Good Protective Properties Research Articles

Graphene/polyaniline waterborne composite coatings for metallic bipolar plates

Waterborne composite coatings were formulated for protection of metallic bipolar plates. The challenges lied in two aspects, one was the confliction between high electrical conductivity and good corrosion protection properties; the other was the water dispersibility of the constituent phases. Water-solubility of polyaniline (PANI) were controlled by adding polystyrene sulfonic acid during the polymerization of aniline. Graphene was functionalized by p-aminobenzoic acid and p-phenylenediamine to enhance the compatibility with PANI, while keeping the electrical conductivity of graphene at around 169 S/cm. Upon in-situ polymerization of the functionalized graphene/PANI composites, the electrical conductivity varied significantly from 41 S/cm to 91 S/cm with the surface functionality of graphene. The composite coatings were prepared thereafter with functionalized graphene/PANI/carbon black on the surface of 316 L stainless steel by centrifugal spraying coating. The interfacial contact resistance of the coatings reached 4 mΩ·cm2, comparable to Au coatings, but the corrosion current density was 4.37 μA/cm2 due to the existence of the hydrophilic groups in waterborne coatings, like amino groups and sulfonic acid groups. A post-treatment was carried out to consume some of the amino groups, so that the corrosion current density was decreased to 0.88 μA/cm2.

Application of bio-based modified graphene oxide in epoxy composite coatings

This study focuses on the application of bio-based modified graphene oxide epoxy composite coatings and analyzes the coating properties, such as anticorrosive ability, hydrophobicity and self-healing properties, through experimental studies of modified graphene oxide using substances such as cashew nut phenol, lignin and glutamic acid. Summarizing the latest research progress, it is found that the materials such as cardanol, lignin and glutamic acid are from a wide range of sources, are green and have a wide range of application prospects, and it is also shown in the results of EIS analysis that the modified graphene oxide epoxy compliant coatings exhibit higher impedance values at low frequencies, and have good protective properties and barrier properties. The cashew phenol-modified graphene oxide epoxy coating has high densification, high barrier capacity and high hydrophobicity in addition to good coating healing ability using GO modification. The glutamate-modified graphene oxide epoxy coating can be desorbed by using HCL solution to make L-Glu/GO reusable, with good reusability and high application value.

Environmental Dyeing and Functionalization of Silk Fabrics with Natural Dye Extracted from Lac.

Most traditional synthetic dyes and functional reagents used in silk fabrics are not biodegradable and lack green environmental protection. Natural dyes have attracted more and more attention because of their coloring, functionalization effects, and environmental benefits. In this study, natural dyes were extracted from lac and used for coloring and functionalization in silk fabrics without any other harmful dyes. The extraction conditions were studied and analyzed by the univariate method. The optimal extraction process was that the volume ratio of ethanol to water was 60:40 with a solid-liquid ratio of 1:10, and reacting under the neutrality condition for 1 h at 70 °C. Silk fabric can be dyed dark owing to the certain lifting property of lac. After being dyed by Al3+ post-medium, the levels of the washing fastness, light fastness, and friction fastness of silk fabric are all above four with excellent fastness. The results show that the dyed silk fabrics have good UV protection, antioxidation, and antibacterial properties. The UV protection coefficient UPF is 42.68, the antioxidant property is 98.57%, and the antibacterial property can reach more than 80%. Therefore, the dyeing and functionalization of silk fabrics by utilizing naturally lac dyes show broad prospects in terms of the application of green sustainable dyeing and functionalization.

