Study On Bismaleimide Modified Cyanate Ester-polysulfone Resin Foamed Structural Adhesive

Because of the urgent need for the technology in the field of aerospace which is preparing honeycomb structure components with various materials,many kinds of foaming structural adhesives have been developed by the Chinese scientists in recent years,however compared with the foreign advanced technology,there are still some gaps in the types and comprehensive properties of home-made adhesive.To this end,the domestic scientific research departments have been making more efforts to develop new types of foaming structural adhesive.Nowadays,a series of new materials with excellent performances,and novel types of foaming structural adhesive have been developed.The new type of foaming structural adhesive not only has the nice performance which the common one has,but also possesses other properties,such as good high and low temperature resistance,low dielectric constant,dielectric loss and density and high strength,etc.In this study,the ternary materials of cyanate resin,bismaleimide resin and polysulfone resin are used as the matrix resin,and the core-shell particles are employed for the toughening modification.Then the catalyst,filler,foaming agent and other composites are added,after the process of mixing and pressing film forming,etc,the foaming structural adhesive is prepared successfully.And its comprehensive performances are also studied.Firstly,the cyanate-polysulfone resin semi-solid flexible prepolymer is prepared by blending the polysulfone resin with the cyanatewith a special method,then the performances of the blend system of bismaleimide and cyanate-polysulfone resin prepolymer are investigated.Secondly,the bismaleimide modified cyanate-polysulfone resin foaming structural adhesive(bismaleimide-cyanate-polysulfone resin foaming structural adhesive)is prepared,and through the formulation design and performance tests,the effects of different proportions on the properties of the final foaming structural adhesives are studied.Finally,the comprehensive properties of core-shell particles modified bismaleimide-cyanate-polysulfone resin foaming structural adhesive are investigated,and a kind of bismaleimide-cyanate-polysulfone resin foaming structural adhesive whose performances can meet the requirement of international general standard is prepared.From the study on the preparation of bismaleimide modified cyanate-polysulfone resin adhesive film(non-foaming adhesive)by mixing bismaleimide and polysulfone resin prepolymer,it is found that the toughness of the adhesive film decreases with the increase of bismaleimide resin content,but the heat resistance of the colloid is improving.After a prolonged heat aging,the weight loss declines obviously with the increase of bismaleimide content.In addition,the results of normal temperature and 230℃lap shear test indicates that the lap shear strength at 230℃ of this adhesive film is higher than that at normal temperature,which is due to the presence of bismaleimide resin makes the toughness of the adhesive poor at room temperature,and resulting in a low lap shear strength at normal temperature;and at 230℃ its toughness increases,so the shear strength at 230℃is much higher than that at normal temperature.From the study on the preparation,it is also found that there is nearly no differences in the tube shear strength at normal temperature and at 230 ℃,and it is higher at normal temperature that at 230℃.This is due to the less effect of toughness on the tube shear strength.The core-shell particle modified foaming structural adhesive possesses good flexibility and initial adhesion,and the tube shear strength is significantly higher than that of the unmodified foaming structural adhesive after curing.