocean plastic pollution to zero by 2050.
Biodegradable plastics, which break down in the environment into smaller harmless chemicals, already exist. But they are not as strong or water-resistant as ubiquitous commercial plastics like polyethylene. They also cost twice as much as petroleum-based plastics, and can also only be produced in small amounts.
Researchers at Osaka University made the new transparent plastic from cellulose and starch. Both are common, cheap natural biological polymers. Starch is found in corn and potatoes, while cellulose is the main component of plant walls. “Because these materials are cheap and the manufacturing process is simple, we can expect that the developed material will be put to practical use soon,” said applied chemistry professor Taka-Aki Asoh.
The plastic is a membrane made of starch that is reinforced with tiny, microscopic cellulose fibers. It is strong and does not swell in water. But it breaks down in seawater over time.
“We have great expectations that our material will help solve the growing global problem of marine debris accumulation and have a major societal impact,” said Asoh.
Source: Raghav Soni, Taka-Aki Asoh, and Hiroshi Uyama. Cellulose nanofiber reinforced starch membrane with high mechanical strength and durability in water. Carbohydrate Polymers, 2020.