氰尿酸三聚氰胺与氢氧化镁协效阻燃EVA的研究

通过锥形量热器试验、热重分析、拉曼光谱分析、氧指数、垂直燃烧试验及流变性能测试，研究了氰尿酸三聚氰胺(MCA)和氢氧化镁在无卤阻燃乙烯醋酸乙烯共聚(EVA)混合物中的协效阻燃作用。锥形量热器试验结果表明，一定量的MCA可明显延缓材料的点燃时间，降低热释放速率；垂直燃烧和氧指数试验结果显示，MCA可有效改善材料的熔体滴落性能，增强火焰的自熄能力，但会降低材料的氧指数；流变性能测试结果表明，McA的加入可明显降低材料的熔体粘度，改善材料的可加工性；热重分析结果显示，MCA可延缓EVA树脂的热氧降解并能促进炭层的生成；拉曼光谱证明了阻燃材料形成的炭层具有类石墨结构。MCA与氢氧化镁的协效阻燃效果归因于惰性气体保护层和炭层的形成。

Synergistic effects and flame-retardant properties of melamine cyanurate with magnesium hydroxide in halogen-free flame-retardant EVA blends

The synergistic effects and flame-retardant properties of melamine cyanurate (MCA) with magnesium hydroxide (MH) in halogen-free flame-retardant (HFFR) ethylene vinyl acetate copolymer (EVA) blends have been studied using the cone calorimeter test (CCT), thermogravimetric analysis (TGA), laser Raman spectroscopy (LRS), limiting oxygen index (LOI), UL-94 test, and measurements of rheological properties. The data obtained from CCT show that a suitable amount of MCA can prolong the ignition time and reduce the heat release rate. The UL-94 test proves that MCA can efficiently prevent the EVA/MH blends from dripping in a flame and improve the ability of extinguishing itself after ignition. However, the addition of MCA apparently reduces the LOI values of EVA/MH blends, but a suitable amount of MCA can apparently decrease the melt viscosity and thus improve the processability of EVA/MH blends. The TGA data indicate that MCA can retard the thermo-oxidative degradation of EVA by increasing the pyrolysis temperature and promote the formation of char layers. The LRS gives the evidence that the charred layers have the graphite-like structure. The enhanced flame-retardant properties of MCA in the EVA/MH blends can be described as the formation of inert gaseous protection layers around the EVA blends and its interaction with EVA to promote the formation of charred layers.