A novel
halogen-free highly cross-linked supramolecular poly(cyclotriphosphazene-
co
-4,4′-sulfonyl diphenol) (PZS)-functionalized melamine
cyanurate (MCA) (MCA@PZS) hybrid nanosheet fire-retardant (FR) was
synthesized and thoroughly characterized using scanning electron microscopy,
Fourier-transform infrared (FTIR), X-ray diffraction, and X-ray photoelectron
spectroscopy analyses. The polyamide 6 (PA6) composites comprising
MCA, PZS, and the MCA@PZS hybrids were prepared via the melt-blending
technique. The thermogravimetric analysis combined with FTIR and mass
spectroscopy revealed that during thermal degradation, the PA6/MCA@PZS
composites released less toxic gases and small organic volatile compounds
than the neat PA6 and composites containing MCA or PZS solely. Moreover,
compared to neat PA6, the PA6 composite with a 5 wt % MCA@PZS hybrid
exhibited enhanced fire retardation properties, with a 29.4 and 32.1%
decrease in the peak heat and total heat release rates, respectively.
Besides, the PA6 composites with MCA@PZS-5% content achieved a V-0
rating in the UL-94 test. Finally, based on the obtained results from
gaseous and condensed phases, the possible mechanism responsible for
improved FR properties of the PA6/MCA@PZS composites was proposed.