ODA-PMDA型聚酰亚胺纤维的回收研究

摘要

Polyimide (PI) fiber derived from 4,4′-diamino diphenyl ether-pyromellitic dianhydride (ODA-PMDA) was recovered by hydrolysis.The effects of the sodium hydroxide (NaOH) solution concentration and reaction time on ODA yield and the cooling temperature on PMDA yield were discussed.The structure of the hydrolysis product was characterized by Fourier transform infrared spectrometry (FTIR) and hydrogen nuclear magnetic resonance spectrometry (1H-NMR).The results showed that the recovery rate of ODA was 99.3% when the mass fraction of NaOH ultrapure water solution was 30% and PI fiber was added at the proportions of 50%,30%,20% by three times to react for 2 h,2 h and 4 h,respectively;the recovery rate of PMDA was 98.6% when the filtered reaction solution was acidized and cooled to 0-5 ℃ after distilling off the excess solvent;and ODA and PMDA obtained by the hydrolysis recovery of PI fiber was proved to be the target product by FTIR and 1H-NMR.%采用水解法回收4,4′-二氨基二苯醚-均苯四甲酸二酐(ODA-PMDA)型聚酰亚胺(PI)纤维,探讨了氢氧化钠(NaOH)溶液浓度、反应时间对ODA收率的影响以及冷却温度对PMDA收率的影响.利用傅里叶变换红外光谱(FTIR)和核磁共振氢谱(1H-NMR)对水解产物的结构进行了表征.结果表明:最佳的反应条件为NaOH超纯水溶液质量分数30%,PI纤维分3次加入到NaOH超纯水溶液中,加入比例依次为50%,30%,20%,反应时间分别为2,2,4 h,回收的ODA收率为99.3%;将反应滤液酸化,蒸馏出多余的溶剂后冷却至0~5℃,再将分离出的均苯四甲酸升华回收得PMDA,收率为98.6%;FTIR及1H-NMR分析表明PI纤维水解回收得到的ODA和PMMA为目标产物.