Investigation on dynamic deformation behavior of 7A75 aluminum alloy over wide strain rates and constitutive model establishment

The aluminum alloy components on automobile often experience high strain rate deformation during accidents. The dynamic deformation behavior and constitutive model are crucial for analysis of vehicle body collisions and failures. In this work, the 7A75 aluminum alloy plate was heat treated according to standard body manufacturing procedures. Quasi-static and dynamic tensile experiments were conducted on the aged 7A75 alloy in a wide strain rate range from 0.001 s−1 to 500 s−1. The dynamic deformation behavior of the alloy was revealed, and the constitutive models were established. It was found that the 7A75 alloy has strong strain rate sensitivity, and its mechanical properties can be significantly improved with the increase of strain rate. As the strain rate increases, the necking instability strain shifts towards higher values, which leads to a larger uniform deformation ability and fracture elongation. This behavior results in a better energy absorption capacity at high strain rates, thus providing a good collision protection property. The constitutive models, including Johnson-Cook (J-C) and Zerilli-Armstrong (Z-A) types, were established and compared. Note that the conventional J-C and Z-A models exhibit severe prediction distortion. Therefore, a modified J-C model incorporating strain rate compensation was introduced, which decrease the errors by 149% and achieves accurate predictions of both dynamic and static deformation behaviors over a wide range of strain rates.

Preparation and Properties of Cotton Fabric Photocatalyzed by Ag-Doped Madder-Sensitized TiO2

In this study silver nanoparticles (NP) were grown in-situ on the surface of madder-sensitized TiO2 by an in-situ reduction method using silver nitrate as a silver source and a honeysuckle extract as a reducing agent. Silver doped madder-sensitized TiO2 nanoparticles were then prepared, supported on the surface of cotton fabrics to prepare photocatalytic cotton fabrics with high-efficiency self-cleaning properties and excellent antibacterial properties. transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses showed that elemental Ag NPs were deposited on the surface of the madder-sensitized TiO2, and that Ag-doped madder-sensitized TiO2 NPs were successfully loaded on the cotton fabric surface. The results of UV-Visible diffuse reflectance spectroscopy (UV-Vis-DRS) and Photoluminescence Spectroscopy (PL) showed that Ag-doping could further reduce the band gap of madder-sensitized TiO2 than pure TiO2. The absorption of light in the photocatalytic system was increased, and the recombination of electron-hole pairs was effectively inhibited. Compared with madder-sensitized TiO2 photocatalyzed cotton fabric, the degradation rate of nano-Ag-doped madder-sensitized TiO2 photocatalytic cotton fabric for methylene blue (MB) was increased by 10.66% within 2 h, and the degradation process was in line with the first-order reaction kinetic model. After 5 times of washing, the photocatalytic cotton fabric still had excellent photocatalytic performance. Its antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 100 and 99.99%, respectively. In addition, it had good wrinkle resistance and UV protection properties, but the cross-linking modification reduced the breaking strength by about 14%.

A novel modified polydopamine based on melanin-like materials for antibacterial, hydrophobic, and ultraviolet protective of textiles

The development of environmentally friendly multifunctional auxiliaries for textile modification is the focus of attention in textile industry in recent years. Polydopamine is an important biological macromolecule and widely used in biomedicine, nanomaterials, material surface modification and other fields. In this study, the novel multifunctional melanin-like nanoparticles (Nha-PDA NPs) were prepared and used for antibacterial, hydrophobic, and UV protective of textiles. Nha-PDA NPs were prepared with dopamine (DA) and n-hexylamine (Nha) by simple autoxidation copolymerization. Nha-PDA NPs were bound to the fabric surface through the PDA structure in Nha-PDA NPs that has been widely confirmed to have strong adhesion on the surface of many materials. The modified fabrics, Nha-PDA NPs@Cotton, had good hydrophobic, antibacterial and UV protective properties. The static water contact angles of the modified fabrics could reach 120°. The antibacterial rates of Nha-PDA NPs@Cotton against E. coli and S. aureus were above 85 %. The maximum UPF value of the modified cotton was 362, indicating that the ultraviolet protection performance was excellent. The fabric modified with multifunctional melanin-like nanoparticle provides a green way for the multifunctional modification of textiles.

