# Recycling and Reusing of Waste Aircraft Composites in Thermoplastic and Thermoset Matrices

## TL;DR

This paper explores ways to recycle aircraft composites by comparing mechanical and chemical methods, finding that chemical recycling produces better material performance and environmental benefits.

## Contribution

The study introduces a chemical solvolysis process for recycling aircraft composites, demonstrating its superiority over mechanical recycling in terms of material properties and environmental impact.

## Key findings

- Chemically recycled fibers in epoxy achieved a flexural modulus of 9.9 GPa and strength of 112 MPa, outperforming mechanically recycled fillers.
- Chemical recycling in PA12 resulted in a 2.14 GPa modulus and 67.7 MPa strength, showing potential for thermoplastic reuse.
- Life cycle assessment confirmed that both recycling methods significantly reduce global warming potential and aquatic ecotoxicity compared to landfilling.

## Abstract

Unlike typical fiber-reinforced polymers, aerospace composites consist of 90% carbon and 10% glass fabrics impregnated with thermosetting resin. Due to the strong bonding between fibers and the thermoset nature of the matrix, recycling these materials is particularly challenging. This study evaluates mechanical recycling of aircraft composite waste via industrial grinding and chemical recycling through a solvolysis process. Recovered fibrous fractions were integrated into an epoxy matrix at 50 wt% loading using hot-pressing and into polyamide 12 at 15 wt% via a twin-screw extrusion process. The mechanical results showed that chemically recycled fibers in epoxy reached a flexural modulus of 9.9 GPa and strength of 112 MPa, significantly outperforming mechanically recycled fillers (6.1 GPa and 98.0 MPa) compared to virgin carbon fibers (11.3 GPa and 132 MPa). In PA12, the addition of chemically recycled fibers yielded a 2.14 GPa modulus and a 67.7 MPa strength. Furthermore, life cycle assessment confirmed that both recycling routes drastically reduce global warming potential and aquatic ecotoxicity compared to landfilling. These findings indicate that while mechanical recycling is simpler, chemical solvolysis provides a superior pathway for the high-value circular reuse of complex aerospace waste in new thermoplastic and thermoset applications.