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Rapid and facile self-assembly coatings play a crucial role in surface functionalization of materials. In this study, a safe, fast, and environmentally friendly method is proposed to form a metal-phenolic network (MPN) through the assembly of gallic acid (GA) and iron ions ([Fe.sup.3+]), which is used for the in situ polymerization coating of l,3,5,7-tetranitro-l,3,5-7-tetrazacyclooctane (HMX). The surface of the modified HMX crystals become visibly roughened. Thermoplastic polyurethane (TPU) was coated on the surface of modified HMX by water suspension method to form HMX@MPN@TPU double-layer core-shell energetic composite material. Compared with the raw material HMX, the [beta]-[delta] phase transition temperature of the double-layer core-shell structure composite increased by 12.36[degrees]C, the impact sensitivity and friction sensitivity decreased, and the compressive strength increased by 38%, which effectively improved its mechanical properties. Highlights * It has been demonstrated that metal-phenolic networks can self-assemble on the surface of crystals. * A water suspension method was employed to prepare energetic material powder into a polymer-bonded explosive (PBX). * The modified PBX showed significant improvements in various properties, indicating that metal-phenolic networks can serve as excellent modifying materials. KEYWORDS bilayer core-shell energetic composite, HMX, in situ polymerization method, metal-phenolic network, 1 | INTRODUCTION Energetic materials have the advantages of high energy density, high combustion speed, and high explosiveness, so they have attracted wide attention in the military field. (1-3) Among [...]

Polyester-urea coatings were synthesized from corn oil with the help of a series of reactions in three different compositions by varying the amount of urea. Out of all the synthesized compositions, the best composition was optimized based on various parameters. The optimized composition was used as a matrix and graphene oxide (GO) was incorporated in three ratios, for the formulation of corn oil-based CPEUr@GO nanocomposites. Fourier transform infrared spectroscopy was used to confirm all the reactions. The physico-mechanical properties of CPEU[r.sub.2] coating were found to be the best among all the compositions. Therefore, CPEU[r.sub.2] was selected as a matrix for the inclusion of GO nanosheets to prepare CPEU[r.sub.2]@GO nanocomposites. Thermogravimetric analysis results showed that incorporation of GO enhanced the thermal stability of CPEU[r.sub.2] up to 325[degrees] C. The anticorrosive studies revealed the high impedance value of 6.5 * [10.sup.5] [ohm].[cm.sup.2] in case of CPEU[r.sub.2]@G[O.sub.0.5]. Furthermore, it can be concluded that the inclusion of 0.5 wt% GO proved to be the optimized amount to produce sustainable CPEU[r.sub.2] coatings with good performance. These CPEUr@GO nanocomposite coatings can be used for various protective purposes owing to their excellent physico-mechanical thermal as well as anticorrosive performance. Highlights * Corn oil-based polyester-urea, CPEUr, coatings were synthesized in three different compositions. * The best composition was used as a matrix for the formulation of CPEUr@GO nanocomposites. * Graphene oxide of 0.5 wt% was found to be the optimum quantity required to modify CPEUr matrix. * Thermal stability, mechanical durability as well as corrosion resistance performances were enhanced. * The environment friendly approach is suitable for the development of corrosion protective coatings. KEYWORDS corn oil, graphene oxide, nanocomposites, polyurea, 1 | INTRODUCTION Polyurea (PUr) coating represents a recent advancement in the field of coating technology, within the realm of urethane coatings chemistry. (1) PUr coatings exhibit notable mechanical strength [...]

