Research Progress and Application Prospects of Reactive Flame-Retardant Polyamide

Abstract

Reactive flame-retardant polyamide addresses key limitations of additive types, such as low efficiency, dispersion issues, and compromised mechanical properties, providing superior mechanical strength, toughness, and flame retardancy for demanding applications like military textiles, electric vehicle components, and smart grids. Primary systems include phosphorus-based (promoting char formation), nitrogen-based (releasing inert gases and forming char), and silicon-based (forming a protective layer) flame retardancy. Synergistic combinations, such as nitrogen-phosphorus for enhanced gas-phase effects or nitrogen-silicon for reinforced condensed-phase char, offer performance benefits. Current challenges include insufficient flame-retardant heat resistance for polyamide polymerization conditions, low active element content necessitating high loadings that disrupt polymer structure, and limited inherent char-forming varieties with anti-dripping properties. Future development focuses on designing molecular structures to achieve heat-resistant reactive flame retardants with minimal impact on crystallization, enabling high molecular weight resins suitable for high-speed fiber spinning. Concurrently, innovation in flame retardant mechanisms aims to combine flame retardant and polymer chain design, creating intrinsic anti-dripping char-forming polyamide materials that eliminate the wick effect during modification and enable additive-free, cost-effective composites. Renewable bio-based flame-retardant polyamides also present significant potential due to their combined flame retardancy, environmental benefits, and ability to meet performance and sustainability requirements.