Abstract To investigate the influence of chemical compositions of organoclays on the thermal stability and fire behavior of PLA nanocomposites, 2, 6 and 8 wt% of single and hybrid Brazilian organically-modified montmorillonites (OMt), containing ammonium and phosphonium based surfactant - di-(hydrogenated tallow) dimethyl ammonium chloride (HTA), trihexyl tetradecyl phosphonium chloride (TDP), di(alkyl ester) dimethyl ammonium chloride (EA) and ethoxylated tallow amine (ETA) - were added to PLA using a melt-compounding process. It was noticed that the addition of OMt and melt-compounding contributed to a decrease of the initial decomposition temperature and average molecular mass of PLA, assessed by thermogravimetric analysis (TGA) and gel permeation chromatography (GPC), respectively. Moreover, PLA nanocomposites with single OMt (TDP and HTA) showed lower thermal stability than those with hybrid OMt. PLA nanocomposites with hybrid OMt containing EA and ETA displayed higher fire-reaction performance under cone calorimeter test. Comparing with neat PLA, these nanocomposites registered a peak heat release rate (pHRR) reduction of 29% and 38%, and a fire index grow rate (FIGRA) reduction of 32% and 37%, respectively, as well as the absence of melt dripping during combustion. The enhancement of the fire-reaction behavior was related to the nanoparticles high degree of dispersion and compatibility between PLA and nanoparticles, characterized in a previous work ( Alves et al., 2019 ), which contributed to the formation of an effective protective layer on the condensed phase during combustion.

中文翻译：

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巴西有机改性蒙脱石对有机粘土填充聚乳酸纳米复合材料热稳定性和防火性能的影响

摘要 为了研究有机粘土的化学成分对 PLA 纳米复合材料的热稳定性和防火性能的影响，2、6 和 8 wt% 的单一和混合巴西有机改性蒙脱石 (OMt)，含有铵和鏻基表面活性剂 - 二(氢化牛脂)二甲基氯化铵(HTA)、三己基十四烷基氯化鏻(TDP)、二(烷基酯)二甲基氯化铵(EA)和乙氧基化牛脂胺(ETA)-使用熔融复合工艺添加到PLA中。注意到添加 OMt 和熔融复合有助于降低 PLA 的初始分解温度和平均分子量，分别通过热重分析 (TGA) 和凝胶渗透色谱 (GPC) 评估。而且，具有单一 OMt（TDP 和 HTA）的 PLA 纳米复合材料的热稳定性低于具有混合 OMt 的那些。在锥形量热仪测试中，含有 EA 和 ETA 的混合 OMt 的 PLA 纳米复合材料显示出更高的火反应性能。与纯 PLA 相比，这些纳米复合材料的峰值放热率 (pHRR) 分别降低了 29% 和 38%，燃烧指数增长速率 (FIGRA) 分别降低了 32% 和 37%，并且不存在熔体燃烧时滴落。火灾反应行为的增强与 PLA 和纳米粒子之间的纳米粒子高度分散和相容性有关，这在先前的工作中有所表征 (Alves et al., 2019)，这有助于在 PLA 上形成有效的保护层。燃烧过程中的凝聚相。