石墨种类和粒径对高抗冲聚苯乙烯阻燃性能的影响及作用机制

通过熔融共混法将不同种类和粒径的石墨引入到高抗冲聚苯乙烯（PS?HI）基体中，考察了石墨种类和粒径大小对PS?HI阻燃性能的影响和作用机制。结果表明，天然鳞片石墨（NG）对PS?HI的阻燃作用很小，其粒径大小对阻燃性能的影响并不显著，即使用量达到50 %（质量分数，下同）也不能使PS?HI有较好的阻燃性能；与NG相比，可膨胀石墨（EG）的阻燃效率更高，可使PS?HI的阻燃性能大幅度提高，且EG粒径越大，阻燃效率越高，抑烟作用越明显；在PS?HI/EG体系中引入适量微胶囊红磷（MRP）可极大地提高EG的阻燃效率，降低阻燃剂用量，EG与MRP之间有非常明显的协同阻燃作用，而NG与MRP之间几乎无协同阻燃作用；EG的粒径为270 μm、PS?HI∶EG∶MRP质量比为80∶15∶5时20 %的阻燃剂就可使PS?HI具有优异的阻燃性能。

Effects of graphite type and size on flame retardancy of high?impact polystyrene and it’s action mechanism

Graphites with different types and particle sizes were incorporated into high?impact polystyrene （PS?HI） matrix through melt compounding. The effects and flame?retarding mechanism of graphite type and particle size on the flame retardancy of PS?HI were investigated. The results indicated that the flame?retarding effect of natural graphite （NG） on PS?HI was not significant， and the particle size of NG presented a small impact on its flame?retardant performance. The PS?HI/NG composite still showed poor flame?retardant performance even if the loading of NG reaches 50 wt%. In contrast to NG， expandable graphite （EG） exhibited much higher flame retardant efficiency， resulting in a significant improvement in the flame?retardant performance of PS?HI. The larger the EG particle size is， the higher is the flame retardant efficiency and the more noticeable is the smoke?suppressing effect of EG. The introduction of suitable amount of microencapsulated red phosphorus （MRP） into the PS?HI/EG system could improve the flame retardant efficiency of EG and therefore reduced the loading of flame retardant considerably. When the EG particle size is 270 μm， the PS?HI system achieved excellent flame?retardant performance with the addition of 20 wt% flame retardant at a PS?HI/EG/MRP mass ratio of 80/15/5. The PS?HI/EG/MRP composites generated a continuous and compact intumescent char layer.