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The present investigation dealt with the flow behavior and processability of polylactic acid/polystyrene (PLA/PS) polymer blends using a capillary rheometer. For this purpose, PLA/PS blends with different ratios of the concentrations were prepared using a single screw extruder. The shear viscosity, shear stress, shear rate, power-law index, viscous activation energy at a constant shear stress, and elongational stress were determined. PLA/PS blends exhibited a typical shear-thinning behavior over the entire range of shear rates tested, and the viscosity values of the blends would tend to decrease with increasing amount of PLA. In addition, the polymer blend of 70 % PLA and 30 % PS was found to be relatively less sensitive to the processing temperature, implying that the extrusion process was more desirable for fabrication of PLA/PS polymer blend than the injection process. [ABSTRACT FROM AUTHOR]

Starch as an inexpensive and renewable source has been used as a filler for environmental friendly plastics for about two decades. In this study, glycerol was used as a plasticizer for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/polybutene-1(PB-1) blend. PB-1 was melt blended with TPS using a single screw extrusion process and molded using injection molding process to investigate the rheological and mechanical properties of these blends. Rheological properties were studied using a capillary rheometer, and the Bagley's correction was performed. Mechanical analysis (stress-strain curves) was performed using Testometric M350-10 kN. The rheological properties showed that the melt viscosity of the blend is less than that of PB-1, and the flow activation energy at a constant shear stress of the blend increases with increasing glycerol content in the blend. The mechanical experiments showed that both stress and strain at break of the blends are less than that of PB-1, whereas the Young's modulus of the most blends is higher than that of PB-1 which confirms the filling role of TPS in the blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

This work examined the influence of dual incorporation of MoO2 and SiO2 on the corrosion behavior of pure titanium treated via plasma electrolytic oxidation (PEO). To achieve this purpose, pure titanium substrate was treated via PEO in an alkaline-molybdate electrolyte without and with SiO2 nanoparticles. The microstructural observation revealed that the addition of SiO2 nanoparticles into the electrolyte during PEO helped to seal the structural defects in the PEO coating so that a rougher, thicker, and denser coating rich in SiO2 was successfully obtained. From the electrochemical measurements in a 3.5 wt.% NaCl solution, the TiO2-MoO2-SiO2 hybrid coating exhibited a higher corrosion resistance than the TiO2-MoO2 coating which was attributed to the sealing effect by stable SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Nano-hydroxyapatite (nHA)-matrix coatings containing graphene nanosheets (GNS)-nHA were coated on Ti6Al7Nb alloys by plasma electrolytic oxidation (PEO) treatment for the improvement of their surface properties. Crystallographic properties, functional groups, and elemental analysis of coatings were characterized by XRD, ATR–FTIR, and EDS analysis. Surface morphological changes of the coated surfaces were investigated by AFM and SEM. The electrochemical corrosion behavior of the coatings was examined by using the potentiodynamic scanning (PDS) tests under in-vitro conditions in simulated body fluid (SBF). The results showed that the GNS was successfully deposited in ceramic matrix coatings on Ti6Al7Nb alloys. Also, the microstructural observations revealed that the coatings have a porous and rough structure. The XRD and ATR–FTIR quantitative analysis have proved the appearance of HA and GNS in the coating layers. An increase in the coating thickness, surface hardness, and anatase/rutile transformation rate was determined, while the GNS ratio in the coating layers was increased. The microhardness of the nHA coating reinforced with 1.5 wt% GNS was measured at 862 HV, which was significantly higher than that of GNS-free (only nHA) coating (584 HV). The best in-vitro resistance to corrosion in SBF was observed in the nHA/1.5GNS wt% coating. [ABSTRACT FROM AUTHOR]

