In a significant stride towards sustainable construction and energy solutions, researchers have developed a novel method for recycling carbon fibers from composite materials, offering promising implications for the energy sector. Christina Vogiantzi, a researcher at the Laboratory of Technology & Strength of Materials, Department of Mechanical & Aeronautical Engineering at the University of Patras, Greece, led the study published in the European Journal of Materials (translated as “Journal of Materials Science and Technology”).
The research introduces a solvolysis approach that uses a water/ethanol solvent to recover carbon fibers from carbon fiber-reinforced polymers (CFRPs). This method is not only environmentally friendly but also economically viable, addressing a critical need in the energy sector where CFRPs are extensively used in wind turbine blades and other structural components.
Vogiantzi and her team conducted experiments under varying conditions, including different solvent volume ratios, temperatures, and reaction times. They employed a design of experiments methodology to systematically evaluate the influence of these parameters on resin decomposition efficiency (RDE), fiber morphology, and the mechanical and interfacial properties of the recycled carbon fibers (rCFs).
One of the key findings was that RDE efficiency ranged from 35% to 68% at 320°C and increased significantly to 75–92.5% at higher temperatures of 350°C and 380°C. “This indicates that higher temperatures are more effective in decomposing the resin, which is crucial for recovering high-quality carbon fibers,” Vogiantzi explained.
The study also revealed that the mechanical properties of the recycled carbon fibers varied depending on the processing conditions. While some rCFs retained tensile strength and Young’s modulus close to their original values, others experienced degradation of up to 30% due to residual resin or surface damage. “The quality of the recycled fibers is directly linked to the processing conditions,” Vogiantzi noted. “Optimizing these conditions is essential for maintaining the mechanical integrity of the fibers.”
Microbond tests further highlighted the variability in interfacial shear strength. Some rCFs maintained near-virgin values, while others showed reductions ranging from 17% to 48%. This variability underscores the importance of precise control over the recycling process to ensure consistent quality.
To identify the most favorable recycling conditions, the researchers applied the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. This analytical tool helped rank the experimental conditions based on a performance index, ultimately identifying the treatment at 380°C for 90 minutes using pure water as the solvent as the optimal condition.
The implications of this research for the energy sector are substantial. As the demand for sustainable and efficient energy solutions grows, the ability to recycle carbon fibers from CFRPs becomes increasingly important. Vogiantzi’s work provides a roadmap for developing more effective and environmentally friendly recycling methods, which can significantly reduce the environmental impact of the energy sector.
“This research not only advances our understanding of CFRP recycling but also paves the way for more sustainable practices in the energy industry,” Vogiantzi concluded. “By optimizing the recycling process, we can ensure that high-quality carbon fibers are recovered, making them suitable for reuse in various applications.”
As the energy sector continues to evolve, the findings from this study will undoubtedly shape future developments in carbon fiber recycling. The ability to recover and reuse these valuable materials will contribute to a more circular economy, reducing waste and conserving resources. This research is a testament to the power of innovation in driving sustainable progress, offering a glimpse into a future where sustainability and efficiency go hand in hand.