Effect of different IFS ( MWCNTs , BN, and ZnO ) on flame retardant, thermal and mechanical properties of PA6/aluminum diisobutyl phosphinate composites

Abstract In this paper, the effects of the synergistic flame retardation of aluminum diisobutyl phosphinate acid (APBA) with three inorganic fillers of different dimensions (multi‐walled carbon nanotubes [MWCNTs] [1‐dimensional], hexagonal boron nitride [BN] [2‐dimensional], and zinc oxide [ZnO] [3‐dimensional]), respectively, on the properties of nylon 6 (polyamide 6 [PA6]) materials were investigated. It was shown that under the same additive amount, with the increase of spatial dimension of inorganic fillers, the thermal stability and residual carbon capacity were improved. Which would catalyze the formation of more and denser carbon layers in the matrix material, effectively blocked the transfer of oxygen and heat, enhanced the cohesive‐phase flame retardancy of synergistic flame‐retardant PA6 composites, and exerted a better synergistic flame‐retardant effect with APBA. So that the flame‐retardant properties of PA6 composites were gradually improved, and the mechanical properties were also gradually increased. The comprehensive performance of three types of inorganic fillers gradually improves in the order of MWCNTs < BN < ZnO. When the addition amount of ZnO was 2 wt%, the vertical combustion grade (UL‐94) of PA6 composite was V‐0, and the limiting oxygen index (LOI) was as high as 36.5%. The tensile strain increased by 19.11% and impact strength increased by 20.26% compared with PA6, and PA6/APBA‐Zn can be used as a flame retardant PA6 composite material with balanced overall performance. Highlights Diisobutylaluminium hypophosphite and inorganic fillers have efficient synergistic flame retardant effects in PA6. With the increase of spatial dimension of inorganic fillers, the better the synergistic flame retardant effect in PA6. The flame retardant can degrade to release the phosphorous free radicals. Inorganic fillers can cross‐link with the PA6 substrate and promote the charring.