Amino-Functionalized Carbon Nanotube Reinforced Epoxy And Carbon Fiber Composites

Carbon fiber reinforced epoxy matrix composites have been widely used in aerospace, automotive, sports equipment and other fields due to their high strength, high modulus and low density. However, as the weakness of toughness, transverse mechanical properties and interface between epoxy and carbon fiber, the application of composites has been influenced. Among the inorganic nanoparticles, carbon nanotubes have been used as reinforcement dispersed into epoxy matrix or carbon fiber reinforced epoxy composites due to its excellent mechanical properties and chemical stability. Carbon nanotubes can improve the modulus and toughness of epoxy matrix. In other hand, it can improve the interface bonding between carbon fiber and matrix. However, because of the poor dispersion in the epoxy matrix, carbon nanotubes hardly played an important role of the enhancement. However, the various amino-functionalized CNTs will produce different effect in the same epoxy matrix due to the diversity in reactivity, compatibility and dispersion stability.In this paper, the amino-functionalized multi-walled carbon nanotubes (MWCNTs-NH2) were prepared through surface grafting ethylenediamine and diethyltoluenediamine (designated as MWCNTs-EDA and MWCNTs-DETDA), and dispersed into DGEAC/DETDA epoxy resin matrix. The effect of different amino functionalized carbon nanotubes on curing behavior and mechanical properties of carbon fiber/epoxy composites has been researched. However, suitable MWCNTs-NH2/epoxy matrix has been prepared for the manufacture of MWCNTs-DETDA/T700 solvent-method prepreg. In addition, the effect of amino-functionalized carbon nanotubes on curing kinetics for different epoxy matrix has been investigated. And the mechanical properties of MWCNTs-NH2/epoxy nanocomposites have been improve by the pre-curing treatment.In this work, two different amino-functionalized multi-walled carbon nanotubes were prepared through surface grafting. The characterization results show that the extent of functionalization on the surface of MWCNTs-EDA is higher than that of MWCNTs-DETDA.Compared to MWCNTs-EDA, MWCNTs-DETDA showed a better dispersion state and good compatibility in the DGEAC/DETDA epoxy matrix. The curing kinetics results shows that the two MWCNTs-NH2 can participate in the curing reaction and accelerate the curing reaction of epoxy matrix at the beginning stage. However, the mechanical properties and Tg of epoxy matrix exhibited the significant enhanced by adding 0.5wt% MWCNTs-DETDA. After adding 0.5 wt% MWCNTs-DETDA, the unidirectional T700 carbon fiber composites exhibited the significantly enhanced interlaminar shear strength (ILSS) and flexural properties due to the uniform dispersion of MWCNTs-DETDA and the modified interface bonding. The prepreg of MWCNTs-DETDA/T700 carbon fiber/epoxy resin has been prepared by solvent-method. The composite laminate plates have been prepared using the prepreg. However, the interface bonding and flexural properties of composites and have been improved significantly.During the curing kinetics study, the activation energy of amino-functionalized carbon nanotubes in the low-reactive curing agent-epoxy system was decreased, while it was increased in the MWCNTs-NH2/high-reactive curing agent-epoxy system. The activation energy was reduced in MWCNTs-NH2/high-reactive curing agent-epoxy system by pre-curing treatment. However, after pre-curing treatment, the MWCNTS-NH2 was well dispersed in the epoxy system and the nanocoposites exhibited higher flexural properties.