To improve the processability of thermosetting polyimide resin,a modified polyimide resin with excellent thermal properties was synthesized through copolymerization.The reaction mechanism,curing kinetics,and molding process of the resin were studied.The composition changes of the resin during heat treatment were analyzed by Fourier infrared spectroscopy(FT-IR)and 13C nuclear magnetic resonance(13C-NMR)spectrum,and the optimum drying temperature of the resin powder was determined to be 250℃.The curing kinetics equation was established,and the changing trend of curing degree with time under different temperature conditions was obtained,the curing degree reached 100%after 100 min at 340℃.The processing window was wide,the lowest melt viscosity of the resin was 52.1 Pa∙s,and the gel transformation occurred at 28 min under the temperature of 310℃,allowing sufficient operating time for exhaust processes.The molding process of PI resin was determined based on comprehensive characterization,and the copolymerized polyimide resin obtained exhibited good processability and thermal properties,with a glass transition temperature of 370℃.
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