Deleterious Effects of Seawater, acidic water and Alkali water on Mechanical Properties of Nanocomposite adhesives

This paper aims to compare the detrimental effects of different environmental conditions including seawater, acidic water and alkali water on the mechanical properties of nanocomposites. Nanocomposite adhesive specimens were fabricated by the inclusion of different weight percentages (0, 0.1, 0.3 and 0.5) of multi-walled carbon nanotubes (MWCNTs) into an epoxy adhesive. Then, the specimens were immersed in three types of water including seawater (from Persian Gulf), de-ionized water acidified with industrial hydrochloric acid (HCl) and de-ionized water alkalized with industrial sodium hydroxide (NaOH) for 360 hours. The experimental results showed that adding MWCNTs reduced the water uptake and consequently improved the mechanical properties of the adhesive. However, this improving effect depended on the environmental conditions. The nanocomposite adhesive specimen containing 0.1 wt% MWCNTs presented the lowest water uptake and the highest mechanical properties for different environmental conditions. Amongst different environmental conditions, the acidic water imposed the most deleterious effect with the highest water uptake. In seawater, the water ingress was lower than acidic water due to the existence of alkali metal oxides. Finally, the lowest water ingress and destructive effect was found to be for alkali water.