临界区甲醇的聚碳酸酯降解研究

Depolymerization of polycarbonate in critical region of methanol

在间歇高压反应器中研究了聚碳酸酯在甲醇临界区域的降解行为 .降解无需借助催化剂 ,降解温度 2 2 0— 2 6 0℃ ,压力5 2 0— 8 6 7MPa ,时间 5— 4 5min ,通过GC MS与GC FID对液相产物进行了定性和定量分析 ,聚碳酸酯醇解主要产物为碳酸二甲酯 (DMC)和双酚A(BPA) .降解温度和时间为 2 4 0℃和 30min时 ,DMC和BPA的产率分别 91 75 %和 90 0 3% .通过凝胶渗透色谱 (GPC)对 2 4 0℃醇解反应的固相聚合物进行了分析 .降解初期 ,聚合物大分子发生断裂 ,PC的数均分子量 (Mn)迅速下降 ,仅有少量DMC和BPA生成 ;降解的中间阶段 ,低聚物在降解产物中的比例快速增加 ,同时DMC与BPA相应增多 ,最终PC被完全分解 .

Depolymerization of polycarbonate in critical region of methanol was studied in absence of catalysts and in a batch-type autoclave at reaction temperature of 220—260℃ and with reaction time of 5—45?min. The main liquid products were demethyl carbonat (DMC) and bisphenol-A(BPA), which were identified and quantified by GC/MS and GC/FID. In critical region of methanol at 240℃ for reaction time of 30?min, the yield of DMC and BPA reached 91.75% and 90.03%, respectively. Gel Permeation Chromatography was used to measure the number-average molecular weight ((Mn)) of solid products. Based on the experiments, mechanism of methanolysis was proposed in this paper.