Effect of substrate microstructure on corrosion resistance of cast and forged anodised 6082 Al alloy

This work addresses the effect of the surface morphology of a 6082-aluminium alloy on the characteristics of the anodic layer generated by an anodising process using two current densities. The samples tested were horizontal direct chill (HDC), vertical direct chill (VDC) cast billets, and the same material after forged + T6 ageing treatment. Samples were anodised in a mixed citric acid‑sulphuric acid electrolyte using 0.5 A⋅dm−2 and 1.5 A⋅dm−2. D.C. current densities. The protective character of the oxide layer was studied by electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl solution.Microstructural characterisation revealed that the microsegregation and forging processes have a significant effect on the growth of the oxide layer as well as on the optimum anodising conditions. The EIS study showed that the corrosion protection provided by the oxide layer on Al6082 alloy was strongly affected by the manufacturing process, with thinner oxide layers obtained for cast billets. Heat treatment and forging homogenise the microstructure, which positively affects anodising and modifies the growth rate and thickness of the oxide layer. This effect makes obtaining a thicker oxide layer with good corrosion protective properties possible by using lower current densities for forged samples.

COMPOSITE MATERIALS BASED ON ELASTOMER, CO-ОLIGOMER AND BITUMEN

Chemical modification of phenyl-formaldehyde oligomers (PFO) was carried out, and compositions based on elastomer, co-oligomer and bitumen were developed in order to achieve significant improvement of characteristics and expand the areas of PFO application. The phenol-formaldehyde oligomer was modified with carbamide by co-polycondensation in an alkaline medium. The basic physicochemical, physical-mechanical and performance characteristics of the co-oligomer were studied. The co-oligomer of the new composition, obtained at the first stage of the investigation, was used as a binder. At the second stage of investigation, a three-component composition was developed on the basis of elastomer, co-oligomer and bitumen, and a composite material was prepared. This material was shown to exhibit good protective properties, and it may be recommended to provide anti-corrosive protection of the equipment and installations in oil and gas mining industry. The effect of the amounts of introduced components on the major characteristics of the resulting composition was studied. It is shown that the introduction of a nitrogen-containing modifier (carbamide) into PFO causes a decrease in the content of free phenol and formaldehyde, which is important both from the environmental viewpoint and in relation to the hazardous action of these components on the human organism.

Protective and Tribological Properties of Sulfonate Greases

The protective properties and temperature resistance of sulfonate greases based on petroleum oil KS-19 have been assessed. Highly alkaline calcium sulfonates of Russian and foreign production are used as thickeners for such greases. Sulfonate greases have been shown to have good protective properties. It has been established that the ability of sulfonate greases to prevent corrosion depends on the protective properties of calcium sulfonate used as a thickener. Based on the totality of the indicators obtained, the grease based on the Russian-made K-314 thickener has the best properties; in temperature resistance, it is superior to the sample on the foreign thickener Lubrizol 86 GR, and in terms of protective properties, it is on the same level with it.

Physical-chemical properties of fungicides applied for protection of cereals against diseases in Belarus

Physical and chemical properties of fungicides applied for protection of cereals against diseases in Belarus and their mobility in plant tissues are analyzed. The main properties allowing to predict plant mobility of fungicides are water solubility, lipophilicity (partition coefficient – LogP), and dissociation constant (pKa). The higher partition coefficient in nonpolar molecules, the higher are their nonsystemic (contact) properties, and vice versa. For polar molecules, the lower dissociation constant, the higher their mobility in plants. Information of fungicides plant mobility allows to understand their action on pathological process. In nonsystemic (contact) molecules with high LogP have affinity to wax layer of cuticle. Therefore they have good protection (prevention) properties because of their ability to prevent spores germination. Molecules with acropetal properties have good curative action because of their mobility in xylem away from application site. Therefore they may prevent mycelium development after its penetration in plant tissues.

Enhancement of the Functional Performance of Cotton and Polyester Fabrics upon Treatment with Polymeric Materials Having Different Functional Groups in the Presence of Different Metal Nanoparticles.

