Seaweed-based plastic film that doesn’t disrupt the production lines – our work with FlexSea



Joint Industry Project

circular plastics

bio-based materials

FlexSea and iCAST worked together over six months to understand FlexSea’s seaweed-based film formulations and how to control the material’s mechanical and barrier properties.

The need to move away from fossil-fuel based plastics is well understood. Although cheap and extremely useful, regular plastics are a major source of social and environmental issues. They are made out of nonrenewables and they are hard to collect and recycle, thus ending in landfill or in nature. Alternatives are urgently needed.

And there are alternatives – some of them offering excellent gains. For example, some bioplastics offer great properties but still present recyclability and cost challenges. Others are cheaper to produce but are hard to upscale, demand extensive use of land, require intensive processing or depend on less reliable sources. Adapting to such technologies would also require major changes in the production lines.

FlexSea’s mission is to bring truly compostable, biodegradable plastic film to businesses without revolutionising their production lines.

The company proposes red seaweed as their feedstock, a raw material that doesn’t require using pesticides, fertilisers, land or freshwater, so its ecological and environmental impact is nearly zero through its life cycle. Seaweed farming also preserves ecosystems, protects coasts from erosion and sustains local economies.

FlexSea have developed an innovative, home-compostable bioplastic – it derives from carbon sequestering red seaweed species instead of fossil carbon fuels and degrades in ocean water without leaving toxic traces. The film’s processing is easier than in other bio-based alternatives and it does not create waste in the production line, resulting in a competitive price.

The material would be used for packaging of short-term and short-shelf-life everyday consumer goods and dry items, such as takeaways or supermarket fruit and vegetables.

The company approached iCAST to develop a database of the different formulations of their material and their properties, so they could be used and adapted to different packaging applications. Over six months, FlexSea and iCAST worked together in a Joint Industry Project (JIP) that gave them access to world-class facilities to test their film formulations, as well as dedicated academic expertise to improve the material properties of the seaweed-based film.

As a result of this work, FlexSea has steered their focus towards advancing in-house R&D investment, for example exploring other chemical variations of their formula and, thanks to baseline characterisation using iCAST equipment, will be improving water barrier properties by adding by introducing hydrophobic species in the matrix and in secondary layers.

The company is now also prioritising the design and prototyping of an automated production rig ­– a strategic move expected to accelerate the film production process as they enter the next development plan phase, ultimately aiming to scale up production effectively.

In October 2023, FlexSea announced they raised a £3M seed round in equity and grants led by Indico Capital Partners.


iCAST is a partnership between