Effect of natural basalt fiber for EVA composites with nickel alginate-brucite based flame retardant on improving fire safety and mechanical properties

The natural basalt fiber (BF) was incorporated into EVA composites with environmental-friendly nickel alginate-brucite based flame retardant (NiFR), to further improve the flame-retardant effect and mechanical properties. The flame retardancy of EVA composites were characterized by LOI, UL 94, and cone test. With 55 wt% loading, 3BF/52NiFR had the highest LOI value of 31.9 vol.% in all fiber reinforced composites and pass UL 94V-0 ratting. And comparing to 55B composite with untreated brucite, 3BF/52NiFR decreased peak of heat release rate by 47.8%, total heat release by 21.9%, and total smoke production by 35.5% and kept more residue 54.0% during cone test. Moreover, 3BF/52NiFR also enhanced the mechanical properties of composites by better compatibility with EVA matrix. BF/NiFR exert synergistic flame-retardant effect major in promoting charring effect in condensed phase during combustion. The fire-resisted and rigid BF into the char layer reinforced the intensity of protective barrier which prolonged the residence time of pyrolysis carbonaceous groups degraded from EVA matrix, resulting in less heat and smoke release.