An effective and green H2O2/H2O/O3 oxidation method for carbon nanotube to reinforce epoxy resin

Facile green oxidation methods are always desired to functionalize carbon nanotubes (CNTs) in the production of advanced CNT/epoxy composites. In the present work, an optimized H2O2/H2O/O3 oxidation method was developed, and performances of the H2O2/H2O/O3 oxidized CNT in epoxy matrix were tested and compared with that of the H2O/O3 oxidized CNT and the most commonly used concentrated HNO3 oxidized CNT. The physical and chemical characteristics of the obtained oxidized CNTs were systematically characterized via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman. Mechanical performances of the obtained composites were explored by tensile tests, impact tests, dynamic mechanical analysis (DMA) and fracture toughness tests. It was found that the H2O2/H2O/O3 oxidized CNT exhibited all-around overwhelming advantages over the concentrated HNO3 oxidized CNT on reinforcing the epoxy matrix, while the H2O/O3 oxidized CNT only improved the material strength. Reinforcing mechanisms for the different methods oxidized CNTs were studied and compared. The optimized H2O2/H2O/O3 oxidation method makes scaled production possible, avoids environment pollutions, and holds great potentials to replace the most commonly used concentrated HNO3 oxidation method to oxidize CNT during the preparation of the advanced CNT/epoxy composite.