Influence Of Polymer Coatings Research Articles

Influence of Polymer Coatings on the Mechanical Properties of Steel Samples in Tensile and Bending Tests

: An experimental and theoretical study of the effect of polymer coatings on an epoxy-polyester base on the mechanical properties of samples in the form of steel plates has been carried out. It is shown that, despite the fact that the thickness of the coatings is only 100 μm, they have a significant effect on the mechanical properties of plates up to 1,5 mm thick, leading to a decrease in Young's modulus, tensile strength and ultimate deformations of the samples. It was shown that the elastic modulus of the coated plate cannot be determined unambiguously from tests for central tension and three-point bending. In bending tests, there is a more significant reduction in plate stiffness compared to tensile tests. This effect is confirmed by calculations within the framework of classical models of the theory of elasticity.

Влияние полимерных покрытий на обледенение судовых конструкций

Полимерные покрытия находят все более широкое применение в судостроении и судоремонте. Этому способствует многообразие полимерных покрытий с различными свойствами. Одним из распространённых требований, предъявляемым к корпусным конструкциям морских судов является необходимость обеспечения их безотказной работы в условиях воздействия отрицательных температур окружающей среды. При интенсификации процессов обледенения возможно возникновение аварийных ситуаций. В статье рассмотрены различные аспекты влияния полимерных покрытий на обледенение судовых корпусных конструкций. Приведены экспериментальные зависимости адгезии льда к металлу и полимерам от солености воды, от величины шероховатости. Установлено, что изменение шероховатости поверхностей и соленость воды существенно влияют на адгезию полимерных покрытий ко льду. Выявлены клеевые композиции, обеспечивающие полимерным покрытиям наименьшую адгезию ко льду. Исследования позволяют дать рекомендации по совершенствованию методов ремонта и модернизации судовых корпусных конструкций. Polymer coatings are increasingly used in shipbuilding and ship repair. This is facilitated by the variety of polymer coatings with different properties. One of the most common requirements for marine hull structures is the need to ensure their trouble-free operation under the influence of negative environmental temperatures. With the intensification of the processes of icing possible the occurrence of accidents. The article deals with various aspects of the influence of polymer coatings on the icing of ship hull structures. Experimental dependences of ice adhesion to metal and polymers on water salinity and roughness are presented. It was found that changes in surface roughness and water salinity significantly affect the adhesion of polymer coatings to ice. Adhesive compositions that provide polymer coatings with the lowest adhesion to ice are identified. The research makes it possible to give recommendations for improving the methods of repair and modernization of ship hull structures.

Polymer-Coated Cerium Oxide Nanoparticles as Oxidoreductase-like Catalysts.

Cerium oxide nanoparticles have been shown to mimic oxidoreductase enzymes by catalyzing the decomposition of organic substrates and reactive oxygen species. This mimicry can be found in superoxide radicals and hydrogen peroxides, which are harmful molecules produced in oxidative stress-associated diseases. Despite the fact that nanoparticle functionalization is mandatory in the context of nanomedicine, the influence of polymer coatings on their enzyme-like catalytic activity is poorly understood. In this work, six polymer-coated cerium oxide nanoparticles are prepared by the association of 7.8 nm cerium oxide cores with two poly(sodium acrylate) and four poly(ethylene glycol) (PEG)-grafted copolymers with different terminal or anchoring end groups, such as phosphonic acids. The superoxide dismutase-, catalase-, peroxidase-, and oxidase-like catalytic activities of the coated nanoparticles were systematically studied. It is shown that the polymer coatings do not affect the superoxide dismutase-like, impair the catalase-like and oxidase-like, and surprisingly improves peroxidase-like catalytic activities of cerium oxide nanoparticles. It is also demonstrated that the particles coated with the PEG-grafted copolymers perform better than the poly(acrylic acid)-coated ones as oxidoreductase-like enzymes, a result that confirms the benefit of having phosphonic acids as anchoring groups at the particle surface.

