Immersion In Artificial Seawater Research Articles

Large-scale laboratory investigation of the performance of a novel isolation particle layer for offshore final disposal sites

The complex seabed conditions and ocean environment pose significant challenges to the material selection and construction of bottom liners for offshore final disposal sites. To overcome the challenges, this study proposed a novel isolation particle layer for offshore final disposal sites. The isolation particle was composed by salt-resistant bentonite coating material and cement core material (D10 was 10 mm in core diameter and 2 mm in coating thickness; D20 was 20 mm and 4 mm). Upon immersion in artificial seawater, the isolation particles underwent expansion, leading to the formation of the novel isolation particle layers with low hydraulic conductivity less than 1 × 10-7 cm/s and adsorption of heavy metals in bentonite interlayers. Large column tests showed that both D10 and D20 isolation particle layers exhibited remarkable swelling capacity and low hydraulic conductivity (4.3 × 10-9 cm/s and 2.6 × 10-8 cm/s) under 3 m seawater pressure. During one year of observation, water tank test demonstrated that both isolation particle layers displayed remarkable stability and low hydraulic conductivity of 2.73 × 10-10 cm/s and 8.36 × 10-10 cm/s with load. The maximum adsorption capacities of salt-resistant bentonite were 123.55 mg/g for Pb2+, 60.29 mg/g for Cd2+ and 54.22 mg/g for Cu2+. Both isolation particle layers exhibited a high removal rate of over 95 % for heavy metals in water tank tests. The large-scale laboratory tests indicated the significant potential of the novel isolation particle layer for offshore final disposal sites. Subsequently, a testing ocean site will be selected to further investigate its practical engineering performance.

Stabilized Ti3C2Tx-doped 3D vesicle polypyrrole coating for efficient protection toward copper in artificial seawater

A closed 3D vesicle polypyrrole-based composite coating (PPy-STi) was electropolymerized on copper with the support of sodium dodecyl sulfate (SDS)-stabilized Ti3C2Tx-MXene via an inverted-electrode cyclic voltammetry route. Due to the promoted polymer nucleation effect of SDS and active catalysis of hydrogen evolution by well-dispersed Ti3C2Tx, a unique vesicle-like architecture of PPy-STi were formed with twisted diffusion pathways, which endowed a strong barrier against aggressive species. Meanwhile the stabilized Ti3C2Tx with high metallic conductivity facilitated the overall electroactivity of PPy-STi coating, yielding much improved anodic protection for copper in artificial seawater (ASW). Relying on the tolerant physical barrier and robust anodic protection capacity of PPy-STi, the coated copper could sustain its passivated state during 10 days of immersion in ASW. The integration of MXenes in conductive polymer coating with enhanced protection characteristics may provide a new strategy to improve the corrosion resistance of electronic devices in the harsh environment.

Degradation of Kapok Fiber-Reinforced Polyester Composites with Calcium Carbonate Filler in Seawater

This research investigates the development of polyester composites reinforced with kapok fiber and CaCO3 filler to reduce environmental impact. Natural fibers, valued for their lightweight, fire resistance, cost-effectiveness, and biodegradability, are commonly used in composites. However, synthetic fibers, despite their superior mechanical properties, raise environmental concerns. The study focuses on the composites' performance, stability, and endurance in harsh conditions. Kapok fibers were manually extracted, and CaCO3 powder was sieved to 80 mesh. Composite samples were created with varying volume fractions of CaCO3 powder and kapok fibers, using polyester as the matrix. Tensile and bending tests, according to ASTM D3039 and ASTM D790 standards, were conducted on these samples. Additionally, water absorption was assessed gravimetrically, and mechanical strength degradation was studied via immersion in artificial seawater at different temperatures. Results indicated that water absorption increased with higher fiber volume fractions in the composite, primarily due to the water-absorbing capabilities of natural fibers and CaCO3 particles, surpassing that of polyester resin. Increased immersion temperatures accelerated water diffusion, impacting interactions between water molecules, polymer chains, and natural fibers. Furthermore, an increase in the CaCO3 filler volume fraction negatively affected the mechanical strength of kapok polyester-fiber composites. This was attributed to the agglomeration of CaCO3 powder, disrupting the polyester resin's viscosity and damaging the bond between kapok fiber and the matrix. The composites exhibited their highest tensile strength with 10% CaCO3 filler before immersion, but this strength decreased following exposure to high temperatures.

