Study On Preparation And Properties Of Polyimide Fiber And/Quartz Fiber Hybrid Reinforced Cyanate Ester Matrix Composites

The wave-transmitting composite material can ensure the efficient transmission of electromagnetic signals and protect the antenna from environmental erosion.With the development of science and technology,information transmission has become more frequent,and wave-transmitting composite materials have received more and more attention.High-strength and high-modulus polyimide(PI)fiber has excellent dielectric properties,high temperature resistance,ultra-violet resistance,etc.,and can adapt to the harsh environment of high temperature,high humidity,and high radiation.It has great application prospects in the field of wave-transparent composites,but its insufficient compression performance limits its application;Quartz fiber has excellent comprehensive performance and has been widely used in radome.It is expected to reduce the density of the quartz composite material,increase its modulus,and improve the compression performance of the PI fiber composite material by hybridizing PI fiber and quartz fiber.The PI/quartz fiber hybrid composite material has a more balanced performance,which greatly expands its application range.The research contents of this topic are as follows:The PI fiber fabric/quartz fiber fabric hybrid composites were prepared by hot molding process,and its mechanical properties and dielectric properties were analyzed.Through the hybridization of the two fibers,the density of the hybrid composite material is lower than that of the quartz composite material,achieving the effect of weight reduction,and its modulus is improved.Compared with the pure PI composite material,the compressive strength of the hybrid composite material is increased by more than 84.39%.The stacking sequence has a great influence on the performance of the hybrid composites.When the quartz fiber is on the compression side,the flexural strength is as high as 622.62MPa.The flexural modulus of the hybrid composites is the highest,reaching 35.41GPa,when the PI fiber is at the exterior.And the quartz fiber sandwiched PI fiber composites have the best compression performance,with a compressive strength of 304.61 MPa and a compressive modulus of 27.57 GPa.The dielectric constant and dielectric loss of the hybrid composites decrease with the increase of PI fiber content;the wave transmission rate of all hybrid composites is maintained above 94%.The effect of the catalyst on the curing characteristics of cyanate ester was studied,and the cyanate ester was toughened and modified with epoxy resin.After the cyanate ester is introduced into the Dibutyltin dilaurate+nonylphenol mixed catalyst,the reaction activation energy is significantly reduced,and the curing characteristic temperature is lowered by more than 100?.Epoxy resin has obvious toughening effect on cyanate ester,and the impact strength of modified resin reaches 13.19KJ/m2.Epoxy modified cyanate ester resin has excellent dielectric properties,moisture and heat resistance.Water absorption rate is less than 1.8%.The temperature of 5%thermal loss is above 350?.The dielectric constant is 2.85.According to the viscosity-temperature characteristics of the modified cyanate ester resin and the phenomenological kinetic equation,the composite molding process is optimized.After the improvement,the composites have flexural strength of 441.66MPa and Inter-laminar shear strength of 37.62MPa,which is an increase of 9.06%and 24.08%compared with the unimproved case.