Study On The Modification And Application Of Bismaleimide Resin

The emergence of carbon fiber reinforced resin matrix composites has solved the problem of brittleness of carbon fiber alone.Resin matrix,especially high performance resin matrix,as an important component of composite materials,has a crucial influence on the performance of composite materials.Bismaleimide(BMI)resin is widely used as resin matrix for high performance composites because of its simple processing and molding and excellent heat resistance.However,the problem of brittleness and poor toughness of the cured material before the modification of BMI resin has limited its application to some extent.In this paper,thermoplastic modification of BMI resin was carried out to investigate the effect of modification on resin properties,and the modified resin was used to prepare fiber composites,and the comprehensive performance of the composites was studied,and the specific findings are as follows:In this paper,we firstly designed the molecules and used 4,4’-dichlorodiphenyl sulfone to condense with seven diphenylphenols and modified them with capping,and finally prepared eighteen allyl sulfone ether resins,and determined the corresponding structures by infrared characterization,which showed that the shorter the molecular chains of the reactants,the easier the reaction was,and the easier the capping modification was.Among the seven binary phenol monomers,the allyl sulfone ether resin synthesized with bisphenol A as the reaction monomer has the best thermal properties,with glass transition temperatures of 171.66～201.18°C and thermal decomposition temperatures of 373.78～465.26°C.It is more compatible with the BMI system,and the maximum solubility ratio reaches 50%,even for the BPASA2221 resin with the longest molecular chain,the solubility Even for BPASA2221 resin,which has the longest molecular chain,the dissolved amount reaches 20%,which can meet the compatibility requirements for use as a toughening agent.BPASA21 was added to the BMI resin system as a modifier at 0,5%,10%,15% and 20%to study the relationship between the performance of the BMI resin system and the addition of allyl sulfone ether resin;five different molecular chain lengths of bisphenol A type allyl sulfone ether resin were used as toughening agents,and the toughening agent was added at 10% to study the effect of allyl sulfone ether resin on the performance of the BMI resin system.The effect of allyl sulfone ether resin on the performance of BMI resin system was studied.It was found that the best overall performance of the modified BMI resin was achieved when the toughening agent used was BPASA21 and the addition amount was 10%.The modified BMI resin has shorter gelation time,lower apparent activation energy and higher reactivity;the modified resin has better heat resistance and the thermal decomposition temperature of the resin can reach 402.21℃;the dielectric loss is 0.67～1.09%,the relative dielectric constant is2.92～2.97,and the dielectric performance is significantly improved;the water absorption is0.76%,which is more adaptable to humid environment;the tensile strength of the resin is The tensile strength of the resin is 79.58 MPa and the impact strength is 11.6 KJ/m2,which is 27.5%higher than that of the unmodified resin,and the elongation at break of the resin is 3.80%,which is 2.7 times of the elongation at break of the high-strength carbon fiber,and can fully meet the requirements for use as the resin matrix of carbon fiber composites.Two carbon fiber cloth composites and two glass fiber composites were prepared by using BPASA21 as toughening agent with 10% modified BMI resin and pure BMI resin as composite matrix resin.The modified resin carbon fiber composites had higher tensile and flexural strengths than the pure resin carbon fiber composites,and the tensile and flexural strengths of the modified resin carbon fiber composites were 356.6 MPa and 297.5 MPa,respectively,which indicated that the modified resin could play a good interlayer toughening effect.The dielectric loss of modified resin glass fiber composites was 0.73-0.96%,and the relative dielectric constant was 3.63-3.68,which has improved the dielectric properties compared with the pure resin glass fiber composites.In addition,the water absorption rate of modified resin carbon fiber composite is only 0.53%,which is 33.75% lower than that of pure resin carbon fiber composite,with better water resistance and more adaptable to wet environment.