(János Bolyai Research Scholarship of the Hungarian Academy of Sciences.)
In this study, we focused on the chemical recovery of carbon fibres from epoxy matrix
composite wastes. First, we laminated and cured composite panels from carbon fibre-reinforced
prepregs (CFRP) and then aged them under controlled circumstances to simulate their
lifespan. Fibre recovery was then carried out by hydrogen peroxide (H2O2) at 6 bar
and between 60 and 150 degrees C. We chose this material because it results in a rapid,
cost-efficient, and environmentally friendly process. Besides, we expected it would
allow the removal of the polymer matrix without fragmenting the fibres. We aimed to
investigate the matrix decomposition in H2O2, the purity of the obtained fibres and
the retention of their mechanical properties. The purity and the structure of the
obtained carbon fibres were then characterised by using scanning electronic microscopy
(SEM), X-ray diffraction (XRD), thermogravimetry (TGA), infrared spectroscopy (IR),
and X-ray photoelectron spectroscopy (XPS). We found that H2O2 was effective in recovering
carbon fibres, especially at 150 degrees C. The mechanical results showed that the
retention of the modulus was complete, while the tensile strength and elongation at
break decreased by 35% due to microstructural damages. The fibres still have better
properties than glass or basalt fibres; therefore, good-quality composites can be
made using them.
