writer：Guo ZH, Ran SY, Fang ZP*
keywords：flame retardant; Friedel-Crafts reaction; graphene nanoplatelet; char barrier
source：期刊
specific source：J Therm Anal Calorim, 2017.5, 128: 1719-1730
Issue time：2017年
Graphene nanoplatelets (GNPs) were introduced into polystyrene (PS)/brominated polystyrene (BPS) blend to overcome the large amounts of smoke generated from the  brominated flame retardant during combustion. A Lewis acid catalyst (AlCl3) was introduced to initiate Friedel-Crafts reaction to produce the macrocarbocations interacted with graphene sheets by electrostatic attraction, leading to an improved dispersive state of GNPs in polymer matrix. and the scanning electron microscopy (SEM) showed that the more compact and integrated char barrier was formed in PS/BPS/GNPs/AlCl3 composite. The results of cone calorimeter tests revealed that a more continuous and uniform char barrier of GNPs fabricated by Friedel-Crafts reaction prevented the spread of combustion, reduced the heat release in the initial stage of combustion, and especially suppressed the smoke release effectively. The interaction among the char barrier effect of GNPs, the electrostatic attraction between macrocarbocations and graphene sheets, the catalytic degradation of Lewis acid catalyst, the solid lubricant effect for GNPs and the heat gathering effect of GNPs caused the complex changes of micro-structures, which lead to the complex changes of rheological behaviors. The pyrolysis products showed that the light

carbon decreased and the heavy carbon increased in PS/BPS/GNPs/AlCl3 composite,

revealing that the char barrier of GNPs fabricated by Friedel-Crafts reaction played an effective protective layer to prevent polymer form erosion of high temperature.