Devulcanization has the potential to help meet circular economy goals by recovering end-of-life rubber. However, the adoption of devulcanized rubber by manufacturers remains low at the industry level. Devulcanization value chains are complex and involve multiple stakeholders, including waste collectors, sorters, recyclers, compounders, manufacturers and regulatory bodies. This study investigated the barriers compounders and manufacturers face when incorporating devulcanized rubber into new compounds and identified primary underlying causes. The research was conducted through in-depth interviews with compounders and manufacturers of tires and general rubber goods, focusing on the technical, market, institutional, and cultural factors related to incorporating recycled materials, specifically devulcanized rubber. From the results, we identified a number of barriers faced by the industry. A key barrier was the heterogeneity of devulcanized rubber, which made it more difficult to add to new rubber compounds with consistent quality. Other barriers included a lack of standardization and coordination, along with misaligned regulations that hamper the market adoption of devulcanized rubber. This implies that increasing the uptake of devulcanized rubber at the industry level will not be achieved through technological advancements alone or isolated market interventions; instead, it requires comprehensive, systemic solutions.

The short lifespans and rapid innovation cycles of electronic products result in the loss of valuable and critical resources (Bakker, Wang, Huisman, & den Hollander, 2014; Baldé et al., 2024). Strategies aimed at extending product lifetimes, such as design for repair, focus on improving the ease of manual disassembly (De Fazio, Bakker, Flipsen, & Balkenende, 2021). However, connections optimized for repairability can hinder the mechanical separation of materials during recycling. This highlights a critical trade-off: improving repairability can often conflict with recyclability, emphasizing the need for balanced design approaches that address both recovery goals. Navigating these trade-offs requires a deeper understanding of how materials and connection types in electronics affect circular strategies. This research aims to investigate tensions between repairability and recyclability by analyzing a diverse set of electronic products and relating the findings to their design architecture. This study seeks to inform design strategies that optimize for both repairability and recyclability, thus prolonging product lifetime while minimizing resource losses at end-of-life.

Nowadays, the circular economy represents a promising strategy for achieving sustainable development through optimising resource efficiency, extending product lifespans, and reducing environmental impacts. Despite the growing interest in circular design practices, companies often face difficulties integrating these principles into their established New Product Development (NPD) processes. This is mainly due to the overwhelming number of available design tools and methods, which are fragmented, challenging to navigate, overlap in functionality, and lack standardisation. This study provides a comprehensive mapping, classification, and analysis of 77 existing circular design tools identified through a systematic literature review and supplementary online searches. The tools were systematically categorised according to format, data type, industry sector, circular strategies, innovation focus, aims, and applicability across the NPD stages. The results indicate a predominance of physical, qualitative, and sector-agnostic tools, emphasising circularity integration within the Discover, Define, and Develop phases of the design process. This structured classification facilitates stakeholder navigation of existing resources, highlighting opportunities for more targeted, industry-specific tool development, consumer-oriented approaches, and the importance of considering Industry 4.0 technologies in circular design practice. Future research could address these gaps by developing customised frameworks, validating tool effectiveness through real industrial applications, and promoting deeper integration of circular design tools within NPD practices and business objectives.

The validity and reliability of four prevalent reparability scoring systems has been investigated by comparing scores of ten smart phones and six vacuum cleaners versus empirically measured repair times, as well as comparing hypothetical ideal and problematic scenarios. Ease of disassembly methods was also assessed for five smart TVs, four washing machines and six vacuum cleaners. The scoring systems studied were the French Reparability Index (FRI), Joint Research Centre Scoring System (RSS/JRC), iFixit, and ONR19202. Overall scores of products across scoring systems were relatively well correlated, indicating a fair amount of overall reliability. However, the variability in scores for the best and worst case of the same product was often larger than the differences between products. Validity was good for products that are easily repairable, but scorecards often failed to score low when repair is infeasible or too expensive. Repair scores greatly depend on disassembly; since some scorecards count numbers of disassembly steps and other scorecards use proxy times, these two methods were compared against empirical disassembly times for five vacuum cleaners, five televisions, and four washing machines. The proxy time method was found to be highly accurate for all three product categories; the steps method was less so. It indicated the relative ease of disassembly well for washing machines, but not for televisions or vacuum cleaners. Finally, this study proposes improvements to scoring methods, including a limiting factor approach and the development of clearer protocols, to ensure the scoring systems are robust, reliable, and can effectively guide sustainable product design.

