Valorization of leather industry waste in polyurethane composites for reduced flammability

Industrial wastes are considered a major cause of environmental pollution, and studies on valorizing these wastes and converting them into value-added products have gained importance. This study investigated the potential use of buffing dust (BD) waste from chromium-tanned leather as a filler for polyurethane (PU) matrix. PU + BD composites containing different concentrations of filler, ranging from 1 to 4%, were produced. Compressive strength, thermal stability, thermal conductivity, and flammability of PU + BD composites were analyzed. Regarding the compression module, PU with 2% filler performed similarly to neat PU, while 1% and 3% provided comparable results. The addition of 3% leather waste is feasible and preferable as it enables the incorporation of a higher amount of waste without compromising the compressive strength properties of the PU. PU + BD composites had similar heat isolation properties to neat PU and reduced the flammability of the polyurethane composites. Incorporating leather waste particles into PU + BD composites could be a sustainable promising alternative approach for reducing the flammability of PU, where lower flammability is required.