ИЗМЕНЕНИЕ ПЕРЕКИСНОГО ОКИСЛЕНИЯ ЛИПИДОВ В ЯБЛОКАХ ПРИ ХРАНЕНИИ В ЗАВИСИМОСТИ ОТ НАНЕСЕННОГО ПОКРЫТИЯ

The article is devoted to the processes occurring in cells of pome fruits, particularly in pomological apples, such as Jonathan and Reinette Simirenko. The membrane damage is the most likely reason of irreversible defects in the cell, which can be characterized by the level of lipid peroxidation (LPO). Thus, LPO can serve as an integral indicator of the physiological state of fruit tissues, as well as an indicator of availability of membrane components for hydrolytic enzymes. This in turn can cause a change of compartmentation of enzymes of phenolic and peroxide metabolism, which stipulates the existing shifts in tissue metabolism. LPO has been determined by photometry of a colored complex with an absorption maximum at 520 nm appearing during the interaction of thiobarbituric acid (TBA) and malondialdehyde (MDA) formed during the oxidation of unsaturated fatty acids. The paper presents the research results on the influence of polymer coatings on the level of lipid peroxidation (LPO) in biomembranes, isolated from the examined apples. It is shown that the coating applied to the surface of apples, due to the reduction of oxygen supply to the tissues, slows down oxidation processes, including the formation of LPO. The use of the studied options of coating is accompanied by a decrease in the level of LPO and the formation of unsaturated components with a shorter chain: myristic and palmitic acids. The polymer coating on the surface of apples allows you to preserve the structural integrity of fruit tissues. Polymer coatings also slow down fluctuations in the concentration of unsaturated free fatty acids compared to a check sample. The apples processed with polymer coatings retain for a long period of time inherent appearance, color, consistency and flavor.

Interaction of Densely Polymer-Coated Gold Nanoparticles with Epithelial Caco-2 Monolayers

We synthesized a library of polymer-coated gold nanoparticles (AuNPs) with well-defined sizes (5, 10, and 20 nm) and surface properties, and investigated their efficiency to cross the Caco-2 epithelial barrier and disrupt tight junctions connecting the cellular barrier. The positively charged and hydrophobic polymer-coated AuNPs showed little or no translocation across the model Caco-2 monolayer. Most of these positive and hydrophobic nanoparticles were either bound to the surface or internalized within the cell. The neutral and negatively charged polymer-coated AuNPs with a size of 5 nm showed a significantly higher translocation. All polymer-coated AuNPs induced the translocation of small molecules across the cellular monolayer, suggesting the loosening of the paracellular tight junction joining individual cells. The decrease in the TEER values of the monolayers supported the opening of the tight junctions. These tight junctions fully recovered for most polymer-coated AuNPs 12 h after removal of the nanoparticles. The exception was the cationic polymer-coated AuNPs in which the barrier function only recovered up to 62%. The library of polymer-coated AuNPs showed no apparent signs of hemolysis to erythrocytes at physiological pH. Our investigation has provided insight on the influence of polymer coatings on the epithelial barrier.

Influence of polymer coatings on water uptake and germination of onion ( Allium cepa L. cv. Aki) seeds before and after storage

The purpose of this work was to test the effect of different polymer coating materials on water uptake (imbibition and water vapour uptake) and germination performance before and after storage of onion seeds. Coating the seeds with hydrophobic polymers especially LS (linseed oil), PE (polyethylene), PVDC-1 (Daran 8600C) and VA (Vinamul 3240) reduced imbibition, but only PVDC-2 (Daran SL112) significantly reduced water vapour uptake. LS, PE and VA coatings significantly reduced germination before and after storage in 85% RH for 10 weeks at 25 °C. These polymers formed a hard film which appeared to form a physical barrier to primary root protrusion. Moisture contents after storage of untreated and coated seed were similar (between 13.0 and 13.3%), indicating that no coatings reduced water vapour uptake in storage. Guidelines for an appropriate experimental approach in the search for effective coatings to reduce water vapour uptake and increase storage life are discussed.

Influence of Polymer Coatings and Adhesion on the Mechanical Strength, Fatigue and Aging of Optical Fibers

AbstractThe influence of polymer coatings on the mechanical properties of optical fibers is reviewed. Current research is directed at the chemical mechanisms that contribute to mechanical strength degradation. In this review, a chemical kinetics model is applied to describe the influence of polymer adhesion on chemical corrosion of the glass fiber (i.e., its zero stress and stress assisted corrosion).