Biodegradable and biobased plastics are often promoted as sustainable choices for the built environment, interiors, products and packaging. Yet new research from Radboud University shows that these materials are not always as green as they seem. PhD researcher Sara Gonella studies what it takes to build a truly sustainable plastics industry. Her work offers valuable insight for architects, interior and product designers, packaging specialists and automotive designers who face important decisions about material use.

Biodegradable Plastics Don’t Always Support Circularity

Biodegradable plastics are designed to break down in the natural environment. This sounds ideal, but the reality is more complex. When these materials enter existing waste systems — especially those used for mechanical recycling — they can reduce the quality of recycled plastics.

Most recycling facilities are not equipped to separate biobased plastics from conventional polymers. As a result, these materials can disrupt recycling streams instead of improving them. Designers who choose biodegradable plastics should therefore also consider how local waste systems handle these materials.

Biobased Materials Can Create New Environmental Pressures

Many biobased plastics come from crops such as corn, sugarcane or fast-growing wood. Although these resources are renewable, they require large areas of farmland. In some regions, new plantations replace forests, which leads to deforestation, biodiversity loss and higher CO₂ emissions.

For design practices that rely on plant-based materials, this means that the environmental impact of land use is just as important as renewable content. Certified and responsibly sourced feedstocks are essential.

Chemical Additives Complicate Recycling and Safety

Most plastics contain chemical additives that give them flexibility, colour or strength. Some of these chemicals — including plasticisers and PFAS — pose risks to human health and the environment. They also make recycling more difficult.

Gonella argues that the industry needs clearer rules and more transparency about the use of additives. Designers choosing polymers for interiors, buildings, mobility or consumer products can support this shift by selecting low-additive or additive-free materials.

A Life-Cycle Approach Is Essential

Gonella’s research highlights the need for a full life-cycle view of plastics. Production, material sourcing, use, and disposal all have environmental consequences. Waste systems also vary widely between regions, which leads to confusion for consumers and inconsistent recycling results.

International cooperation may help. Since 2022, UN member states have been negotiating a global plastics treaty. Researchers, including Gonella, encourage governments to look at the entire plastics chain — not only plastic waste.

For designers across all disciplines, the message is clear: sustainable material innovation requires more than new plastics. It also demands an understanding of how materials behave throughout their life cycle and how they interact with the systems around them.

Source: Radboud University
Photo: Tara Winstead