Transition-metal-assisted pyrolysis to recover glass fibers from end-of-life wind turbine blades

Abstract

The disposal of end-of-life wind turbine blades (WTBs), typically composed of glass fiber-reinforced epoxy resin thermosetting composites, has become a global environmental challenge. Pyrolysis is an effective method for recycling these WTBs, but the process often leads to significant degradation of recovered fibers due to high pyrolysis temperatures. This study proposed a transition-metal-assisted pyrolysis method to enhance the low-temperature depolymerization of end-of-life WTBs, enabling the recovery of glass fibers with improved mechanical properties. With the assistance of ZrCl₄, the resin decomposition ratio of WTBs at 350 °C increased from 52.13 % to 75.59 %, and the tensile strength of the recovered glass fibers improved by 34.74 %. Characterization studies revealed that Zr^4 + ions accelerated the breakdown of C-O-C bonds within the epoxy resin, promoting its decomposition. Additionally, Zr⁴⁺ ions weakened polycondensation and dehydrogenation reactions during the formation of pyrolysis char, reducing its degree of graphitization and improving its oxidative reactivity, thereby shortening the oxidation duration. Consequently, the diffusion of surface defects in the recovered fibers was suppressed, significantly enhancing their mechanical properties. These findings offer valuable insights into addressing the disposal of end-of-life WTBs while simultaneously recovering glass fibers with excellent mechanical properties, thus supporting their circular utilization.