Spreading behavior and advancing contact angle of a low viscosity epoxy resin on three commercially available nanoclays — Cloisite® Na+, Cloisite® 15A and Cloisite® 25A — at 52°C is investigated. In addition, effect of temperature on spreading dynamics of epoxy on Cloisite® Na+ is analyzed at 33, 52 and 77°C. For wetting experiments, nanoclay powder is compressed into 12.7mm diameter disk shaped compacts under 20MPa pressure. The surface topologies of the compacts are analyzed by scanning electron microscopy (SEM), where as energy dispersive x-ray analysis (EDXA) is utilized to quantify the chemical composition of the surface. An epoxy drop is placed on each of the compacts and spreading is monitored via a CCD camera equipped with a high magnification lens. Temporal evolution of the advancing contact angle as well as drop penetration into the nanoclay compact is determined using the drop profiles extracted from the sessile drop images. Spreading of epoxy on Cloisite® Na+ is observed to be 12-fold faster at 77°C compared to 33°C. Analogous to its spreading speed, rate of penetration of resin into the nanoclay compact increased 20-fold in the same temperature range. Behavior of different nanoclay types are assessed by repeating the wetting experiments on Cloisite® 15A and Cloisite® 25A compacts. Unlike Cloisite® Na+, which did not have a finite static contact angle, Cloisite® 15A and Cloisite® 25A yielded static contact angles of 59.2°and 40.1°, respectively. These differences are attributed to different surface energies as a result of different chemical compositions of the surfaces and dissimilar surface topologies.
Development and Use of New Polymer Adhesives for the Restoration of Marine Equipment Units