Experimental study on the mechanical properties of CFRP/epoxy composite plates under seawater immersion

This study investigates the effects of seawater immersion at different temperatures on the degradation and viscoelastic behavior of carbon fiber-reinforced polymer (CFRP) composite plates. The present study investigated the effects of seawater immersion on the degradation of mechanical properties at 20 °C, 40 °C, and 60 °C of the carbon fiber reinforced polymer (CFRP) composite plates. The specimens were prepared by hand lay-up and cured under water for 7 days before immersion in artificial seawater for 6 months. Interlaminar shear strength (ILSS), tensile strength, and dynamic mechanical analysis (DMA) tests were performed periodically over a six-month exposure period, and scanning electron microscopy (SEM) was used to characterize aging damage and fracture morphology. The long-term shear behaviour of CFRP plates in seawater has been predicted using the Arrhenius theory. The results show that immersion in seawater significantly reduces ILSS, especially at higher temperatures and longer immersion times. However, the overall tensile properties of CFRP plates were not significantly affected. Dynamic mechanical analysis (DMA) revealed a decrease in the damping (tan δ), indicating a reduction of the fiber-matrix adhesion. The long-term life prediction showed that CFRP plates subjected to seawater immersion are susceptible to degradation, with a stable retention of interlaminar shear strength at 70% for the composite laminate.

Spray-Drying Hydrophobic Cellulose Nanocrystal Coatings with Degradable Biocide Release for Marine Antifouling.

With increasing awareness about the ecological environment, increased attention has been paid to the application of eco-friendly materials in the field of marine antifouling. In this work, a novel coating having good mechanical strength and static marine antifouling characteristics was fabricated using cellulose nanocrystals (CNCs) as the skeleton material, with in situ growth of SiO2 as the basic superhydrophobic material and introducing hexadecyl trimethyl ammonium bromide (CTAB) and 4-bromo2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile (Econea) into the coating. Due to the high strength and rod structure of CNCs, the coating maintained super-hydrophobicity after 50 cycles of abrasion tests. Moreover, the addition of CTAB during the synthesis of SiO2 led to the hydrolysis and polycondensation of tetraethyl orthosilicate at the micellar interface. Econea was fully mixed with SiO2 nanoparticles, thus slowing down the rate of release of Econea. Meanwhile, the adhesion between the coating and the substrate reached 1.9 MPa, which can meet the application requirements for marine environments. The bioassay using bacteria (Escherichia coli) and diatoms (Nitzschia closterium) showed that the rate of inhibition of the coating on bacteria and diatoms could reach 99 and 90%, respectively, after immersion in artificial seawater for 28 days. This research provides a facile and promising fabricating solution of an eco-friendly CNC-based coating having strong antifouling characteristics suitable for marine environments.

Hybrid Zinc Coatings with Chitosan/Alginate Encapsulated CuO-Nanoparticles for Anticorrosion and Antifouling Protection of Mild Steel

The construction of anticorrosion coatings containing antifouling agents is an effective way to ensure the long-term durability of marine steel infrastructures. In this work, an innovative hybrid coating was prepared by introducing biocide CuO nanoparticles in ordinary zinc coating to improve its protective ability for steel in aggressive salt water environments. The CuO nanoparticles were embedded inside the matrix of chitosan/alginate complexes to prevent spontaneous copper leaching during corrosive attacks. Two procedures were applied for the electrodeposition of hybrid/composite zinc-based coatings on low-carbon steel substrates (DC current): first—the co-electrodeposition of encapsulated CuO nanoparticles with zinc on a cathode (steel) electrode from a sulfate electrolyte with a relatively low pH value of about 4.5–5.0 and second—the encapsulated CuO nanoparticles were electrodeposited from aqueous solution as an intermediate layer between two zinc deposits. The particles size and stability of suspensions were evaluated using dynamic light scattering. Both hybrid coatings were compared in terms of surface morphology and hydrophilicity (SEM and AFM analysis, contact angle measurement) and corrosion resistance (potentiodynamic polarization curves, polarization resistance). The protective characteristics of the coatings were compared in a 3.5% NaCl solution and artificial sea water. The hybrid coating showed 2–4 times higher polarization resistance than the bare zinc coating during a 30 day immersion in artificial sea water, indicating that this coating has the necessary characteristics to be used in a marine environment.

