Streams of all things plastic floating across our oceans are now common news footage. By 2040, the amount of ocean plastic globally could triple to 29 million metric tonnes. Of the plastic we throw out, about a third is lost in the environment, while only about 14 %of plastic is collected for recycling, according to the Ellen MacArthur Foundation. The fight against the COVID-19 pandemic is also mainstreaming single-use plastics, increasing pressure on the environment.
Life with plastic? Not fantastic. At least, not if we continue our current plastic diet. Yet options for creating, using, and disposing of plastics more sustainably are out there and research of solutions is ongoing, a recent report from the European Technology Platform for Sustainable Chemistry (SusChem), points out.

Towards a circular plastic economy

Taking on our plastic waste problem requires a circular approach, SusChem’s Sustainable Plastics Strategy argues: a new economic model in which we make the most of our resources for as long as possible, then recover and give them a new use, with minimal environmental harm.
Creating a circular plastic economy is not just about keeping plastic trash out of the environment, but also rethinking plastics’ life. This ranges from producing plastics from low-carbon sources, designing them to last longer, and be easier to sort, recycle and upcycle at the end of their lives. According to the Ellen MacArthur Foundation, building a circular plastics economy would be hugely beneficial, for nature and economies. By 2040, this could slash the volume of plastics going into the oceans by more than 80%, save about $200 billion per year, cut greenhouse gas emissions by a quarter, and generate 700,000 extra jobs.
SusChem’s report looks at how we could go full circle by pointing out existing solutions and research gaps in plastic design, recycling, end of life processing and raw materials.
“There is no single solution to the complex challenge of plastic waste, which is why we highlight that to further improve plastics circularity it is crucial that a holistic approach to the management of plastics is applied,” says SusChem. “This holistic approach to plastics waste should be based on a measurable science-based framework that aims at preventing waste, enabling consumer awareness, and implementing eco-design-based solutions towards a circular economy.”

Making plastics sustainable-by design

Making plastics sustainable-by design is the first step towards the circular economy. Sustainability by design means making plastics with safe, durable, re-usable, recyclable, easy-to-dismantle, eco-friendly materials. But these plastics also need to last longer, perform as expected, be cost-efficient, scalable and attractive to markets and investors, so that sustainability-by-design becomes mainstream.
Like living creatures, plastics also tend to degrade and age. Extreme heat or cold, radiation, humidity, mechanical stress, and other forces can affect the plastic’s structure and its functioning. Repairing its structure can be challenging, especially for complex plastic composites for aerospace, windmills or cars, where scrap rates can go up to 20-30 %. Producing plastics that include so-called self-healing polymers, smart materials that can automatically fix emerging cracks and damage, could be one way to prolong their life, the SusChem report argues. Experts are also studying how material-efficient composites that strengthen plastics could be used in complex products. Another option could be enriching plastics with nano-scale chemical additives that would help them adapt to various environmental conditions and delay aging.

Durable or degradable?

Common polyethylene (PE) and polypropylene (PP)-based plastics are extremely durable, but that means they also take long to degrade. Producing new plastics from materials that degrade on demand, then get chemically recycled, is being explored. Adding compatibilizers, additives that allow polymers to bond and stabilize, could also help create new plastics serving multiple functions, using otherwise highly incompatible materials (e.g. high-density polyethylene, HDPE and PET). That would allow, for instance, for a single material to serve as packaging, adhesive, and protective film, simplifying sorting and recycling.
The circular economy is also based on making more plastic easily biodegradable. Yet we still do not know enough about how particular industries and environmental conditions affect plastic degradation. Humidity, pH, temperature, solvents, catalysts, light, micro-organisms and enzymes play different roles, and their interactions also impacts degradation. We need different biodegradable polymers, but ones that also make economic sense. Using enzymes and bacteria that digest plastic are documented solutions, though not yet scalable.
Reducing the amount of waste in nature also means reducing the weight of single-use plastics discarded. For example, producing drink pouches from a single polymer layer can reduce their weight by up to a quarter.