Consumers often replace electronic products prematurely due to performance issues (Van den Berge et al., 2021). Repair is a promising strategy to extend product lifetime by correcting faults to restore functionality (Pamminger et al., 2017) or realigning the product performance with users’ functional expectations via upgrades (Godfrey et al., 2022). However, repair activities declined over the past decades with 60% consumers disregarding repair when products malfunction (Magnier & Mugge, 2022). Recent consumer studies have revealed the barriers to repair. Consumers often struggle to diagnose product failures (Ackermann et al., 2018; Pozo Arcos et al., 2021), causing uncertainty about repair paths. Previous negative repair experiences further demotivate repair (Sonego et al., 2022), making consumers doubt its value (Svensson-Hoglund et al., 2022). The uncertainty about the availability of spare parts, clear repair instructions, and trustworthy repair services increase concerns about repair (Jaeger-Erben et al., 2021; Sonego et al., 2022). These lead to a lack of consumers’ trust, acceptance and adoption of repair practices. […]

Innovation is crucial to meet the circular economy goals for tire recycling. Devulcanization, an innovative recycling method of reprocessing tire rubber, offers a pathway towards achieving circular economy objectives. While previous research on devulcanization has primarily focused on technical aspects, this study shifts the focus towards identifying opportunities and barriers for innovation through devulcanization. This research utilizes the Technological Innovation System framework as a basis to analyze the dynamics of innovation within value chains and innovation networks. Across Europe, 36 organizations were identified that develop and utilize devulcanization to transform rubber from end-of-life tires into a valuable resource for new rubber products. In this study, a semi-structured in-depth interview approach was applied to interview 12 organizations that have developed or utilize technologies for the devulcanization of tire rubber. It was found that the development of various devulcanization approaches for diverse types of products has created opportunities for upscaling. To capitalize on these opportunities, organizations need to collaborate throughout the entire value chain of tire production and recycling. Achieving this collaboration requires interventions across the industry.

Bio-based polymers may present a sustainable, circular way to reduce the environmental impact of plastics because they are produced from biomass that absorbs CO₂ during its growth. However, sourcing (type of biomass used and cultivation location), production, and end-of-life affect the environmental impact of bio-based plastics. We assessed the effect of sourcing and end-of-life options on the environmental impact of bio-based high-density polyethylene (bio-HDPE) in 31 sourcing scenarios and five end-of-life options. Our study found that careful consideration of biomass sourcing (biomass type and production location) and end-of-life is needed to optimize the environmental impact of bio-based plastics. If these aspects are not considered, the environmental impact of bio-HDPE may exceed that of its petrochemical-based counterpart. The direct availability of fermentable sugars indicated a lower environmental impact. The production location affected the resources needed for biomass cultivation and the environmental impact of processing due to the energy mix. Recently published guidelines do not allow biogenic carbon to be accounted for during the production stage, but only upon the incineration of the plastic. Our results show that this way of attributing biogenic carbon results in an apparent disadvantage for bio-based plastics compared to petrochemical-based plastics. Furthermore, it disadvantaged mechanical recycling of bio-based plastics compared to incineration, a result out of line with circular economy principles.

Using additive manufacturing for spare part production can ensure that spare parts are available for a long time. However, spare parts are currently not designed for additive manufacturing. This study aimed to find how the production of 3D-printed spare parts can be facilitated in the design of plastic parts. We used a literature review and illustrative case to find how the design requirements for standard injection moulded plastic parts relate to the manufacturing capabilities of additive manufacturing for spare parts. The design requirements were defined by assigning corresponding structural and material properties. These requirements were then used to construct and evaluate the capabilities of additive manufacturing compared to injection moulding. It was found that additive manufacturing is especially suitable for requirements like Accuracy, Heat resistance, and Chemical resistance. However, to fully enable 3D-printed spare parts, certain design challenges still need to be tackled. Designers should pay careful attention to the synergies and trade-offs between design requirements and the challenges that might arise from the combination of certain requirements. Also, designers should ensure products are easily reparable before considering 3D-printed spare parts. If we target these challenges in the design phase, we can facilitate 3D-printed spare parts that enable product repairability.

