基于异构三苯二醚二酐的热塑性共聚酰亚胺的合成

摘要

A series of polyimides (PI) were prepared from 3,3′,4,4′–hydroquinone diphthalic dianhydride(4,4′–HQDPA), 2, 2′,3,3′–hydroquinone diphthalic dianhydride (3,3′–HQDPA) with different ratios of the isomers and 4,4′–oxydianiline (4,4’–ODA) by the conventional two-step method. Solubility, thermal properties and melt processability of the copolyimides were investigated and compared with corresponding homopolyimides. The results show that all the polyimides exhibite excellent thermal stabilities with the 5% weight loss temperatures (Td5%) of 500~521℃ in air and 507~538℃ in nitrogen respectively. With the increasing of 3,3′–HQDPA,the polymers exhibite a regular increase in solubility and glass transition temperatures (Tg), andTg increase from 223 to 257℃. The melt processability is found to be dependent on the ratios of dianhydride units,Tg,solubility and melt flowability of copolyimides could be adjusted by the mole ratio of the isomers,so that the copolyimides could satisfy different applications. The copolyimides show better melt fluidity than the homopolyimides,and the copolyimide exhibite the best melt flowability when the mole ratio of 3,3′–HQDPA and 4,4′–HQDPA is 1∶1,which could be used as high performance melt–processable polyimides.%以2，2′，3，3′–三苯二醚四甲酸二酐(3，3′–HQDPA)、3，3′，4，4′–三苯二醚四甲酸二酐(4，4′–HQDPA)为二酐单体，邻苯二甲酸酐为封端剂，与4，4′–二氨基二苯醚(4，4′–ODA)进行无规共聚。通过改变二酐的比例，用两步法制备了一系列热塑性共聚酰亚胺粉料，并对其热性能、溶解性能、熔体性能等进行了表征，与均聚酰亚胺进行了比较。结果表明，聚合物均具有良好的热稳定性，热分解5%的温度在空气中为500～521℃，在氮气中为507～538℃；随着3，3′–HQDPA含量的增加，玻璃化转变温度(Tg)由223℃升高至257℃，溶解性也逐渐提高。与均聚物相比，共聚物的熔体流动性有了显著地提高。可以通过调控异构二酐的比例来调控共聚酰亚胺的Tg、溶解性和熔体流动性，满足材料在不同应用上的要求，当二酐的比例为1∶1时，共聚酰亚胺的熔体流动性最好，可作为高性能、易加工的热塑性工程塑料使用。