Preparation and flame retardancy of 3-(hydroxyphenylphosphinyl)-propanoic acid esters of cellulose and their fibers

New 3-(hydroxyphenylphosphinyl)-propanoic acid (3-HPP) esters of cellulose were synthesized in N, N-dimethylacetamide/LiCl homogeneously by the method of in situ activation with p-toluenesulfonyl chloride. Chemical structure and thermal properties of the cellulose esters were investigated by FTIR, C-13-NMR, TGA, RT-IR and Py-GC/MS, and their flame retardancy was studied by limiting oxygen index (LOI) test and vertical flammability test. It was found that the degree of substitution (DS) of cellulose esters, in the range from 0.62 to 1.42, had an obvious effect on solubility of cellulose esters. According to the FT-IR and Py-GC/MS results, flame retardant 3-HPP reacting with cellulose could accelerate dehydration action and decrease flammable released products. Besides, ESEM observation also confirmed that flame retardant cellulose (FRC) fibers with 3 wt% cellulose acetate prepared by dry-wet spinning technique possessed good flame resistance.

采用对甲苯磺酰氯原位活化法，在N,N - 二甲基乙酰胺/氯化锂体系中均相合成了新型纤维素3 -（羟基苯膦酰基）丙酸（3 - HPP）酯。通过傅里叶变换红外光谱（FTIR）、碳 - 13核磁共振（C - 13 - NMR）、热重分析（TGA）、实时红外光谱（RT - IR）和裂解气相色谱/质谱（Py - GC/MS）研究了纤维素酯的化学结构和热性能，并通过极限氧指数（LOI）测试和垂直燃烧试验研究了其阻燃性。研究发现，纤维素酯的取代度（DS）在0.62至1.42范围内，对纤维素酯的溶解性有明显影响。根据FT - IR和Py - GC/MS结果，阻燃剂3 - HPP与纤维素反应可加速脱水作用并减少可燃释放产物。此外，环境扫描电子显微镜（ESEM）观察也证实，采用干湿纺丝技术制备的含3 wt%醋酸纤维素的阻燃纤维素（FRC）纤维具有良好的阻燃性。