Recovery and restoration of glass fibers from end‐of‐life composite waste through pyrolysis and partial oxidation processes combined with hot alkaline surface treatments

Abstract Environmental hazards caused by the ever‐increasing end‐of‐life (EoL) glass fiber reinforced polymer (GFRPs) composite waste is of major concern for the sustainable development of the industry. Compared to land filling or incineration, pyrolysis is one of the most promising environmentally friendly methods of disposal of EoL GFRPs. Pyrolysis not only results in recovery of clean glass fibers but other valuable products, such as oils. However, long processing time at elevated temperature leads to aggravation of already existed surface flaws along with the structural changes. Therefore, thermal conditioning of glass fibers results in severe deterioration of the strength in recovered fibers and hence limiting the use of recovered fibers to low end‐products. In this study, a new strategy was adopted where instead of complete cleaning of the fibers at pyrolysis stage, the fibers were partially oxidized and the complete removal of char from the surface of glass was done during hot alkaline etching. This strategy was opted to enhance the quality of the required fibers while reducing the processing time. The results showed ~200% increase in strength of fibers after the combined treatment of pyrolysis and post etching compared to the just pyrolyzed samples with etching time of just 1 min. Highlights End‐of‐life panels of GFRPs were pyrolyzed under inert environment of Argon. Residual char was partially removed through post oxidation under flowing air. Hot alkaline etching resulted in complete removal of char and surface defects. Partial oxidation and short etching cycles resulted in improved strength of recovered glass fibers.