Breathing new life into old materials

While the newest materials tend to run away with all the attention, it can be good to take a step back every now and then to look at the bigger picture. According to Plastics Europe’s Fast Facts 2024 report, over 90% of the 414 million tonnes of plastics that were produced globally in 2023 were conventional, fossil-based materials. In this context, the ‘threat’ of new materials that we looked at in the previous article in this series is perhaps not so threatening after all, given that traditional plastics continue to dominate the industry to such a high degree.

However, the same trends that drive the development of new and alternative materials – i.e. consumer expectations around sustainability, new legislation etc. – do affect the traditional plastics industry too, forcing it to adopt more of a start-up mentality. Established plastic suppliers are having to find new and innovative ways of dealing with everything from improving the performance of their materials to redefining the ways that we design with plastics in the first place.

Starting with design, I think it’s fair to say that we are leaving a period behind when designers were used to specifying materials without having to worry too much about factoring in sustainability. Where in the past we were perhaps a bit prone to over-specifying materials, we now have to do more with less in order to reduce environmental impact. Among other things, this means that conventional, supposedly well-known commodity plastics like polypropylene are suddenly becoming interesting again and being considered in applications that probably would have been out of the question just a few years ago. It might be difficult to argue the case for polypropylene as a cutting-edge, innovative material, but revisiting this material and others like it can lead to some very innovative applications, such as the Revo range of sofas and other seating by the Polish office furniture brand Profim that uses recycled expanded polypropylene foam as a lightweight, yet strong and durable structural element across the entire range.

On the cutting edge of performance, functionality and aesthetics, the Swiss sportswear brand On Running developed the Cloudneo running shoe exclusively using polyamide materials. From the outsole to the woven textile upper, the entire shoe is made with materials derived from the same basic chemistry, meaning that it can be ground up and recycled without separation at the end of life. This is key in enabling On Running’s circular Cyclon subscription model, where users sign up for a monthly fee and return the shoes for refurbishment or recycling when they are either worn out or the subscription ends.

But design is just one piece of the puzzle. Among many other things, the plastics industry is also having to reckon with its sizable energy footprint. Based on numbers provided in Plastics Europe’s Fast Facts 2024 report and assuming that plastics production uses on average 90 megajoules of energy per kilo of material produced, this would give the plastics industry in the European Union an energy footprint of just under 1100 terawatt hours, enough to power each and every one of the 173 million households in the EU for an entire year. It’s also worth noting that this number doesn’t take into account the energy needed for injection moulding, extrusion and all the other processes needed to convert plastic raw materials into products. No wonder that plastics suppliers are willing to go quite far to secure alternative energy sources – from 1 January 2025, all of BASF’s European production sites are powered entirely with renewable energy, while Arkema has signed several agreements with renewable energy suppliers in France, including an annual 300 gigawatt hours of energy from a supplier that uses bio-methane derived from local agricultural waste.

Additives are another major contributor to the environmental impact of the plastics industry and recent years have seen much greater scrutiny of the colourants, fillers, stabilizers and other ingredients that are used to improve the aesthetics, performance and functionality of plastics. Besides adding to the overall environmental impact of plastic compounds, the use of additives can also have other, less immediate consequences that may not become apparent until plastic products are discarded. For example, carbon black, currently one of the most widely used pigments in plastic compounds, is incompatible with the kind of near-infrared (NIR) scanners that many plastic recyclers use in order to be able to quickly and efficiently identify and separate large volumes of mixed plastic waste. NIR-compatible alternatives to carbon black include pigments derived from other sources, such as the forest industry by-products used in BioMotion pigment from the Finnish supplier UPM, or even the kind of algae-based ink used in Nike’s limited edition Alpha Force sneakers designed in collaboration with Billie Eilish. Other approaches may include using recycled pigment – the UK-based wetsuit brand C-Skins have been using recycled carbon black pigment from scrap car tyres, reportedly leading to a significantly reduced carbon footprint as the rubber material in wetsuits typically consists of 12-15% black pigment.

Plastic recycling is a complicated business, but as the effects that additives are having on recycling are becoming more widely understood, design guidelines are starting to emerge. Recyclass, a European certification scheme that promotes traceability, quality control and transparency in plastic recycling, and it’s US Equivalent, the Association of Plastic Recyclers (APR), have databases that are constantly being updated with colorants, other additives and secondary processes that are certified as being compatible with standard mechanical recycling of plastics. Resources like these are excellent places to start for any designer wanting to ensure that plastic products are compatible with established waste streams and recycling processes.

Beyond pigments, many other plastic finishes can also be problematic in recycling. Paints, laminates and metallic coatings will typically contaminate recycled materials, leaving clearly visible residue and particles in recycled materials, but a new generation of secondary coatings and decorative processes for plastics are being developed with circularity in mind to be compatible with established plastic recycling processes. Several suppliers offer printing inks and primers for plastics that can be ‘de-inked’ or washed off during standard mechanical recycling, such as Genesis Washable Inks from INX International and Evolution inks from Flint Group. Similarly, Circular IMD (in-mould decoration) films from Kurz have obtained a Recyclass certificate for being compatible with conventional mechanical recycling. Metallic coatings can be more problematic, typically being shunned by recyclers because these coatings show up as shiny, reflective flakes in recycled resins, but suppliers are developing recycling friendly options in this category too. Singulus, a German maker of PVD equipment, has found a way to coat plastics with a thin PVD coating that has passed APR’s requirements for mechanical recycling, while the German bathroom fittings brand Hansgrohe has developed an innovative process for removing chrome plating that is extensively used in plastic shower heads, knobs and other products across their portfolio.

Functional additives is another area that is being reassessed. Mineral powder is widely used in plastic compounds to improve material properties like rigidity and temperature resistance in a wide range of plastics, while being seen as not having a negative effect on plastic recycling. Rather than using virgin material, suppliers including Switzerland-based Omya have started offering post-industrial recycled mineral powders derived from mining waste and natural stone processing by-products, for example. Other suppliers are exploring more unusual sources of raw materials, such as the Swedish start-up EasyMining that offers a whole portfolio of minerals and other materials derived from sewage water. A new plant in the south of Sweden capable of processing 30.000 tonnes of sewage sludge annually and EasyMining presented a wide range of material case studies at Stockholm Design Week in 2024, including silica-based paint, concrete, terrazzo and terracotta, while highlighting the alarming scale of illegal minerals mining that is happening across the world.

So, while the gap between new and emerging alternative materials and more established, so-called ‘legacy’ plastics can look extremely wide at times, I hope that this article has been able to show the trends and tendencies that are driving a shift towards more circular business models and a reduction of the overall environmental footprint of the materials industries as a whole is the same on both sides of the divide. Conventional fossil-based materials continue to dominate the global plastics market, but this doesn’t mean that the field is static and there is a lot of potential for innovation within these well-known and widely used materials. Many suppliers that are actively exploring the kind of raw materials, compounds, additives and finishes covered in this series of articles will be present at K 2025, offering a unique and extremely broad snapshot of the current state of the plastics industry, as well as a glimpse of how it’s likely to evolve in the future.