以三聚氰胺甲醛预聚体(MFP)与红磷粉末为原料, 过硫酸钾(KPS)为催化剂, 采用原位聚合法成功制备出具有高热稳定性的微胶囊红磷(MRP)。 通过DSC, SEM, FTIR及XPS等分析手段研究了红磷微胶囊化效果。 结果表明, KPS的加入有助于提高MFP的反应活性, 使三聚氰胺甲醛树脂有效地包覆在红磷颗粒表面, 缩短了反应时间, 且此时制备的MRP包覆效果最佳, 其氧化反应峰温为480 ℃, 较红磷原料要高出很多, 可使用范围变宽。 采用熔融挤出法制备了多组不同配方的聚丙烯(PP)复合材料。 研究发现, MRP或氢氧化镁(MH)单独使用时阻燃效率低, 将它们复配使用后能有效地提高材料的阻燃性能。 当PP∶MRP∶MH=100分(phr)∶15(phr)∶50(phr)时, MRP/MH/PP复合材料的极限氧指数为26%, 垂直燃烧达到UL-94标准的V-0级。 此外, 还探讨了可能的阻燃机理。

In the present study, the melamine-formaldehyde prepolymer (MFP) was first synthesized at pH 8-8.5 under about 80 ℃ with melamine, formaldehyde, triethanolamine and methanol as the starting materials. Subsequently, the microencapsulated red phosphorus (MRP) was successfully prepared by in-situ polymerization at pH 5.5 under 65 ℃, using MFP and red phosphorus (RP) powders as raw materials, and potassium persulphate (KPS) as catalyst. The obtained products were detected by differential scan calorimetry (DSC), scanning electron microscope (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). It was found that KPS is useful in enhancing the reaction activity of MFP, which can make RP be well encapsulated by melamine-formaldehyde resin (MF) and reduce the reaction time. The DSC, SEM and XPS results show that it won’t get well-encapsulated MRP only under acidic condition and without any KPS. When a proper quantity of KPS is employed, the RP particles can be almost completely-encapsulated by MF and the peak temperature of oxidation reaction for MRP is 480 ℃, which is much higher than that of RP, extending the applications for MRP. The FTIR spectrum demonstrates that the coating material on the surface of RP accurately is MF, in agreement with the reference. Polyproplene (PP) composites with different formulations were prepared by melt extrusion. It was shown that the flame-retardant efficiencies are very low when the PP composites only contain MRP or MH. However, the flame-retardant property can obviously improve if MRP and MH are both used in the PP composites. When PP∶MRP∶MH=100 (phr)∶15 (phr)∶50 (phr), the limited oxygen index of the MRP/MH/PP composite is 26%, and vertical firing ranks UL-94 V-0. In addition, the possible flame-retardant mechanism of the PP composites has also been discussed, and further verified by FTIR and Raman spectroscopy.