In this study, fly ash (FA) was used as a synergist to enhance the fire resistance of intumescent flame retardant polypropylene containing hydroxymethylated lignin. Effects of fly ash on flame retardancy and thermal stability properties of polypropylene (PP) composites were investigated using a limiting oxygen index (LOI) meter, UL‐94 vertical combustion tester, cone calorimeter, and thermogravimetric analyzer. The results showed that during combustion, incorporation of FA can effectively solve the dripping problem of the PP composites. Addition of 0.5% loading amount fly ash into the PP composite (0.5FA/IFR/PP) enhanced the flame retardancy significantly. Additionally, its LOI value increased from 28% to 33%, and UL‐94 vertical burning passed V‐0 grade from V‐2 rate. Notably, owing to addition of the fly ash, the peak of heat release rate of the pure PP decreased by 58.0%. Moreover, the release of CO₂ and CO was largely suppressed, and higher char residue was obtained for 0.5FA/IFR/PP. Fire safety of the PP composites was significantly improved. From the analysis of charring residues, a possible flame retardant mechanism was proposed. That is, incorporation of fly ash increased the formation of a denser and intact char layer, which is important in inhibiting heat and flammable gases generated during combustion of underlined matrix.

中文翻译：

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粉煤灰对含羟甲基化木质素的阻燃聚丙烯的协同作用：阻燃性和热稳定性

在这项研究中，粉煤灰（FA）被用作增效剂，以增强含羟甲基化木质素的膨胀型阻燃聚丙烯的耐火性。使用极限氧指数（LOI）仪，UL‐94垂直燃烧测试仪，锥形量热仪和热重分析仪研究了粉煤灰对聚丙烯（PP）复合材料的阻燃性和热稳定性的影响。结果表明，燃烧过程中掺入FA可以有效解决PP复合材料的滴落问题。在PP复合材料（0.5FA / IFR / PP）中添加0.5％的粉煤灰可显着提高阻燃性。此外，它的LOI值从28％增加到33％，UL-94垂直燃烧从V-2速率通过了V-0级。值得注意的是，由于添加了粉煤灰，纯PP的放热率峰值降低了58.0％。而且，CO的释放₂和CO被大大抑制，并且对于0.5FA / IFR / PP获得了更高的炭渣。PP复合材料的防火安全性得到显着改善。通过对炭化残渣的分析，提出了一种可能的阻燃机理。即，掺入粉煤灰增加了致密且完整的炭层的形成，这对于抑制带下划线的基体燃烧期间产生的热量和可燃气体是重要的。