The Effect of the Salt Water Aging on the Mechanical Properties of Epoxy Adhesives Compounds

Abstract

The objective of this study is to compare the effect of selected operating factors on the mechanical properties of epoxy adhesive compounds aged in salt water. Five different water environments were tested: tap water, normal seawater (reference salinity value), seawater with double reference salinity value, seawater with half of the reference salinity and seawater with a quarter of the reference salinity value. Samples of two different adhesive compounds were prepared using the epoxy resin and triethylenetetramine curing agent. One of the compounds was filled with calcium carbonate. The samples were aged in five different water environments for three months, one month and one week, respectively. Mechanical properties of the cured adhesive compound samples were determined via strength tests performed on the Zwick/Roell Z150 testing machine in compliance with the EN ISO 604 standard. The objective of the experiments was to determine the effect of different seawater environments on selected mechanical properties (including strength) of the fabricated adhesive compounds.Polymers 2020, 12, 843 2 of 20 used as aging environments of DCB (Double Cantilever Beam) and ODCB (open-DCB) specimens. Bordes et al. [21] investigated the long-term behavior of adhesively bonded double lap shear steel joints aged in seawater and the degradation of mechanical properties of an epoxy adhesive. Aging on bulk adhesive was performed in deionized water, salt and seawater at three temperatures, 20, 40 and 60 • C. Heshmati et al. [15] investigated the effects of aging the epoxy adhesive and bonded joints (fiber-reinforced-polymer/steel joints) in five harsh environments, including salt water solution at various temperatures (20 • C and 45 • C). Three-dimensional (3D) moisture diffusion properties of different FRPs (fibre reinforced polymer/steel) and adhesive material in various aging conditions were characterized. In another work, Heshmati et al. [9] presented the effects of cyclic wet-dry, freeze-thaw and combined wet and freeze-thaw conditions (distilled water and salt water, when combined with freeze-thaw for 125 and 250 cycles) on the mechanical behavior of bonded FRP/steel joints. The results have shown, among other things, that the ductility of the adhesive is reduced after it has been dried from the wet state.The objective of this study is to compare the selected mechanical properties of cured adhesive compounds (unmodified and modified alike) aged in seawater environments with different salt concentrations. The experiments aim to determine and compare the compressive strength, compression modulus and compressive strains of the cured epoxy adhesives under study.Polymers 2020, 12, 843 4 of 20 filler were weighed (Table 3) and mixed. After that, the curing agent was added to the compound. The preparation process parameters for both modified and unmodified epoxy adhesive compounds were the same. Shape, Dimensions and Fabrication of the Adhesive Compound Samples

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