Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM
A misunderstanding is a communicative disturbance resulting from the difference between what is meant by a sender and what is understood by the recipient. It often occurs due to a lack of knowledge. We want to counteract this with this blog article, which deals with the misunderstood role of adhesive bonding technology in discussions about the circular economy.
Adhesive bonding technology and the circular economy - this combination does not bode well. It is often assumed that adhesive bonding technology is a stumbling block for the circular economy. The rather fact-based positive assessment at expert level contrasts with the rather emotion-based negative assessment by the public. This is aggravated by the fact that the public often equates the circular economy with recycling and reduces the assessment of adhesive bonding technology to recyclability. In this context, bonding appears to prevent effective recycling. However, recycling is seen by the public as the eco-strategy. And if adhesive bonding technology is seen as the antagonist of this strategy, to what extent can it be seen as contributing to compliance with the European Green Deal? We will get to the bottom of these questions in this interview with Prof Dr Groß, Head of the Training and Technology Transfer department at Fraunhofer IFAM.
| Green Deal: The overarching goal of the European Green Deal is to achieve climate neutrality in Europe by 2050, which can only be achieved through a climate-neutral and resource-efficient economy. The transition from a linear economy to a circular economy plays a central role in this. Adhesive bonding technology has the potential to drive these new requirements forward with technical innovations, as it can optimise life cycle assessment effectiveness in many areas[1]. |
| R strategies: The aim of the circular economy is to reduce the consumption of natural resources and improve the recycling of materials, which simultaneously results in less waste (see illustration). The central element of the implementation of the circular economy is the EU Waste Framework Directive, whose core concept consists of the so-called R-strategies. See the diagram for an overview of the R-strategies. |
Prof Dr Groß, what role does adhesive bonding technology play in terms of sustainability and ecology?
In discussions about the relevance of adhesive bonding technology in the circular economy, its role is often misunderstood. This is because the focus is usually on the last strategy element R9 - recycling (see illustration) and the overarching strategy elements R2 - R8 tend not to be taken into account. Firstly, I would like to make it absolutely clear that adhesive bonding technology does not contradict recycling, i.e., R9! All bonds, including the bonded ones, can be released again, even for recycling purposes. Tetra Pak soft packaging - consisting of paper (approx. 75%), plastic (approx. 20%, polyethylene, PE) and aluminium (approx. 5%) - is an example of how, despite the assumption that a glued product is not recyclable, the separation of the layers is still possible through industrial processes and is also carried out to a high degree.
As I said, the assumption that bonding and recycling are mutually exclusive and the apparent conclusion that bonding could contribute little to achieving the European Green Deal does not in any way do justice to bonding and its technological and ecological performance potential. On the contrary, the fact is that bonding contributes to the R-strategies R2 - R8 (see illustration) in an ecologically value-adding way to the circular economy.
So the misunderstanding is that the options of reducing the amount of material used in a product and extending the service life of products are not being considered as a central part of the circular economy?
That's exactly the case! In my experience - and as the ARD documentary "The Recycling Lie" published last year also showed - recycling cannot be seen as the only solution by any stretch of the imagination. Even with the most innovative design and optimised production and use, products and product parts become waste after the longest possible life cycle. The reason is easy to understand: The effort required for strategy elements R4 - R8 (see illustration) becomes too great both economically and ecologically. The latter is due to additional consumption of materials and energy.
In contrast, the use of adhesive bonding technology has the effect of improving the longevity of products in the sense of R2 - rethink. What does this mean for a circular economy? A material usage cycle for the circular economy is extended and, as a result, the proportion of waste or the proportion of material that can only be reused at a low value-added stage is minimised when viewed over several cycles. Areas of application in which adhesive bonding technology supports the longer use of a product include automotive, aircraft and rail vehicle construction. Optimised surface treatment processes improve the long-term durability of the adhesive bond, known as adhesion, and therefore product longevity. And in metal bonding, the adhesive between the metal parts to be joined extends the product service life by preventing contact corrosion throughout the product's service life. Lightweight construction, i.e. achieving the same functionality with less material in the long term, corresponds to R 3 - reduce. Lightweight construction is one of the most effective, resource-efficient eco-design strategies and adhesive bonding technology is both a key technology and an enabler. Furthermore, bonding is probably already the most frequently used repair method (R5 - repair). A repair extends the product's useful life and therefore keeps raw materials in the cycle for longer. Conserving resources through gluing! From an ecological point of view, the service life of a product should be as long as possible, even if newer product generations are more energy-efficient, for example, as new production often requires more energy and materials.
We continue to live in a throwaway society in which increasing thought is being given to how a used or broken product can be recycled. Extending the service life of products is too often disregarded as a solution. For example, recycling cannot be the only solution to the problem of problematic electrical waste, as we can see from the landfill sites in the Global South - only 17% of electrical waste is actually recycled. In addition, we now know that, according to current knowledge, the raw materials to produce smartphones will run out by the end of this century.
By gluing, however, we can extend the life of a smartphone. This brings us to a specific point of "eco-design" - the possibility of extending the service life through maintenance and repair must also be considered in the design process for bonded products, regardless of the economic interests of the manufacturer. Accordingly, there must be a better understanding of adhesive bonding technology, i.e. one that is focussed on this issue, on the part of adhesive and product manufacturers, service providers, consumers and disposal companies in order to clarify the central role of adhesive bonding technology in and for the circular economy.
And something else that is often forgotten: Adhesive bonding is also an integral part of the energy transition! Bonding enables modern systems for alternative and reliable (!) energy generation on a large scale. The rotor blades of wind turbines are joined exclusively by adhesive bonding. Bonding technology is used in photovoltaics. Electromobility without adhesive bonding is inconceivable. The keywords here are: Assembly of the magnetic cores, sealing of the battery cells, thermal management of the batteries. Fuel cells must be hermetically sealed and the bipolar plates used must be bonded.
You mentioned the documentary film "The Recycling Lie" from 2022. The question that these revelations about recycling raise all the more is: Is recycling really the solution to climate neutrality?
Once again, recycling is undoubtedly part of the solution. But recycling is undoubtedly not the solution. In 2021, only just under 10% of global plastic production was actually recycled in the sense of obtaining so-called secondary raw materials.
So, it's about a change in awareness, or rather a "broadening of awareness". We must think holistically and see the entire R-strategies. We must not detach a single aspect, such as R9 - recycle, from the overall context and make it the sole basis for decision-making. To put it simply: 9 R instead of just R9!
[1]Source: Fraunhofer IFAM, https://www.klebstoffe.com/wp-content/uploads/2022/01/IVK_Wie-Klebstoffe-die-Ziele-des-Green-Deals-unterstuetzen.pdf