Abstract:
Carbon nanotubes (CNTs) are considered to be the ideal reinforcing fillers for polymer matrixes to achieve high performance and multifunction, and have been widely used in a variety of applications such as translation, construction, aerospace and automotive industries because of their outstanding mechanical, electrical and thermal properties. However, the properties of CNT-reinforced composites are still far beyond of what is theoretically predicted. Because of high aspect ratio and intrinsic van der Waals force, CNTs tend to entangle with each other and exist in the form of bundles and ropes. As a result, homogeneous dispersion in media is still not easily obtained, especially in polymers. Furthermore, the bonds associated with the smooth surface of CNTs to the matrix are noncovalent, which results in ubiquitous interfacial slippages and a limited loading transfer from the polymer matrix to CNTs. CNTs are typically pulled out rather than fractured from the polymer matrix under failure. Poly (ethylene glycol) has received significant attention in bio-related applications because of its biocompatibility as well as non-toxicity. In this paper, we used an industrially desirable method to synthesize a nonionic poly (PM) (ether amine) via the reaction of aromatic diamine monomer containing two tert-butyl groups with poly (ethylene glycol) diglycidyl ether. The CNTs modified with PM (CNTs-PM) can be highly dispersed in organic solvents and water with high stability, and also incorporated readily into epoxy to form composites. Characterizations by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and ultra-violet and visible light (UV-vis) show that PM is wrapped on the surface of CNT (CNT-PM) through the formation of C—O—N and C—O—C bonds. With an aid of PM, CNT can disperse homogeneously into epoxy matrix, in which a strong interfacial interaction between CNT and epoxy (EP) matrix can be observed. EP/CNT-PM composites presented the improved mechanical properties. The impact strength of composites increased gradually with CNT-PM loading from (21.7±1.1) kJ/m
2 for pure EP to (73.5±2.1) kJ/m
2 for EP/CNT-PM with 0.7% loading. Moreover, the glass transition temperature (
Tg) of EP/CNT-PM was found to increase to a significant extent.