PASUTE

Fire and flame retardants from industrial side streams

Flame retardants mitigate fires and serve as an important component in building structures. Their purpose is not necessarily to prevent fires from occurring, but to slow them down so that people have more time to evacuate and, on the other hand, rescue personnel have more time to arrive at the scene. Flame retardants can influence the rate of fire development, fire spread, fire intensity, and the amount of smoke produced.

Alternative substances are being sought for currently used flame retardants because, for example, widely used halogenated flame retardants have been found to have harmful effects on human health and the environment. Recycling materials treated with these substances is also challenging. Alternative flame retardants are being developed from renewable sources, i.e., substances derived from various types of biomass. These materials are environmentally friendly, inexpensive, and readily available. By chemically modifying them or adding compounds containing, for example, phosphorus, flame retardants can be produced that can be utilized in a variety of materials.

“Industrial biomass side streams contain a wealth of useful components that can be applied in sometimes surprising ways, such as in flame retardants,” says the project manager Mikko Junttila.

The aim of the PASUTE project is to combine side streams from the wood processing industry with phosphorus-containing side streams from the inorganic chemical industry in the production of flame retardants. Condensed tannins are compounds found, for example, in the bark of trees such as spruce, pine, and birch. During a fire, tannins char and form a layer that slows heat transfer and the flow of oxygen to the burning material. Flame retardants containing condensed tannins isolated from biomass have been tested, for example, in wood fire protection. Studies have shown that tannins alone do not provide sufficient fire protection for wood and therefore cannot compete with the more effective substances currently used. By combining tannins with phosphorus-containing compounds, the fire-retardant performance of tannins can be improved. The project generates knowledge on utilizing phosphorus-containing side streams from the chemical industry as additives in biomass-based flame retardants containing condensed tannins.

Fire tests are used to investigate how the developed flame retardants affect the burning behavior of different materials. A particular focus is on the fire protection of wood-based construction materials. The project also examines fire protection for other materials such as plastics and textiles.