Thermal Conversion Properties of Glass Fiber Reinforced Polymer in End‐of‐Life Wind Turbine Blades

End‐of‐life wind turbine blades (EoL‐WTBs) contain large amounts of glass fiber reinforced polymer (GFRP) composite for which an efficient recycling route is still lacking, resulting in considerable resource waste. This study provides an in‐depth investigation of the thermochemical conversion behavior of GFRP and systematically examines the influence of atmosphere and heating rate on its thermal degradation. The oxidation behavior of the solid residue and the resulting recovered fibers was characterized in terms of surface morphology, functional groups, molecular structure, and mechanical performance. GFRP exhibits similar thermal decomposition behavior under N 2 and CO 2 , with a slightly lower peak temperature and a higher maximum reaction rate under N 2 . Increasing the heating rate shifts the main pyrolysis peak to higher temperatures and increases the apparent activation energy. The evolved volatiles are dominated by H 2 O, CO 2 , phenols, and aromatic hydrocarbons, which are released primarily between 300°C and 430°C. Oxidation at 500°C for 30 min effectively removes residual char from the fiber surface. Fibers derived from pyrolysis at 800°C present the lowest char residue; however, elevated temperatures introduce more oxygen‐containing defects and reduce structural order. These findings offer theoretical insights and experimental evidence for the high‐value recycling of GFRP from EoL‐WTBs.