Abstract
The increasing deployment of wind energy has led to a growing volume of end-of-life wind turbine blades, predominantly composed of glass fiber reinforced polymers (GFRP). Pyrolysis is a promising recycling technology that recovers glass fibers and generates energy from the organic matrix. However, the mechanical properties of recovered fibers often degrade due to thermal damage and residual char. This study investigates the tensile strength, modulus, and interfacial shear strength of glass fibers recovered from commercial GFRP wind turbine blade sections via a two-step pyrolysis process at 450°C and 550°C. Recovered fibers were characterized using single-fiber tensile testing, scanning electron microscopy, and Weibull statistical analysis. Results show that fibers pyrolyzed at 450°C retained 78% of their original tensile strength, while those at 550°C retained only 52%. The addition of a post-pyrolysis oxidation treatment at 500°C for 30 minutes improved strength retention to 85% and 61%, respectively. Interfacial shear strength with epoxy resin was reduced by 20-35% compared to virgin fibers, but remained adequate for secondary structural applications. The study demonstrates that optimized pyrolysis conditions can yield glass fibers with mechanical properties suitable for reuse in non-critical composite components, supporting a circular economy for wind turbine blade materials.