Syntheses of intrinsically flame-retardant polyamide 6 fibers and fabrics

In this study, flame-retarded polyamide 6 (FR-PA6) was prepared via the direct co-condensation of epsilon-caprolactam with two different organophosphorus compounds in a typical melt-polymerization process. Polymer microstructures, especially the incorporation of the phosphorus-containing comonomers, as well as the thermal and physical properties of the resulting copolyamides have been studied in detail. The phosphorus-modified PAs have a P-content of 0.10-0.30wt %, possess high relative viscosities of 2.2-2.4 and good thermal stability. FR-PA6 multifilaments were prepared by melt spinning and show tensile strengths up to 40cN/tex and tenacities up to 0.5 GPa. Knitted fabrics of FR-PA6 exhibit high limiting oxygen index values around 35%. Due to the very low phosphorus content, there is no impairment of the material properties of PA6. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47829.