Preparation And Properties Of Thermosetting-thermoplastic Composite Polyimide Aeroge

With the development of science and technology,materials with excellent performance and light weight are widely used in the aerospace field.Among them,polyimide aerogels have attracted widespread attention because of their low density,high porosity,strong adsorption and good heat insulation.Traditional polyimide aerogels are mostly composed of thermoplastic polyimide,although this aerogel has excellent flexibility,but the heat resistance is not ideal,the glass transition temperature is mostly between 350-400 °C.At the same time,it has a weak compressive strength.Therefore,improving the comprehensive performance of aerogels has become the focus of researchers.In this paper,a new type of composite polyimide aerogel preparation concept is proposed.By adjusting the molecular structure to molar mass ratio,ten thermosetting polyamide aqueous solutions containing phenylacetylenyl groups were obtained as impregnating solutions after a series of synthesis.This solution is well stable and has ideal thermal properties.The maximum Tg measured by DMA is 452°C,and the temperature of Td5% under air atmosphere is up to 623°C.The thermosetting impregnating solution was compounded with the thermoplastic aerogel skeleton at room temperature by in-situ impregnation method,and the intermolecular force-hydrogen bond and van der Waals force were used to complete the self-assembly of the thermoplastic-thermosetting interface,and a new type of composite polyimide aerogel was obtained.The test results show that the stable molecular force between the bilayers promotes the synergistic effect of the bilayers: that is,when subjected to external impact,the two achieve the inward diffusion of the common weakening force,thereby improving the mechanical properties,and the maximum compression modulus is 5.96MPa(at room temperature).At the same time,the crosslinked network structure gives the composite aerogel good thermal properties,the maximum glass transition temperature can reach 458 °C,and the maximum thermal weight loss temperature is 648 °C.It has certain guiding significance for the preparation of composite polyimide aerogels with good comprehensive performance.