Kinetic study of the decommissioned wind turbine blade oxidative liquefaction based on differential scanning calorimetry

Differential scanning calorimetry using high-pressure crucibles was used to assess waste wind turbine blades oxidative liquefaction process kinetics. The total enthalpy change recorded at investigated temperatures 230, 250, and 265 °C were on average −650 kJ/kg, while the H₂O₂ decomposition contribution was determined during the control run as −365 kJ/kg. The apparent, isoconversional kinetic parameters yielded valuable information about the general decomposition pattern, with peaks of activation energy and pre-exponential profiles suggesting the decomposition of H₂O₂ with Eα peak of 20 kJ/mol at α = 0.4, and 2-stage decomposition of the epoxy during oxidative liquefaction with 2 consecutive Eα at α = 0.65 of 55.1 kJ/mol and 52.2 kJ/mol at α = 0.86. The master plot method identified the nth order autocatalytic model (Cn) transitioning to the Prout-Tompkins function (Bna) governing the process. The decomposition pathway was proposed, based on epoxy-radical reactions, resulting in autocatalytic epoxy decomposition during the process, paradoxically similar in mechanism to epoxy curing. The 2-stage consecutive model was formed and optimized, providing fit to the experimental data with quality assessed by R² = 0.996. The activation parameters of the proposed model were 57.18 kJ/mol, 2.22 log(min⁻¹), and 49.78 kJ/mol, 2.98 log(min⁻¹) for the first and second stages respectively.