Study of functionalization influence of carbon nanotubes on mechanical properties of CNT-epoxy nanocomposites

Abstract

Carbon nanotubes (CNTs), specially the functionalized ones, have been added to epoxy resin due to its unique mechanical, electrical and thermal properties. The nanocompósitos properties are related homogeneity and CNT functionalization. CNT agglomeration let the final properties of nanocomposites are worse than neat resin. In addition, even when they are well dispersed CNT modifies the cure kinetics of epoxy resin, which can produce nanocomposites non-totally cured samples. Therefore, functionalized CNTs show different level of homogeneity, cure kinetics and mechanical properties. Nanocomposites prepared with highly homogenously dispersed CNTs, but with different functionalization agents can let to materials with different mechanical properties. The main objective of this doctoral project is to study how the functionalization of CNTs (carboxyl, lactone, amine, etc) obtained by chemical or plasma methods, influences the mechanical properties (especially tensile and flexion strength) of CNT/epoxy resin nanocomposites. In order to attain the main objective it is necessary to know how the functionalization also influences on homogenization, cure kinetic and chemical interaction between CNT and resin.The functionalization type was determined by FT-IR and its amount by XPS and Boehm titration. These techniques have been used by our research group. The homogeneity will be analyzed by SEM and rheology. The cure kinetics will be studied by FT-IR. The intensity of the peak related to epoxy ring decreases with the cure reaction, relating its intensity with a peak of a chemical group that is not consumed during the temporal evolution of the reaction the cure extension can be determined. The kinetic parameters can be determined using this technique. The interaction between CNT and resin will be studied by FT-IR. The mechanical properties of the nanocomposites are strengthened by the presence of covalent chemical bonding between CNT and resin, which can observed by SEM throughout the broken CNT over the surface fracture.