The intrinsic value of composite materials at the end of their first life is so high, we have to reuse them, says Volker Mathes of AVK

Are there some key points that can be learnt from this study? Which of the technologies studied have become commercial?
Volker Mathes: At the moment we are able to recycle composites, but there must always be a balance between costs and outcome. There are several processes available at a lower technical readiness level, or already on an industrial scale, which don’t suit glass fibre reinforced plastics well, because the glass fibre is too cheap.

We have the regrinding process for glass fibre reinforced plastics, we have energy recovery and we have the cement kiln route, on an industrial scale. But we have so many projects running currently, we are in position to get to the next level. We will have new processes available in five to ten years, which will perhaps be more suitable for glass fibre reinforced plastics.

The cost is a challenge, and also the ecological footprint, because virgin glass fibre has a good ecological footprint. If you put much more energy into the recycling process then it makes no sense from an ecological point of view. I’m a big fan of recycling, but if it doesn’t make sense economically and ecologically, then we cannot do it.

How would you define “recycling” in the context of composites?
Volker Mathes: Recycling is when you can use the intrinsic value of a part beyond its first life. For me, recycling is open loop as well as closed loop. I want to get rid of landfill and incineration. The intrinsic value of the material is high, so it should be reused.

Open loop recycling really makes sense at the moment, like using the material in rail sleepers. Perhaps 20, 30, 50 years in the future we’ll have some kind of closed loop recycling. But producing a wind blade, using it for 25 years, then bringing it back down and using it in a wind blade again – this is complicated, especially with thermosets, because of the structure of the material, which is designed for long life and low maintenance. Why not use material from the wind industry for the infrastructure industry?

Which are the most important regulations and standards driving recycling? Are there ways they need to change?
Volker Mathes: We can’t build up a logistics chain for composite waste because we don’t have a waste code (European List of Waste code). This is step one. It’s that simple. If you want to bring recycling companies into the market they need a specific amount of material, and if we don’t have a waste code, you will not find it in the waste stream and they will not step in.

When a wind blade from Spain is declared as waste, it’s not allowed to bring it to Germany. This makes no sense because the amount of material is still so small that you need international solutions.

The next step is that you have lots of rules for specific applications. We have one rule for end-of-life vehicles, and another for the electrical industry. But they are not harmonized, and often they mention plastics and not composites, which need different processes. Thermoplastics have a higher potential for recycling, but it’s not used today. 70 or 80% of thermoplastic composites go into the automotive industry, but you can’t find it in the waste streams to get it out and recycle it. These topics need to be resolved on an international level and not on a national level.

What standards and good practice in design, manufacturing and through life will help to get the best value from composites at end of life?
Volker Mathes: When it comes to design, we have to rethink lots of parts we are building today. In the automotive industry, there is a lot of talk about multi-material systems. From a recycling point of view, this is the wrong way. It would be better to use single material applications, because then you can remanufacture or recycle it much more easily.

There is a conflict because most composite products are built to last a long time, in the best case without maintenance. Recycling wants the opposite, to get it separated easily and quickly. Even thermoplastic material is not easy to separate.

The intrinsic value of the material is still so high after 20 or 30 years of use, we have to find solutions to use this. It’s much too high to just put it into a hole and bury it. We need to bring in the whole value chain to work on solutions. This means raw material suppliers, producers, users and the recycling companies.

The study was carried out by the Professor Hans-Josef Endres, Director of IKK (Institut für Kunststoff- und Kreislauftechnik / Institute of Plastics and Circular Economy), and Dr. Madina Shamsuyeva at Leibniz University Hannover, with the support of industry representatives from the AVK expert working group. It is available in German at https://www.avk-tv.de/news.php?id=505#.