Salt crystallization-assisted degradation of epoxy resin surface in simulated marine environments

Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

“…They are basically used only in the lab, not Based on the understanding of the synergistically accelerated effect of salt water immersion and UV irradiation, the degradation of an organic coating in the marine tidal and splash zones may be better predicted. For example, it has been estimated that the acceleration effect of the E NaCl+UVA on epoxy degradation in the lab is approximately 20 times stronger than the natural environment in Xiamen island if the other factors can be neglected [120]. In other words, a one-month lab test will be equivalent to a 20-month island exposure.…”

“…Experimentally, the epoxy resin surface after the alternate water immersion and UVA irradiation was indeed much rougher (see Figure 7). There was an obvious synergistic effect between the UV irradiation and the NaCl solution immersion on the coating degradation [120].…”

“…Precipitated salt crystal particles may grow inside the pores or defects of a coating during drying in a wet-dry cycle, similar to the salt crystallization in a porous material [117][118][119]. This may lead to salt crystallization-assisted degradation of the organic coating in marine environments, which had not been realized before until the investigation by Feng et al [120]. When fast evaporation of the remaining solution on a coating surface particularly in a windy day leads to precipitated NaCl crystal particles growing in the microdefects or pores in the surface layer of a coating, a force ( p) would be built up after the NaCl crystal particles in contact with the pore inner walls [117,121,122].…”

“…Experimentally, the epoxy resin surface after the alternate water immersion and UVA irradiation was indeed much rougher (see Figure 7). There was an obvious synergistic effect between the UV irradiation and the NaCl solution immersion on the coating degradation [120]. Based on the understanding of the synergistically accelerated effect of salt water immersion and UV irradiation, the degradation of an organic coating in the marine tidal and splash zones may be better predicted.…”

“…In different marine conditions, a coating may have different degrees of degradation or damage [120]. For example, epoxy resin fully immersed in 5 wt.% NaCl solution (E NaCl ) was found to have some small "particles" on the surface, while after alternate NaCl solution immersion and UV irradiation (E NaCl+UVA ) it had a rough surface with a layer of particles.…”