COMPOCYCLE prepares recyclable biocomposites for industry
Composites based on natural fibres – such as hemp, flax, or bamboo – have been gaining traction for some time as sustainable alternatives to traditional building materials. Thanks to the thermosetting resins that bind these fibres together, they are strong, lightweight, UV and heat resistant, and resistant to aggressive chemicals – but also resistant to recycling. For instance, a biocomposite window frame, after years of faithful service, can still end up in an incinerator. The COMPOCYCLE research project aims to change this and was recently awarded a €3 million subsidy from the Dutch Growth Fund project Biobased Circular.
Jurian Rademaker (Director Qconcepts Design & Engineering) explains that the use of recyclable biocomposites is a strategic priority for their company: ”A powerful step towards a future where high-performance and circularity go hand in hand. The real strength of the COMPOCYCLE project lies in bridging advanced material development with real-world application. That’s where we step in, using our engineering expertise and production capabilities to translate promising lab results into scalable, high-quality components.”
Within COMPOCYCLE, researchers led by Wageningen University & Research are collaborating with partners, to develop 100% biobased, thermosetting composites that are both recyclable and immediately deployable for industry.
The problem with thermosetting resins is that they consist of chain polymers that form an irreversible network after curing, unlike so-called thermoplastics, which can be easily melted. “Imagine it like a plate of spaghetti,” explains the project leader Arijana Susa at Wageningen Food & Biobased Research (WFBR). “If the spaghetti are thermoplastics, the strands can move again upon (re-)heating. But if the spaghetti are thermosets, there are rock-hard bridges between all the strands, the so-called crosslinks. These fix everything in place and no longer melt even upon (re-)heating. This makes it virtually impossible to separate and recycle the fibres and resin in composites.”
COMPOCYCLE is attempting to develop biobased resins in which these crosslinks or bridges can be deliberately broken down even after curing, via external stimuli. Think of temperature, UV light, or a slight acidity – depending on the intended use. Business Developer Raphael Fredon (WFBR) adds: “If you use a material outdoors, for example, you don’t want it to break down due to UV or water. But for indoor use, that could be a suitable degradation mechanism.” Susa: “This way, we want to recover not only the fibres, but also the biobased resin. That’s precisely where the innovation lies.”
Lab and practice
The COMPOCYCLE project follows two research lines. The first (RL1) focuses on the development of new biobased monomers and crosslinkers at lab scale. This is all about chemistry: creating biobased, non-toxic resins with built-in degradability, according to the so-called Safe-and-Sustainable-by-Design approach. This degradability can, for example, be achieved by incorporating esters or ketals (chemical compounds) that detach under certain conditions.
The resins developed for this can be made from humins – residual streams from the biorefining of sugars. In addition, the use of other platform chemicals is possible, such as xylose, levulinic acid, and dimethyl fumarate. “So, we are not dependent on one raw material,” emphasises Fredon. “There is also enough biomass available to scale up if the project succeeds.” COMPOCYCLE is therefore looking beyond the lab phase from the start.
In Research Line 2 (RL2), the application of these new materials is examined. Prototypes are made – such as façade panels or traffic signs – which will also actually be tested in real-life conditions, namely at The Green Village on the TU Delft campus. Fredon: “There, we look at how UV, rain, and wind affect the materials. This not only concerns mechanical performance, but also the measurement of ageing and necessary maintenance.”
Broadly applicable
Although the initial applications are found in construction – specifically for window frames (VHZ group) and façade panels (NPSP)– the composites developed can be designed for use in many other industries. “We also have formal support from parties in the furniture industry, aviation, and automotive sectors,” says Fredon. “For example, for bed frames or interior parts. Although these parties are not official consortium members, they remain involved in the project.”
According to Susa, the modular nature of COMPOCYCLE’s chemical approach is key here. “The concept remains the same, but you can adjust the molecules for different properties: rigid or flexible, water or UV resistant. This way, you can make materials for very different applications based on the same core principle.”
Upcycling
COMPOCYCLE distinguishes itself from earlier projects focused on making biocomposites recyclable, such as the recently completed ESTELLA project. ESTELLA made significant progress by developing new biobased thermoset formulations with the focus on the efficient reprocessing of thermoset materials, enabling them to be reused in the same/ similar type of application; an approach known as closed-loop recycling. With COMPOCYCLE, the focus is mainly on practical use. “We don’t get exactly the same thermoset resin back, but a new usable thermoplastic raw material,” says Susa. “The goal is not one-to-one recycling, nor downcycling, but potentially even upcycling. Perhaps it was first a façade panel and then becomes a piece of furniture or car interior.”
Big impact
The potential impact of COMPOCYCLE is significant. By replacing fossil plastics with biobased and recyclable alternatives, the project contributes to less waste, lower CO₂ emissions, and reduced dependence on fossil raw materials. It also aligns with the EU Green Deal, circular economy goals, and producer responsibility regulations.
According to the project plan, COMPOCYCLE aims for a 5% market share in the European biobased composites market – good for approximately 12,500 tonnes per year. And that’s just the beginning. In the longer term, applications are conceivable in the wind energy sector, electronics, or even aerospace.
Consortium partners COMPOCYCLE:
Qconcepts – composite producer | Wageningen Food & Biobased Research – coordination and technology development | Allnex – resin producer | TU Delft – composite manufacturing and testing | NPSP – biocomposite producer for construction and infrastructure | Bambooder – natural fibre producer (bamboo) | VHZ Groep – producers of window frames | The Green Village – living lab, test facility | CompositesNL – Dutch composite industry association | Michelin Engineering Polymers – raw material supplier (humins)