Influence of Hydrolysis Medium on Matrix Degradation and Carbon Fibre Recovery from Epoxy-Based CFRPs
- 1Faculty of Mechanical Engineering, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia
- 2Faculty of Electrical Engineering and Computer Science, University of Maribor, Koroška cesta 46, 2000 Maribor, Slovenia
Abstract
The increasing use of carbon fibre-reinforced polymers (CFRPs) has intensified the need for efficient recycling technologies capable of recovering high-value carbon fibres from end-of-life composites. This study compares neutral and alkaline hydrolysis for recycling epoxy-based CFRPs under identical conditions (250 °C, 37–40 bar). CFRP waste generated during the manufacture of Formula Student race car components was treated in deionised water or 1.04 M NaOH for 60 or 120 min. Matrix degradation and fibre recovery were evaluated by gravimetric analysis, pH and conductivity measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Neutral hydrolysis resulted in only 4.5% mass loss and limited matrix degradation. In contrast, alkaline hydrolysis achieved mass losses of 34.2% and 38.7% after 60 and 120 min, respectively, with more extensive matrix removal observed after the longer treatment. Under strongly alkaline conditions, hydroxide ions can promote the cleavage of susceptible bonds within the epoxy network, facilitating matrix depolymerisation and removal. After 60 min, partial matrix removal was observed, whereas 120 min resulted in nearly complete matrix removal and successful carbon fibres recovery. FTIR, SEM, and XRD confirmed effective matrix removal while preserving fibre morphology and crystalline structure. The results demonstrate that alkaline hydrolysis is significantly more effective than neutral hydrolysis for recycling epoxy-based CFRPs and highlight the importance of combining complementary analytical techniques to reliably evaluate recycling efficiency.
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BibTeX
@article{erjavec2026influence,
title = {{Influence of Hydrolysis Medium on Matrix Degradation and Carbon Fibre Recovery from Epoxy-Based CFRPs}},
author = {Alen Erjavec and Tjan Budja and Kenan Kapetanović and Sara Perša and Michela Sossi and Silvo Hribernik and Julija Volmajer Valh},
journal = {Polymers},
year = {2026},
month = oct,
doi = {10.3390/polym18202458},
url = {https://www.mdpi.com/2073-4360/18/20/2458},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Influence of Hydrolysis Medium on Matrix Degradation and Carbon Fibre Recovery from Epoxy-Based CFRPs
AU - Alen Erjavec
AU - Tjan Budja
AU - Kenan Kapetanović
AU - Sara Perša
AU - Michela Sossi
AU - Silvo Hribernik
AU - Julija Volmajer Valh
PY - 2026
DA - 2026/10/01
JO - Polymers
DO - 10.3390/polym18202458
UR - https://www.mdpi.com/2073-4360/18/20/2458
AB - The increasing use of carbon fibre-reinforced polymers (CFRPs) has intensified the need for efficient recycling technologies capable of recovering high-value carbon fibres from end-of-life composites. This study compares neutral and alkaline hydrolysis for recycling epoxy-based CFRPs under identical conditions (250 °C, 37–40 bar). CFRP waste generated during the manufacture of Formula Student race car components was treated in deionised water or 1.04 M NaOH for 60 or 120 min. Matrix degradation and fibre recovery were evaluated by gravimetric analysis, pH and conductivity measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Neutral hydrolysis resulted in only 4.5% mass loss and limited matrix degradation. In contrast, alkaline hydrolysis achieved mass losses of 34.2% and 38.7% after 60 and 120 min, respectively, with more extensive matrix removal observed after the longer treatment. Under strongly alkaline conditions, hydroxide ions can promote the cleavage of susceptible bonds within the epoxy network, facilitating matrix depolymerisation and removal. After 60 min, partial matrix removal was observed, whereas 120 min resulted in nearly complete matrix removal and successful carbon fibres recovery. FTIR, SEM, and XRD confirmed effective matrix removal while preserving fibre morphology and crystalline structure. The results demonstrate that alkaline hydrolysis is significantly more effective than neutral hydrolysis for recycling epoxy-based CFRPs and highlight the importance of combining complementary analytical techniques to reliably evaluate recycling efficiency.
SN - 2073-4360
ER -