PEO coatings are formed by subjecting a metal substrate to an electrolytic plasma discharge, resulting in the formation of a porous and rough oxide layer. Herein, the significant role of the chemical composition of the electrolyte system and additives in the formation of an oxide coating on brass alloy in the PEO process was investigated. It was observed that the coating created with 8 g/l aluminate, 1 g/l NaOH, and 1 g/l KF electrolyte had higher homogeneity than other coatings. This is because a composite oxide coating of Cu 2 O, ZnO, and AlCuO 2 was formed. Methylene Blue (MB), a widely used dye in various industries, is known to be persistent and environmentally harmful. The photocatalytic activity of the PEO coating on brass for the removal of MB was investigated under visible light exposure. According to the results, the presence of the sample produced in an electrolyte containing 8 g/l Aluminate, 1 g/l NaOH, and 1 g/l KF resulted in a degradation rate of approximately 65 % for MB photodegradation after 6 h of irradiation. The PEO-coated brass shows promising photocatalytic efficiency compared to our research group's PEO-coated TiO 2 coatings, indicating its potential as a photocatalyst. The results highlight that PEO coating on brass could be a potential candidate for photocatalytic and photoelectrochemical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface modifications of Ti-based LDH enhanced photodegradation of dyes. • Incorporating metals and metal oxides improve Ti-LDH photocatalytic activity for dye degradation. • Co-precipitation and hydrothermal methods are commonly used to prepare Ti-LDH materials. • Developing new surface modifications to improve the photocatalytic performance of Ti-LDH is a promising area for future research. Due to their distinctive physical and chemical characteristics, two-dimensional semiconductor heterostructures of titanium-based layered double hydroxide (LDH) materials have appeared as potential photocatalysts for the degradation of dyes. LDH materials have several benefits, including morphological versatility, unique structural features, brucite light structure, ion exchange capabilities, homogenous metal cation distributions, and anion intercalation in interlayers. In particular, however, the photocatalytic activity of titanium-based LDH materials towards organic dyes would be limited because of the quick recombination of charges and inactivation under visible light (only 4% active in visible light). Therefore, in this study, we will summarize the current developments in surface modification of Ti-based LDHs for photocatalytic decomposition of contaminants in aqueous solutions. The typical synthesis techniques, namely the in-situ hydrothermal method, ion exchange method, and coprecipitation method will be highlighted. The surface modification of those materials by metals, metallic oxides, and other inorganic materials and their impacts on photocatalytic behavior will be discussed in terms of a specific area, energy band gap, pore size, porosity level, and Schottky barriers. Additionally, the photocatalytic mechanisms and absorption capacities, as well as future aspects of titanium-based LDH catalysts will be outlined. [ABSTRACT FROM AUTHOR]

• When lasers are used for PEO coating, the combined laser/PEO process exhibits superior corrosion and wear resistance compared to the standalone PEO process. • Laser surface processes, including LSM, LST, and DMLS, can markedly change the surface structure of PEO layer, thereby significantly improving the corrosion and wear resistance of Al-based alloys. • Following the laser treatment, there is a reduction in the size and number of pores on the surface of the coating. • The hybrid coatings demonstrate superior interfacial adhesion with little effect on the adjacent area because of heat. • The decrease in pores and defects in the laser/PEO coating can effectively hinder the corrosive electrolyte from penetrating the coating, thus improving the corrosion resistance. The inadequate resistance to corrosion and wear of Al-based alloys is a major hindrance to their extensive use. Plasma electrolytic oxidation (PEO), a common and efficient coating technique, creates an oxide coating similar to ceramic on the surface of Al-based alloys, thereby improving their ability to withstand corrosion and wear. Studies have shown that PEO treatment can significantly enhance the short-term corrosion and wear resistance of Al-based alloys. To improve the long-term corrosion resistance of PEO coatings, researchers are now exploring the combination of laser processes with the PEO process. Laser processing is a simple yet efficient technique known for its flexibility, precision, and control. Various laser procedures are recognized for their ability to improve the resistance to wear and corrosion of PEO coatings applied on Al substrates and their alloys. Laser melting procedures have the capability to standardize and modify the microstructure of aluminum-based alloys. This review focuses on enhancing the anti-corrosion and anti-wear properties of aluminum alloys through the integration of laser surface treatments with PEO technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • The impact of fluoride additives in Liquid PEO reviewed. • Varied fluoride types' effects on surface transformations explored. • Mechanisms such as passivation, hydrolysis, and oxide integration were examined. • Comprehensive review delves into PEO's fluoride-enhanced effects. Magnesium (Mg) alloys are lightweight materials with excellent mechanical properties, making them ideal for aerospace, automotive, and biomedical applications. However, their application is limited due to high susceptibility to corrosion, particularly in saline environments. Plasma electrolytic oxidation (PEO) is an effective method for enhancing the anti-corrosive properties of Mg alloys by forming protective oxide coatings. Despite these advantages, PEO coatings can suffer from limitations such as porosity, which compromises long-term protection. To address these issues, fluoride additives including F−, SiF 6 2−, ZrF 6 2−, TiF 6 2−, and AlF 6 3−, have been introduced into the PEO process. These additives significantly improve the anti-corrosive properties by forming MgF₂ and other stable metal oxide layers, which act as protective barriers. This review explores the effects and mechanisms of various fluoride additives in optimizing PEO coatings for Mg alloys, comparing their effectiveness in enhancing corrosion resistance and modifying surface morphology. It emphasizes the significance of fluorinated PEO in improving the performance and durability of coatings, providing valuable insights into optimizing coating processes for industrial applications. [ABSTRACT FROM AUTHOR]

