The Effect Of Stoichiometric Ratio Of Epoxy And Amine On The Mechanical Property Of Epoxy/curing Agents Fabrication

As an important composite with high specific strength,high specificmodulus,good dimensional stability, good precessability andelectromagnetic shielding property,CF/epoxy composites was applied in avariety of industria field such as aerospace industry,transportationindustry,wind power and oil industry,sports equipments and so on.Someresearch declared the compression property of the carbon fibercomposites was dependent upon the modulus of the epoxy matrix.But theinfluence of the matrix modulus on composites has not been investigatedsystematically yet.To investigate the effect of epoxy matrix modulus on the mechanicalproperty of composites,we use3different kinds of aromatic amine curingagents DETDA、DDS and DDM with different quantity of them.The different molecular structure and quantity of the curing agents will resultin modulus change of the epoxy resin.In this paper,the results showed thatthe tensile strength,tensile modulus and glass transition temperature ofDDS curing system was the best.The mechanical properties of DDMcuring system was better than DETDA system with same amine/epoxyequivalent ratio r.In the4formulas r=0.5,r=0.75,r=1,r=1.25of all3curingsystems,with the increasing of curing agents,the tensile modulus and thestorage modulus of DMA analysis decreased.The tensile strength of the3curing system increase with the increasing of r at first then decreased.Thedecreasing point of DDM system appears earliest in the3systems. Withthe increasing of r,the glass transition temperature of all3curing systemsincrease first then decrease. In all formulas of the3curing systems,r=0.75of the DDS curing system has the highest glass transition temperature，which was227.55℃. Adding0.5%amine modified carbon nanotubes tothe resin whose tensile strength is low can enhance tensile strength.On thecontrary,0.5%amine modified carbon nanotubes causes tensile strengthdecreas in high tensile strength resin system.And using amine modifiedcarbon nanotubes can enhance the resin modulus.Especially as the resinmodulus is low,the modulus enhancement is to a greater extent.In all the3curing composites with different curing agents,theinterlaminar shear strength,storage modulus of DMA analysis of theformula with higher modulus in the matrix resin was better.The glass transition temperature of the composites was lower than the pure resinwith the same quantity of curing agents. The glass transition temperatureof the composites were higher when the the glass transition temperatureof the matrix was better.The The glass transition temperature of thecomposites ranked as followed:DDS system>DDM system>DETDAsystem.The interlaminar shear strength of DDS system and DDM systemwere better than DETDA system. In the DETDA cured composites with0.5%amine modified carbon nanotubes formula, the storage modulus ofthe two composites formulas with carbon nanotubes were significantlyincreased.