An investigation on the effects of synthesis on the mechanical properties of nanoclay/epoxy

Abstract

Many studies in recent years have addressed the improvement of the mechanical properties of epoxy through the use of nanoparticles. However, a limited number of studies have focused on the effect of nanocomposite preparation methodologies on mechanical properties. In this research, the influence of different methodologies, including direct dispersion and solution blending of montmorillonite (MMT) nanoclay (Cloisite® 20A), on the mechanical properties of the epoxy is investigated. In direct dispersion, first, nanoclay-containing nanocomposites with various nanoclay contents (1, 2, and 3 wt.%) were prepared; then, the epoxy reinforced with 2 wt.% nanoclay modified with 3-Aminopropyltriethoxysilane (APS) was constructed. Modified nanoclays were characterized by X-ray diffraction analysis (XRD) and Fourier-transformed infrared spectroscopy (FTIR). In the solution blending methodology, the effect of n-hexane and toluene solvents was addressed in the fabrication of epoxy nanocomposites containing 0.2, 0.4, and 0.8 wt.% Cloisite 20A. The effect of methodology on the micro-porosity percentage was explored by X-ray tomography; while the pattern and intensity of the nanoparticle distribution on the fracture surface were assessed by energy dispersive X-ray spectroscopy (EDX). Tensile and three-point bending tests were also carried out to determine the tensile strength and modulus, flexural strength, toughness modulus, and strain to failure. The fracture surface and the failure mechanisms of the tensile test samples were evaluated by optical microscopy, laser profilometer and field-emission scanning electron microscopy (FE-SEM). Finally, it was observed that the nanocomposites prepared by solution blending using toluene, which contained 0.2 wt.% nanoclay, managed to exhibit the optimal mechanical properties by improving the tensile strength, toughness modulus, and flexural strength by 17.40%, 50.12%, and 11.91%, respectively.