The development of sustainable polyimides (PIs) from abundant renewable biogenic feedstocks has been limited by the bio-based content and the lack of mechanical and thermal properties. This study synthesized a series of daidzein-based PIs with a high bio-based content of up to 53%, which was significantly higher than the reported bio-based content (approximately 40%). The mechanical and thermal stability of the obtained polymer is comparable with that of commercial PIs, with the tensile strength of 148.6 MPa and the glass transition temperature (T g ) of 318.2 Β°C. Additionally, the daidzein-based PIs showed excellent fluorescence characteristics with a maximum fluorescence efficiency of 45.18 ns and an absolute fluorescence quantum yield of 14.1%. Such a performance combination has not been reported in bio-based PIs, even petrochemical PIs. Interestingly, the integration of experiments and density functional theoretical calculations revealed an effective intermolecular and intramolecular conjugation and the inhibition effect of intramolecular charge transfer by "enone and ether bonds" in daidzein-derived PIs. This work provides a possible route for the design and synthesis of multifunctional PIs with high bio-based content.
In order to meet the needs of rocket innovation practice learning that takes into account both low-cost and high-level engineering practical training, the design of flight mission of the model guided rocket is proposed and the technical index analysis is carried out in the present study. The design of the rocket thrust system is completed using two paralleled YSR-32 motor, whose total engine impulse is 296.14π΅ β π; The mathematical model of the integrated aerodynamic / ballistic design optimization problem of rocket is constructed, adopting the aerodynamic configuration of side strip wing and x-shaped tail rudder and using Boost-Glide trajectory. Take the farthest range as the objective function, the influence of 8 variables on it is analyzed; By using Astrolab, a rapid overall design optimization platform of the rocket, the integrated simulation process of the aerodynamic / ballistic performance of the rocket is established; The maximum range of the optimization results is 1.29 ππ, the takeoff mass is 2.8 ππ, the speed at the shutdown point is 93.6 π/π, and the maximum flight time is 28.4s; The single use cost of the guided rocket is not exceed 1300 yuan.
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