The project ran between November 2023 and April 2024.
More than 50 million tons of lignin are produced from wood pulping and other biorefinery industries annually. Although bioplastics is a large and growing global market, the proportion of lignin-based bioplastics is negligible today. On the other hand, the global Athletic Footwear Market is expected to reach $196 billion by 2030. Of which, little over 5% covered the ‘sustainable footwear market. This presents an enormous opportunity for growth. High-performance foams for cushioning are at the core of such products. The plastic materials in one sneaker takes about 40 years to decompose in a landfill, and around 300 million sneakers are discarded annually.
RISE has a long history of working with most lignin suppliers. RISE has also over the years developed expertise in modifying lignin into a bendable, stretchable material (elastomer). KRAM has worked extensively with prominent manufacturers of athletic footwear in the sportswear and fashion industries. KRAM also has the unique ability turning new materials into small-scale prototypes, therefore quickly evaluating their potential. This in turn significantly fast-tracks the decision-making process of their customers.
In this project, by combining the material and production knowledge and characterization tools at RISE with the design and prototyping capabilities of KRAM, the project aimed to make some small-scale prototypes and test suitability in athletic footwear market. The project would study the market potential and look into possibilities to mass-manufacture these materials.
Participants
RISE-Research Institutes of Sweden AB and Reed Kram AB.
Budget
The project’s total budget was 1 MSEK.
Results
The project built on existing knowledge of preparing elastomeric materials from modified lignins crosslinked with epoxidized linear polymers, such as Poly(ethylene glycol) diglycidyl ether (PEGDE), to develop elastomeric foams. Different modified lignins, additives and blowing agents that expand during crosslinking were investigated. The primary application area was cushioning foams for athletic products.
During the project, foamed elastomers were successfully produced using expandable polymeric beads (Expancel, supplied by Nouryon). By varying the additives, it was possible to tailor key material properties, including stiffness and springback. Initial litre-scale foam production trials demonstrated the feasibility of producing expanded elastomeric foams and controlling important mechanical properties, although the trials were intended to demonstrate proof of concept rather than optimize the process.
The project also compiled an overview of commercially available athletic products containing bio-based foams, based on publicly available information and non-confidential discussions with industry representatives at trade fairs. The review showed that several products on the market claim to contain bio-based foams, although the bio-based content is often limited to fillers and the meaning of the term “bio-based” is not always clearly defined.
Overall, the project demonstrated that expanded elastomeric foams based on crosslinked lignin materials can be produced with tailored mechanical properties. The results also indicate a significant market opportunity, with growing demand for bio-based elastomeric materials in athletic products and relatively few commercially available solutions.