Effect of ZnCl₂ Treatment Parameters on the Thermo-Hydrolysis of Recycled MDF for Epoxy Composites

The aim of this study is to determine the hydrothermal recycling of medium-density fiberboard (MDF) wastes using zinc chloride (ZnCl₂) as an acidic catalyst to obtain reinforcing fibers for epoxy-based composites. For this purpose, during the hydrothermal recycling process (110 °C, 0.4 bar), zinc chloride solutions with different concentrations (0% to 30%) were applied at different time intervals (20 to 60 min). The recycled fibers were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope-energy dispersive spectrometry (SEM-EDS), carbon (C) (%), hydrogen (H) (%), and nitrogen (N) (%) contents, and fiber classification. The fibers were added as a filler (1% w/w) to epoxy composites. The compression strength and of the epoxy composites as assessed and differential scanning calorimetry (DSC) characterization was performed. According to the results, nitrogen content decreased with increasing ZnCl₂ concentration. Furthermore, the fine fibers ratios increased with increasing treatment time. The results suggest that recycled fibers can be used as a filler in epoxy composites; however, a long treatment time adversely affects the compression strength of epoxy composites.