This work examined the functional properties of three different treated fabrics, cotton, polyester, and cotton/polyester, with different polymeric materials (polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), or chitosan) in the presence and absence of two synthesized metal nanoparticles to impart and enhance fabric properties. Both metal nanoparticles (silver nanoparticle (AgNPs) and Zinc oxide nanoparticles (ZnONPs)) were synthesized using Psidium guajava Leaves and characterized using different techniques. The different treated fabrics were dyed with Reactive Dye (Syozol red k-3BS) and evaluated for their color strength, fastness properties, ultraviolet protection, antimicrobial activity, and mechanical properties. Results showed that treatment with polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), or chitosan enhances the functionality of all fabrics, with improved color strength, UV protection, and antimicrobial properties. Additionally, mechanical properties were slightly increased due to the creation of a thin film on the fabric surface. All dyed treated fabrics showed good ultraviolet protection and antimicrobial properties. The K/S of all treated textiles including nanoparticles and polymers was marginally greater than that of the treated materials without polymers. The UPF values demonstrate that the three investigated polymers and both metal nanoparticles enhance the fabrics' ability to block UV radiation and shield people's skin from its damaging effects. All treated textiles had UPF values that are higher than those of untreated textiles. Further research demonstrates that ZnONP-treated textiles exhibited greater UPF values than AgNP-treated textiles when the polymer component was present. Antibacterial examination demonstrated that treated materials had robust microbial resistance. This resistance is diminished by washing, but still prevents bacterial growth more effectively than untreated textiles.

Therapy of mitochondria-targeted hybrid nanozymes for reactive oxygen species-induced diseases

The development of enzyme mimetics that clear excess mitochondrial reactive oxidative stress (ROS) could provide effective treatment for a wide variety of diseases. Herein, nanomaterials were used to create artificial hybrid nanozymes. These nanozymes are composed of metal nanoparticle cores that act as centers of enzymatic activity and modifications for mitochondrial targeting capabilities. The artificial nanozyme possesses both catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx)-like properties. In spite of low doses, it exhibits cytoprotective properties against ROS-mediated damage and significantly enhances therapeutic effects after acute spinal cord injury (SCI), acute colitis, collagen induced arthritis (CIA), and obesity. Moreover, this artificial nanozyme ensures biocompatibility. This study demonstrates good biocompatibility and protective properties of this artificial nanozyme, which will facilitate recovery from ROS-related diseases and lay the groundwork for future development of nanozyme.

Development of BioPolyurethane Coatings from Biomass-Derived Alkylphenol Polyols-A Green Alternative.

Bio-based polyols were obtained from the thermochemical liquefaction of two biomass feedstocks, pinewood and Stipa tenacissima, with conversion rates varying between 71.9 and 79.3 wt.%, and comprehensively characterized. They exhibit phenolic and aliphatic moieties displaying hydroxyl (OH) functional groups, as confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. The biopolyols obtained were successfully employed as a green raw material to produce bio-based polyurethane (BioPU) coatings on carbon steel substrates, using, as an isocyanate source, a commercial bio-based polyisocyanate-Desmodur® Eco N7300. The BioPU coatings were analyzed in terms of chemical structure, the extent of the reaction of the isocyanate species, thermal stability, hydrophobicity, and adhesion strength. They show moderate thermal stability at temperatures up to 100 °C, and a mild hydrophobicity, displaying contact angles between 68° and 86°. The adhesion tests reveal similar pull-off strength values (ca. 2.2 MPa) for the BioPU either prepared with pinewood and Stipa-derived biopolyols (BPUI and BPUII). Electrochemical impedance spectroscopy (EIS) measurements were carried out on the coated substrates for 60 days in 0.05 M NaCl solution. Good corrosion protection properties were achieved for the coatings, with particular emphasis on the coating prepared with the pinewood-derived polyol, which exhibited a low-frequency impedance modulus normalized for the coating thickness of 6.1 × 1010 Ω cm at the end of the 60 days test, three times higher than for coatings prepared with Stipa-derived biopolyols. The produced BioPU formulations show great potential for application as coatings, and for further modification with bio-based fillers and corrosion inhibitors.

