Monomaterial Instead of Material Mix: How the "Monomaterial Kit" Rethinks Circular Product Design
11.03.2026
Why are many durable plastic products today hardly recyclable – even though they are technically sophisticated? The answer often lies inside the products themselves. Different types of plastics, bonded or firmly joined together, ensure stability or lightweight construction. Yet what performs well functionally becomes a problem in the circular economy. This is where the Fraunhofer Cluster Circular Plastics Economy CCPE comes in with its "Monomaterial Kit".
Multi-Material Systems in the Plastics Industry: Why They Complicate Recycling
Multi-material systems have become standard in many sectors – whether in mobility, furniture or technical consumer goods. Different polymers are combined to generate specific properties such as impact resistance, stiffness or insulation performance.
However, this creates a structural problem for the circular economy: different types of plastics are difficult to separate in a pure form. Adhesives or permanent bonds prevent clean material flows. High-quality recycling is therefore considerably hampered – often leaving only downcycling as an option.
The central insight is therefore: material purity is the prerequisite for high-quality circular systems – and it begins in the design phase.
What is Monomaterial in Plastics?
In the plastics industry, monomaterial refers to a product or component made entirely from a single plastic – that is, one polymer such as PET, PLA or PA.
Unlike multi-material systems, no different plastics are combined. Instead, different functions arise through:
- different morphologies (e.g. fibre, foam, sheet)
- adapted geometries
- different processing technologies such as injection moulding or thermoforming
Monomaterial concepts are considered an important approach within Design for Recycling, as they facilitate separation by type and can improve the recyclability of plastic products.
Two Design Strategies Compared:
Aspect
Multi-Material
Monomaterial
Typical Areas of Application
Highly stressed components, composite systems, applications with extreme property requirements (e.g. automotive interiors, technical housings, multi-layer packaging)
Durable products with a focus on recyclability and pure material streams (e.g. packaging)
Mechanical Performance
Maximum combination of properties possible (e.g. stiffness + elasticity)
High performance possible, depending on material selection and design
Design Freedom
High flexibility through targeted material combinations
New degrees of freedom through structural and process diversity
Recyclability
Often limited, complex separation required
Improved through material uniformity, although higher design requirements may apply
Complexity in Development & Supply Chain
Higher due to material diversity
Reduced through material uniformity
Circular Economy Potential
Limited, depending on separability and recycling technology
Increased where effective collection and recycling systems are in place
Multi-material systems enable highly specialised property profiles that have been optimised over decades in many applications. The monomaterial approach does not fundamentally question this logic – but it shifts the priority: from maximising material combinations to maximising circularity.
The "Monomaterial Kit" developed by Fraunhofer CCPE is aimed at designers and developers who want to consistently integrate Design for Recycling. The basic principle is both simple and demanding: a single thermoplastic is used within a product in different structural forms.
The same material can appear, for example, as:
- fibre or textile structure
- foam
- self-reinforced sheet
- injection-moulded component
This approach has so far been tested with PET, PLA and PA. The desired product properties are achieved not by changing materials, but by specifically varying the morphology.
The "Monomaterial Design Set" demonstrates how different manufacturing technologies – such as thermoforming, injection moulding or sandwich structures – can be combined within a monomaterial concept. This makes it possible to realise both simple sheets and complex 3D components.
The idea behind it: performance is created through structure – not through material diversity.
Monomaterial Kit: Circular Economy Through Design
The Monomaterial Kit is more than a material concept. It integrates additional aspects that are crucial for the circular economy:
- avoidance of adhesives
- development of recyclable colour pigments
- recycling-compatible flame retardants
- adaptation to regional recycling infrastructures
Practical Examples of Monomaterial: Demonstrators from Mobility and Logistics
Within the cluster, specific demonstrators have already been developed, including a "circular child seat" and an insulating reusable transport box. Both examples illustrate that complex and safety-relevant products can also be realised using a monomaterial approach.
The concept can be transferred across industries – particularly for:
- mobility applications
- durable consumer goods
- logistics solutions
- furniture and interior applications
A current practical example is the scientific support of the "Re:think Design Competition" organised by Nowy Styl DACH. Designers are developing recyclable soft-seating furniture based on the Monomaterial Kit. The winners will be announced in April 2026. Circular Design is therefore not only being discussed, but actively tested in practice.
What Does This Mean for the Industry?
For designers
- Circular design is becoming a mandatory design principle – not an optional extra
- Function must be derived more strongly from morphology, geometry and process design
- Material choices directly influence subsequent recyclability
- Monomaterials require early coordination with design and production
For developers
- Product architectures must systematically take end-of-life scenarios into account.
- Reduced material diversity can reduce interfaces and complexity.
- Material selection and construction are becoming more closely linked.
- Recycling infrastructure is becoming a development parameter.
For companies with durable plastic products
- Design decisions become strategic competitive factors
- Recyclability influences regulatory compliance and market opportunities
Conclusion: Design For Recycling Begins in Product Development
Circular plastic products are not created through subsequent recycling optimisation, but through consistent material and design decisions at the beginning of product development.
This change in perspective is becoming increasingly important right now: rising recycling rates, stricter recycling requirements and growing expectations along the value chain are increasing the pressure to act. Products that are not designed to be recyclable today could lose their competitiveness tomorrow.
The Fraunhofer CCPE's monomaterial construction kit shows that circular design is not a sacrifice, but a systemic approach to innovation: one material, diverse morphologies, combinable manufacturing technologies – and a clear focus on recyclability.
Author: Elena Blume | K-Mag
Elena Blume has been writing for various industry magazines for eight years and joined the K-Mag editorial team in 2021. She is particularly interested in topics related to innovative plastics solutions that contribute to sustainability and address current challenges relevant to industry and society.
At a glance
- The "Monomaterial Kit" from Fraunhofer CCPE uses one thermoplastic in different morphologies – instead of combining several plastics.
- Recyclability is considered during product development rather than addressed only at the end of life.
- Monomaterial strategies can reduce material complexity and enable higher-quality material streams within the circular economy.
Key Takeaway:
Anyone who takes the circular economy seriously must rethink material decisions.