Many people do not realise just how much polystyrene is used, and in so many different applications, said Julien Renvoise. Trinseo is working hard to change that misconception.
“We need to communicate more," he said.
According to Renvoise, recycling & marketing manager EMEA and NAA at Trinseo, polystyrene is one of the ‘best’ materials available for food packaging. “It’s been used for the past 70-80 years,” he said. And while it is, for the most part associated by many with single-use and disposable applications, it has found much wider application in other sectors as well.
As he told Sustainable Plastics during a recent telephone interview, PS is also, for example, the material of choice for fridge liners and, when foamed, serves as the core material in insulation panels. This ubiquitous use of PS means that it is imperative to seek the best disposal solution for the material at the end of life.
“Of course, we need to consume less, and to generate less waste. And for the waste that we have, we think that recycling is the best way to dispose of these materials,” said Renvoise. Yet, while mechanical recycling is an excellent solution in many cases, the ‘complex, multi-layered structure of much packaging, that is moreover often highly contaminated’, presents a challenge.
“Moreover, we see a big deterioration in properties with mechanical recycling,” he said. This is the reason why Trinseo is looking at other solutions.
The company has been a major driver behind the development of chemical recycling processes for PS – the ‘holy grail to address the challenge of plastic waste’, said Renvoise.
“Chemical recycling offers a broader scope, but it costs more energy. There is an urgent need for a parallel development: in other words, not one or the other, but both kinds of recycling are needed if we are to reach the recycling targets of the European Commission,” he explained.
Moreover, PS is a polymer with unique circularity potential, as it is most easily reversed into its original monomer, at high yield, with the help of the latest chemical recycling technologies. The liquid state of its monomer enables easy purification and the recycled monomer is identical to the virgin monomer. It can thus be processed into virgin-like styrenic polymers, suitable for all applications, including food contact. Also, from there it can be continuously recycled, over and over again.
The voice of styrenics recycling
Three years ago, therefore, Trinseo decided to put its money where its mouth was when it became one of the founding members of an initiative launched by PlasticsEurope to promote innovative recycling solutions for polystyrene, in a push to support the European Union’s circular economy plan. Known as Styrenics Circular Solutions (SCS), the initiative emerged a year later as an independent legal entity after its four founding members - INEOS Styrolution, Total, Trinseo and Versalis (Eni) – all of which were styrenics suppliers, signed the SCS incorporation agreement.
The platform has since been joined by other members from across the styrenics value chain and has made significant progress on the development of technologies aimed at enabling polystyrene, EPS and other styrenic based plastics to be fully recycled so that they can be reused in high-quality applications, ultimately also for food contact.
“We - SCS - are the voice of styrenics recycling,” said Renvoise. He emphasised that communication was one of the three pillars on which the platform was founded.
“We have three aims: we want to develop the best recycling technology for styrenics; second, we are seeking to develop the right waste stream to collect the waste. It is vital that we have the right feed. And third, we need to communicate our message. Brand owners, retailers, converters, recyclers: they all need to know about us,” he said.
Closing the loop in the US
Next to the SCS initiative, Trinseo has embarked on other chemical recycling projects in collaboration with partners, both in Europe and in the USA. Via polystyrene supplier Americas Styrenics (AmSty), a joint venture equally owned by Trinseo LLC and Chevron Phillips Chemical Company LP, AmSty has set up Regenyx, a joint venture with Agilyx, an Oregon-based chemical recycling company that has developed technology to convert waste plastics to low carbon fuels and chemicals.
The process, called PolyUsable, converts used polystyrene products back into their original liquid form, styrene monomer. New polystyrene products can then be made from this recycled styrene monomer without any degradation of quality or value. The new joint venture, Regenyx, took over the assets of Agilyx’s Oregon, facility, which was already shipping recycled styrene monomer to AmSty based on an offtake agreement signed the previous year.
Trinseo is also collaborating with Ineos Styrolution and Agilyx in Europe, to build a commercial-scale chemical recycling plant in Europe, at a location that remains to be announced. “The new plant will be capable of processing up to 18,000 metric tons per day of post-consumer PS feedstock into styrene oil, which will be used by Trinseo and Ineos to produce virgin quality PS,” Renvoise said.
Trinseo has two “well-located” plants in Europe, he continued, one in Belgium, Tessenderlo, and another in Germany, in Schkopau, which will process the styrene monomer from the project. “It will be operational by 2022,” said Renvoise. The project was initiated by SCS as part of the commitment to drive up European styrenics recycling rates and follows the promising results of an evaluation study in which SCS, engaged Agilyx to perform tests with samples of post-consumer PS food packaging waste.
Agilyx evaluated the composition of the waste feedstock and successfully recycled it back into its original liquid monomer. Another project involves a collaboration with a Belgian recycler, who has developed a depolymerisation process in which polyolefins are broken down into naphtha and wax, while polystyrene waste is depolymerised into styrene monomers.
Critical to the success of all these initiatives, however, is the need for the basics to be in place and functional. “We need a fundamental focus on each step: collection, sorting and recycling,” Renvoise urged.
“In many countries, we see the recycling goals outpacing the waste collection. In France, for example, the blue bin or yellow bin scheme currently applies in only 40% of the country. This will reach 100% by 2022, so that curbside collection of waste plastic is available to everyone,” he said.
Recyclers too need to rethink their sorting procedures. “PET, LDPE, PP – these materials are all well sorted at the sorting centres. PS is not that well sorted, which means that efforts are required on the part of the PS suppliers to convince them that this material is worth sorting,” Renvoise noted.
“We are taking a long-term commitment with them, to demonstrate the investment is worthwhile.”
Polystyrene is eminently recyclable and should not end up being incinerated. It is a message that Trinseo, together with SCS, is striving to get across to the industry. But what about ABS, one of the other mainstays of the plastics industry?
“Chemical recycling is far less advanced,” said Renvoise. “There is a European project which is investigating this, but it is a more challenging material. We will get there, of course, but not yet.”
PS, on the other hand, with its uniquely simple chemistry is far more easily depolymerised. “Also compared to polyolefins,” said Renvoise. “Depolymerisation occurs at relatively low temperatures, which means that less energy is needed. It is easy to purify and easy to process. It has a positive carbon footprint. And it has a low migration coefficient, which means that contaminants do not migrate in or out. Whichever approach we use - whether we transform PS waste into fuel, from which we derive the monomer to make the full range of PS polymers, or convert the PS waste through depolymerisation into styrene monomers, and then polymerise this into PS, it remains one of the best materials for chemical recycling.”
Consumers are a driving force
The growing awareness of consumers is the main force behind the push for more recycling, thinks Renvoise. This increased consumer awareness is also felt by the public authorities, which has led to a broad range of new goals, rules and regulations on the national and European level regarding recycling and circularity. “What we need is a scientific, rather than an emotional approach,” he declared. “As a value chain, we need to collaborate in order to achieve the goals we have set. And we need to communicate better. Obviously, as an industry, we have a credibility issue. But we consider that to be simply another challenge we must seek to overcome.”