Effect of Phosphorus and Chlorine Containing Plasticizers on the Physicochemical and Mechanical Properties of Epoxy Composites

The possibility of using tris(2-chloroethyl) phosphate, tris(1-chloro-2-propyl) phosphate and tris(4-methylphenyl) phosphate as effective plasticizers for epoxy polymers has been studied. As a result of the research the optimum content of plasticizers (40 parts by mass) has been determined, which has the best effect on the strength and fire safety properties of epoxy composites. Modification of the epoxy polymer with presented plasticizers influences carbonization process increasing char yield and reducing the amount of volatile thermolysis products released into the gas phase, thus improving fire safety parameters of epoxy composites, reducing mass loss on ignition in air from 78 to 2–9% and increasing limiting oxygen index (LOI) values from 19 to 25–31% by volume, giving good fire protective properties to epoxy composites (UL-94 rating—V-0/V-1). The thermo-protective properties and the structure of the char formed by polymer combustion have been studied and the correlation between the thermo-protective properties of the char and the combustibility of the composite has been determined. Furthermore, the behaviour of the modified composite during high rate pyrolysis has been analyzed.

Corrosion-resistant coating on AZ91D magnesium alloy based on one-step hydrothermal

ABSTRACT Magnesium alloys are widely used due to their excellent properties, but their corrosion resistance is limited by their high chemical activity. This paper proposes a one-step hydrothermal method with a relatively short reaction time and simple experimental steps for synthesising magnesium alloy coatings with good corrosion protection properties. The surface morphology, chemical composition and corrosion resistance of the in situ generated coatings were investigated using measurements such as field emission scanning electron microscopy (SEM), adhesion cross-cut tape (ACCT) test, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), electrochemistry and immersion test, the results revealed that the corrosion current density (Icorr) of the coatings decreased by approximately four orders of magnitude and had good corrosion resistance.

Gelatin/poly(vinyl alcohol)-based functional films integrated with spent coffee ground-derived carbon dots and grapefruit seed extract for active packaging application

Nanoparticles are attractive, functional additives with great potential to be applied in biomaterial and food packaging. However, these particles are not soluble in water, thus limiting their widespread application. Here, we report a facile fabrication of carbon dots (CDs) using the spent coffee ground as the carbon source through a hydrothermal method. The CD was added to the gelatin/poly(vinyl alcohol) (Gel/PVA) film and grapefruit seed extract (GSE) to prepare multifunctional packaging films. The functional films' physiochemical and functional properties and packaging application were investigated. The composite film showed good UV protection properties with a slight decrease in transparency. The composite film containing CD/GSE showed strong antioxidant activity, scavenging >38 % DPPH and 100 % ABTS radicals. The film also exhibited significant antibacterial activity against the foodborne pathogens Listeria monocytogenes and Escherichia coli, completely eradicating the growth of these bacteria within 9 h of exposure. The CD/GSE-incorporated Gel/PVA films were used for pork packaging. The films were able to enhance the pork shelf life by reducing the L. monocytogenes bacterial growth in meat by 2 Log CFU/mL lower than the control wrapping film. The multifunctional Gel/PVA films are expected to be used for the active packaging of meat products.

Electrochemical and Economic Analysis of No-Rinse, “True-Cr-Free” Surface Conversion Coatings for a Green, Cost-Saving, Corrosion Protection of 8079 Aluminium Alloy

Increasing the corrosion resistance of aluminium alloys using surface treatments while reducing the processes’ environmental impact and saving natural resources has become an urgent need. Some companies that typically use pollutant substances in their process lines have started to test low-environmental-impact products. This paper shows the results obtained using two commercial products for the conversion coating of AA8079 rolled-samples: the first, rinse, containing CrIII (the so-called “Cr-free” products), the second one, no-rinse, utterly free of Cr, based on hexafluorotitanate and dihydrogen hexafluorozirconate. The bare conversion-coated, and organic-coating-covered samples were compared with each other, evaluating their corrosion resistance when immersed in NaCl 3.5 wt.% aqueous solution. The experimental results showed that the completely Cr-free no-rinse conversion coatings demonstrate performance comparable to that of the so-called “Cr-free”. In addition, a comparison of the amount of water used in the “rinse” and the “no-rinse” industrial process is reported. Finally, an estimation of the economic balance for the process is presented, considering the waste reduction to be disposed of and the water quantity used. The aim of this paper was to demonstrate that some commercial conversion-coating products, completely free of Cr and no-rinse, are available nowadays, showing good protective properties and low environmental-impact, while guaranteeing an economic saving which is not negligible.

