Preparation And Microwave Absorption Performance Of Polyimide/Triglycidyl Isocyanurate Epoxy Composite

With the development of the 5G era,electromagnetic equipment is rapidly evolving and radar detection technology is constantly improving.As a result,the survival ability of various weapons and equipment in warfare is facing severe challenges,making stealth technology and stealth materials a research hotspot in many countries for gaining an edge in modern warfare.The research and development of radar-absorbing materials,an important component of stealth technology,holds great strategic significance.Additionally,to effectively play their role,the absorptive materials need to be combined with a resin matrix,which plays an important role in achieving properties such as light weight,corrosion resistance,complex environment resistance,and improved mechanical performance.Therefore,it is urgent to launch research and development of new wave-absorbing matrices based on good absorbing performance.Triglycidyl isocyanurate(TGIC)is an epoxy resin with certain corrosion resistance,chemical resistance,and mechanical properties.Its backbone structure contains a large number of active groups,making it an ideal candidate for modification into a matrix material with effective absorbing performance.In this study,polyimide(PI)with different conjugated structures and polyperylene imide(PPI)with different groups were chemically grafted onto TGIC,resulting in the production of an absorbing matrix with excellent comprehensive properties that can be controlled by adjusting the content of polymer.Firstly,the PI/TGIC structure was designed by crosslinking and curing imide polymers with different conjugate structures(benzene,naphthalene,and perylene)onto the TGIC matrix.The i MPact of the conjugate structure on the dielectric constant was investigated,and the results showed that the loss ability of the PI/TGIC matrix for electromagnetic waves increases with an increase in the number of π-π conjugated structures.The PPI-D/TGIC matrix with perylimide group demonstrated the best absorbing performance,with a minimum reflection loss of-15.6d B(f=16.4 GHz,d=2.5 mm).Next,different groups(diethylamine,ethylenediamine,butylenediamine,and urea)were introduced into the PPI through amide polymerization,cross-linking,and curing with TGIC to prepare PPI/TGIC epoxy composites.The influence of the introduced groups on the dielectric constant and absorbing performance of the PPI/TGIC composites was investigated,and the results showed that the PPI-U/TGIC(with urea group)composite demonstrated the strongest loss ability for electromagnetic waves.This is attributed to the interaction of the π-π conjugate structure from perylene imide and the polar group of urea carbonyl group.Finally,a series of PPI-U/TGIC epoxy composites with different doping amounts of PPIU(mass ratios of 0.5:4,1:4,1.5:4,2:4,2.5:4,and 3:4)were prepared,and the influence of the doping amount on the dielectric constant and absorption performance was studied.The best absorbing performance for composites was obtained with a doping mass ratio of 1:4(PPI-U:TGIC,PPI-U/TGIC-0.5).If the amount of doping is too high,more complex loss mechanisms will be stacked repeatedly in space,resulting in ineffective electromagnetic wave loss and weakened absorbing performance.The prepared PPI-U/TGIC-0.5 epoxy composite demonstrated a minimum reflection loss of-18.6 d B at f=16.5 GHz,excellent complexities with matching thicknesses between 2 mm to 6 mm,and an effective absorption bandwidth of about3 GHz.