Study On Liquid Oxygen Compatibility Of Polyarylene Ether Containing Phyrazinone Structure And Its Composite Materials

At present,the payload of launch vehicle technology is low and cannot meet the needs of space missions.Under the current situation that the power of rocket engines cannot be greatly increased,the weight reduction of space vehicles is imminent.The thruster system accounts for60%-70%of the total weight of the launch vehicle.The liquid oxygen storage tank is an essential storage tank for the propellant system.It has strong versatility,and its structure is of great significance for weight reduction.Carbon fiber reinforced resin matrix composites have become the first choice for rocket weight reduction due to their high specific strength and specific modulus.Aiming at the two fatal problems of low-temperature permeation failure and liquid oxygen incompatibility in the application of composite liquid oxygen storage tanks,based on the intrinsic high toughness and flame-retardant polyarylene ether thermoplastic resin,the development of aerospace liquid oxygen storage Resin-based composite materials for boxes.The main research contents are as follows:1.Designed and prepared 9 types of poly（phthalazinone ether）thermoplastic resins,and systematically characterized their structure and basic properties.The liquid oxygen compatibility of the polymer was judged through the liquid oxygen shock sensitivity test.The test results showed that PPBEK,PPBESK have achieved liquid oxygen compatibility.The comparison shows that the favorable order of monomers for polymer liquid oxygen compatibility is:BP>DHPZ>AF;DFBN>DSC>DFK>DFKK.After PPBEK and PPBESK were soaked in liquid oxygen for 20 days,PPBEK is still liquid oxygen compatibility.The thermal decomposition process of the polymer was tested and analyzed by TGA-FTIR-GCMS.The results showed that the polymer produced a negative impact on the polymer during the thermal decomposition process.The combustible gases CO and H₂,which have a greater influence on the compatibility of liquid oxygen.In addition,the higher the energy absorbed by the elastic strain energy of the polymer,the more beneficial the liquid oxygen compatibility of the polymer.2.Using liquid oxygen compatible polymer PPBEK、PPBESK as the matrix,carbon fiber composite materials are prepared by hot pressing,in which CF-PPBEK realizes the liquid oxygen compatibility of composite material level.The low-temperature leakage resistance of the CF-PPBEK composite material was studied through the low-temperature-room temperature hot and cold cycle test.The composite material appeared microcracks after 3cycles.The test results of the mechanical properties of composite materials show that the flexural strengths of CF-PPBEK and CF-PPBESK at room temperature are 1380MPa and1432MPa,respectively;the flexural strengths under low temperature environment are2203MPa and 2187MPa,respectively.SEM test results show that the composite material exhibits brittle fracture at low temperature,which is different from the ductile fracture exhibited by composite material at room temperature.The composite material was tested by DMA,and the results showed that the glass transition temperatures of CF-PPBEK and CF-PPBESK were 223^oC and 255^oC,respectively;the storage modulus were 74000MPa and89000MPa,respectively;the loss factor was 0.76 and 0.6,respectively.Based on free radical theory and hotspot theory,the physical and chemical interaction model between polymer and liquid oxygen is established to reveal the liquid oxygen compatibility of poly（phthalazinone ether）resin under the action of force-heat-chemical multi-energy field mechanism.Research and establish the influence law and correlation between polymer liquid oxygen compatibility,low temperature leakage and composite material liquid oxygen compatibility and low temperature leakage.