Owing to the inherent properties of polymeric materials, such as excellent compressive strength, tensile strength, impact strength, coupled with adequate flexural strength, rigidity and young modulus, together with high dimensional stability, optimization of surface properties of metals with polymers has been the focus of extensive research in the past decade. Here, this review takes magnesium as a base material and focuses on discussing the advantages, shortcomings, and applicability of a variety of polymer coatings to modify the surface properties of anodic films produced by plasma electrolytic oxidation (PEO). The various methods used to fabricate polymer/ceramic composites are outlined, focusing on dip coating, electrophoretic deposition, spin coating, etc. Based on the experimental data and industrial applications, every polymer has been discussed with its unique structure and its distinctive impact on the surface characteristics of ceramics coatings by taking into accounts the following aspects, application site, biocompatibility, biodegradation rate, and anti-corrosion properties. Finally, current progress and challenges in the field of PEO/polymer composites are summarized to identify knowledge gaps and future research directions that help to achieve multifunctional materials suitable for massive-scale industries. • PEO/polymer coatings are outlined. • Effect of polymer type on the properties of PEO film is significant. • Applications of PEO/polymer coatings and future prospects are discussed. [ABSTRACT FROM AUTHOR]

Catalysts derived from Metal-Organic Frameworks (MOF) present a compelling blend of cost-effectiveness and superior performance in reduction reactions. In this study, polymer-decorated MOF-Cobalt (MOF-Co) was deposited onto porous magnesium oxide (MgO) layers, acquired through surface modification of AZ31 Mg alloy via plasma-assisted oxidation, with the aim of fabricating novel catalysts for reduction reactions. Herein, this synthesis involved the utilization of Cobalt-benzene dicarboxylic acid (Co-BDC), where cobalt ions served as metal nodes and 1,4-benzene dicarboxylic acid (H 2 BDC) functioned as an organic linker, with and without the presence of polyvinylpyrrolidone (PVP) as an active site enhancer. The morphology of the prepared catalysts was affected by several factors such as pH, hydrothermal treatment duration, PVP content, and the presence of a MgO layer. The optimal catalyst, designated as metal-organic frameworks-cobalt at 80 °C temperature and 1 h of hydrothermal treatment at pH 4 (MOF-Co 1.4), was synthesized on the MgO layer using a solution containing 1.7 g of PVP, H 2 BDC, and Co(NO₃)₂.6H₂O. The paper-like morphology of the MOF-Co 1.4 catalyst facilitated exceptional performance, efficiently degrading p-nitrophenol (p-NP) under visible light irradiation with an impressive 99.74 % efficiency within just 5 min of exposure, while also demonstrating stability over five successive cycles. ·O 2 − species was found to drive the reduction reaction to p-aminophenol, with harmless compounds as byproducts, while GC-MS analysis identified intermediates in the reduction of p-NP. Density functional theory (DFT) calculations suggested that H 2 BDC and PVP jointly provided multi-active sites, enabling effective contact with reactants and rapid electron transfer, thus playing a synergistic role in the catalytic reduction process. This study pioneers a novel method for designing efficient bulk catalysts, achieving high efficiency and stability in pollutant degradation with fast, low-energy fabrication. [ABSTRACT FROM AUTHOR]

