ODPA/异构ODA共聚酰亚胺的合成及其性能研究

采用3,3′,4,4′-二苯醚四甲酸二酐(3,3′,4,4′-ODPA),4,4′-二氨基二苯醚(4,4′-ODA)和3,4’-二氨基二苯醚(3,4′-ODA)为原料合成了共聚酰亚胺,实验中还以邻苯二甲酸酐(PA)为分子量调节剂,制备了理论分子量为10000的共聚酰亚胺,主要研究了其热性能和结晶性能。结果表明,与均聚型聚酰亚胺(ODPA/4,4′-ODA为原料合成)比较,间位异构体3,4′-ODA的加入使聚酰亚胺的玻璃化转变温度降低。经过等温结晶处理后,能够在DSC测试中出现较明显的熔融峰,而且延长结晶时间或者升高结晶温度有利于晶体的进一步完善。但是当共聚单体3,4′-ODA的加入量增加到10%(摩尔比)时,即使经过较长时间的等温处理,该共聚酰亚胺依然为无定形结构。

Study on the synthesis and property of copolyimide derived from ODPA/isomeric ODA

A series of copolyimides based on 3,3′,4,4′-oxydiphthalic dianhydride(3,3′,4,4′-ODPA) and isomeric oxydianiline(4,4′-ODA and 3,4′-ODA) were synthesized.The molecular weights were controlled using phthalic anhydride(PA) as end capping agent.The thermal property and crystalline behavior were investigated by means of TGA,DSC,and WAXD.The results showed that,compared with the homopolyimides from 3,3′,4,4′-ODPA and 4,4′-ODA,the glass transition temperature of copolyimides decreased with increasing content of meta isomer 3,4′-ODA.Obvious fusion peaks appeared in the subsequent DSC heating scan after isothermal crystallization process,In addition,crystal domains become more perfect through prolonging the time of isothermal crystallization and/or elevating the crystallization temperature,demonstrated by higher melt temperature(Tm) and fusion enthalpy.However,the copolyimide with more 3,4′-ODA loading(over 10%,molar ratio) showed no crystalline behavior,even after isothermal treat.