Enhanced Compostability for Sustainable Plastics
Scientists at Michigan State University’s renowned School of Packaging have devised an innovative technique to enhance the biodegradability of a promising sustainable alternative to petroleum-based plastics.
Under the guidance of Rafael Auras, the team has created a compostable bio-based polymer blend suitable for both home and industrial composting. Their achievement is documented in ACS Sustainable Chemistry & Engineering.
The United States and the world grapple with a significant challenge concerning plastic waste. Less than 10% of plastic waste undergoes recycling in the U.S., leading to an accumulation of plastic debris with economic, environmental, and health implications.
Rafael Auras, a professor at MSU and the Amcor Endowed Chair in Packaging Sustainability, remarked, “By crafting biodegradable and compostable solutions, we can mitigate some of this waste, lessening landfill impact.”
Enhanced Compostability for Sustainable Plastics: plastics designated for composting
Moreover, plastics designated for composting wouldn’t necessitate meticulous cleaning of food residues—a substantial hurdle for efficient plastic recycling. Recycling facilities often face the choice of investing time, water, and energy in purifying contaminated plastic waste or disposing of it.
Auras offered an analogy, stating, “Consider a coffee cup or microwave tray stained with tomato sauce. No rinsing or washing would be required; composting would suffice.”
The researchers collaborated with a substance called polylactic acid, or PLA, which initially appears as a logical choice. PLA has been a packaging staple for over a decade, originating from plant sugars instead of petroleum. When managed effectively, PLA generates natural waste byproducts: water, carbon dioxide, and lactic acid.
Enhanced Compostability for Sustainable Plastics: industrial composting
Furthermore, the scientific community is aware of PLA’s ability to biodegrade within industrial composting environments. These settings, with higher temperatures, offer more favorable conditions for bioplastic breakdown compared to home composters.
Nevertheless, the notion of rendering PLA compostable within home composting presented a seemingly insurmountable challenge to some. “I recall people dismissing the idea of establishing home composting for PLA as a viable option,” recalled Pooja Mayekar, a doctoral candidate in Auras’ research group and the lead author of the recent publication. “This skepticism stemmed from the fact that microbes cannot naturally consume and digest PLA. It needs to be broken down to a stage where they can utilize it as nourishment.”
While industrial compost facilities can reach this stage with PLA, it doesn’t necessarily guarantee swift or complete degradation.
Industrial composting facilities have been hesitant to accept bioplastics like PLA, according to Auras. In their research, supported by the U.S. Department of Agriculture and MSU AgBioResearch, the team exhibited that PLA can remain intact for about 20 days before microbes initiate digestion in industrial composting settings.
The potential for home composting
To minimize this lag and facilitate the potential for home composting, Auras and his team incorporated a carbohydrate-derived substance known as thermoplastic starch into PLA. This starch offers microbes in the compost an easier-to-digest source while the PLA breaks down.
Pooja Mayekar stressed that they meticulously balanced the starch addition to ensure optimal PLA degradation while preserving its inherent properties.
Fortunately, postdoctoral researcher Anibal Bher had been developing diverse PLA-thermoplastic starch blends to maintain the strength, clarity, and other desirable attributes of conventional PLA films. Collaborating with doctoral student Wanwarang Limsukon, Bher and Mayekar tracked the breakdown of these films throughout the composting process under varying conditions, assessing the entire degradation pathway.
Custom-built systems
The team constructed and operated these experiments using custom-built systems developed over Auras’ nearly two decades at MSU. Access to MSU’s external research resources further enriched the process.
Bher lauded the collaboration, saying, “Working with Dr. Auras, the School of Packaging, MSU — it’s great. We aim to eventually create actual products, and MSU offers abundant resources for material production and property testing.”
Mayekar echoed the sentiment, stating, “The School of Packaging at MSU is recognized for good reason. It provides an exceptional environment for our work.”
Read the original article on sciencedaily.
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