Study On The Preparation Of Heat-resistant Polyimide Honeycomb Core

With the improving of aircraft's speed,the request for material's mechanical properties,heat-resistant property and light weight is much more urgent.Honeycomb core material is a kind of light weight,high strength and high stiffness material,which could be manufactured to structural member and functional parts like insulation pad or noise reduction.However,aluminum honeycomb and aramid fiber honeycomb materials could not be used at 200?,while the density of mental honeycomb is too high.In order to meet the application requirement,it is necessary to make a breakthrough for the producing technique of 300?-resistant honeycomb material.This passage mainly studies the preparation technique of heat-resistant polyimide FRP honeycomb sandwich structure.The paper first studies the preprocessing technology of glass fabric.By experiments,the synthesis condition of BTDA-ODA resin is to reacting at 0?for 5 hours,when the ration of anhydride and di-amine is 1.02.When the content of BTDA-ODA resin is between 4.0wt%to7.0wt%,the resin on the glass fabric is neat,and there is not node resin penetration phenomenon.The composite has been prepared by BTDA-ODA resin and SW110 glass fabric.The bending strength of BTDA-ODA/SW110 composite at 300?is 184MPa,which has a retention rate of 50.4%.The shear strength of BTDA-ODA/SW110 composite at 300?is15.1MPa,which has a retention rate of 43.3%.The result shows that BTDA-ODA resin has strong bonding strength with glass fiber.The preparation of node resin has been studied later.With an addition of 10wt%TPPI resin to original resin matrix,the shear strength of resin system becomes 6.58MPa at 300?,which is 11.34%higher than original resin.The impact strength of resin system increases from 23.18MPa to 27.5MPa.With 2wt%nano-inorganic additive added into resin system,the shear strength of the resin system becomes 8.17MPa,which is 24.2%higher than original resin.The mechanical property of node resin at high temperature has been improved.The new node resin is called XTJ-300.The initial temperature of XTJ-300 node resin is 195.8?,the peak temperature is 254.1?and the final temperature is 305.4?,tested by dynamic DSC.The rate equation of curing reaction is d?/dt=2.57×10⁶exp??13663.7/T??1???^0.9507.Considering the DSC curve and viscosity-temperature curve of XTJ-300 node resin,and the study of the influence of curing pressure and curing time to the mechanical properties of honeycomb core,its curing method is to be RT?130?¹50?/30min,curing pressure is0.6⁰.8MPa?250?²70?/2h.The paper studies the curing and shaped technology of honeycomb core and its properties characterization finally.It is be found that the unit weight of honeycomb core structure increase with the increasing of the proportion of impregnating resin.When the heating rate of curing is fast,the amination rate of impregnating resin is too fast,which means the release rate of micromolecule is too fast,thus a serious resin bubbling phenomenon shows up.When the heating rate of curing is reduced to 0.5?/min and the proportion o impregnating resin is 0.94,the honeycomb core has a neat structure and good mechanical properties.The passage studys the influence of curing temperature and time of impregnating resin to mechanical properties of honeycomb core.The curing temperature of KH308 resin is300³20?,and the curing time is 3⁴h.At 300?,the flat compression strength of honeycomb core is 2.13MPa,the L direction shear strength is 1.17MPa and the W direction shear strength is 0.62MPa.The mechanical properties of the honeycomb core structure prepared in the paper are better than the domestic similar materials and closed to the materials abroad,which is the foundation of engineering application in the future.