Production and Characterization of Flame Retardant Leather Waste Filled Thermoplastic Polyurethane

Discovering new applications for discarded materials, such as leather waste (LW), has proven to be an effective approach to an ecofriendly and sustainable production. The manufacture of halogen-free flame retardant LW containing thermoplastic polyurethane (TPU)-based samples containing an organic phosphinate (OP)-based flame retardant additive would represent an advance in this area. The effects of LW and OP levels on the thermal, flame retardant, and tensile properties of the samples using thermal gravimetric analysis (TGA), limiting oxygen index (LOI), vertical UL-94 (UL-94 V), mass loss calorimetry, and tensile tests have been assessed. OP is highly effective in LW-filled TPU. The highest UL-94 V rating of V0, LOI value of 31.4%, the lowest peak heat release rate (93 ± 3 kW/m²), and total heat evolved (49 ± 2 MJ/m²) values are obtained with the use of 20 wt % OP. OP is primarily promoted through the creation of a compact intumescent residue structure in the condensed phase. LW exhibits an adjuvant effect by producing nonflammable gases in the gas phase and raising the residual yield in the condensed phase. The most remarkable effect of the LW presence is observed in fire performance index (FPI) and fire growth rate (FIGRA) values. The highest FPI value of 0.49 sm²/kW and the lowest FIGRA value of 0.91 kW/m²s are observed with the use of 20 wt % LW.