Decluttering our Landfills: Biodegradable Plastic in Production

Petroleum-based nonbiodegradable plastics harm marine life—Yang and his lab want to change that. Illustration by Vera Villanueva (‘21)

Half of the plastics we use today are used once and then left to accumulate in landfills. This statistic is symbolic of a greater issue: given our ever-increasing rate of plastic consumption, overstuffed landfills will create dire problems for future generations. And while humans eventually will have to face the consequences of plastic pollution on land—if we aren’t doing so already—plastic pieces are currently floating in our oceans, being ingested by marine animals and contaminating natural habitats.

Reducing our plastic consumption is certainly one way to address this issue, but researcher Yiqi Yang and his team at the University of Nebraska-Lincoln have an even better solution: biodegradable plastics. Yang believes that his lab may have found a way to create a cost-effective biodegradable plastic that targets the textile industry, where polyester plastics are a big source of plastic consumption. Production of these plastics requires a lot of petroleum, a limited resource.

Petroleum-based nonbiodegradable plastics harm marine life—Yang and his lab want to change that. Illustration by Vera Villanueva (‘21)

Other researchers have designed biodegradable plastics in the past. For example, polylactic acid (PLA) was the first and largest-scale biopolymer produced from annually renewable resources such as corn starch and sugarcane. Biopolymers like PLA are very long molecules consisting of a biologically-relevant repeating subunit. However, PLA’s limitations make it ineffective for use in the textile industry: “Others have been able to find biodegradable products such as PLA, but those products cannot be used widely in the textile industry because they are easily hydrolyzed at high temperature,” Yang said. Hydrolysis refers to the degradation of a plastic by breakdown into its subunits. PLA-based plastics risk being too soft and too easily broken-down, and are thus not suitable for textile materials. While engineers have made some progress, the main problem today isn’t finding a biodegradable product, but rather one that is both cost-effective for manufacturers and has the properties necessary for a quality plastic.

The plastics we use daily have the opposite problem. Most plastics are too stable and stick around in landfills or natural habitats for a long time, unable to biodegrade. After some experiments, however, Yang and his team have developed a biodegradable plastic without those shortcomings. In their experiments, the team obtained two biopolymers, poly-L-lysine (PLL) and poly-D-lysine (PDL). With these biopolymers, they formed plastic fibers and employed a thermal treatment to form tighter structures with strong interactions between the polymers. This key process ultimately decreased the plastic’s sensitivity to hydrolysis, especially at high temperatures.

Several experiments testing the new plastic’s properties show that Yang’s team may indeed have the key to tackling the two main problems in plastic development (hydrolysis and softness at high temperatures). However, until their materials are examined in large-scale production, they can’t say for sure whether their plastic will work on the industrial scale.  The next step for Yang and his team is to test the plastic on a small scale in the textile industry. From there, they can target other industries. Nonetheless, Yang and his team have gotten a step closer to making a product that will hopefully prove useful in decreasing, if not eliminating, plastic waste.

The impact of a biodegradable plastic in reducing plastic pollution is far-reaching. Currently, animals on land and in oceans are easily harmed by ingesting plastic microparticles or by getting caught in large pieces of plastic. For humans, plastic remains in our landfills for far too long, and we’re running out of space. Yang also cautions that tap water from all around the world contains microscopic pieces of plastic, and without our knowing, we could be accumulating plastic in our bodies.

Since demand for plastic is growing exponentially as the human population grows, it is especially critical for us to find a sustainable resource that meets our needs without damaging our environment. As we move in the direction of finding cost-effective and useful forms of biodegradable plastic, we can rest assured that researchers like Yang and his team are on the case.