Time-Varying Pattern and Prediction Model for Geopolymer Mortar Performance under Seawater Immersion.

In this study, immersion experiments were conducted on the geopolymer mortar (GPM) by using artificial seawater, and the effects of alkali equivalent (AE) and waterglass modulus (WGM) on the resistance of geopolymer mortar (GPM) to seawater immersion were analyzed. The test subjected 300 specimens to 270 days of artificial seawater immersion and periodic performance tests. Alkali equivalent (AE) (3-15%) and waterglass modulus (WGM) (1.0-1.8) were employed as influencing factors, and the mass loss and uniaxial compressive strength (UCS) were used as the performance evaluation indexes, combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the time-varying pattern of geopolymer mortar (GPM) performance with seawater immersion. The findings demonstrated a general trend of initially growing and then declining in the uniaxial compression strength (UCS) of geopolymer mortar (GPM) under seawater immersion. The resistance of geopolymer mortar (GPM) to seawater immersion decreased with both higher or lower alkali equivalent (AE), and the ideal range of alkali equivalent (AE) was 9-12%. The diffusion layer of the bilayer structure of the waterglass particle became thinner with an increase in waterglass modulus (WGM), which ultimately led to the reduction in the resistance of the geopolymer structure to seawater immersion. Additionally, a support vector regression (SVR) model was developed based on the experimental data to predict the uniaxial compression strength (UCS) of GPM under seawater immersion. The model performed better and was able to achieve accurate prediction within 1-2 months, and provided an accurate approach to predicting the strength of geopolymer materials in a practical offshore construction project.

Recycled aggregate seawater–sea sand concrete and its durability after immersion in seawater

Recycled coarse aggregate (RCA), seawater, and sea sand are sustainable and environmentally friendly materials that may be combined to make a new green building material. In this study, mineral admixtures were added to improve the properties of recycled aggregate–seawater–sea sand concrete (RASSC). The specimens were prepared with different replacement ratios of RCA, fly ash (FA), and silica fume (SF). The design compressive strength was set at C40 and optimized by orthogonal design. The durability of RASSC with the optimal mix proportion after immersion in artificial seawater at room temperature was studied in terms of axial compression performance, and flexural properties. The results showed that the compressive strength of RASSC with mineral admixtures could reach 47.8 MPa and that SF had the greatest influence, followed by RCA and FA. The continuous hydration and pozzolanic reaction of cement, FA and SF in the RASSC resulted in an increase in the axial compression performance and flexural properties at the initial stage of immersion. As the immersion time increased, chloride ions reacted with the cement product and formed Friedel salts, sulfate ions reacted with calcium hydroxide to form ettringite, gypsum and salt crystals, and the RASSC was more brittle with a poor ductility, resulting in the flexural failure mode changed from interface transition zone of recycled aggregate to recycled aggregate failure, fracture interface characterization results provided the evidence. The theory of plasticity was still applicable to RASSC, and the stress–strain relations was proposed.

Polyethylene Glycol-b-poly(trialkylsilyl methacrylate-co-methyl methacrylate) Hydrolyzable Block Copolymers for Eco-Friendly Self-Polishing Marine Coatings.

