Flexible polyurethane (PU) foams are widely used in many industrial applications including automotive and aeronautics as fillers for seats, headrests etc. They are made from a reaction of two primary ingredients: an isocyanate and a polyol. Originally, these raw materials were derived from petrochemical feedstocks. The use of bio-polyols, i.e. derived from vegetable oils, as an alternative to standard polyols started around 2004 due to the rising costs of petroleum feedstocks and a growing concern for the environment.
But, these bio-polyols can only replace a portion of the polyol part in the formulation and they need to be blended with petroleum-based polyols to maintain the foam physical and mechanical properties. Face to a growing demand for products based on renewable resources, foam manufacturers need to increase that ratio in the formulations while delivering the same foam quality.
On top of that, foams used in the aircraft industry, for seat cushions for instance, need to pass highly stringent fire performance tests. It is well-known that the chemical nature of the polyurethane, its low density and the open cell structure cause this material to be highly flammable. In order to achieve high flame resistance requirements, polyurethane foams must be formulated with flame retardants. A multiplicity of flame retardants is known and commercially available for this purpose, like halogenated flame retardants. However, considerable toxicological reservations frequently stand in the way of their use and alternatives are expected.
In the FIBIOSEAT project, AXYAL, an innovative SME specialised in the industrial transformation of plastics and composites which owns a leading edge expertise in PU foaming and fireproofing materials, proposes to develop a sustainable alternative for current flexible foams which will comply with aircraft fire resistance requirements while meeting the comfort and durability expectations of end users.
A green polyurethane foam containing 30% in mass of bio based polyol was manufactured. This foam respected all the aircraft requirements in terms of fire resistance/mechanical behaviour/comfort. We have qualified two versions: with graphite expandable and without.