An inorganic (zirconium) – phosphorus (P) – nitrogen (N) PIN flame retardant was experimentally developed and tested in polyamide (PA6). The FR was produced in a one-step reaction from α-ZrP (alpha zirconium phosphate) at 3 – 30%, melamine and cyanuric acid. The α-ZrP-melamine cyanurate (α-ZrP-MCA) was then blended with PA6 using a screw extruder.
UL94-V0 was achieved at 12% loading of FR (with α-ZrP > 5%) and fire performance was significantly better than PA6 without FR or PA6 with melamine cyanurate only (no α-ZrP). SEM (scanning electron microscopy) showed that the integration of α-ZrP results in a more compact, homogenous, ceramic-like char, acting as an effective barrier against fire. The α-ZrP-MCA PIN flame retardant showed not only to improve the fire performance of polyamide, but also to improve crystallinity and to maintain good mechanical properties.
“Effects of α-ZrP on Crystallinity and Flame-Retardant Behaviors of PA6/MCA Composites”, Y. Xiao, Int J Polymer Science, 2017, Article ID 6034741 https://doi.org/10.1155/2017/6034741