Molecular Simulation And Properties Of Carbon Fiber Reinforced Thermoplastic Polyimide Composites

Since the appearance of advanced resin-based composite materials in the people’s field of vision in the 1960 s,it has been the object of intensive research by researchers from all walks of life and the excellent engineering performance and unparalleled structural characteristics of this new material have made it widely researched and developed after entering the 21 st century.However,with the continuous deepening of the industrialization process nowadays,people’s demands for material properties have become wider and wider.Not only are they required to have superior mechanical properties,but in recent years,they have also proposed green and lightweight targets.In this paper,carbon fiber(CF)is used as the reinforcement,and thermoplastic polyimide(TPI)is used as the matrix.The purpose is to prepare carbon fiber reinforced thermoplastic polyimide composite(CF/TPI)with excellent performance through process optimization and composite interface design.For the design of the preparation process,this paper uses Materials Studio~? V8.0(MS)software to first predict the properties of TPI resin at high temperature,and uses the software to perform molecular dynamics(MD)calculations on the resin simulation system.According to the characteristics of the polymer,the temperature-specific volume is plotted under the simulated state.Image,predict the resin glass transition temperature(T_g)interval,and conduct a simulated shear test at discontinuous temperature at the same time,predict the resin viscosity change trend at high temperature,and predict the best temperature processing interval of TPI is 550～700 K.Through DSC、infrared and other tests combined with simulation results,it was determined that TPI had a T_g of 277 °C,a Tm of 375 °C,a Tm of 554 °C,and fluidity at 380 °C.Comprehensive analysis to determine the preparation route of CF/TPI: the use of compression molding process,three-stage heating and pressurization,the pressure setting of 0.5 Mpa temperature is 300 ℃,380 ℃ and 300 ℃,TPI mass fraction is fixed at 50%.In the part of interface optimization design,this paper uses dopamine(DA)self-polymerization to form polydopamine(PDA)layer to modify CF,and at the same time,the fiber is treated with silver ammonia solution to deposit silver nanoparticles in situ to prepare Ag-PDA-CF modified fiber.Prior to this,first of all,the molecular dynamics simulation calculation of polydopamine modified carbon fiber(PDA-CF)system,and the reaction potential was analyzed through the obtained data.The results showed that the potential energy of the two-phase interaction inside the PDA-CF system was-737.89 kal/mol,there is mutual adsorption between the two phases.The preparation and testing of modified fibers were conducted under the guidance of simulation results.The test results showed that the roughness of Ag-PDA-CF was improved by 66.5% compared with unmodified fibers,and the average monofilament tensile strength was 3.20 GPa,and the strength did not decrease compared with the original.In this paper,material preparation and testing were carried out on the basis of the above.The average tensile strength of modified fiber reinforced TPI composite is 345.28 Mpa,which is 4.37% higher than that of None-CF/TPI;the average Ag-PDA-CF/TPI sample The ILSS value is 41 Mpa,which is nearly 40% stronger than the None-CF/TPI specimen.