Modified expandable graphite; Ferric hydroxide; Interaction; Ammonium polyphosphate; Linear low density polyethylene; Residual characteristics

The influence of expendable graphite (EGFe) modified by ferric hydroxide and its interaction with ammonium polyphosphate (APP) on combustion behavior and thermal stabilities of linear low density polyethylene (LLDPE) were investigated. Results showed EGFe presented better flame retardation than the normal expandable graphite (EG). A 30 wt% EGFe improved the limiting oxygen index (LOI) of LLDPE from 17.6% to 28.1%. Furthermore, the combination between EGFe and APP improved the LOI of 70LLDPE/20APP/10EGFe to 31.6%, and the vertical combustion UL-94 level reached V-0. EGFe and APP were both beneficial for the improvement of composite thermal stabilities, and there was synergistic performance between them which had been testified by the LOI results. Union between EGFe and APP was of benefit for the formation of continuous and compact char layers, which makes 70LLDPE/20APP/10EGFe composite show better flame retardation than the independent 70LLDPE/30APP or 70LLDPE/30EGFe composite.