Dyeing of curcumin and durable press finishing with citric acid on cotton fabric using one step process

Cotton is an affordable and durable option for clothing. However, cotton garments tend to wrinkle easily. Therefore, cotton fabrics were studied to improve their wrinkle resistance properties. In this work, curcumin was mixed in an aqueous solution of citric acid and its catalyst and applied to cotton fabric using pad-dry-cure process for both the dyeing and finishing properties. Aloe vera extract and chitosan were used to compare for the reaction of their functional groups with carboxyl groups of citric acid on cotton fabrics. The mixture of curcumin and citric acid solution showed anti-wrinkle properties on the treated cotton. There were no functional groups of curcumin detected on the FTIR spectrum of the fabric. Furthermore, acetyl group of chitosan and methyl in acetyl group of aloe vera extract were found on the spectra of the fabrics treated with each compound. It was also found that the treated fabric showed good UV protection properties and good antibacterial gram-positive properties. This fabric has physical potential to be used for healthcare, hygiene and medical textile products.

Sulfasalazine-loaded nanoparticles for efficient inflammatory bowel disease therapy via ROS-scavenging strategy

Inflammatory bowel disease (IBD) is a life-threatening organ dysfunction amplified by complex interactions between genetic, environmental, and immune factors. Sulfasalazine (Sul), an immunosuppressant, can potentially treat autoinflammation-induced disorders; however, clinical application of Sul is hindered by its inability to be directly taken up by cells. To address this challenge, we developed Mn doped prussian blue nanozymes (MPBs) to directly deliver Sul for targeting reactive oxygen species (ROS)-enriched microenvironment. The artificial nanozyme (Sul-MPBs) exhibits reactive oxygen species (ROS)-scavenging properties against hydrogen peroxide (H2O2)-mediated mitochondrial dysfunction and possesses both catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx)-like properties in vitro. Furthermore, it significantly enhances therapeutic effects in treating dextran sulfate sodium salt (DSS)-induced IBD via alleviating ROS-mediated inflammatory responses. This study demonstrates good biocompatibility and protective properties of this artificial nanozyme, thus potentially leading to a highly innovative and translational approach to treat IBD efficiently and safely.

КЕРАМИЧЕСКИЕ ИМПЛАНТАТЫ — БУДУЩЕЕ ДЕНТАЛЬНОЙ ИМПЛАНТОЛОГИИ

The subject of the study is the main properties of ceramic dental implants.
 Objectives. A systematic analysis of modern domestic and foreign literary sources to determine the main advantages of ceramic dental implants.
 Methodology. The study was based on the search and study of original articles on the dental implantology in the databases: Russian State Library, eLibrary, PubMed, The Cochrane Library, Google Scholar. The main selection of materials was carried out by keywords.
 Results. Currently, dental ceramic implants are attracting more and more attention from both dentists and patients. Every year, the clinical use of ceramic implants is becoming wider. Only in Europe every year there are 3 major congresses on ceramic implantology. In many countries, the number of associations dealing with this particular topic has increased, ceramic implants have unlimited potential for clinical use.
 Numerous studies show that the clinical use of zirconium oxide implants is practically not accompanied by manifestations of peri-implantitis, and gum epithelial tissues are able to firmly and reliably attach to their surface. Zirconium forms a dense ZrO2 dioxide film on the surface with good protective properties. Zirconia is bioinert to other materials found in the oral cavity and is particularly suitable for patients who are allergic or intolerant to metals. The latest materials and techniques, which include zirconium dioxide, have important advantages, and its use as dental implants significantly increases the clinical effectiveness of treatment. Therefore, when planning dental implantation, preference should be given to zirconia implants, which will avoid the development of a negative effect of treatment on both organs and tissues of the oral cavity, and the body as a whole.
 Conclusions. The review of literature sources on the effectiveness of ceramic dental implants showed evidence-based possibilities for the clinical use of this type of implants in modern dentistry.