writer：Kaiyuan You, Hongyan Yao, Yunhe Zhang, Yu Liu, Shanyou Liu, Ying Song, Shaowei Guan
keywords：hyperbranched polyimide
source：期刊
specific source：HIGH PERFORMANCE POLYMERS,2015,27,970-978
Issue time：2015年
In the past decades, 4-phenylethynyl phthalic anhydride has been the most commonly used endcapper for polyimide (PI). A series of different groups of terminated hyperbranched PIs (HBPIs) were synthesized from 1,3,5-tris(2-trifluoromethyl-4-aminophenoxy)benzene, bis[4-(3,4-dicarboxyphenoxy)phenyl]ether dianhydride, and 4-phenylethynylphthalic anhydride or 4-(1-naphthylethynyl)phthalic anhydride. The glass transition temperatures (T(g)s) of the polymers varied from 166 degrees C to 193 degrees C. The 5% weight loss temperatures of polymers were in the range of 548 to 571 degrees C and those of the endcapped HBPIs increased to the range of 600 to 601 degrees C after curing. The PIs exhibited rather low melt viscosity at processing temperature and the complex viscosity increased continuously with the temperature increase. Because there is a large temperature difference between the T-g and cross-linking exothermic temperature, HBPIs provided a wide processing window.