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Bio-based polyurethane foam

The Bio2Foam project aims to develop a bio-based polyurethane (bio-PUR) foam, a non-degradable polymer derived from renewable raw materials. Specifically, the polyol used in this foam will be sourced from sugarcane bagasse, an abundant by-product of the sugar industry.

Background

What are polyurethanes?

Polyurethanes (PURs) are a class of polymers formed by the reaction of polyols with isocyanates, enabling a broad range of structural and functional materials. Their versatility arises from the ability to tailor mechanical, thermal, and chemical properties through the choice of raw materials and formulation. As a result, PURs are used in applications ranging from coatings, adhesives, and elastomers to high-performance foams found in everyday products and technical systems.

What are polyurethane foams?

Polyurethane foams (PUFs) represent more than half of the total polyurethane market. Depending on their formulation and manufacturing process, they can range from very soft and elastic to rigid and load-bearing. This wide spectrum of mechanical and physical properties makes PUFs one of the most adaptable materials in modern industrial and consumer applications.

The structure of PUFs is characterized by a network of polymer chains that can contain thousands of interconnected gas-filled cells. These cells may be open or closed, depending on the desired properties. Open-cell foams are lightweight, flexible, and breathable, commonly used in cushioning, sound insulation, and packaging. Closed-cell foams, by contrast, have sealed pores that make them denser and more resistant to water and gas permeation—ideal for thermal insulation panels, construction materials, or automotive components.

Production begins when the two liquid reactants - polyol and isocyanate - mix and react, releasing carbon dioxide or another blowing gas that expands the polymer matrix. Catalysts, surfactants, and additives fine-tune aspects like reaction speed, foam density, and fire resistance. This high degree of adjustability enables manufacturers to tailor PUFs to meet precise technical needs, from ultra-soft memory foam mattresses to rigid insulation boards used in energy-efficient buildings. One of the key reasons PUFs are so widespread is their combination of light weight, durability, and cost-effectiveness.

Development of bio-based polyurethane foams

Traditionally, both raw materials are derived from crude oil. However, the drawbacks of fossil-based resources—such as the release of climate-damaging carbon dioxide (CO2)—have driven recent efforts to replace them with renewable alternatives. In particular, various feedstocks, including castor oil, palm oil, and lesquerella oil, are being explored as substitutes for polyols due to the hydroxyl groups present in their fatty acids. Lignin, a natural polymer abundant in plants and a by-product of the pulp and paper industry, is also frequently used as a renewable resource in polyol production. The bio-based polyol used to produce PUFs in this project is derived from sugarcane bagasse, an abundant by-product of the sugar industry.