Materials

The Making of Biodegradable Plastic Could Take Off With This New Technique

Petroleum-based plastics are nearly impossible to break down, and finding a viable alternative has become an urgent priority for scientists.

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Plastic waste continues to pose one of the largest threats to Earth’s oceans and wildlife, to the point where it’s even in the seafood on our plate. The US recycles less than 22 percent of its garbage, which includes petroleum-based plastics that are nearly impossible to break down.

With plastic fiber consumption on the rise, finding a viable alternative is becoming an urgent priority for many scientists and environmentalists.

“Fiber consumption has substantially increased in the last decade from 50 million tons to 100 million tons worldwide,” Yiqi Yang, a professor of biological systems engineering at University of Nebraska, told Seeker.

A lack of recycling makes this an even larger problem, he added — “not just in the US, but [throughout] the world.”

Biodegradable plastics are already used in a variety of products, including drink bottles, packaging materials, and even some furniture, but they often lack the durability of petroleum-based plastics, rendering them costly and inefficient to mass produce. Yang believes he and his colleagues may have found a solution to this problem.

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Yang’s team recently conducted tests on a bioplastic called polylactide (PLLA), a biodegradable polymer that can be made from corn starch or sugarcane. He and his colleagues experimented with a new process that involves heating the polylactide to nearly 400 degrees Fahrenheit and then slowly cooling it.

Not only was this process faster than traditional approaches to plastic-based plastic manufacturing, it also negated the need for chemical solvents and other expensive techniques that are typically involved in the production of biodegradable plastic production. The disposal of these chemical agents brings a fresh set of environmental concerns, which diminishes some of the benefit of the plant-based plastics and makes large-scale production near impossible.

One of the most important things Yang discovered is that using this technique greatly increased the PLLA plastic’s resistance to heat and moisture, which he sees as a significant indicator that corn-based plastics can compete with the durability of petro-plastics.

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“We believe polylactide has the best chance to compete against petro-based plastics currently,” Yang told Seeker. So far, the team has only used this thermal process to test polylactide, but they’re confident that other bio-based materials could work as well.

Yang proposed that NatureWorks in Blair, Nebraska, jointly owned by Cargill and Thailand’s PTT Global Chemical, could be a potential manufacturer of corn-based plastics using this process in the future.

“Cargill is the leading producer of PLLA,” Yang said, noting that they are “an ideal supplier for large-scale production, due to the quality of its PLLA and the price.”

Another benefit of this thermal approach is that polylactide was able to withstand 100 degrees F of heat and could be submerged in water up to 250 degrees F while still retaining its strength. This means it can meet the requirements for use in dyed textiles.

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Every year, Americans throw away approximately 80 pounds of clothing per person. Because so many of our clothes are made from petro-based plastic fibers, a biodegradable textile fiber could have enormous environmental as well as financial benefits. 

“PLLA has major advantages over petro-based fibers,” Yang said, “mainly in environmental impacts and sustainability, [and] it is cost competitive.”

With the environmental consequences of traditional plastic consumption continuing to pile up, some experts believe that perfecting the process of manufacturing biodegradable plastics is really the only viable way to substantially mitigate plastic pollution.

“Having more land for natural fibers is certainly not the answer. Producing more petro-based fibers is also not a good choice,” Yang said. “Finding sustainable sources for the greener production of degradable materials is one of the best answers to the problems we face.”

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