Role of epoxy functionality in microstructure–property relationships within elastomeric nanocomposites

Abstract

The contribution of epoxy functionalities in hybrid filler microstructures and interfaces within different binary and ternary particulate elastomeric nanocomposites, prepared by open two-roll mixing, was analysed. The epoxy percentages of the elastomeric phase were varied at three different levels (e.g. 0, 25 and 50%). Among the ternary samples, the most uniform distribution and dispersion were achieved in the case of the sample based on ENR-25 (epoxidised natural rubber matrix having 25 mol-% of epoxy group), as observed by small angle X-ray scattering (interfacial roughness) and transmission electron microscopy. Clay and carbon black jointly form hybrid microstructures like ‘nanounit’. Uniform distributions of such morphologies are reflected in tensile strength, elongation at break and half height width of the tan δ peak. Although the cross-link density improves as the epoxy percentage is increased, the level of synergism between two different fillers in terms of cross-linking density gradually reduces with the increased epoxy percentages. Except for solely clay filled samples, the thermal stability enhances as the epoxy percentage is increased.