Abstract
In recent years, due to rapid growth of industrial and academic development, carbon reinforced polymer composite has been paid much attention and further applied to a wide variety of fields from industrial applications to daily necessities. This study is going to choose benzoxazine/epoxy copolymer as the matrix of composite in which carbon nanotubes is added to bridge the matrix and fiber in order to achieve the goal of improvement in mechanical properties and fatigue behavior. To enhance the ability of dispersion and interfacial property of carbon nanotubes in the matrix, carbon nanotubes will be firstly treated by nitric acid, which is to increase the surface reactivity. Carbon nanotubes are then chemically modified by 4, 4’-Methylenediphenyl diisocyanate (MDI) so as to improve the compatibility among different phases of materials. In the end of this study, mechanical properties and fatigue behavior will be clearly discussed. Success of chemical modification of carbon nanotubes can be proved by a series of chemical identifications such as Raman spectrum, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA) and so on. Additionally, the result of Dynamic mechanical analysis (DMA) also shows that glass transition temperature of modified carbon nanotubes based polymer composite increases by about 12 degrees and that the increasing cross-linking density significantly improves the mechanical properties compared with pure polymer matrix. Last but not least, the results of static mechanical properties and dynamic fatigue behavior are investigated and revealed great improvement by adding chemical modified carbon nanotubes, which are able to keep carbon fiber laminates from delaminating so easily and effectively lengthen the fatigue life of carbon fibrous composite.