脂肪族聚醚型聚氨酯弹性体热降解机理及热稳定性

采用酯交换缩聚法，以聚四氢呋喃醚二醇（PTMEG）和1，6-六亚甲基二氨基甲酸甲酯（HDU）为原料，以1，4-丁二醇（BDO）为扩链剂，以二丁基氧化锡为催化剂制备脂肪族聚醚型聚氨酯（PU）弹性体。用TGA和FTIR考察聚氨酯弹性体的热降解机理及原料组成对聚氨酯热降解过程的影响。结果表明：聚氨酯弹性体的热降解过程包括两个阶段，分别为硬段（氨基甲酸酯）和软段（聚醚多元醇）的降解，其中硬段（氨基甲酸酯）的降解主要降解产物为碳化二亚胺、CO₂、四氢呋喃及水，软段（聚醚多元醇）的降解主要产物为四氢呋喃和水。随着硬段含量的降低，聚氨酯弹性体初始热降解温度由282℃上升至327℃，聚氨酯弹性体的热稳定性升高。

Research on thermal degradation mechanism and thermal stability of aliphatic polyether-polyurethane elastomer

Aliphatic polyether-polyurethanes elastomer (PUs) were prepared by transesterification polycondensation from polytetramethylene glycol (PTMEG), dimethyl-hexane-1,6-dicarbamate (HDU) and 1,4-butanediol in the presence of dibutyltin oxide as catalyst. The degradation mechanism of PU and effects of raw material ratio on its thermal stability were examined by TGA and FTIR. The results showed that PU samples presented a two-stage degradation associated with the degradation of urethane hard segment and PTMEG soft segment, and the degradation products of urethane hard segment included carbondiimide, CO₂, tetrahydrofuran (THF) and water, while that of PTMEG soft segment were tetrahydrofuran (THF) and water. Moreover, thermal stability of PU increased with the decrease of hard segment content, and the initial degradation temperature was raised from 282℃ to 327℃.