Hydrolyzable block copolymers consisting of a polyethylene glycol (PEG) first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-methyl methacrylate (MMA)) second block were synthesized by RAFT polymerization. Two PEGs with different molar masses (Mn = 750 g/mol (PEG1) and 2200 g/mol (PEG2)) were used as macro-chain transfer agents and the polymerization conditions were set in order to obtain copolymers with a comparable mole content of trialkylsilyl methacrylate (~30 mole%) and two different PEG mole percentages of 10 and 30 mole%. The hydrolysis rates of PEG-b-(TRSiMA-co-MMA) in a THF/basic (pH = 10) water solution were shown to drastically depend on the nature of the trialkylsilyl groups and the mole content of the PEG block. Films of selected copolymers were also found to undergo hydrolysis in artificial seawater (ASW), with tunable erosion kinetics that were modulated by varying the copolymer design. Measurements of the advancing and receding contact angles of water as a function of the immersion time in the ASW confirmed the ability of the copolymer film surfaces to respond to the water environment as a result of two different mechanisms: (i) the hydrolysis of the silylester groups that prevailed in TBSiMA-based copolymers; and (ii) a major surface exposure of hydrophilic PEG chains that was predominant for TPSiMA-based copolymers. AFM analysis revealed that the surface nano-roughness increased upon immersion in ASW. The erosion of copolymer film surfaces resulted in a self-polishing, antifouling behavior against the diatom Navicula salinicola. The amount of settled diatoms depended on the hydrolysis rate of the copolymers.

Influence of Sharklet-Inspired Micropatterned Polymers on Spatio-Temporal Variations of Marine Biofouling.

This article aims to show the influence of surface characteristics (microtopography, chemistry, mechanical properties) and seawater parameters on the settlement of marine micro- and macroorganisms. Polymers with nine microtopographies, three distinct mechanical properties, and wetting characteristics are immersed for one month into two contrasting coastal sites (Toulon and Kristineberg Center) and seasons (Winter and Summer). Influence of microtopography and chemistry on wetting is assessed through static contact angle and captive air bubble measurements over 3-weeks immersion in artificial seawater. Microscopic analysis, quantitative flow cytometry,metabarcoding based on the ribulose biphosphate carboxylase (rbcL) gene amplification, and sequencing are performed to characterize the settled microorganisms. Quantification of macrofoulers is done by evaluating the surface coverage and the type of organism. It is found that for long static in situ immersion, mechanical properties and non-evolutive wettability have no major influence on both abundance and diversity of biofouling assemblages, regardless of the type of organisms. The apparent contradiction with previous results, based on model organisms, may be due to the huge diversity of marine environments, both in terms of taxa and their size. Evolutive wetting properties with wetting switching back and forth over time have shown to strongly reduce the colonization by macrofoulers.

Eco-friendly self-polishing antifouling coating via eugenol ester hydrolysis

Ships and underwater facilities suffer from marine biofouling, which causes great harm. The most effective method against biofouling is to use self-polishing antifouling coatings. However, traditional coatings achieve antifouling performance by releasing toxic heavy metal antifouling agents, causing ecological problems. To solve this contradiction, a self-polishing antifouling coating polymer based on eugenol methacrylate was prepared. The hydrolysis of phenolic ester group realizes the transformation of resin segment from hydrophobicity to hydrophilicity. The self-polishing process releases eugenol, which is natural and non-toxic into seawater. It is the first time when self-polishing coating polymer achieves self-polishing by hydrolysis of phenolic ester groups and release of natural phenolic products. Eugenol release rate was the fastest at the beginning of immersion of the coating, reaching 0.48 μg·cm−2·day−1 for EMFP-25. After immersion in artificial seawater for 15 days, the release rate of eugenol from the coating tends to be stable, and the EMFP-25 with the highest release rate can reach 0.14 μg·cm−2·day−1. The resin has good antibacterial and anti-algae properties, and the mussel attachment experiments show that mussels have a tendency to avoid resin coatings with high eugenol content.

Water Rewarming After Seawater Hypothermia Mitigates IL-1β in Both Intestinal Tissue and Blood.

