The recent circular economy movement has raised awareness and interest about untapped environmental and economic potential in the manufacturing industry. One of the crucial aspects in the implementation of circular or closed-loop manufacturing approach is the design of circular products. While it is obvious that three post-use strategies, i.e., reuse, remanufacturing, and recycling, are highly relevant to achieve loop closure, it is enormously challenging to choose “the right” strategy (if at all) during the early design stage and especially at the single component level. One reason is that economic and environmental impacts of adapting these strategies are not explicit as they vary depending on the chosen business model and associated supply chains. In this scenario, decision support is essential to motivate adaptation of regenerative design strategies. The main purpose of this paper is to provide reliable decision support at the intersection of multiple lifecycle design and business models in the circular economy context to identify effects on cost and CO₂ emissions. The development of this work consists of a systematic method to quantify design effort for different circular design options through a multi-method simulation approach. The simulation model combines an agent-based product architecture and a discrete event closed-loop supply chain model. Feasibility of the model is tested using a case of a washing machine provided by Gorenje d.d. Firstly, design efforts for reuse, remanufacturing, and recycling are quantified. Secondly, cost and emissions of different design options are explored with different business model configurations. Finally, an optimization experiment is run to identify the most cost-effective combination of reused, remanufactured, and recycled components for a business model chosen on the basis of the explorative study results.

This study evaluates the industrial-scale feasibility of injection moulding of a recycled polypropylene composite reinforced with recycled fibers derived from an industrial waste stream. Although previous laboratory-scale research has demonstrated the potential of natural fiber-reinforced thermoplastics, their large-scale industrial implementation remains limited due to uncertainties related to processability, reproducibility, and manufacturing robustness. In this work, the composite material is validated through injection moulding trials carried out in four independent industrial companies located in Andalusia (Spain) and three industrial case studies across different industrial sectors in Slovenia, operating under real production conditions. The extrusion process was characterized in terms of process stability, confirming continuous operation with automated dosing and stable material flow without interruptions under industrial conditions. Injection processing parameters, cycle stability, part quality, and defect formations are also considered important when assessing the manufacturing feasibility. The multi-site validation approach enables the evaluation of reproducibility across different injection moulding systems and mould geometries, providing critical insights into the scalability and technological readiness level of recycled natural fiber-reinforced polypropylene composites. Although direct energy consumption measurements were not systematically recorded, the observed processing stability and cycle repeatability indicate a consistent and energy-efficient operation under industrial processing conditions. The results contribute to bridging the gap between laboratory-scale material development and real industrial implementation.

This study addresses the development, thermal characterisation, and dimensional stability of circular composites based on a post-industrial recycled polypropylene (rPP) matrix from household appliances. The matrix was reinforced with natural (B600 and BC300) and recycled (SIS250, PWC500, and ZZC500) cellulosic fibres at 10%, 20%, and 30% dosages, using 3% MAPP as a compatibilizer. Processing was conducted via twin-screw extrusion and injection moulding. Systematic evaluations (TGA-DTG, DSC, and DIL) showed a minor reduction (2.6–5.1%) in thermal degradation onset, maintaining a safe processing window. Cellulosic fibres generally promoted matrix crystallization through heterogeneous nucleation, increasing matrix crystallinity up to 39.3% in composite B600-30 compared to 20.4% for the reference rPP matrix. Furthermore, the reinforcements acted as dimensional stabilizers, reducing the linear thermal expansion coefficient (α₄₀₋₁₂₀) by up to 28.9% (ZZC500-30) while increasing thermal conductivity by up to 32.7% (B600 series). This approach demonstrates a viable upcycling strategy, yielding high-secondary-content circular composites by combining post-industrial recycled polypropylene matrices with reinforcements (virgin wood cellulose benchmarks (B600 and BC300), pre-consumer recycled cellulose (PWC500), post-consumer recycled cellulose (ZZC500), and recycled technical sisal (SIS250), complemented by 3 wt.% commercial MAPP compatibilizer.