FEATURE u Plastics & Injection Moulding
The science of solving plastic pollution
Dr Ashlee Jahnke, Head of Research at Teysha Technologies, explains how the company has developed a polymer platform that uses natural building blocks, which may offer a suitable transition from petrochemicals to bioplastics.
T
he Centre for Environmental Law estimates that 99 per cent of plastics are made from petrochemicals
found in crude oil, which contains a mixture of thousands of different hydrocarbon compounds. Through the process of distillation, these are separated into fractions of differing sizes and structures. These fractions are then isolated and purified and go on to form the feedstocks for plastics and other commodity chemicals. This process, known as polymerisation, depends on factors such as the type of monomers and the polymerisation conditions used. These processes can produce thermoplastics and thermoset plastics, both with very different mechanical and chemical properties. However, they do share a commonality – they are both extremely energy intensive.
ENVIRONMENTAL IMPLICATIONS Harvesting valuable feedstock from crude oil involves an extensive, multi-part process made up of extraction, distillation and refining. This consumes around 2,000 times the energy it takes to treat and distribute tap water and generates harmful pollutants that damage the Earth’s atmosphere. 19 per cent of greenhouse gas emissions come from the extraction of fossil fuels, and 350 million tonnes of gas and oil per year are used to make plastic. The products subsequently made from plastic pose an even bigger problem. A single- use plastic water bottle, whose contents may take minutes to consume, will persist in the environment anywhere from 450 years to several thousand years. That’s a tall price to pay for a short-lived convenience. The result is that there are now 80,000 tonnes of plastic in the Great Pacific Garbage Patch alone, according to The Ocean Clean Up. Low end estimates indicate that at least one million additional tonnes of plastic enter the oceans each year. We now know that these materials break down into microplastic particles that are consumed by marine life, only to work their way back through the food chain and end up on our plates.
PROPOSED STRATEGIES Two main areas need to be addressed: feedstock sourcing and the useful lifecycle
26 January 2022 Irish Manufacturing
of plastic. These have been addressed in the past using a variety of strategies. The first sought to drive an awareness campaign to change people’s behaviour. However, campaigns promoting slogans like “reduce, reuse, recycle” have had mixed results. Not only do campaigns like this face the challenge of changing human behaviour, they swim against the current of a growing global population that increasingly depends on the convenience offered by single-use plastics. So, despite the best efforts of campaigners, plastic production continues to increase. Another strategy has been to develop bioplastics, two of which have been particularly popular for use in single-use disposable products such as plastic cutlery and packaging. The first is polylactic acid (PLA), a biodegradable, bioactive thermoplastic aliphatic polyester derived from renewable sources such as corn starch, cassava roots or sugarcane. The second is polyhydroxyalkanoate (PHA), a polyester synthesised naturally by microorganisms in nutrient-deficient conditions, including through bacterial fermentation of sugars or lipids. While significant progress has been made to use these bioplastics in disposable products, their ultimate fate in the environment is still not fully understood. Many only degrade under very specific disposal conditions, which means that if these conditions are not met, they may well persist beyond their useful lifetime despite their natural origins.
A POLYMER PLATFORM Teysha Technologies has been working to solve this problem and has developed a platform technology, rather than a single polymer system. This plug-and-play system uses sustainable feedstocks in the form of various modified natural-product monomers and co-monomers to generate polycarbonate materials. Our current focus is on incorporating monomers derived from starches or agricultural waste products. One of the key benefits of using this
platform is that the material’s physical, mechanical and chemical properties can be tuned by carefully controlling the chemistry, formulation and polymerisation conditions. As well as these properties, the material’s degradation rates can also be tuned. The key difference between this platform and other bioplastics is that we’ve developed a system where the main mechanism of polymer degradation is water driven. This means the material can break down in any environment that contains sufficient moisture and not necessarily one that requires microbial activity. By considering sustainable feedstocks and the entire lifecycle of a plastic product, rather than short-term benefits, we can begin to shift the tide away from petrochemical-based plastics and towards truly natural materials. Before we know it, the relationship between our coffee and plastic will run even deeper.
Teysha Technologies
https://teyshatech.co.uk/ www.irish-manufacturing.com
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