Hazardous substances, or substances of concern (SoC), are present in numerous products and may be the source of significant risks to human health and the environment. In addition, the presence of SoC in products challenges the transition towards a circular economy. By implementing strategies such as reuse or recycling, SoC can be reintroduced in subsequent lifecycles, generating new forms of risk. Addressing SoC in the early stages of the product development process is necessary to mitigate the hazards and risks they may present throughout multiple lifecycles. Product designers hence need appropriate tools and methods to address SoC in products. However, we have observed that current research primarily focuses on the development of non-toxic chemical alternatives and approaches that mitigate the risks of SoC at a chemical and material level (i.e., substitution), lacking the necessary holistic approach to avoid trade-offs or unforeseen consequences. Available design specific methods, tools, and information to address SoC in products are extremely limited and have too a material focus. To address this, we investigated five cases to understand how SoC were dealt with across the product lifecycle and identify mitigation interventions used. We then analyzed the interventions and classified them into five levels of influence, i.e., chemical, material, component, product, and system, and evaluated their respective implications for design, advantages, and drawbacks. Our analysis results in three groups of mitigation strategies that are specifically relevant to product design: Avoid, which entails any modification to the product that eliminates the SoC, Control, in which the SoC remains in use, but its emissions are prevented, and Reduce, which includes any modification that results in the reduction of the volume of the SoC or its emissions. Our findings establish the potential contribution of designers in the mitigation SoC in products and constitute a basis for the development of methods or guidelines to address SoC from a product design perspective.

This research project, part of the Green Intensive Care Unit (ICU) initiative at the Erasmus University Medical Center (EMC), is focused on reducing the environmental impact of syringes at the ICU by designing solutions based on circular economy principles. Based on a Material Flow Analysis of the EMC ICU, syringes and their packaging have been identified as one of the main environmental impact hotspots. Therefore, this project aimed to redesign the syringes, their packaging, and their use, according to circular design strategies suitable for medical products to decrease their environmental impact, while remaining convenient and safe in use for the healthcare staff and patients. Research was executed to understand the context from multiple perspectives. The outcomes demonstrated that decreasing the impact of syringes is not only related to the design of the syringe itself. Manufacturing, preparation, use and disposal, all contribute to the environmental impact of the syringe. Various possible interventions were derived to reduce its impact:

1.
Adapting the infection prevention protocol and behaviour of the staff;

2.
Separating infectious waste from general hospital waste;

3.
Redesigning the syringe itself;

4.
Optimising the filling process of syringes.

The final design is an optimised filling process for prefilled sterilised syringes (PFSs), based on circular strategies such as reduce, reuse, rethink and repurpose. Interventions include: eliminating a redundant sterilisation phase, reducing residual medication and changing from steam to gamma sterilisation. This resulted in decreasing the amount of waste, material, energy and water consumption, while offering similar convenience and safety for the staff and patients of the ICU.

Time is a crucial element in design, and even more so when it comes to designing for sustainability. Many designers approach sustainability from a problem-solving perspective, according to which time is linear (and therefore quantifiable) and the future is predictable (and therefore designable). Designerly time appears quintessentially modern and human. A welcome antidote can be found in more-than-human design perspectives, where a multitude of actants and agencies and their appropriate temporalities are given consideration and space. In this paper we add to such approaches by exploring in practice two ways to engage with more-than-human temporalities: noticing and care. We illustrate how these approaches may give way to new design practices by discussing the conceptualization and construction of a music festival stage in France. We argue that such design practices integrate ecological care into the design process by attuning the designer to the different scales and rhythms of ecosystems and their more-than-human members.