Shell materials play significant impact on corrosion resistance and mechanical properties on self-healing coating of composite with core-shell nanofiber. In this paper, three promising shell materials were investigated to optimize the performance of self-healing coating. Self-healing core-shell nanofibers with different shell materials were prepared with coaxial electrospinning. The resulting nanofibers were used to prepare self-healing corrosion resistance coating. The tensile test revealed a notable enhancement in the tensile strength of PA6 core-shell nanofiber epoxy composite coatings compared with the epoxy coating, demonstrating increase of 26.92%. Friction and wear test indicated reductions in the friction coefficients of PAN, PVDF, and PA6 core-shell nanofibers by 13.82%, 12.44%, and 26.27%, respectively. The self-healing and anti-corrosion abilities were evaluated through electrochemical impedance spectroscopy (EIS) test. All three coatings exhibited exceptional self-healing efficiencies exceeding 90%, highlighting the substantial potential of the chosen shell materials as nanocontainers for self-healing agent. Results indicate that the nanofibers with PA6 as shell material can achieve the best enhancement performance, which has a greater potential for the corrosion protection and long-lasting use of offshore wind turbine tower coatings. Highlights * Optimizing coating performance by screening coaxial nanofibers for shell materials * Shell material can improve the tensile strength of coating up to 26.92% * Friction coefficient of PA6 nanofiber coating was about 15% lower than PAN and PVDF * All three coatings exhibited exceptional self-healing efficiencies exceeding 90% KEYWORDS coating, core-shell nanofibers, mechanical properties, self-healing, shell material, 1 | INTRODUCTION Offshore wind turbine towers are easy to be corrosive under high humidity and high salt spray marine environments. (1) Application of anti-corrosion coating with self-healing ability is [...]

We propose an approach to the construction of generalized boundary conditions of radiant-convective heat exchange of bodies with the ambient medium through nonplanar multilayer coatings. This approach is based on the use of the exact heat-conduction equation in the coating layers and the expansion of the temperature function in a power series with respect to the coordinate directed along the normal to the body-coating interface. We obtain some computational versions of the generalized boundary conditions valid with different accuracies. We also deduce the formulas for the reconstruction of temperature distributions across the thickness of the coating in terms of the boundary values of temperature and its derivative in the body. Keywords: heat conduction, thin coating, multilayer coating, generalized boundary conditions, radiant-convective heat exchange., Introduction The construction of generalized boundary conditions (GBC) for the problem of heat exchange of the bodies with the ambient medium through thin coatings was considered in numerous works [1, [...]

Pipelines in the offshore sector make common use of polypropylene (and other polymer) coating systems to protect the infrastructure and provide thermal insulation. High pressure high temperature pipelines are subject to large axial loads due to restraint by seafloor soils of thermal strains in the pipe wall. Friction between pipe coating material and seafloor soil plays a defining role in the build-up of axial stress and the formation of lateral buckling. Accurate quantification of pipe-soil interface friction is key to robust pipeline stability design and possibilities to enhance or manipulate the friction coefficient may be attractive to designers. An extensive campaign of soil and interface tests using a range of granular materials and polypropylene surface specimens engineered to achieve varying surface textures was carried out. The results show that interface friction primarily depends on stress level and the magnitude of the surface texture in relation to the particle size. Herein, a new relative texture parameter, [T.sub.a], is developed that, unlike alternative relative roughness parameters, can be obtained using conventional profilometry measurement techniques. An expression for estimating the friction coefficient in relation to texture and stress level is proposed that can serve as a useful predictor of pipe-soil interface friction. Key words: interface friction, laboratory tests, pipes and pipelines, direct shear, polymer, sand. Les pipelines du secteur offshore utilisent couramment des systemes de revetement en polypropylene (et autres polymeres) pour proteger l'infrastructure et assurer l'isolation thermique. Les pipelines a haute pression et haute temperature sont soumis a des charges axiales importantes en raison de la retenue par les sols du fond marin des contraintes thermiques dans la paroi du tuyau. Le frottement entre le materiau de revetement des tuyaux et le sol du fond marin joue un role determinant dans l'accumulation des contraintes axiales et la formation du flambage lateral. La quantification precise du frottement de l'interface tuyau-sol est la cle d'une conception robuste de la stabilite des pipelines et les possibilites d'ameliorer ou de manipuler le coefficient de frottement peuvent etre interessantes pour les concepteurs. Une vaste campagne d'essais de sol et d'interface utilisant une gamme de materiaux granulaires et des specimens de surface en polypropylene concus pour obtenir differentes textures de surface a ete menee. Les resultats montrent que le frottement d'interface depend principalement du niveau de contrainte et de l'importance de la texture de surface par rapport a la taille des particules. Un nouveau parametre de texture relative, [T.sub.a], est developpe qui, contrairement aux autres parametres de rugosite relative, peut etre obtenu en utilisant les techniques de mesure de profilometrie conventionnelles. Une expression permettant d'estimer le coefficient de frottement en fonction de la texture et du niveau de contrainte est proposee, qui peut servir de predicteur utile du frottement de l'interface tuyau-sol. [Traduit par la Redaction] Mots-cles : friction d'interface, essais en laboratoire, tuyaux et canalisations, cisaillement direct, polymere, sable., 1. Introduction Offshore pipelines undergo significant changes in effective axial stress between their as-laid condition and their operational state caused by variations in pipe temperature and internal pressure, typically in [...]

