Story of Plastic tracks the journey of package plastic from an Espoo school to a 3D-printed piece of outdoor furniture

20.10.2022 7.55

Recycled plastic collected from Espoo pilot schools was given a new lease of life as outdoor furniture. Now, the first piece of industrial robot-printed furniture is ready.

Though plastic is considered a disposable material, the candy wrappers and kitchen packaging plastics of Espoo schools can be processed into new products that do not require a single drop of oil as raw material in their manufacture.

This multi-stage journey was described in the Story of Plastic exhibition around Espoo for almost a year, most recently at the Lippulaiva Library.

“Espoo is expanding the sorting of plastic and other waste fractions to more schools. The Story of Plastic – From Waste to Product project increases knowledge about the recycling of plastics and shows how properly sorted plastic waste becomes material for a new product,” says Mia Johansson, pilot project leader at the Espoo Centre of Excellence for Sustainable Development.

The cooperation partner was the LAB University of Applied Sciences. Their circular economy laboratory started to unravel the challenge from the other end. Laboratory researchers experimented to determine the best way to process sorted plastic waste into raw materials for new products.

The project is in its final stages, but the actual final products, outdoor furniture made of recycled plastics, have not yet reached the exhibition.

Hopefully, they will soon. The zero-hour is after the last exhibition weekend in Espoo and the dismantling of the exhibition. The 3D model of a garden bench/flowerpot combination is ready and waiting on a computer in the circular economy laboratory. Project worker Eetu Mäntynen promises to put the giant, industrial robot-based 3D printer to work first thing Monday morning. 

Plastic has an undeservedly bad reputation

“The bad reputation of plastics is a little undeserved,” says Outi Hynynen from the City of Espoo.

It is not that plastic as a material is to blame. It is a good, dense and lightweight material and performs great in preventing food waste in food packaging, for example.

“The problems are due to emissions and littering. They can be prevented by efficient plastic recycling,” Hynynen says.

When recycling opportunities are provided, non-decomposable candy wrappers do not end up in the environment and polluting water but can be reused.

Virgin food packaging material has strict purity and quality criteria. Recycled plastic does not necessarily meet those. “We set out to try in our circular economy laboratory if recycled plastic could be used for simpler products,” Eetu Mäntynen says. LAB designers have designed, for example, a bike rack and a flowerpot suitable for urban outdoor spaces.

The exhibition tour through the many stages of plastic recycling reveals to the visitors what kind of questions must be solved along the way.

There are dozens of different types of plastics. In existing recycling plants, they are separated by a heavy industrial process. Different plastic grades are identified by their buoyancy and laser scanning and picked up from the recycling line one item at a time.

Researchers at LAB University of Applied Sciences set out to determine whether it is possible to leave out the laborious separation of different plastics by using new manufacturing technology, 3D printing.

“The cleaner the packaging plastic that ends up in recycling, the cheaper it is to use it. It encourages the use of recycled plastic as a raw material,” say Mia Johansson (right) and Outi Hynynen from the Espoo Centre of Excellence for Sustainable Development.Photo: Petja Partanen

Unique products by 3D printing

Domestic plastic items are manufactured in large quantities from carefully selected plastic grades using moulds and injection moulding technology. 3D printing, on the other hand, is suitable for producing unique products or small series. If the design is simple enough, it does not matter if the raw material is a mix of different plastics. “We wanted to test in the circular economy laboratory how we could make recycled raw materials available to smaller companies,” Eetu Mäntynen explains.

According to Mia Johansson, the composition of recycled plastic collected from schools was a surprise. “We assumed most plastic would come from the school corridors, but the material came mainly from the kitchens.” A kitchen of just one school could produce many sacks of recycled plastic a day,” says Johansson, who was involved in carrying the sacks.

Plastic material collected from the schools was taken to LAB’s circular economy laboratory, where the researchers developed a suitable further processing process. First, the dirty plastic was shredded. Next, it was washed with water and put in a dryer that operated with the same principle as the spin of a washing machine. If there was excessive food leftover contamination or similar in the batch of plastic, it had to be discarded.

Eetu Mäntynen picks up a glass jar with clean plastic shredding in it from the showcase.

“This quality is quite good for outdoor furniture.”

The lightweight plastic shredding still needs to be put through the granulate machine that melts and moulds it into small plastic granules. Plastic granules are basic raw materials for making new plastic products.

“Its colour varies according to the composition of the recycled plastic.”

Designer Eetu Mäntynen shows washed plastic shredding with sufficient quality for reuse. Photo: Petja Partanen

The circular economy laboratory’s ‘plastic factory’ is a large 3D printer based on ABB’s industrial robot. Its pick-up arm was replaced by a printer head that extracts molten plastic granules layer by layer to create a new plastic object.

Next week, the project team received good news. The remaining difficulties had been overcome, and Eetu Mäntynen could report that the first test furniture was printed without any problems.

The test piece was printed with commercially available recycled granules, with the next pieces gradually increasing the proportion of recycled plastic collected from the schools.  3D printing is also being tried with three other outdoor furniture models designed by the designers.

“Furniture made of packaging plastic gains more strength when you add pure wood fibre to the mix,” says Mäntynen.

The recycled furniture will soon be part of the Story of Plastics exhibition that moved during the week from Espoo to the LAB University of Applied Sciences’ Luja-Galleria gallery in Lahti.

Photo: Eetu Mäntynen

Learning from practice

The theory of the circular economy is simple. “We use natural resources in a sustainable way to minimise waste and losses,” explains Mia Johansson.

But only practical experiments reveal whether good ideas are feasible. What did we learn from the pilot?

Outi Hynynen says that people are enthusiastic about sorting. In Espoo schools, the plastic collection experiment started at the request of pupils and teachers. “In future, sorting will continue to expand to new schools and other sites in Espoo,” Hynynen says.

LAB University of Applied Sciences’ circular economy laboratory has accumulated a lot of knowledge on how different plastic grades behave in 3D printing and how they can be processed for reuse.

Knowledge and experience are probably the most important raw material in promoting the circular economy. The production of oil-based plastic from virgin materials has been practised since the beginning of the success story of plastics in the 1950s. With recycled plastic, we are still in the early stages.

TEXT: Petja Partanen

Story of Plastic – From Waste to Product is a joint project by the City of Espoo and the LAB University of Applied Sciences, and it has received funding from the Ministry of the Environment’s support programme for the Plastics Roadmap trial and pilot projects. The project started at the beginning of 2021 and will continue until the end of September 2022.

See the Story of Plastic online brochure(external link) to explore the theme further.

  • Sustainability