甲基膦酸三聚氰胺的制备及高效阻燃不饱和聚酯研究

Preparation and Application of Melamine Methylphosphonate for Highly Efficient Flame Retardancy of Unsaturated Polyester

以甲基膦酸和三聚氰胺为原料,合成了聚甲基膦酸三聚氰胺(MMP),通过傅里叶红外测试对其结构进行了表征。结果表明,阻燃剂的起始热分解温度为228℃,800℃残炭率为41.2%,MMP具有良好的热稳定性和成炭性能;MMP添加到不饱和聚酯(UPR)材料中,当添加量为21%(质量分数,下同)时,材料在垂直燃烧测试时达到了UL 94 V-0级,极限氧指数为38.5%,表现出了很好的阻燃效率;MMP的加入促进了UPR的提前降解和成炭,提高了材料在高温时的成炭率,使得材料在燃烧时形成了膨胀致密的炭层,有效抑制了内层材料的降解和燃烧,从而提高了材料的阻燃性能。

Melamine methylphosphonate (MMP) was synthesized through a reaction of methylphosphonic acid with melamine, and its chemical structure was characterized by Fourier transform infrared spectroscopy.Thermogravimetric analysis (TG) indicated that MMP exhibited an initial thermal decomposition temperature of 228 ℃ and a char yield of 41.2 wt.% at 800 ℃, suggesting an excellent thermal stability and charring capability. MMP was used for flame retardancy of unsaturated polyester resin (UPR), and the resulting thermosetting compounds achieved a UL 94 V-0 classification in the vertical burning experiment and a limiting oxygen index of 38.5 vol.% when 21 wt.% MMP was incorporated. This result demonstrated that the synthesized MMP had a high efficient flame retarding effect on UPR. The TG results indicated the introduction of MMP could promote the decomposition and charring of UPR and thus improved its char formation and thermal stability at high temperature. Scanning electron microscopic observation confirmed the formation of a compact and expanded char layer for the compounds during combustion. It was believed that the formed char layer inhibited the mass and heat transfer and consequently protected the underlying materials from further degradation. As a result, the flame retardant performance of UPR compounds was enhanced.