Invasive wood species as a resource for wood-polymer composites

This work presents a method for the sustainable use of waste generated by the logging of black cherry trees, an invasive species in western and central Europe. For the first time, the relation between modification of wood with sorbitol and citric acid (SorCA) and thermogravimetric properties of polymer composites filled with this wood species was established. The obtained materials were characterized by significantly improved biological resistance to fungal strains: Aspergillus niger, Alternaria sp., Fusarium oxysporum, Penicillium brevicompactum, Chaetomium globosum and the bacterial strains Listeria monocytogenes and Listeria innocua. Due to wood modification, the β-phase content in the polypropylene (PP) structure increased, reaching up to 39 % for the composite with a filler content of 30 %. The absence of a transcrystalline layer on the modified filler surface and the higher amount of the β-phase were related to the biological resistance of the composites. Increasing the β-phase content improved the impact strength to 64 kJ/m2 for composites with a modified filler content of 10 %, and allowed the other mechanical properties to be maintained at satisfactory levels. The thermal properties of the material above 300 °C deteriorated due to modification. However, the deformability of the composite samples was improved, and was expressed by lowering the heat distortion temperature (HDT) by an average of 30 °C and the Vicat softening temperature (VST) by an average of 5 °C for all filler contents. Despite the limitations of the studies—including a narrow range of microbial strains or the conduct of only selected tests without an evaluation of their change over time—composites with many practical applications in industries such as construction, automotive, and household appliances have been successfully obtained.