In this study, the rat models of severe hypothermia induced by seawater immersion were established in artificial seawater immersion at 15°C for 5 hours. With the rewarming measurement of 37°C water bath, the rewarming effects were evaluated by monitoring basic vital signs and dynamically detecting intestinal inflammation cytokines. Fifty Sprague-Dawley rats were randomly divided into five groups including the control group (group C), hypothermia group (group H), 2-hour rewarming group (group R2), 6-hour rewarming group (group R6), and 12-hour rewarming group (group R12), with 10 in each group. The basic vital signs of rats (i.e., core temperature, respiration, heart rate, and muscle tremor) were constantly recorded. The inflammatory factors were detected in the intestinal tissue via a protein chip GSR-CAA-67 of Innopsys, and the verification by reverse transcription-quantitative polymerase chain reaction. The levels of cytokines (interleukin IL-1β, IL-6, and IL-10) were detected from blood samples collected at the end of the observation period via enzyme-linked immunosorbent assay. The expression landscape of IL-1β in the intestinal tissue was validated by immunohistochemistry. Five hours of immersion in artificial seawater at 15°C successfully induced severe hypothermia of rats. After 2 hours of constant water bath rewarming at 37°C, the basic vital signs recovered to the normal level and maintained stably as well as the acute inflammatory reaction alleviated effectively, which indicated that 37°C of water immersion rewarming had the potential to be a suitable method for early treatment of water immersion hypothermia. After the process of hypothermia, several inflammatory cytokines of rats in rewarming groups changed distinctly with IL-1β, showing the most significant variations compared with group C, which confirmed IL-1β as a potential monitoring biomarker referring to the therapeutic effect of rewarming for severe hypothermia caused by seawater immersion.

Influence of Surface Pretreatments on the Anticorrosion of Polypyrrole Electro-Polymerized Coatings for Copper in Artificial Seawater

Plasma discharging treatment (hydroxylation) was conducted on copper surfaces for the subsequent electro-polymerization procedure of polypyrrole (PPy) coating (d-PPy). The hydroxylated surface could solve the criticized adhesion strength and protection efficiency of electropolymerized coatings for metal substrate in corrosive media. Compared with the counterpart obtained via passivation pretreatment (p-PPy), a well-adhered d-PPy layer was acquired on the hydroxylated copper surface, which earned a satisfactory adhesion grade, compactness and conductivity. Appreciable protection of d-PPy was measured for copper in the artificial seawater (ASW) at 298 K via electrochemical and surface analyses. Results of electrochemical measurements indicated that d-PPy coating effectively retarded copper corrosion in ASW with a lowered corrosion current density and improved charge transfer resistance. Surface analysis revealed that the typical morphology of PPy was retained after 240 h immersion in ASW. A favorable physical barrier and anodic protection efficacy might account for the superior protection of d-PPy coating for the underlying copper. Molecular dynamics simulations for the deposition of PPy chains on pristine and hydroxylated copper planes provided a definite correlation between the theoretical calculations and experimental observations. Theoretical modelling also disclosed in-depth the anchoring nature and anticorrosive mechanism for PPy toward the hydroxylated copper in ASW.

Effect of Ammonia-Soda Residue on the Strength and Chloride-Resistance Performance of Steel Slag-Granulated Blast Furnace Slag-Based Concrete after Immersion in Artificial Seawater.

Ammonia-soda residue (ASR) is the main solid waste generated from soda manufacturing and is hard to reuse due to its complex chemical composition. This study investigated the influence of ASR content on the strength and chloride-resistance capacity of concrete based on basic oxygen furnace slag and ground blast furnace slag. The hydration and chloride resistance mechanisms were analysed by comparing the hydrate products and pore structural changes. The results showed that adding ASR had the greatest impact on early strength. ASR-introduced chloride ions may participate in the hydration process to generate Friedel’s salt and decrease ettringite. The optimum pore distribution appeared when the ASR-to-desulphurisation gypsum ratio was 2:3 because of the introduction of nucleation sites and the decrease of C–S–H gels. The two chloride resistance-capacity measurements were affected differently by the ASR content. The apparent chloride diffusion coefficient was mainly affected by the percentage of pores that were larger than 10 nm. However, electric flux increased when ASR increased due to the influence of introduced chloride. The crystallisation pressure of Friedel’s salt decreases the strength of concrete with ASR content after high-concentration artificial-seawater immersion. The significant chloride-resistance property provided an alternative use for the concrete containing ASR.

