Aluminum Hydroxymethylphosphinate and Melamine Pyrophosphate: Synergistic Flame Retardance and Smoke Suppression for Glass Fiber Reinforced Polyamide 6

In this manuscript, synergistic effect was found when aluminum hydroxymethylphosphinate (AHMP) and melamine pyrophosphate (MPyP) with a suitable mass ratio were used together for glass-fiber-reinforced polyamide 6 composites (GFPA6). Both vertical burning test (UL-94) and limited oxygen index (LOI) results showed that GFPA6 containing 5 wt % AHMP and 25 wt % MPyP had excellent flame retardance, i.e. its LOI value was 31.0 and UL-94 reached V-0 rating even for the sample with 1.6 mm thickness. Besides, the flammable properties and smoke suppression of GFPA6 were also improved demonstrated by cone calorimetry results. The thermal stability and the decomposition activation energies (Eα) were studied by TGA. Moreover, the morphology of char after the LOI test was investigated by SEM. It was found that the interaction existing between PA6, AHMP, and MPyP resulted in the higher char content and stable char layer on the GFPA6 surface, which is helpful in improving the flame retardancy of GFPA6.