Fraunhofer develops laser process for high-quality carbon fiber recycling

Researchers at the Fraunhofer Institute for Structural Durability and System Reliability LBF have developed a novel technology for recycling carbon fiber composites. The process enables the reclamation of continuous carbon fibers from composite materials without significantly diminishing their quality. High-power lasers are employed to locally degrade the matrix of multi-layered fiber-reinforced plastics at high temperatures.

Carbon fiber composites are valued for their exceptional strength and low weight, making them key materials in industries such as aerospace and automotive. However, their disposal and recycling have posed significant challenges. Conventional methods, like shredding, shorten the fibers and lead to downcycling, reducing their potential for reuse. The new Fraunhofer EMI process prepares fibers from used composites for reuse without negatively impacting their mechanical properties.

The method is particularly relevant for thermosetting composites, which cannot be melted and reprocessed. Fraunhofer EMI researchers utilize high-power lasers for controlled reclamation of the fiber reinforcement from these materials. Through localized pyrolysis, the matrix surrounding the carbon fibers is removed, leaving the fibers largely undamaged. The researchers have identified an optimal process window where matrix pyrolysis and simultaneous unwinding of the fiber roving occur efficiently without damaging the carbon fibers.

This innovative method presents both ecological and economic advantages. By applying heat locally and continuously reclaiming the fibers, prolonged pyrolysis times and high process costs are avoided. Furthermore, the laser-assisted reclamation process requires approximately one-fifth of the energy needed to produce new fibers. Fraunhofer EMI will present the project at the Hannover Messe from March 31 to April 4, 2025.