This paper surveys the char forming effect of urea-formaldehyde resin (UF) and the flame retardancy of UF cooperating with ammonium polyphosphate (APP) for polypropylene (PP). UF was firstly synthesized and then modified by a silane coupling agent 3-aminopropyltriethoxysilane (KH-550). UF and KH-550 modified urea-formaldehyde resin (M-UF) were characterized by field-emission scanning electron microscope (FE-SEM), energy-dispersive analysis (EDS), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Compared with UF, M-UF had better thermal stability and higher mass of residue char. Afterwards the intumescent flame retardants (IFRs), consisting of UF + APP and M-UF + APP respectively, were introduced into PP. The flame retardant efficiency of PP composites was investigated by limiting oxygen index (LOI), UL-94 vertical burning, and micro combustion calorimetry (MCC). The possible decomposition mechanisms were investigated by TGA, FT-IR and EDS. When the addition of PP, APP and UF was 70, 24 and 6 wt%, the LOI value reached 23.5 and UL-94 test could not pass. However, when the loading of PP, APP and M-UF was 70, 20 and 10 wt%, the LOI value reached 29.5 and UL-94 test was V-0. The residual char layers of some PP composites were analyzed by Laser Raman spectroscopy (LRS) and FE-SEM. The LRS and FE-SEM presented that the char layer of 20%APP+10%M-UF/PP was more compact and had higher strength than 20%APP+10%UF/PP. Furthermore, tensile tests showed that M-UF/APP could improve break strength and toughness for PP compared with the same ratio of UF/APP. To sum up, M-UF + APP/PP have better flame retardant efficiency and tensile properties compared with UF + APP/PP.

本文综述了脲醛树脂（UF）的炭化效果以及UF与聚磷酸铵（APP）配合使用对聚丙烯（PP）的阻燃性。首先合成了UF，然后用硅烷偶联剂3-氨基丙基三乙氧基硅烷（KH-550）对其进行了改性。通过场发射扫描电子显微镜（FE-SEM），能量色散分析（EDS），傅里叶变换红外光谱（FTIR）和热重分析（TGA）对UF和KH-550改性脲醛树脂（M-UF）进行了表征）。与UF相比，M-UF具有更好的热稳定性和更高的残炭质量。之后，分别由UF + APP和M-UF + APP组成的膨胀型阻燃剂（IFR）被引入PP中。通过限制氧指数（LOI）研究了PP复合材料的阻燃效率，UL-94垂直燃烧和微燃烧量热法（MCC）。通过TGA，FT-IR和EDS研究了可能的分解机理。当PP，APP和UF的添加量分别为70、24和6 wt％时，LOI值达到23.5，UL-94测试无法通过。但是，当PP，APP和M-UF的负载量分别为70、20和10 wt％时，LOI值达到29.5，UL-94测试为V-0。通过激光拉曼光谱（LRS）和FE-SEM分析了某些PP复合材料的残留炭层。LRS和FE-SEM表明，20％APP + 10％M-UF / PP的炭层比20％APP + 10％UF / PP的炭层更致密，强度更高。此外，拉伸试验表明，与相同比例的UF / APP相比，M-UF / APP可以提高PP的断裂强度和韧性。总结一下，