In the present work we consider the AZ31 Mg alloy for applications as medical implants with bone contact. The alloy has the advantages that it combines a high strength with light weight. Most importantly, it eventually dissolves in the body environment and there is therefore no need to remove implants by additional surgery. However, this dissolution should not happen too fast in order to guarantee mechanical integrity during the healing process. This requires the application of appropriate composite coatings. In a first step, an inorganic protective layer is formed by plasma electrolytic oxidation (PEO) using an electrolyte which contains calcium glycerophosphate (CaGP). Special emphasis is placed on the effect of varying CaGP concentrations in the electrolyte, considering molar concentrations between 0.01 and 0.03 mol/l. In a second step, polymer coatings were applied on composite layers to find out whether the system properties can be further improved. Two types of polymer layers were developed using a spin coating method, based on the biodegradable polymer systems polycaprolactone and polyethylene glycol. The results obtained in the present investigation suggest that introducing CaGP into the electrolyte of plasma electrolyte oxidation induces a composite layer consisting of MgO and CaP compounds. The coatings developed in 0.02 mol/l CaGP electrolyte exhibit superior adhesion strength. A significant tenfold increase in corrosion resistance and the highest cell viability are observed on coatings developed in 0.02 mol/l CaGP electrolyte and then superimposed with PCL. These results suggest that a coating on AZ31, after PEO in an electrolyte with 0.02 mol/l CaGP and then superimposed with PCL, represents a promising candidate for applications as bio-absorbable bone implant material. The coated material by far outperforms the material with no surface treatment. • Introducing CaGP into the electrolyte of PEO results in a composite layer of MgO and CaP compounds. • Coatings developed in 0.02 mol/l CaGP electrolyte exhibit superior adhesion strength. • A significant tenfold increase in corrosion resistance of 2 CaGP is achieved by superimposing a PCL layer. • The highest cell viability is observed on coating developed in 0.02 M CaGP and then superimposed with PCL. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effectiveness of chromophoric organic compounds in modifying the surface of AZ31 Mg alloy using the plasma electrolytic oxidation (PEO) process. In particular, the study examines the deposition of cochineal extract and indigotin extract on PEO coatings and evaluates their impact on the morphology, structure, and properties of the resulting coatings. The PEO coatings were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), while the anti-corrosive properties were characterized by potentiodynamic polarization (POL) measurements. The results indicate that the deposition of chromophores of cochineal extract on PEO coatings leads to a smoother surface morphology, while indigotin deposition results in a partially sealed surface with large cracks. The combined solution of both the organic extracts results in a higher carbon content but does not effectively seal the surface, likely due to the formation of larger molecules that cannot fully penetrate the pores of the PEO coating. Overall, this study demonstrates the potential of chromophoric organic compounds for surface modification of Mg alloys and highlights the importance of careful selection and characterization of the post-treatment compounds. • Cochineal extract deposition leads to the complete sealing of the structural defects in PEO coating. • Indigotin extract deposition results in a partially sealed surface with large cracks. • Combined organic extracts increase carbon content but don't effectively seal PEO-coating pores. • The cochineal-based coating showed excellent anti-corrosion properties. [ABSTRACT FROM AUTHOR]

This work aims to enhance the anti-corrosion and photocatalytic activity of porous inorganic layers through a novel approach involving the exploitation of chromophores derived from phytochemicals and pheromones. Herein, organic acid (carminic acid) and organic salt (indigo carmine) obtained from pheromones and phytochemicals, respectively, are utilized to modulate the porous surface of inorganic layers produced on AZ31 Mg alloy via plasma electrolytic oxidation. Such pheromones and phytochemicals coatings have a double link inside them along with negatively charged functional groups, which enabled the sealing of the sponge-like structure of the inorganic layer through a couple of bonding mechanisms, such as hydrogen bonding, π-π interaction, as well as electrostatic interactions between polar parts of such organic molecules and cationic species generated from the inorganic layer. The phytochemical coating exhibited superior electrochemical stability compared to other samples, as demonstrated by its high polarization resistance (1.27 × 10+8 Ω.cm+2). Additionally, the phytochemical coating demonstrated the ability to photodegrade methylene blue, achieving a photocatalytic efficiency of 99.47 %. The stacked and parallel interactions of the phytochemical and/or phermonic layer on the surface of inorganic layers were explored with the aid of density functional theory. [Display omitted] • Organic corrosion inhibitors are amalgamated with inorganic PEO coating. • Coral-reef like structure is formed by the deposition of pheromone coatings. • Chromophores assist the adsorption of organic molecules into porous PEO coating. • Homogeneous deposition by Stacked/parallel interactions of pheromones and phytochemicals • The phytochemical coating showed excellent anti-corrosion and photocatalytic properties. [ABSTRACT FROM AUTHOR]

