Preparation, characterization and thermal decomposition of polyimides with main chain containing cycloaliphatic units

摘要

Two polyimides with main chain containing cycloaliphatic units were synthesized by conventional two-step polycondensation of two diamines, 1,4-bis (4-aminophenoxymethylene) cyclohexane (BAMC) and 1,4-bis (4-aminobenzoyoloxymethyl) cyclohexane (BAZMC), with a dianhydride 3,3', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), respectively. The resulting polyimides showed exceptional thermal properties with glass transition temperatures of 212 and 178 degrees C, and temperature for 5% weight loss of 461 and 421 degrees C in nitrogen, respectively. Meanwhile, thermogravimetry coupled to Fourier transform infrared spectrometry (TG/FT-IR) was used to study the thermal degradation behavior of the resulting polyimides. It was found that the thermal decomposition occurred by a double-stage process; the major evolved products from the nonoxidative thermal degradation were hydrocarbon, CO, CO2, H2O, and aromatic compounds.