The Use of Carbon Fibers Recovered by Pyrolysis from End-of-Life Wind Turbine Blades in Epoxy-Based Composite Panels

Abstract

This work is devoted to evaluating the effectiveness of the recovery of carbon fibers from end-of-life wind turbine blades in the pyrolysis process, and the use of those fibers in the production of flat composite panels. The recovery of carbon fibers from wind turbine blades uses a pyrolysis process at 500–600 °C in a non-oxidizing atmosphere, in such a way that makes it possible to preserve the shape and dimensions of the fibers. Using recycled carbon fibers, flat CFRP sheets with epoxy resin matrix were produced by pressing. Seven different series of samples were tested, which differed in fiber length, fiber orientation, and pressure holding time. The results obtained on the recycled fibers were compared to the original carbon fibers, cut to corresponding lengths. Additionally, one of the series was reinforced with a biaxial fabric. The most favorable pressing parameters are empirically found to be pre-pressing 2 MPa (10 min), and further pressing at a pressure of 7 MPa until the resin completely cross-linked (about 120 min). A number of tests were carried out to demonstrate the usefulness of pyrolytic fibers, including tensile strength of carbon fibers, bending strength, SEM observations, FT-IR, and Raman spectroscopy. The tests carried out on the carbon fibers show that the pyrolysis process used leaves about 2% of the matrix on the surface of the fiber, and the tensile strength of the fibers drops by about 20% compared to the new carbon fibers. The research results show that the use of the recycled carbon fibers in the production of flat composite plates is reliable, and their mechanical properties do not differ significantly from plates made of corresponding original carbon fibers. Composite panels with the pyrolytic fibers (274 MPa) show up to a 35% higher flexural strength than similarly produced panels with the original new carbon fibers (203 MPa), which means that the panels can be used in the production of elements for footbridges, bridges, pipelines, or structural elements of buildings and roofing.

Unlocking the Potential of Wind Turbine Blade Recycling: Assessing Techniques and Metrics for Sustainability

“…Figure 3 presents a comprehensive diagram, providing a detailed illustration of the pyrolysis-based recycling process designed for EOL WTBs. Hence, recycling WTBs is a significant approach [22,[42][43][44][45]. Furthermore, one of the advantages of pyrolysis is its potential for large-scale application in material recovery [42].…”

Experimental Study on Microwave Pyrolysis of Decommissioned Wind Turbine Blades Based on Silicon Carbide Absorbents

“…Compared with the mechanical method and the chemical solvent method, the pyrolysis method can realize the cracking and separation of the resin at medium-and low-temperature conditions, recover the glass fiber more completely, generate combustible gas and liquid tar in the process, and better preserve the mechanical properties of the fiber. Thus, they can meet the requirements of the circular economy and become one of the most promising technologies for the treatment of decommissioned wind turbine blades [14][15][16][17][18].…”

An Overview of the Usability of Recycled Carbon Fiber (rCF)- Based Composites in Aerospace Engineering Applications

“…The matrix consists of thermosetting polymers and chemicals used to support the carbon fibers in the structure of the composite. The polymeric matrix is selected from thermosetting or thermoplastic polymers and is used to bind the carbon fibers together and fill the gaps between the fibers and layers [1][2][3][4].…”