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

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

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PSHI/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270μm、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。

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 PSHI was not significant,and the particle size of NG presented a small impact on its flame-retardant performance. The PSHI/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.