Replacing fossil-based feedstock with renewable alternatives is a crucial step towards a circular economy. The bio-based plastics currently on the market are predominantly used in single-use applications, with remarkably limited uptake in durable products. This study explores the current state of the art of bio-based plastic use in durable consumer products and the opportunities and barriers encountered by product developers in adopting these materials. A design analysis of 60 durable products containing bio-based plastics, and 12 company interviews, identified the pursuit of sustainability goals and targets as the primary driver for adopting bio-based plastics, despite uncertainties regarding their reduced environmental impact. The lack of knowledge of bio-based plastics and their properties contributes to the slow adoption of these materials. Furthermore, the lack of recycling infrastructure, the limited availability of the plastics, and higher costs compared to fossil-based alternatives, are significant barriers to adoption. Product developers face significant challenges in designing with bio-based plastics, but opportunities exist; for example, for the use of dedicated bio-based plastics with unique properties. When designing with bio-based plastics, product developers must think beyond the physical product and consider sourcing and recovery, which are not typically part of the conventional product design process.

Within a circular economy, prioritizing product integrity and durability is crucial for circular product design. However, in addition to efforts in strategies like reuse and repair, products inevitably require recycling. This paper critically assesses the current state of Design for Recycling guidelines and methods in the field of electronics, focusing on their Efficacy and Effectiveness. We conducted a literature review using Scopus, Web of Science, and Google Scholar. Following the methodology outlined by Hagen-Zanker and Mallett [1], we identified relevant literature and used snowballing to find additional sources. The search led to 16 articles (1993–2023) proposing methods, tools, guidelines, or frameworks targeting product designers and aimed at the design for improved recyclability of electronics. The final Design for Recycling methods and guidelines were assessed using an adapted version of the method evaluation framework [2] in the context of method content theory [3]. The inclusion of only 18 sources in the review, consisting of nine peer-reviewed and nine non peer-reviewed articles, indicated a limited development in the field since 1993. Many of the methods and guidelines presented were insufficient based on common recycling and design practices, they also lacked validation through recycling tests and were rarely tested with design practitioners. The findings show an urgent need for a substantiated and validated Design for Recycling method, which helps lower the environmental impact of electronics, is tailored to design practitioners, and aligns with common recycling practices.

The availability and storage of spare parts are the main barriers to product repair. One possibility would be to 3D print spare parts, which would also enable the repair of products not intended to be repaired. Besides manufacturers, 3D printing spare parts is an interesting option for self-repair by consumers. However, the digitisation of spare parts for 3D printing is a challenge. There is little guidance on how to make a 3D-printed version of the original part. This paper establishes a framework through a literature review and experimental study to describe how to use 3D printing to produce spare parts for repair. Additionally, qualitative data coding was used to find the influence of previous experience, process implementation, and part complexity on the overall success of the 3D printing for repair (3DPfR) process. Our study showed that the 3DPfR process can be described as an iterative design for an additive manufacturing process that is integrated into a repair process. Additionally, it was found that the incorrect implementation of process steps was the most important predictor of the repair result. The steps that were performed incorrectly the most were synthesising design concepts (64%) and validating print quality (also 64%).

Materials form the basis of modern technological society. The extraction and processing of raw matter and the disposal of material things is at the heart of most of the environmental and social crises, and has important implications for the design and deployment of computation systems. In this paper, we present an analysis of the way in which materials are selected during the design process: how designers determine whether a given material is fit for purpose. While originally addressing specific functional or aesthetic purpose, with increasing urgency designers have begun to select materials that also consider a broader environmental purpose (eg. CO2 footprint) or ethical purpose (eg. Fair Trade). The analysis also unveils a missing category: the need to consider the social relations that emerge in the creation of materials across their supply chains. Fit for political purpose is thus proposed to create a bridge between the nuts-and-bolts material design of technology and the socio-political impacts of its production.

Bio-based plastics are attracting increasing attention due to their perceived sustainability and circularity. While enabling circularity by using renewable feedstocks, they still contribute to plastic pollution. Furthermore, their rapidly growing market will cause bio-based plastics to constitute significant fractions of plastic waste, necessitating efficient recovery at end-of-life. Technical overviews of potential recovery pathways for bio-based plastics exist, although these have not yet been translated into product design recommendations. In this article, we assess the impact of material composition and product design on the feasibility of eight recovery pathways for bio-based plastics. The ability to recover a plastic not only depends on the plastic composition, but also on the way a product is designed. The alterations made to tailor plastics to be applied in products, and the product architecture, can enable or prohibit some recovery pathways. The outcomes highlight the importance of establishing a wider range of recovery pathways for plastics, and the crucial role of product design in enabling a circular economy for bio-based plastics. We also present a first guidance for product design to enhance the recovery of bio-based plastics.

