Zhang Yi, Yang Weiwei, Zhao Wei, Ruan Fang, Li Shulei, Liu Jiping
School of Materials Science and Engineering, Beijing Institute of Technology Beijing 100081 China
Department of Biology and Chemical Engineering, Shandong Vocational College of Science &Technology Weifang 261053 China.
RSC Adv. 2020 Aug 3;10(48):28654-28663. doi: 10.1039/d0ra05167e.
In this study, a flame retardant agent, 2,4,8,10-tetraoxo-3,9-diphosphospiro[5.5]undecane spirophosphate-4,4-diaminopair benzene disulfone-1,3,5-himetriazine (SPDSCD), is synthesized through a direct polycondensation reaction. SPDSCD is a chemically expanded phosphorus-containing flame retardant in epoxy resins (EP). The molecular structure of SPDSCD and thermal stability are characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, and thermogravimetric analysis, and EP/SPDSCD composites were investigated in detail. These properties are associated with the phosphorus-containing spiro structure on the main molecular chain which can promote condensation polymerization into carbon during pyrolysis, the new nitrogen-containing carbon source, and the triazine structure. SPDSCD shows good thermal stability and low flammability, the weight loss from 500 to 800 °C was only 6.1 wt%, and the residual mass at 800 °C was 48.9 wt%. With the addition of SPDSCD, the flame retardant quality of the composites was gradually enhanced, the carbon residue becomes denser, which isolates heat transfer and inhibits the volatilization of flue gas. The addition of 20 wt% SPDSCD in the EP sample was associated with a limited oxygen index (LOI) value of 26% and a vertical burning V-0 rating. Cone calorimeter test shows that the peak heat release rate is reduced by 75%; the heat release rate curve enters the heat release platform area with a value lower than the first peak, TSP is reduced by 24%, the ac-COY value reduced by 25.6%, indicating that SPDSCD/EP produced less CO, which obviously prevented the combustion of volatile gas. SPDSCD exerted a charring and barrier effect in the condensation phase. Using basic characterization and flame retardancy testing, this work determined that SPDSCD has good flame retardancy when added to EP.
在本研究中，通过直接缩聚反应合成了一种阻燃剂，即2,4,8,10 - 四氧代 - 3,9 - 二磷杂螺[5.5]十一烷螺磷酸酯 - 4,4 - 二氨基对苯二砜 - 1,3,5 - 均三嗪（SPDSCD）。SPDSCD是环氧树脂（EP）中一种化学膨胀型含磷阻燃剂。通过核磁共振、傅里叶变换红外光谱和热重分析对SPDSCD的分子结构和热稳定性进行了表征，并对EP/SPDSCD复合材料进行了详细研究。这些性能与主分子链上的含磷螺环结构有关，该结构在热解过程中可促进缩聚成碳，新的含氮碳源以及三嗪结构。SPDSCD表现出良好的热稳定性和低可燃性，500至800℃的失重仅为6.1 wt%，800℃时的残余质量为48.9 wt%。随着SPDSCD的加入，复合材料的阻燃性能逐渐增强，残炭变得更致密，从而隔绝热传递并抑制烟气挥发。在EP样品中添加20 wt%的SPDSCD时，其极限氧指数（LOI）值为26%，垂直燃烧等级为V - 0。锥形量热仪测试表明，峰值热释放速率降低了75%；热释放速率曲线进入热释放平台区域，其值低于第一个峰值，总烟释放量（TSP）降低了24%，一氧化碳产率（ac - COY）值降低了25.6%，这表明SPDSCD/EP产生的CO较少，明显阻止了挥发性气体的燃烧。SPDSCD在凝聚相中发挥了成炭和阻隔作用。通过基础表征和阻燃测试，本研究确定SPDSCD添加到EP中时具有良好的阻燃性。
