Preparation and characterization of flame-retarded polyamide 6 fibers with hexaphenoxycyclotriphosphazene

The aim of this work was to develop flame-retarded polyamide 6 fibers using the hexaphenoxycyclotriphosphazene (HPCP) as a flame retardant by melt spinning. The influence of HPCP on the spinning process was investigated. HPCP caused a lower melting point and a higher crystallinity of polyamide 6 chips. The melt spinning temperature of the polyamide 6/HPCP composite fibers was less than the pure polyamide 6 fibers and the achievable draw ratio was determined. Structural and morphological characterization of the melt-spun fibers demonstrated good dispersion of HPCP additive. The introduction of HPCP did not change the crystal configuration of fibers in which the γ-crystal phase was predominant. The loss of mechanical properties of polyamide 6 fibers was mitigated by HPCP. The thermal behavior and flame retardancy of the polyamide 6/HPCP composite fibers was also enhanced effectively.