Wind turbines are crucial for the energy transition, but their end-of-life treatment presents a challenge. Most wind turbine blades, made from composites, are currently sent for disposal or recycled through methods that degrade the value of the material. Structural reuse through blade segmentation was introduced as a recovery method that maintains high material value throughout subsequent life cycles. Most recovery attempts focus on thermoset composites, but thermoplastics are becoming more common. Unlike thermosets, thermoplastics can be reshaped through thermoforming processes, which offers the opportunity of adapting the geometry of a blade to new reuse applications. This paper introduces selection strategies to identify secondary applications of reshaped thermoplastic blade sections. A new methodology is proposed based on Landru's selection strategies and the Material Driven Design method (MDD). The Circular Applications Through Selection Strategies (CATSS) methodology proposes understanding a material at different levels to identify applications. Each sectioning level of the blades yields different material characteristics, such as the reshapability, that are then put into Landru's three selection strategies: substitution, selection by function, and inverse selection. Substitution directly supplants other materials with blades in an existing application; selection by function compares material properties and performance indices to derive the most relevant functions (i.e. "light-weight beams"); and inverse selection identifies suitable market sectors. The CATSS method is a systematic approach to exploring the reuse of blade sections across multiple life cycles, taking into consideration the changes in blade geometry introduced by each sectioning level. For example, the second use cycle might use blade segments for infrastructural applications like electrical transmission poles, while 3rd and 4th cycles reuse blade elements or blade units for urban furniture or automotive parts, respectively. Thus, by identifying multiple use cycle applications at various sectioning levels, we introduce structural reuse and reshaping as a long-lasting recovery pathway for decommissioned wind turbine blades. The selection strategies presented on the one hand can help identify new applications for thermoplastic composite products at their end-of-life, while on the other hand they indicate which aspects need to be considered in the original design, thus contributing to more circular practices in the composites industry.

Spare parts availability is crucial for extending the life of consumer products. However, long-term availability could lead to high stocks of spare parts, which might not be used. Instead, on-demand manufacturing of spare parts with additive manufacturing (AM) is a promising alternative. This paper presents a method to evaluate parts on their eligibility for AM spare parts. The parts evaluation is based on AM technology accessibility as well as part requirements. This method was tested by assessing all parts of the Dyson V11 broom-stick vacuum-cleaner and validated by printing and testing a selection of parts. For this, both plastic and metal spare parts were made through fused deposition modelling (FDM), stereolithography (SLA), binder jetting (BJ), material jetting (MJ), selective laser melting (SLM), selective laser sintering (SLS), and multi jet fusion (MJF), using both desktop FDM printers and off-site service providers. Based on these results, we conclude that currently only a small number of parts can be replaced by additive manufactured parts without considerable redesign efforts. AM parts can compete on price with the current stocked parts, but may be more expensive for other products. We also identified additional functional requirements for evaluating the eligibility of a spare part for AM.

Product repairs are at the core of sustainable consumption and user manuals can play a relevant role in facilitating them. They are the accredited source of product information for end users and are therefore sought as an important means for the diagnosis and subsequent repair of household appliances. However, despite increasing societal demand for repairable products, few studies have been conducted on the extent to which manuals contribute to
the fault diagnosis and subsequent repair process. In this study, we analysed current guidance provided by manuals for the diagnosis process, answering the research question: ‘To what extent do user manuals provide sufficient information to diagnose the most frequent faults in household appliances?’ We examined the diagnosis instructions provided in the user manuals of four different household appliances using data on the appliances’ most frequently failing components, and a framework that considers three steps towards a suc-
cessful diagnosis: fault detection, fault location, and fault isolation. In total, we analysed 150 user manuals of 48 brands available on the European market. We show that manuals do not instruct the diagnosis of frequently failing components. They mainly refer to causes of failure and directly recommend corrective actions after fault detection. Thus, they rarely include a three-step fault diagnosis process to identify and isolate a faulty component.
Based on these results, we have extended the framework for the process of fault diagnosis to include a step from cause identification to corrective action. Both routes, the component- oriented and the cause-oriented route in fault diagnosis, should be considered during the design of products for easy fault diagnosis, and should be included in future regulations that address product reparability