Achieving flame retardancy in epoxy resin (EP) while preserving its essential properties, including strength, toughness, and thermal stability, offers considerable challenges in the application of flame retardant EP modifications. In this study, we were successful in synthesizing a novel ionic-based flame retardant, organophosphinic acid salt (DPM), using a simple ionic reaction. DPM possesses a unique structure consisting of rigid groups and flexible chain segments. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) techniques were used to characterise the structure of DPM. Incorporating DPM into the EP yielded remarkable improvements in mechanical properties, reduced fire hazard, enhanced processability, a lower curing temperature, and good thermal stability. The EP/DPM-7.5 composites demonstrated excellent flame retardancy by effortlessly achieving a V-0 rating in vertical combustion (UL-94) testing, while an impressive limited oxygen index (LOI) value of 36.3% was attained, a substantial 42.4% enhancement compared to the EP. Moreover, cone calorimeter (CC) tests revealed that EP/DPM-7.5 exhibited a 41.7% decrease in peak heat release rate (PHRR), a decreased fire growth rate index (FIGRA), and an increased fire performance index (FPI). Additionally, the tensile strength and flexural strength of EP/DPM-7.5 improved by 26.0% and 23.7%, respectively. Comparatively, EP/DPM-5 maintained the glass transition temperature (T) and thermal stability of the EP while significantly enhancing the impact strength by 85.4%. The newly developed flame retardant, DPM, exhibited excellent comprehensive performance and fire safety characteristics, thereby demonstrating the significant potential for practical applications in flame retardant EP systems.

中文翻译：

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一种新型有机次膦酸盐，用于轻松合成并同时赋予环氧​​树脂阻燃性、增强性和增韧性

在环氧树脂 (EP) 中实现阻燃性，同时保留其基本性能，包括强度、韧性和热稳定性，这给阻燃 EP 改性的应用带来了相当大的挑战。在这项研究中，我们利用简单的离子反应成功合成了一种新型离子基阻燃剂有机次膦酸盐（DPM）。 DPM具有由刚性基团和柔性链段组成的独特结构。傅里叶变换红外（FTIR）和核磁共振（NMR）技术被用来表征DPM的结构。将 DPM 纳入 EP 显着改善了机械性能、降低了火灾危险、增强了加工性能、降低了固化温度并具有良好的热稳定性。 EP/DPM-7.5 复合材料在垂直燃烧 (UL-94) 测试中轻松达到 V-0 等级，展现出优异的阻燃性，同时获得了令人印象深刻的 36.3% 的有限氧指数 (LOI) 值，大幅提高了 42.4%与EP相比。此外，锥形量热仪 (CC) 测试表明，EP/DPM-7.5 的峰值热释放率 (PHRR) 降低了 41.7%，火势增长指数 (FIGRA) 降低，防火性能指数 (FPI) 提高。此外，EP/DPM-7.5的拉伸强度和弯曲强度分别提高了26.0%和23.7%。相比之下，EP/DPM-5 保持了 EP 的玻璃化转变温度 (T) 和热稳定性，同时冲击强度显着提高了 85.4%。新开发的阻燃剂DPM表现出优异的综合性能和防火安全特性，从而展示了在阻燃EP系统中实际应用的巨大潜力。