中文摘要：

利用间歇式高压反应装置研究了高性能聚合物聚酰亚胺（PI）在亚临界水中的解聚情况.同时,采用气-质联谱（GC-MS）、反相高效液相色谱（HPLC）、傅里叶红外光谱（FT-IR）等方法对解聚产物进行定性定量分析,确定解聚产物主要为4,4＇-二苯醚二甲酸、4,4＇-二氨基二苯醚（4,4＇-ODA）、苯胺和对苯二酚.在350℃、17.5MPa、水-聚酰亚胺投料质量比20：1、反应时间30min条件下,PI解聚率达到99%以上,4,4＇-二苯醚二甲酸产率为81.04%,4,4＇-ODA产率为8.18%.针对解聚产物4,4＇-ODA产率远低于理论值的问题,进一步考察了反应温度、时间对4,4＇-ODA稳定性的影响,确定4,4＇-ODA在实验条件下会分解为苯胺.通过实验数据关联分析,得出亚临界水中4,4＇-ODA分解反应级数为一级,反应活化能为73.59kJ.mol-1.此外,在可视微型毛细管反应器中结合显微镜研究了4,4＇-ODA在热水中的相态变化,发现加热过程中,4,4＇-ODA先熔融后溶解,温度高于199℃时,完全溶于水中,形成均相水溶液.

英文摘要：

Depolymerization of polyimide（PI） in sub-critical water was studied in a batch autoclave reactor.PI was efficiently depolymerized to 4,4＇diaminodiphenyl ether（4,4＇-ODA）,4,4＇-oxydibenzoic acid,aniline and hydroquinone,as characterized by GC-MS,HPLC and FT-IR.Over 99% PI was converted,producing yields of 81% for 4,4＇-oxydibenzoic acid and less than 10% for 4,4＇-ODA,when the reaction was conducted with a reactant ratio of water to PI at 20：1 for 30 minutes at 350 ℃ and 17.5 MPa.Further stability tests revealed that 4,4＇-ODA was unstable and partially converted to aniline,reducing its yield.Additional kinetic analysis suggests that 4,4＇-ODA in sub-critical water follows a first-order reaction kinetics with activation energy of 73.59 kJ.mol-1.Upon examination in hot water inside a fused silica capillary reactor under a microscope,phase changes were observed when 4,4＇-ODA was heated.It started to melt at a low temperature,then dissolved completely above 199 ℃ and eventually became aqueous fluid coexisting with vapor phases.