The effect of alternate heating rates during cure on the structure–property relationships of epoxy/MMT clay nanocomposites

This paper investigates the effect of both the mixing technique and heating rate during cure on the dispersion of montmorillonite (MMT) clay in an epoxy resin. The combination of sonication and using a 10 °C/min heating rate during cure was found to facilitate the dispersion of nanoclay in epoxy resin. These processing conditions provided a synergistic effect, making it possible for polymer chains to penetrate in-between clay galleries and detach platelets from their agglomerates. As the degree of dispersion was enhanced, the flexural modulus and strength properties were found to decrease by 15% and 40%, respectively. This is thought to be due to individual platelets fracturing in the nanocomposite. Complementary techniques including X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX), transmission electron microscopy (TEM) and optical microscopy were essential to fully characterise localised and spatial regions of the clay morphologies.

► Effect of mixing method and heating rate on dispersion of MMT in epoxy investigated.
► Sonication and a 10 °C/min heating rate facilitated the dispersion of MMT in epoxy.
► As the degree of dispersion was enhanced, the flexural properties decreased.
► XRD, SAXS, SEM–EDX, TEM and optical microscopy fully characterised clay morphologies.