Plastics have become indispensable in modern life due to their versatility and affordability. However, their widespread use has resulted in far-reaching environmental damage, including the accumulation of plastic waste, fossil fuel depletion, and significant greenhouse gas emissions. Bio-based plastics have been proposed as a sustainable, circular solution to the environmental issues associated with plastics. However, bio-based plastics are not implicitly sustainable or circular. These aspects are influenced by how a plastic is produced and how it is recovered at end-of-life, implying that careful attention needs to be paid to material development and product design. This thesis explores the sustainability and circularity of bio-based plastics by looking at: how they are perceived by value chain actors, potential recovery pathways in a circular economy, and environmental impact.


Although bio-based plastics have the potential to be sustainable, the emissions associated with producing them depend heavily on the biomass sourcing. At the same time, bio-based plastics are not de-facto biodegradable and thus efficient recovery at end-of-life needs to be guaranteed. Circular product design with bio-based plastics requires careful consideration of biomass sourcing and recovery. Although much information regarding these aspects is still missing, the research presented in this dissertation provides some guidelines for circular product design with bio-based plastics. In order to reduce environmental impacts, bio-based plastics should be produced with agricultural by-products or with biomass types with a high conversion efficiency. Biomass for bio-based plastics should be cultivated with minimal use of land, water, chemicals and fossil fuels. Environmental impacts can be reduced further by using renewable energy in the production process. Product designers should also consider what recovery pathway they want to target at end-of-life of a product. The plastic composition and product architecture need to reflect the targeted recovery pathway.@en

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.

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Bio-based plastics are gaining attention as a sustainable, circular alternative to the current, petrochemical-based plastics. The main application of bio-based plastics is in single-use packaging with short lifetimes. Extending the application of bio-based plastics products towards durable consumer products requires the involvement of different value chain actors. An online interactive workshop, with 46 participants representing the entire value chain, produced a list of drivers for using bio-based plastics in durable consumer goods and barriers to overcome. The primary barriers to using bio-based plastics in durable products were related to their underdeveloped value chain and a need for more knowledge. The underdeveloped value chain was associated with high costs and no infrastructure for recovery at end-of-life, reducing potential environmental benefits. Participants indicated that they did not expect the value chain to mature without substantial government stimulations. Participants also noted a lack of knowledge among value chain actors as well as end-users. Value chain actors expressed that they need more clarity about what bio-based plastics are available and how they can be used in a sustainable way. While the market demand for sustainable alternatives is growing and bio-based plastics are a valuable marketing tool, users are poorly informed, and marketing should be thoughtful to avoid greenwashing.@en

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.@en

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.@en

The use of self-healing (SH) polymers to make 3D-printed polymeric parts offers the po-tential to increase the quality of 3D-printed parts and to increase their durability and damage toler-ance due to their (on-demand) dynamic nature. Nevertheless, 3D-printing of such dynamic poly-mers is not a straightforward process due to their polymer architecture and rheological complexity and the limited quantities produced at lab-scale. This limits the exploration of the full potential of self-healing polymers. In this paper, we present the complete process for fused deposition model-lingof a room temperature self-healing polyurethane. Starting from the synthesis and polymer slab manufacturing, we processed the polymer into a continuous filament and 3D printed parts. For the characterization ofthe 3D printed parts,we used a compression cut test, which proved useful when limited amount of material is available. The test was able to quasi-quantitatively assess both bulk and 3D printed samples and their self-healing behavior. The mechanical and healing behavior of the3D printed self-healing polyurethane was highly similar to that of the bulk SH polymer. This indicates that the self-healing property of the polymer was retained even after multiple processing steps and printing. Compared to a commercial 3D-printing thermoplastic polyurethane, the self-healing polymer displayed a smaller mechanical dependency on the printing conditions with the added value of healing cuts at room temperature.@en

Fabrics treated to repel water, superhydrophobic, and water and oil, superamphiphobic, have numerous industrial and consumer-level benefits. However, the liquid repellency decreases in the course of time. This is largely due to chemical or physical changes of the coating due to prolonged exposure to relatively harsh environments. To develop more durable fabric treatments for specific applications, it is necessary to measure the extent to which the treated fabrics retain their low-wettability after being subjected to controlled aggressive environmental conditions. In this study, plain weave fabrics made from polyester filaments and coated with silicone nanofilaments in-solution were exposed to aerodynamic icing conditions. The coated fabrics showed superhydrophobic behavior, or superamphiphobic for those that were fluorinated. The wettability of the fabrics was progressively evaluated by contact angle and roll-off-angle measurements. The coated fabrics were able to maintain their low-wettability characteristics after exposure to water droplet clouds at airspeeds up to 120 m/s, despite damage to the silicone nanofilaments, visible through scanning electron microscopy.@en