Simultaneous Enhancement of Flame Retardancy and Mechanical Strength in PA6/GF Composites via a Synergistic Interfacial Design

Abstract

To resolve the conflict between flame retardancy and mechanical properties in glass fiber (GF)‐reinforced polyamide 6 (PA6) composites, a synergistic strategy combining bulk synergy and interfacial functionalization was developed. A flame‐retardant system comprising melamine polyphosphate (MPP) and aluminum diethylphosphinate (ADP) as the main agents, together with polytetrafluoroethylene (PTFE) as an anti‐dripping agent, was incorporated to promote char formation and gas‐phase inhibition within the PA6 matrix. The composites were prepared via melt blending followed by injection molding. To further suppress the “wick effect” of GF, MPP was covalently grafted onto the GF surface via a silane coupling agent, constructing a multifunctional interface that enhances both flame retardancy and mechanical performance. A synergistic strategy combining bulk flame retardancy (MPP/ADP/PTFE) and interfacial MPP‐grafted GF is developed for PA6/GF composites, achieving UL‐94 V‐0, LOI 29.2%, reduced heat release, and improved mechanical properties (tensile 133.2 MPa, flexural 157.2 MPa, impact 10.7 kJ/m2). Finite element analysis validates optimized stress dispersion. This work offers an effective approach for designing high‐performance PA6/GF composites with integrated flame retardancy and mechanical robustness.