The microplastics issue

Scientific studies showing accumulation of microplastics in wildlife and humans have multiplied over recent years. Yet according to SusChem, we need better insight into how microplastics travel, spread, and degrade in nature, and the dangers they pose to ecosystems and health. We also don’t know enough about how environmental conditions help secondary microplastics, created by larger plastics breakdowns, enter our food chain. To date, the default for measuring the amount of microplastics out there has been counting the plastics removed from the environment and analyzing polymers using spectroscopy. Numerical modeling is trying to address this. Currently math simulations focusing on marine environments are looking at how plastic particles interact with ocean currents, relative to their entry point in the sea. But only expanding calculations to other places with plastic debris, i.e. rivers, crop fields or cities, and overlapping them with field data could provide a more accurate image of our microplastics issue.

Make it easier to recycle

Durability is highly prized in plastics. But as the Plastics strategy shows, while we do need plastics to do their job throughout their useful life, we also need them to recycle easily and become other reusable, high-quality materials. This is still a major challenge, but including Life Cycle Assessments (LCAs) and environmental criteria into plastic design is essential to ensure new plastics can tick all these boxes.
Of the 14 % of plastic collected for recycling, not all of it ends up recycled. Several issues, from plastic design to recycling technologies, are still preventing the full recovery and reuse of plastics, the SusChem report argues.
Contamination remains a major issue. Cleaning packaging which has been in contact with solid or liquid contaminants, as well as inks is difficult, costly and energy intensive. Health and safety concerns also exclude reusing the recycled packaging in the food industry. This may lead to some parts of packaging not being recycled or being downcycled into products of lower value. Treating plastics with solutions that solubilise and extract contaminant is currently used in the industry. But to get a high-purity recycled plastic we need to identify nature and sizes of contaminants more precisely, a job for highly sensitive sensors. While existent, the technology is expensive.
Sorting errors also lower the amount of plastics recycled. SusChem supports boosting the use of robots, especially for separating all the different types of plastic ground in mills. Using machinery with thermal, chemical, and magnetic separation, as well as imaging tools that can spot the exact nature of polymers should be promoted, according to the report. Tracer-based sorting (TBS), although costly, uses optics to detect light signals specific to each type of polymer, while near-infrared detection can help separate, for instance, polysterene from mixed plastic waste.
Artificial intelligence-based robots could also improve sorting precision and lessen the burden on human workforce. But creating plastics that are already easy to sort should also be a priority, especially in construction and packaging, SusChem stresses.

Polypropylene, polyethylene and bio-based polymers

There is also the issue of polyolefins, most commonly taking the form of polypropylene (PP) or polyethylene (PE), used in consumer plastic. In Europe, about 50% of total annual plastic consumption is made up by polyolefins. Decontaminating plastics such as PE to recycle them into reusable, food-safe packaging has not been achieved yet, as residues in recycled plastic are still over the FDA and EFSA-approved thresholds. Finding a successful plastic washing process that renders PE fit for re-industrial use would boost recycling rates and circularity of plastic within its original markets.
The report also looks at how we could lower plastics’ carbon footprint, by using bio-based polymers as raw materials or feedstock. Forest residues provide a potentially sustainable source of biomass. For instance, lignin, an organic polymer that supports plant tissue can be converted into renewable building blocks for the construction industry, while plant dry matter (or lignocellulose) can be transformed into thermoplastic materials. Packaging solutions involve combining wood fibres with natural polymers, lighter on the environment but with the same qualities of traditional plastics.

The Circular Plastics Alliance

Making the economic case for these technologies is challenging. “To achieve a full circular economy for plastics, large investments are needed in collection and sorting facilities and the subsequent costs to develop recycling technologies (i.e. chemical routes) to scale,” according to SusChem. “In addition, research and innovation funding is essential to ensure materials and products are safe and sustainable by design. Moreover, economic incentives are needed to boost the use of recycled plastics instead of virgin ones.”
Set up in 2019, the Circular Plastics Alliance (CPA) – which includes several SusChem members – wants to boost the EU market for recycled plastics to 10 million tonnes by 2025. Making plastics fit the vision and standards of a circular economy plays a key role in achieving that. Though not a straightforward task, many solutions are in the pipeline or need scaling up. Plastic-hungry sectors like packaging, automotive, construction, agriculture, and electrical equipment (EEE) will need to lead on innovation and foster cooperation across plastics’ supply chains, helping to deliver the goals of EU’s Green Deal.

Note: The Sustainable Plastics Strategy received inputs from plastics value chain experts from the SusChem platform, the European Composites, Plastics and Polymer Processing Platform (ECP4), European Plastics Converters (EuPC), and PlasticsEurope.