• 关键词：亚临界水  聚酰亚胺  解聚  4,4'-二氨基二苯醚  稳定性

• 基金项目：国家自然科学基金(No.20777070,20677052)

• 黄园园
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 金赞芳
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 刘丽
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 柳颖萍
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 林春绵
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 潘志彦
• 浙江工业大学生物与环境工程学院, 杭州 310032

• 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 ℃、17.5 MPa、水-聚酰亚胺投料质量比20 ∶ 1、反应时间30 min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73.59 kJ·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.

• Abstract：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.

• Key words：sub-critical water  polyimide  depolymerization  4,4'- diaminodiphenyl ether  aniline  stability

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