The Research Of Hyperbranched Epoxy Bismaleimide Toughened And Enhanced Benzoxazine Resin

Benzoxazine resins have excellent heat resistance,chemical resistance,flame resistance,electrical insulation,and no small molecule byproducts release and can occur of autocatalytic during the curing process,without the need for acid or alkali catalyst,what's more,the volume shrinkage rate is almost zero after curing.However,the curing temperatures up to 200 ?which is not conducive to industrial production,it also has poor toughness,low cross-linking density and,the heat resistance also not up to the standard of high performance resin.Based on this,this article use hyperbranched epoxy resin and bismaleimide resin to modify benzoxazine resins in order to achieve the purpose of toughening.By an A₂+B₃ polycondensation reaction,employing 1,2,7,8-diepoxyoctane?DEO?as the A2 monomer,1,1,1-tris?hydroxymethy 1?ethane?THME?as the B3 monomer and tetra-n-butylammonium chloride?Bu4NCl?as the catalyst,through one-step to synthesize a novel hyperbranched aliphatic epoxy resin?AHEP?.IR and 1H NMR spectra proved that the structure of AHEP is right.Dynamic viscosity analysis tests showed AHEP has a lower viscosity;molecular weight is 4150 and the epoxy value is 0.25 mol/100 g.The different components of DDM/AHEP blend cured is prepared by melt blending,DSC results showed that AHEP can significantly reduce the initial curing temperature of DDM;when the addition amount of AHEP is 5%,compared to the pure DDM,the flexural modulus of DDM/AHEP cured increased 11.5%,impact strength increased 167%,although its heat resistance is lower than the pure DDM,still have good heat resistance and the Tg is 204 ?.SEM analysis showed that DDM and AHEP have no phase separation,they have excellent compatibility.The different components of DDM/AHEP/BMI blend cured is prepared by melt blending and characterized by a series of performance tests.DSC results showed that DDM/BMI/AHEP ternary blends only has one apparent curing reaction exothermic peak,this mean the three resin has excellent compatibility,and in the curing process,the reaction occurred in the same temperature regions,we called concerted reaction.TGA test showed that,with the BMI added,the ternary systems' heat resistance and char yield at 800 ? have dramatically increased,achieve the purpose of remedy DDM/AHEP blends thermal losses in same degree.Mechanical tests showed that BMI' s added have different effects on the flexural properties and impact strength of DDM/BMI/AHEP blends,but generally still maintained a good mechanical properties and when the content of AHEP is 5%,BMI is 10%,the comprehensive performance is the best.