Tailoring TiO₂-lignin hybrid materials as a bio-filler for the synthesis of composites based on epoxy resin

In this publication, the functional TiO₂-lignin hybrid materials were designed and characterized. Based on elemental analysis and Fourier transform infrared spectroscopy, the efficiency of the mechanical method used to obtain systems was confirmed. Hybrid materials were also characterized by good electrokinetic stability, in particular in the inert and alkaline environments. The addition of TiO₂ improves thermal stability in the entire analyzed range of temperatures. Similarly, as the content of inorganic component increases, the homogeneity of the system and the occurrence of smaller nanometric particles increase. In addition, a novel synthesis method of cross-linked polymer composites based on a commercial epoxy resin and an amine cross-linker was described as a part of the article, where additionally newly designed hybrids were also used. Subsequently, the obtained composites were subjected to simulated tests of accelerated UV-aging, and then their properties were studied, including changes in wettability (using water, ethylene glycol, and diiodomethane as measurement liquids) and surface free energy by the Owens-Wendt-Eabel-Kealble method. Changes in the chemical structure of the composites were monitored by FTIR spectroscopy due to aging. Microscopic studies of surfaces were also carried out as well as measurements in the field of changes in color parameters in the CIE-Lab system.