Novel inexpensive materials are the focus of modern research for efficient hydrogen evolution reactions (HER) to substitute scarce and expensive platinum (Pt) based electrocatalysts. The ideal material should be durable, low-cost, efficient and possess high surface area. Earth abundant Transition metal dichalcogenides (TMDCs) are the potential group of materials for providing inexpensive source of durable HER catalysts with high surface area and active edges due to their layered structure. Here, we report a scalable single-step microwave-assisted solution phase synthesis of NiTe 2 with core-shell configuration over porous three-dimensional nickel foam (3D-NF). This surface heterojunction catalyst possesses high surface area, unique needlelike morphology, and efficient performance for hydrogen evolution reactions. NiTe 2 needles decorated on porous 3D-NF displayed fast HER kinetics with a reasonable overpotential of ~ −0.36 V to drive a current density of 100 mA cm−2. A small Tafel slope of ~55 mV dec−1 is observed. The catalyst showed higher stability with negligible performance degradation even after 8 h of potential cycling operation. It also demonstrated negligible current density variation at a constant applied potential for more than 15 h in 0.5 M sulfuric acid (H 2 SO 4) solution. The 3D porous skeleton allowed high impregnation of electrolyte while the dense needlelike morphology provided high surface area and active edge sites for reactions. A thin 7 nm of amorphous oxide overlayer shell on highly crystalline NiTe 2 core structure makes it a surface heterojunction catalyst (SHC) which is reported to facilitate hydrogen desorption upon charge take up and makes it an efficient electrocatalyst. [Display omitted] • NiTe 2 proved to be an efficient catalyst for hydrogen evolution reactions. • Microwave-assisted synthesis of NiTe 2 proved to be a rapid and scalable approach. • Synthesized NiTe 2 catalyst showed needle-rods-like morphology. • The higher surface area of catalyst provides a high interfacial surface area to react and catalyze. [ABSTRACT FROM AUTHOR]

The present work examined the influence of anion type on incorporating WO 3 into the MgO layer produced via plasma electrolytic oxidation of AZ31 Mg alloy. Here, three different anions, such as aluminate (AlO 2 -), silicate (SiO 3 2-), and phosphate (PO 4 3-) were added separately into an alkaline electrolyte containing WO 3 nanoparticles. The microstructural observations revealed that the incorporation of the WO 3 nanoparticles is affected by the diameter of discharge channels associated with the type of anion added into the electrolyte. The sample produced from phosphate electrolytes had higher thickness but was more porous than those obtained in aluminate or silicate electrolytes. Regardless of anion type, the amounts of WO 3 nanoparticles incorporated into the inner layer of PEO coating were more significant than those incorporated into the outer layer, where a WO 3 -rich inner layer was obtained in the case sample coated in electrolyte with silicate anions. The electrochemical measurements in a 3.5 wt% NaCl solution indicated that the corrosion resistance of the sample coated in silicate electrolyte was superior to other samples in which the sample coated in phosphate electrolyte exhibited the lowest corrosion resistance. This behavior is explained by a mechanism in which every anion produces its microstructural defects under the influence of discharge types, such as type-A, B, C, D, and E, thus, affecting the physical incorporation of WO 3 into the MgO layer under plasma conditions. • Incorporation of WO3 nanoparticles is affected by the anion type. • The anion type affects the types of plasma discharges developed during PEO. • WO3 nanoparticles affected by discharge type affiliated with particular anion. • Effect of SiO32- anions on the corrosion behavior of PEO coating is significant [ABSTRACT FROM AUTHOR]

[Display omitted] • NiTe 2 proved to be an excellent catalyst for the detoxification of wastewater. • Microwave-assisted synthesis of NiTe 2 proved to be a rapid and scalable approach. • Synthesized NiTe 2 catalyst showed needle-rods-like morphology. • Photocatalytic dye degradation showed higher performance relative to catalytic degradation. • The 3D solid structure of catalyst can solve the major issue of catalyst separation after treatment. Microwave-assisted synthesis of NiTe 2 , a metal dichalcogenide, is reported here as a facile and rapid preparation method for energy-efficient and scalable photocatalysis application and detoxification of water pollution. Synthetic dyes as organic pollutants in water, such as Methylene blue, Congo red, and Methyl orange cause serious health and environmental issues, which are degraded effectively by heterogeneous photocatalysis using NiTe 2 as a catalyst. The photons from a UV-source generates excitons within the surface of NiTe 2 that can react with O 2 , H 2 O, and hydrogen peroxide (H 2 O 2) initiator to convert them into reactive superoxide anions (−O 2), hydroperoxyl (HOO), and hydroxide radicals (OH) which holds strong oxidizing power to degrade organic dye molecules. The UV irradiation can also perform photolysis in the presence of a hydrogen peroxide initiator within the catalyst system. The 3D-support structure of nickel foam substrate and needlelike rod structure of NiTe 2 catalyst provides a high surface area. This 3D solid structure can solve the major issue of catalyst separation after treatment which is a major problem in powder catalysts. Our study demonstrates excellent photocatalytic dye-degradation efficiency within a very short treatment time, can replace other Fenton-based catalysts that produce a large amount of iron sludge, and are difficult to remove. [ABSTRACT FROM AUTHOR]