Combining topography and peptide to inhibit algae attachment: Preparation of peptide‐modified microstructured surfaces

Marine facilities and ships are easily plagued by biofouling. Synergistic surfaces combining surface reactive ion etching and peptide modification were designed and prepared to tackle surface biofouling. Six microstructural surfaces were first designed and machined based on the contact point theory; the synergistic surfaces were then prepared by peptide modification. Laser confocal scanning microscope (LCSM), scanning electron microscopy (SEM), contact angle measurement, and X‐ray photoelectron spectroscopy (XPS) were utilized to analyze the surface morphology and surface chemical properties; the results demonstrated that six synergistic surfaces were prepared successfully with 0.8‐μm depth, surface contact angle increased from 75° to 116.99°, and the surface chemical compositions were also changed significantly due to peptide modification. Antibiofilm assays showed that surface modification and surface topology could slightly reduce the formation of biofilm. While the synergistic surfaces possess strong anti‐algal performance, and anti‐Chlorella pyrenoidosa (C. pyrenoidosa) and anti‐Phaeodactylum tricornutum (P. tricornutum) rates reached 78.56% and 87.80%, respectively after 7‐day immersion in artificial seawater. Compared with the single surface treatment method, the antifouling performance of the synergetic surfaces were stronger. This strategy demonstrated a realistic paradigm for the further improving surface antifouling performance in a green method.

Experimental investigation of mechanical properties of Acrylonitrile Butadiene Styrene (ABS) based polymer for Submersible pumps

Now a day’s many companies manufacturing the most advanced submersible pumps with Acrylonitrile Butadiene Styrene (ABS) based polymer, which is available in the market for use in domestic, commercial and even research activities. ABS based pumps are widely used in mining, construction and chemical industries. Acrylonitrile Butadiene Styrenehasmuch application in the temperature range from -20 to 80°C. The ABS based polymer composites are used in submergible pumps due their important properties such as corrosion resistance, light weight, erosion resistance, etc. In the current work, the technique used for the fabrication of GFRP- ABS laminateis compression molding, as per the ASTM standard. The various tests are conducted as per Design of Experiments. Analysis of experimental data was performed using Minitab software and tests were conducted for Flexural strength, Inter Laminar Shear Stress, Tensile strength. Three factors areconsidered for the Design of Experiments namely, fibre-to-resin ratio, fibre orientation and period of immersion in artificial sea water. The outcomepoints towards Flexural strength; ILSS and Tensile Strength areat highest along 40:60 fibre-to-resin ratio with 0°/90°fiber orientation, longer the contact to sea water more is the fall in the strength of the composite material and also due to sea water diffusing into the composite material specimen, there is an increase in its weight.

Experimental study on the bond behavior of GFRP plate-high-strength concrete composite interfaces under the coupled effects of sustained load and seawater immersion

This paper presents an experimental study on the bond behavior between glass fiber-reinforced polymer (GFRP) plate and high-strength concrete under the coupled effects of sustained load and artificial seawater (60 °C constant temperature and 5 times seawater concentration) immersion. A specially designed preloading system was used to apply the sustained load on the specimens, and a new type of U-shaped shear key was applied under the coupled effect. A total of 48 double-lap shear specimens were tested to investigate the effects of coupled-effect time and interface type. The main properties of the bonded joints were examined, including the failure modes, ultimate load and load-slip curve. The test results showed that (1) the bonding performance between high-strength concrete and epoxy resin was substantially affected by the artificial seawater immersion; (2) the ultimate load of the double-lap shear specimens with four types of interfaces was reduced significantly with increasing coupled-effect time; (3) the premature failure occurred for each dry bond (DB) interface specimen with coupled effects, and the DB interface was not recommended under the coupled effects; (4) the ultimate load of the shear key combined with wet bond (SK-WB) interface was significantly greater than that of the other three types of interface under different coupled-effect ages; (5) the DB interface was the worst and the SK-WB interface was the best under the coupled effects in terms of the interface stiffness.

