作者：Lala Rukh Sidra, Guofei Chen,* Nafeesa Mushtaq, Lubo Xu, Xiaoqi Chen, Yantao Li, Xingzhong Fang
关键字：Melt processable, Hydroquinone diphthalic anhydride, 2-(4-aminophenyl)-5-aminobenzimidazole
论文来源：期刊
具体来源：Polymer
发表时间：2018年

To extend the upper operating temperature range of melt processable PIs, two series of end-capped copolyimides based on hydroquinone diphthalic anhydride (HQDPA) isomers were designed by varying the contents of appropriate diamines. Thus, copolyimides PI-(0a~20a) based on 3,30-HQDPA were prepared by varying the ratio of rigid 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) and flexible 4,4''-oxydianiline (ODA). The resulting copolyimides demonstrated good properties, such as excellent solubility, high Tg ranging from 328 to 354 C as determined by dynamic mechanical analyzer (DMA), besides, exhibited good thermal stability based on 5% weight loss temperature (T5%) of 502e514 C and low melt viscosity in the range of 291e935 Pa$s. Most importantly, PI-20a showed a good combination of low melt viscosity simultaneously with significantly high Tg (328 C). Furthermore, this system was modified by copolymerization with different feed ratio of 4,40-HQDPA isomer and produced another series PI-(20a~20e), that exhibited high Tg in the range of 315-330 C with T5% of 502-543 C and minimum complex viscosity in the range of 291e479 Pa$s. All PIs form tough and flexible films that have remarkable tensile strength and moduli in the range of 93-116 MPa and 3.7-4.7 GPa, respectively.