Study on isothermal pyrolysis and product characteristics of basic components of waste wind turbine blades

Pyrolysis is an effective method for recycling waste wind turbine blades. However, there have been few studies on the pyrolysis mechanism of the basic components of blade composites. In this study, isothermal pyrolysis experiments on four basic components (epoxy resin, thermoplastic polyurethane, carbon fiber and glass fiber) of blades were carried out in a tube furnace at 600 celcius. The product distribution and properties of each basic component were then analyzed after pyrolysis. The results showed that the pyrolysis reactions of the matrix materials were intense, and the mass loss rates reached 90%. A certain amount of gas products, mainly CO2 and CO, were released during the pyrolysis process; CO2 was eliminated from the ester and carboxyl groups of the aromatic compounds and CO was formed from the decomposition of the carbonyl groups. A large number of liquid products were also produced, including phenol and p-isopropenylphenol, and these could be reused as industrial raw materials. The resins were decomposed from blocks into fragments after pyrolysis. The pore structures of resins became more abundant and developed mesopores and micropores, and the microcrystalline structures were disordered. The fiber materials barely reacted, and the mass loss of each was only approximately 1%. The surface morphologies and microcrystalline structures of the fiber materials did not change significantly, but the pore diameter distributions showed diametrically opposite trends relative to those of the resins. These results indicated that the resin matrix could be removed from the composites via pyrolysis and that the structures of the fiber materials could be retained. This research on the pyrolytic characteristics of the basic components of blade composites shows the thermochemical characteristics of each component and provides basic data and reference information for pyrolytic recycling of scrap blades.