Synthesis And Modification Of BMI Resin

BMI/DBA resin was synthesized through reasonable experimental plan and process.And then,different kinds of BMI composite materials were prepared by the addition of different modified materials.Finally,micro-controlled electronic universal testing machine,impact testing machine,digital viscometer,infrared absorption spectrum(FT-IR),scanning electron microscopy(SEM)and thermal gravimetric analysis(TGA)were used to characterize the properties of the products.Experimental results show that the preferable mechanical properties of BMI/DBA resin can be achieved with a monomer mass ratio of 100:75,at the temperature of 140?for 20min and relatively rapid mixing(multifunction governor output voltage is 60V).In this case,the tensile strength,impact strength,flexural strength and modulus of the resin are 27.5MPa,11.5KJ/m²,141MPa and 4.0GPa,respectively.The more appropriate addition amount of HGCR-300,HGCR-350 and HGCR-400 model MWCNTs is 1wt%,0.25wt%and 0.75wt%,respectively,in BMI/DBA/MWCNTs nanocomposites with a modified reinforcing effect.The suitable addition amount of analytical grade nano-silica is0.5wt%in BMI/DBA/Si O₂ nanocomposites with the best enhancement effect,however,the whole mechanical properties are reduced when the white carbon black is added.The preferred curing time is 3h,more suitable curing pressure is 10MPa of BMI/DBA/CF composites by compression molding.Thermal analysis shows the temperature of 5%thermal weight loss of BMI/DBA cured resin system containing small amounts of nanoparticles or not reach up to 420?.The longer the length of the carbon tubes,its heat resistance is better.Viscosity test results show that the viscosity of the resin is lower when the prepolymerization time is 20min and the pre-polymerization temperature is between140-150?which is considered to be the preferred processing window.The low viscosity of the resin make it easy to operate.Scanning electron microscopy test results show that impact fracture without holes,holes and other defects of BMI/DBA resin belongs to brittle fracture.The interface combined effect of MWCNTs and BMI/DBA matrix resin is relatively well.White carbon black which agglomerate into spherical particles was dispersed in the matrix resins and reduced the mechanical properties of the resin itself due to the combined effect of such large spherical particles and the resin was not good.Carbon fibers which were treated by epoxy arranged more compact and the arranged direction more consistent.So it is difficulty to remove the gas in the compression molding process of preparing the composite materials,and then there will be holes and other defects in the products.Finally,lead to its mechanical properties was reduced compared to BMI/DBA/CF composites with the CF which was untreated by epoxy.In summary,three composites BMI/DBA/MWCNTs,BMI/DBA/Si O₂ and BMI/DBA/CF were prepared in this study,compared with BMI/DBA resins,the mechanical properties of composite materials have been enhanced.