After the surface silylation with 3-methacryloxypropyltrimethoxysilane, silica nanoparticles were further modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The immobilization of DOPO on silica nanoparticles was confirmed by Fourier transform infrared spectroscopy, UV–visible spectroscopy, magic angle spinning nuclear magnetic resonance, and thermogravimetric analysis. By incorporating the DOPO-immobilized silica nanoparticles (5 wt%) into polypropylene matrix, the thermal oxidative stability exhibited an improvement of 62 °C for the half weight loss temperature, while that was only 26 °C increment with incorporation of virgin silica nanoparticles (5 wt%). Apparent activation energies of the polymer nanocomposites were estimated via Flynn–Wall–Ozawa method. It was found that the incorporation of DOPO-immobilized silica nanoparticles improved activation energies of the degradation reaction. Based on the results, it was speculated that DOPO-immobilized silica nanoparticles could inhibit the degradation of polypropylene and catalyze the formation of carbonaceous char on the surface. Thus, thermal stability was significantly improved.

中文翻译：

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使用 DOPO 固定化二氧化硅纳米粒子提高聚丙烯的热稳定性

在用 3-甲基丙烯酰氧基丙基三甲氧基硅烷进行表面硅烷化后，二氧化硅纳米粒子被 9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物 (DOPO) 进一步改性。通过傅里叶变换红外光谱、紫外-可见光谱、魔角旋转核磁共振和热重分析证实了 DOPO 在二氧化硅纳米粒子上的固定化。通过将 DOPO 固定的二氧化硅纳米粒子 (5 wt%) 掺入聚丙烯基质中，热氧化稳定性在半失重温度下提高了 62 °C，而加入原始二氧化硅纳米粒子后，热氧化稳定性仅提高了 26 °C。 5 重量％）。通过 Flynn-Wall-Ozawa 方法估计聚合物纳米复合材料的表观活化能。研究发现，加入 DOPO 固定的二氧化硅纳米粒子提高了降解反应的活化能。基于这些结果，推测DOPO固定的二氧化硅纳米粒子可以抑制聚丙烯的降解并催化表面碳炭的形成。因此，热稳定性显着提高。