Enhancing flame retardancy and mechanical strength of glass fiber-reinforced biomass polyamide composites with surface-functionalized black phosphorus

Fiber-reinforced polyamide exhibits exceptional mechanical properties and durability; however, its widespread application is impeded by potential fire hazards. In this study, a hybrid material consisting of black phosphorus (BP) and polyhedral oligomeric silsesquioxane (POSS) was synthesized, denoted as BP-CO-POSS. The fire safety of fiber-reinforced polyamide demonstrated significant enhancement upon the incorporation of aluminum diethyl phosphinate (Alpi) and BP-CO-POSS. This enhancement was evident in various aspects, including the suppression of heat release behaviors, reduction in the emission of toxic gases, and an increase in the UL-94 rating. Notably, with the additional inclusion of 0.5 wt% BP-CO-POSS, a substantial decrease in both heat release rate (31.15 %) and total heat release (37.59 %) was observed when compared to the application of Alpi and BP alone, thus affirming the existence of a synergistic effect. This observation was substantiated through a comprehensive analysis of results obtained from both gas and condensed phases. This study offers a practical methodology for the widespread utilization of phosphorus-rich advanced materials, thereby further enhancing the fire safety of fiber-reinforced polymers.