A procedure is developed for the separate determination of the Sn(II) and Sn(IV) in the range of 0.05-0.25 M in acidic aqueous and ethylene glycol solutions in the presence of Ni(II), Cu(II), F.sup.-, a surfactant (OS-20), and citric or oxalic acids. The direct iodatometric titration of Sn(II) is used before and after the reduction of Sn(IV) with aluminum. The procedure is applicable to the analysis of electrolytes for the deposition of tin and Ni-Sn and Cu-Sn alloys and can be used to monitor changes in the concentrations of Sn(II and IV) as a result of redox processes in electrolytes and the hydrolysis of tin compounds. The interfering effect of copper consists in the interaction of Cu(II) with Sn(II) and Al with the formation of Cu(I) ions, reacting with iodate ions, and is eliminated by the introduction of oxalic acid. The relative error in determining the concentration of tin in the absence of copper(II) ions and in the presence of other components does not exceed 2.2%, and in the presence of Cu(II) the error is 4.3%., Author(s): A. A. Kudaka [sup.1], M. G. Galuza [sup.2], T. N. Vorobyova [sup.1] [sup.2] Author Affiliations: (1) grid.17678.3f, 0000 0001 1092 255X, Faculty of Chemistry, Belarusian State University, , 220006, [...]

Salt fog originating from the offshore zone can easily accumulate in the semi-enclosed space (called the gridiron space) formed by the beams and slabs of a pile-supported wharf. Such accumulation can lead to the premature failure of the durability of the wharf's substructure. Previous works have mainly focused on material-level measures to eliminate the adverse effects of salt fog accumulation, such as the use of anti-corrosion concrete and anti-corrosion coatings, which could result in increased construction costs. In fact, salt fog can be extracted from a gridiron by natural ventilation in some cases, so it is important to examine the flow characteristics of the gridiron space. In this work, a numerical simulation was conducted with natural ventilation and auxiliary ventilation groups. The critical value of the shield ratio (defined as the height ratio of edge stringer to air inlet) that led to the weakest turbulence of airflow inside the gridiron was studied in the natural ventilation group. In addition, the effect of various configurations of vents was discussed; in accordance with the results, design recommendations were proposed to enhance the durability of a pile-supported wharf. Key words: piled beam-slab wharf, salt fog, gridiron space, ventilation. Le brouillard salin provenant de la zone extracotiere peut facilement s'accumuler dans l'espace semi-clos (appele espace-grillage, <>) forme par les poutres et les dalles d'un quai sur pilotis. Une telle accumulation peut entrainer la defaillance prematuree de la substructure du quai. Les travaux anterieurs ont principalement porte sur les mesures au niveau des materiaux visant a eliminer les effets nefastes de l'accumulation de brouillard salin, comme l'utilisation de beton anticorrosion et de revetements anticorrosion, ce qui pourrait entrainer une augmentation des couts de construction. En fait, le brouillard salin peut etre extrait d'une grille par ventilation naturelle dans certains cas, alors il est important d'examiner les caracteristiques d'ecoulement de l'espace-grillage. Dans le cadre de ces travaux, une simulation numerique a ete effectuee avec des groupes de ventilation naturelle et auxiliaire. La valeur critique du rapport de protection (definie comme le rapport de hauteur de poutre de bord a l'entree d'air) qui a conduit a la turbulence la plus faible du flux d'air a l'interieur de l'espace-grillage a ete etudiee dans le groupe de ventilation naturelle. De plus, on a discute de l'effet des diverses configurations des events; conformement aux resultats, des recommandations de conception ont ete proposees pour ameliorer la durabilite d'un quai sur pilotis. [Traduit par la Redaction] Mots-cles: quai en dalles sur pilotis, brouillard salin, espace-grillage (<>), ventilation., 1. Introduction With the rapid development of economic globalization, harbors play a significant role in the commodity trade as the center of the global modern transportation system. Considering the importance [...]