Functionalizing Carbon Nanotubes by Plasma Modification for the Preparation of Covalent-Integrated Epoxy Composites

Abstract

A novel method for preparing a fully integrated nanotube composite material through the use of functionalized multi-walled carbon nanotubes (MWNTs) is presented in this study. The functionalization of MWNTs was performed via plasma treatment; subsequently, maleic anhydride (MA) was grafted onto the MWNTs (CNTs-MA). Nanotube-reinforced epoxy polymer composites were prepared by first mixing the CNTs-MA and a diamine curing agent, followed by a further reaction with the epoxy matrix. In this hybrid nanocomposite system, the CNTs-MA were covalently integrated into the epoxy matrix and became part of the cross-linked structure rather than just a separate component. Fourier transform infrared (FT-IR) and high resolution X-ray photoelectron (XPS) spectroscopes were used to characterize the functional groups on the surface of the MWNTs after the plasma modification. In addition, observations of scanning electronic microscopy (SEM) and transmission electron microscopy (TEM) images showed that the functionalized nanotubes, CNTs-MA, had a better dispersion than the unfunctionalized nanotubes, u-CNTs, on either the composite fracture surfaces or inside the epoxy matrix. Moreover, CNTs-MA/ epoxy nanocomposites presented obvious improvements in mechanical properties and conductivity (from 10 -12 to 10 -4 S/m) with only a small quantity (0.1-1.0 wt %) of the CNTs-MA addition.

Effective functionalization of carbon nanotubes for bisphenol F epoxy matrix composites

“…Figure 6 shows the SEM images of the fracture surface of nanocomposites with a thin gold coating, providing some insight into the CNTs-IL dispersion state. Most of the CNTs-IL dispersed without solvent showed 2012; 15 (4)and voids arising from the high amounts of the CNTs-IL added to the system 17,25 . A strong interaction between the CNTs and the polymer matrix was proved by the increase in the tensile strength and better dispersion of nanotubes.…”

“…Polymeric matrices, such as polyethylene (PE) 5,6 , poly(methyl methacrylate) (PMMA) 7,8 , poly(vinyl alcohol) 9,10 , polyimide 11,12 , and polystyrene (PS) [13][14][15] , have been investigated for CNT/polymer composites fabrication. Among polymer composites, epoxy resins have high strength and are very important materials for aircraft, space shuttles, electronic products, and other industrial applications [16][17][18][19][20] . Currently, there are two major challenges encountered in the successful fabrication of nanocomposites systems.…”

“…Also, all of the organic groups attached on the CNT wall will increase the contact resistance between individual CNTs and the bundles, or even insulate the CNTs from the polymeric matrix. This would allow a better compatibility between the CNTs and the polymer 17,26 . On the other hand, the functionalization of the CNTs reduces the length to diameter ratio, which can be detrimental for the overall conductivity, and leads to stabilization of the dispersion and the formation of an isolating polymer layer around the nanotubes in an unlikely case 27 .…”

Epoxy resin nanocomposites reinforced with ionized liquid stabilized carbon nanotubes

“…All specimens failed immediately after the tensile stress reached its maximum value. Conceptually, the inorganic/organic nanocomposites are often expected to become stiffer and more brittle upon the incorporation of inorganic fillers [13]. For the f-CNT/epoxy nanocomposite system, the tensile strength increases with the increase of the f-CNT loading.…”

“…Many polymers have been applied in the CNTs/polymer nanocomposites for various target applications. The introduction of the CNTs into a polymer matrix has improved the electrical conductivity as well as the mechanical properties of the polymer matrix [11][12][13][14][15][16][17][18].…”