Preparation Of Conductive Material:Functionalized Oxidized-Carbon Nanotubes/Epoxy Resin Composite

Combining conductive nanofillers is a new way to improve electrical and mechanical properties of epoxy composites. Carbon nanotubes (CNTs) exhibit high conductivity and mechamical properties, the addition of CNTs can improve strength, stiffness and fracure toughness of the epoxy resin matrix. Due to its high surface energy, the purified CNT easily aggregate in epoxy matrix. Covalent treatment results in destruction to CNTs structure and inherent π-bonds, and it also requires harsh reaction conditions and cumbersome separation process. Consequently, non-covalent physical treatments, such as application of surfactants are particalarly attractive because the physical adsorption seldom damages the structure and π-bonds of CNT, nor disturbs the inherent of CNTs. Non-covalent physical treatments also provides strong binding force between CNTs and epoxy matrix, and endows further improved conductive and mechanical properties.The CNTs functionalized with three dispersants, Pyrogallol, Tween-80 and Triton-100, respectively, were used as fillers in the epoxy resin to prepare composites via solution mixing and situ polymerization methods. UV-vis spectra, FT-IR, Differential Scanning Calorimetry (DSC), mechanical tensile and conductive tests were used to characterize the composite materials; the fracture surface morphology is investigated by Scanning Electron Microscopy.The results of FT-IR spectrum indicate the carboxyl group of CNTs and the hydroxyl groups in pyrogallol react with epoxy groups. The other two dispersants did not react with epoxy resin, although they also contain hydroxyl groups, because of the difference in reaction activities of their hydroxyl groups. The amount of the heat released by pyrogallol/epoxy resin is larger than those of the other two systems, this also verified the reaction between pyrogallol and epoxy resin.The ratio of CNTs to epoxy was optimized based on conductivity and mechanical properties of the composite materials. Electrical conductivity mechanism of epoxy/CNTs composite material was analyzed from micro-level, and model diagram of pyrogallol functioned CNTs/epoxy composite material was proposed.