A novel DOPO derived multi-claw reactive flame retardant (DMCFR) was designed to improve the flame retardancy of lyocell fabric. The chemical structure of DMCFR was identified by proton nuclear magnetic resonance (¹H-NMR) and Fourier transform infrared spectroscopy (FT-IR). The chemical structure and elemental composition of the modified lyocell fabric were investigated by FT-IR and X-ray photoelectron spectroscopy. The vertical burning test, limiting oxygen index (LOI) and cone calorimetry were applied to evaluate the flame retardancy of the original and treated samples. The results showed that the peak heat release rate and total heat release of the flame retardant lyocell (FR-lyocell) were significantly reduced by 90.6% and 65.5% compared to control sample. In addition, the LOI value of FR-lyocell fabric was up to 33% and remained 26% even after 20 laundering cycles (LCs). The thermal stability and char-forming capacity of the samples were measured by thermogravimetric analysis, and the residual char of the treated sample was as high as 9.15% and 42.5% under air and nitrogen atmosphere respectively, which were much higher than that of the original sample. Furthermore, the flame retardant mechanism was evidenced via scanning electron microscopy (SEM), Raman spectroscopy, thermogravimetric combined with Fourier transform infrared spectroscopy (TG-IR) and pyrolysis–gas chromatography-mass spectrometry (PyGC-MS), which supported the condensed and gas phase flame retardant mechanism.

Graphical abstract

中文翻译：

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DOPO衍生的新型多爪反应型阻燃剂赋予莱赛尔织物高效阻燃性

一种新型 DOPO 衍生的多爪反应型阻燃剂 (DMCFR) 旨在提高莱赛尔织物的阻燃性。DMCFR的化学结构经质子核磁共振鉴定（¹H-NMR) 和傅里叶变换红外光谱 (FT-IR)。通过FT-IR和X射线光电子能谱研究了改性lyocell织物的化学结构和元素组成。应用垂直燃烧测试、极限氧指数（LOI）和锥形量热法来评估原始样品和处理过的样品的阻燃性。结果表明，与对照样品相比，阻燃莱赛尔（FR-lyocell）的峰值放热率和总放热显着降低了90.6%和65.5%。此外，FR-lyocell 织物的 LOI 值高达 33%，即使经过 20 次洗涤循环 (LC) 后仍保持在 26%。通过热重分析测量样品的热稳定性和成炭能力，处理后的样品的残余焦炭分别高达9.15%和42。在空气和氮气气氛下分别为 5%，远高于原始样品。此外，通过扫描电子显微镜 (SEM)、拉曼光谱、热重结合傅里叶变换红外光谱 (TG-IR) 和热解-气相色谱-质谱 (PyGC-MS) 证明了阻燃机理，支持凝聚和气相阻燃机理。

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