Sustainable Flame Retardant System with Thermomechanically Modified Stinging Nettle Tailored for Polyamide 12

ABSTRACT

The growing demand for environmentally responsible flame retardant solutions is driving the development of systems that combine conventional phosphorus chemistry with renewable plant‐based components. This study explores a novel strategy for developing a flame‐retardant system for polyamide 12 (PA12) based on the synergistic action of melamine polyphosphate (MPP) and thermomechanically modified stinging nettle (U) as a bio‐derived component. Thermal treatment is employed to enhance the stability of the lignocellulosic structure, enabling incorporation into high‐performance polymer formulations. Materials containing 20 wt.% of flame retardant system, in which 5 or 10 wt.% of the modified plant additive was used, were manufactured to assess their contribution to thermal and fire behavior. Flammability was assessed using a thermogravimetric analysis and evolved gas analysis (TGA/FTIR), limiting oxygen index (LOI), UL 94 test, pyrolysis combustion flow calorimetry (PCFC), and cone calorimetry. These techniques were supported by microstructural characterization to correlate internal morphology with macroscopic performance. The results demonstrate that the thermomechanically modified plant component actively participates in the flame retardant mechanism, improving the efficiency of MPP by enhancing char formation and altering degradation pathways. The proposed approach offers a viable route to sustainable flame retardant materials, suitable for advanced engineering applications.