Zwitterionic modified electrostatic flocking surfaces for diatoms and mussels resistance

Environmentally friendly antifouling coatings without biocide release need to be developed. Herein, a vertical array of nylon fibers coated with poly(sulfobetaine methacrylate) (PSBMA) was prepared by the electrostatic flocking technique and free radical polymerization catalyzed by Fe2+, which are called zwitterionic electrostatic flocking surfaces (ZEFS). The ZEFS showed resistance to diatoms because the fiber diameter was smaller than the diatom size. At the same time, the ZEFS prevented mussels adhesion. The number of plaques on the ZEFS was reduced by more than 98% and 96% compared with the glass surface and polydimethylsiloxane (PDMS) after a 4-day assay. The special surface morphology of the vertical arrangement of fibers makes it difficult for the mussels to empty seawater. Zwitterionic surface modification further enhanced the resistance to mussel adhesion. The ZEFS showed strong hydrophilicity with an underwater oil contact angle of up to 152 ± 2.4°, which reduces the adhesion work of mussel protein adhesion to the fibers and the wettability of the protein on the fiber surface. In addition, the zwitterionic layer exhibited good stability in artificial seawater, and it retained more than 96% stability after 30 days immersion in artificial seawater.

Experimental study on the interfacial bond behavior of FRP plate-high-strength concrete under seawater immersion

The excellent bonding performance of the glass fiber-reinforced polymer (GFRP) profile-high-strength concrete interface is the key to ensuring the safety, reliability and durability of a composite structure. Therefore, it is necessary to study the durability of the composite interface. In this paper, a total of 48 GFRP plate-high-strength concrete double-lap joints were tested to investigate the effect of the epoxy resin type, interfacial type and artificial seawater immersion time on the bonded interfaces. The main properties of the bonded joints were examined, including the failure mode, ultimate load, load-slip curve, typical strain and shear stress distributions along GFRP plates. The results showed that the ultimate loads of each type of interface gradually decreased with increasing immersion time. After 360 days of artificial seawater immersion at a constant temperature, the ultimate load of the wet bond (WB) interface had the largest reduction, and the ultimate load of the dry bond (DB) interface showed a minimal decrease. The ultimate load of the shear key combined with wet bond (SK-WB) interface was significantly greater than that of the other three interfaces under different immersion ages. In general, the durability of the interface with the CFSR type (B-type) epoxy resin was superior to that of the Sanyu L-500 type (A-type) epoxy resin. The strain and interfacial shear stress distributions along GFRP plates of the DB interface specimens were different from that of the SK-WB interface specimens under different immersion ages.

Superhydrophilic Stainless Steel Mesh for Oil–Water Separation with Long‐Term Durability, Impressive Corrosion Resistance, and Abrasion Resistance

Durable properties of oil–water separation materials are challenging issue during the development from laboratory to practical application. Herein, twill woven stainless‐steel mesh is modified through oxidation and conversion steps, and applied for oil–water separation. The modified mesh displays excellent superhydrophilic property with water contact angle ≈0° and underwater oil contact angle up to 159°. Oil–water separation performance is evaluated using a series of oil–water mixtures. The results demonstrate that oil–water mixtures can be separated under gravity with oil rejection >99% and water permeate fluxes in the range of 40–60 k L m−2 h−1. Moreover, the modified mesh shows long‐term durability, excellent chemical corrosion resistance, abrasion resistance, and fouling resistance. It can maintain stable oil rejection and water flux even after 100 cycles separation for machine oil–water mixture, or after 300 days immersion in artificial seawater, or after 15 days immersion in corrosion acidic or alkaline solutions. Furthermore, the modified mesh exhibit impressive abrasion resistance that keep oil rejection >99% after 80 m abrasion under 1000 g. These excellent performances of the modified mesh are further explained from the special texture of twill woven stainless‐steel mesh and the formed water film due to its superhydrophilicity.