Marine Field Test Research Articles

Biodegradable Poly(ester- co-acrylate) with Antifoulant Pendant Groups for Marine Anti-Biofouling.

Polymer resins are critical for marine anti-biofouling coatings. In this study, degradable poly(ester- co-acrylate) with antifoulant pendant groups has been prepared by the radical ring-opening polymerization of 2-methylene-1,3-dioxepane, methyl methacrylate, and N-methacryloyloxy methyl benzoisothiazolinone. Such a polymer containing main-chain esters can hydrolytically and enzymatically degrade. Both degradation rates increase with main-chain ester content. Moreover, since the antifoulant groups are chemically grafted to the degradable main chain, their release can be controlled by the degradation besides the hydrolysis of side groups. Our study shows that the copolymer coating is efficient in inhibiting the accumulation of marine bacterial biofilm of Pseudomonas sp. and diatom Navicular incerta. Marine field test reveals that the copolymer has excellent efficiency in preventing biofouling for more than 6 months.

Cr-modified low alloy steel reinforcement embedded in mortar for two years: Corrosion result of marine field test

This paper describes a study of the corrosion behavior of Cr-modified steel reinforcement exposed at marine splash zone for a period of two years. The corrosion behavior was analyzed by the weight loss method, optical and electron microscopy, and X-ray photoelectron spectroscopy. The Cr-modified reinforcement exhibited high corrosion resistance in the actual marine environment. The protection mechanism of the Cr-modified reinforcement at the corrosion propagation stage was that Cr improved the protective quality and buffering ability of the rust layer against aggressive species, by increasing the Fe2+ and OH− content within the iron oxides and improving the compact degree of the rust layer.

Biodegradable poly(ester)-poly(methyl methacrylate) copolymer for marine anti-biofouling

Being biodegradable and eco-friendly, polyesters are promising in marine anti-biofouling. However, the slow degradation and poor adhesion limit their applications. In the present work, we have prepared poly(ester)-poly(methyl methacrylate) copolymer via radical ring-opening copolymerization of 2-methylene-1,3-dioxepane (MDO) and methyl methacrylate (MMA). The copolymer coating has good adhesion to substrate due to the incorporation of MMA moieties. The main-chain ester bonds from MDO enable the copolymer to enzymatically and hydrolytically degrade, and the degradation rate increases with the ester content. The polymers can serve as a carrier and controlled release matrix for organic antifoulant 4,5-dichloro-2-octylisothiazolone (DCOIT), and the release rate increases with the ester content. Marine field test shows the system of the copolymer and DCOIT has excellent antifouling performance for more than 3 months.

Indoor accelerated corrosion test and marine field test of corrosion-resistant low-alloy steel rebars

Macrocell corrosion test and accelerated alternating wet–dry experiment combined with marine field test were employed to study the corrosion behavior of HRB400 carbon steel, 1.5Cr steel, and 5Cr steel in a simulated concrete pore solution and mortar. The macrocell current significantly decreases in samples added with Cr compared with that in HRB400 steel. The corrosion rate is decreased by Cr but increased by Cl−; as a consequence, the corrosion rates of 1.5Cr and 5Cr steel are lower than that of HRB400 steel. However, the corrosion products differ slightly in terms of the contents of α-FeOOH (goethite), γ-FeOOH (lepidocrocite), γ-Fe2O3, and Fe3O4 (maghemite or magnetite). The addition of Cr increases the content of the protective α-FeOOH and reduces the content of γ-FeOOH. Both ordinary and high-performance epoxy coatings remain intact after 1year of marine field test. Among the bare steel rebars, HRB400 steel shows extensive localized corrosion on the surface, whereas 1.5Cr steel exhibits less severe corrosion. The scarcely visible corroded areas in 5Cr steel indicate that this rebar is in the passive state, consistent with results of the indoor accelerated test. Hence, the durability of concrete structures can be prolonged with the utilization of corrosion-resistant low-alloy rebars.