An efficient bio‐safe cyclophosphazene flame retardant, 1,5,9,13,16,20‐Hexaoxa‐7,14,21‐triaza‐6λ⁴,8λ⁴,5λ⁴‐triphosphatrispiro[5.1.5.1.5.1]heneicosa‐6,8(14),15(21)‐triene (HCPO), was synthesized, and then was incorporated into polylactic acid (PLA) to improve the fire safety. The chemical structure of HCPO was confirmed by Fourier‐transformed infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of the compound was characterized by thermogravimetric (TG) analyzer. The cytotoxic effects of HCPO to cells were evaluated. Fire behavior and thermal stability of PLA composites were investigated by vertical burning, limiting oxygen index (LOI), TG analysis, and cone calorimeter. The morphology of residual charring was observed by scanning electron microscope. The results showed HCPO was bio‐safe, and highly effective to enhance the flame retardancy of PLA composites. The LOI value was increased from 18.4 to 27.5 and UL‐94 grade achieved V‐0 for the PLA composite containing only 2% HCPO and 2% pentaerythrotol. It was demonstrated that intermolecular cross‐linking reaction between pentaerythrotol and HCPO in high temperature range could accelerate the formation of compact char layers.

中文翻译：

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生物安全的环磷腈衍生物阻燃剂，用于聚乳酸复合材料：易燃性和细胞毒性

一种有效的生物安全环磷腈阻燃剂，1,5,9,13,16,20六氧7,14,21三氮杂- 6 λ ⁴，8 λ ⁴，5 λ ⁴合成了−triphosphatrispiro [5.1.5.1.5.1] heneicosa-6,8（14），15（21）-triene（HCPO），然后将其掺入聚乳酸（PLA）中以提高消防安全性。HCPO的化学结构已通过傅里叶变换红外光谱，质谱和核磁共振光谱得以确认。该化合物的热稳定性通过热重（TG）分析仪表征。评估了HCPO对细胞的细胞毒性作用。通过垂直燃烧，极限氧指数（LOI），TG分析和锥形量热仪研究了PLA复合材料的燃烧行为和热稳定性。通过扫描电子显微镜观察残留炭化的形态。结果表明，HCPO具有生物安全性，对增强PLA复合材料的阻燃性非常有效。LOI值从18增加。对于仅含2％HCPO和2％季戊四醇的PLA复合材料，其V至0为4至27.5，UL-94为V-0。结果表明，在高温范围内，季戊四醇与HCPO之间的分子间交联反应可以促进致密炭层的形成。