Mechanical and thermo-mechanical properties of nanoclay/epoxy composites: Synergistic effects of silanization and surfactant application

In the present work, montmorillonite based bentonite nanoclay was modified with surfactant application and silanization, sequentially. The chemically modified clay/epoxy nanocomposites were prepared with three different filler concentrations (0.5%, 1% and 2% wt) and produced with conventional casting technique. The XRD and FTIR techniques were used to reveal the effects of modification process. Based on FTIR, the modified clay particles exhibited alterations that confirmed the modification effect and the XRD results pointed out that the characteristic peak of neat nanoclay transformed into a hump, which was probably the indication of amorphous phase presence/increase. The tensile performance of modified clay based samples did not satisfy the expectations and showed slightly lower properties. However the flexural modulus of modified clay/epoxy specimens showed 11.1% improvement while their strength values decreased with the introduction of more powder. Similarly, same nanocomposite group exhibited an enhancement in terms of glass transition temperature-Tg (3.6 °C-4.9 °C) and storage modulus (approaximately 23.2%) as compared to neat epoxy. Nevertheless it was also observed that the neat clay based samples mostly achieved better quasi-static and viscoelastic performence than chemically modified structures. This situation can be mainly attributed to the penetration capacity decrease of epoxy due to the excessive/various modifiers existence within the clay galleries. © 2018 IOP Publishing Ltd