Empa Develops Flame-Retardant, Fully Recyclable Epoxy-Glass Fiber Composite for Aircraft and Train Interiors
Why It MattersThe breakthrough could let aerospace interior manufacturers move away from landfill-bound epoxy composites toward recyclable, fire-compliant sandwich structures for cabin construction.
Researchers at Empa, the Swiss Federal Laboratories for Materials Science and Technology, have developed a composite material made of epoxy resin and glass fibers that is both flame-retardant and fully recyclable, combining properties not previously achieved together in an epoxy-based composite. The material, intended for aircraft and train interiors including passenger cabin floors, takes the form of a multilayered sandwich with an aramid honeycomb core covered on both sides by flat-woven glass or carbon fiber layers bound with epoxy resin.
Conventional epoxy cannot be recycled chemically or thermally, so composites containing it typically end up in landfills or are incinerated. The Empa team, led by Sabyasachi Gaan of the Advanced Fibers laboratory, developed a phosphorus-containing additive that makes the cured epoxy both flame-retardant and capable of being softened and reshaped, a process the researchers call thermomechanical recycling.
The project, supported by Swiss innovation agency Innosuisse and carried out with Elantas, part of the German specialty chemicals group ALTANA, used a solvent combined with moderate heat to break the sandwich structure down into its aramid honeycomb, woven fiber layers, and epoxy matrix. Gaan said the material complies with fire safety regulations and achieves nearly the same mechanical properties as conventional epoxy while allowing complete recycling. Fiorenzo Lenzi, Head of the Aerospace/Ballistic Product Line at Elantas, said the system demonstrates for the first time that fire protection, lightweight construction, and recyclability can be combined in a single aerospace composite, with the next step being to scale up production and recycling processes.
