Study On Processing Modification And Toughening Modification Of Bismaleimide

4,4'-diphenylmethane-type bismaleimide(BDM),as one of the most commonly used aerospace resin matrix,has the advantages of excellent mechanical strength and high heat resistance,but the traditional 4,4'-diphenyl Methane-type bismaleimide has poor toughness and poor processability due to poor curing.Aliphatic bismaleimide resin(HMDA-BMI)is a type of bismaleimide resin that contains aliphatic chains on the main chain and does not have a polar group benzene ring.Compared with traditional bismaleimide,it has Low viscosity,excellent processability.However,because there is only an imide ring in the molecular chain and the lack of a highly polar group,the resin system has poor toughness and poor heat resistance.Therefore,in this experiment,BDM and HMDA-BMI were used in a ratio of 1:1,and diallyl bisphenol A(DP)was added as a copolymer modifier as a matrix resin system(BDM/HMDA-BMI/DP).Titanium nitrile rubber(CTBN)and poly(aryl ether sulfone ketone)(PPESK)as toughening modifiers are used to toughen the BDM/HMDA-BMI/DP blend system,in order not to reduce the bismaleimide The amine resin system improves heat resistance and improves its toughness and processability.Viscosity-temperature curve of polymer system were analyzed by rheometer;curing process of modified blend system was determined by differential scanning calorimeter(DSC)analysis;thermogravimetric analyzer(TG)and dynamic Thermomechanical analyzer(DMA)analyzes the heat resistance and glass transition temperature of the modified blend system;uses infrared spectroscopy(FIR)to analyze the degree of curing reaction;uses a universal electronic testing machine to test the normal temperature and high temperature shear strength and temperature of the cured product Peel strength of honeycomb rollers;the cross-section morphology of the cured product after brittle fracture was analyzed using an electron scanning microscope(SEM).The test results show that when the PPESK content is 15 phr,the comprehensive performance of the PPESK/CTBN/BDM/HMDA-BMI/DP modified blend system is the best.At this time,the viscosity-temperature curve shows that the system reaches a minimum viscosity of 38 Pa·s at 129°C;DSC analysis results show that the best curing process of the system is 160°C×2 h+180°C×2 h+200°C×2 h+230°C×4 h The weight loss curve shows that the temperature at 5%weight loss of the system is as high as 424°C,and the residual carbon ratio reaches 41%at 500°C;the DMA analysis results show that the glass transition temperature of the system reaches 303°C,and the storage modulus of the blend system is below 293°C No obvious decrease,showing good heat resistance;infrared spectrum shows that the system is completely cured;peel strength of honeycomb roller at room temperature is 12.67 N/mm;shear strength at room temperature is 15.74 MPa,232°C and 316°C high temperature shear strength It was 17.24 MPa and 6.79 MPa;the impact strength reached 14.87 k J/m~2;the cross-sectional scan showed ductile fracture.