The UK is pressing ahead with its ban on single-use plastics, to take effect in April 2020. Yet eight million tonnes of single-use plastics are still produced each year. So, how can the ban overcome this growing reliance? Dr Ashlee Jahnke, director of research at plastic substitute specialist Teysha Technologies, explains why a breakthrough in biopolymers might hold the key.
The shortcomings of alternative biodegradable or compostable plastics are becoming ever more apparent. This is generally because they require certain environmental conditions to biodegrade within a reasonable time.
Large companies like Coca-Cola and the Co-Op supermarket chain have stepped away from making packaging using fossil-fuel derived plastics. Coke is producing bottles with bioplastics made from plants or other renewable resources, like plant-based starches. The Co-Op uses a starch-based material for its compostable carrier bags. These are found to last for two years in soil or disappear within three months in seawater — but it’s unclear what chemicals they release into the ocean.
Meanwhile, a quarter of all compostable plastics sold worldwide are made from polylactic acid (PLA), used for transparent cold drinks cups, clear windows on food packaging, drinking straws and more. PLA meets the EN-13432 European compostability standard: the packaging breaks down within 12 weeks to water, CO2 and biomass and leaves no more than 10 per cent of the original material. Yet again, this can only happen under industrial-scale composting conditions. PLA is also non-biodegradable in sea water — so, no better than any other plastic.
The wider issue is that there is no such thing as a sustainable material. There are only sustainable systems and, presently, the UK has none to deal with the increasing volume of compostable plastics that are used daily. The Department for Environment, Food and Rural Affairs (Defra) has acknowledged that “appropriate treatment infrastructure” is needed to make compostables truly viable within our ecosystem.
Nevertheless, these scenarios overlook a key evolution in bioplastics — one that can address these issues and also meet industry demands. One solution, AggiePol, is a biopolymer made with polycarbonates from natural, sustainable feedstocks. Teysha Technologies has developed the product to address two main challenges posed by traditional petrochemical plastics.
What challenges must be overcome by bioplastics?
Firstly, the sustainable sourcing of monomer feedstocks. Our technology uses a wide variety of renewable, natural products as feedstocks. The focus is to incorporate monomers derived from starches or agricultural waste. Additionally, we’re working to use green and sustainable manufacturing processes — such as carbon dioxide capture and reagent recycling — for the synthesis of all our polymer building blocks.
We refer to AggiePol as a platform because, instead of being a single polymer system, it can be thought of as a plug-and-play system where various modified natural product monomers and various co-monomers are employed. In addition, various additives can be used to modify the properties of the final polymer produced.
This versatility allows for the formation of a variety of materials that can vary greatly in their thermal and mechanical properties. Put simply, the characteristics of the plastic can be finely tuned for a range of products and applications.
The second key challenge was to minimise the environmental impact of plastic products after the end of their useful lifetime.
To address this, Teysha has developed a system where the main mechanism of polymer degradation is water-driven. This is different to other bioplastics because the material can break down in any environment with sufficient moisture — not necessarily one that requires microbial activity or industrial composting conditions.
This can eliminate the need for an “appropriate treatment infrastructure.” What’s more, the physical, mechanical and chemical properties can be tuned for a variety of applications — such as single-use packaging, disposable cups or syringes.
AggiePol is not yet at the commercialisation stage, but it has already proven to be a highly versatile means of creating environmentally friendly alternatives to traditional plastics. As this technology develops, we may see a new era in single-use biodegradable plastics — one that is led by a sustainable material.
Click here to read about a Japanese bioplastic research project.