Char barrier effect of graphene nanoplatelets on the flame retardancy and thermal stability of high-density polyethylene flame-retarded by brominated polystyrene
writer：Ran SY, Chen C, Guo ZH*, Fang ZP.
keywords：High-density polyethylene; Brominated polystyrene; Graphene Nanoplatelets; Char barrier effect; Flame retardance
source：期刊
specific source：J. Appl. Polym. Sci., 2014.8, 131(15): 40520
Issue time：2014年
Char barrier effect of graphene nanoplatelets (GNPs) on the flame retardancy and thermal stability of high-density polyethylene (HDPE) flame-retarded by brominated polystyrene (BPS) and antimony oxide (Sb2O3) was investigated. Thermogravimetric (TG) analysis, limited oxygen index (LOI) and vertical burning test (UL-94) showed that the presence of GNPs led to enhanced thermal oxidation stability and significantly reduced flammability. Addition of 1 wt% of GNPs to PE/BPS-Sb (mass ratio: 92/6/2) led to the UL-94 grade from NG (first burning time longer than 30 s) to V-2 (total burning time of 14 s), and the LOI value increased from 23.4% to 24.1%. The results of pyrolysis products gave the evidence that GNPs restricted volatilization. The morphology of chars also proved the formation of charred layer, which could act as a barrier to isolate the material from the flame and retard the vaporization of flammable gases via tortuous pathway.