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The aim of this work was to obtain a protective ZrO2 coating on diamond particles, which was to protect diamond from oxidation and graphitization, enabling sintering of diamond at higher temperatures and lower pressures than its thermodynamic stability in atmospheric conditions. The coatings were obtained by mixing diamond with zirconium and oxidizing in air or oxygen. Mixtures of diamond and 80 wt% zirconium were sintered by SPS method at temperatures of 1250 °C and 1450 °C. To stabilize the tetragonal structure of ZrO2, 3 mol% Y2O3 was added to zirconium before the milling process. The composition of powder phases, morphology, and microstructures of sintered materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS). Diffraction studies show the presence of zirconium monoclinic and tetragonal oxides in coatings, after oxidation in air, and in oxygen. Oxidation in oxygen flow is possible for lower temperatures (75 °C), which results in the presence of unreacted zirconium. In ZrO2 doped with yttria after the oxidation process in oxygen, there is no monoclinic ZrO2. It is possible to sinter the ZrO2–diamond composite at 1250 °C using the spark plasma sintering method without graphitization of the diamond. The sintered material consists of monoclinic and tetragonal ZrO2 structures. [ABSTRACT FROM AUTHOR]

The shift from fossil-based packaging materials to more sustainable alternatives is driven by evolving environmental regulations aiming for enhanced recyclability and biodegradability. Dispersion coatings, as opposed to extrusion-based approaches, offer significant advantages by reducing the coat weights, but generally, multiple coating layers are needed to meet functional performance requirements. This study explores the application of upscaled multilayer dispersion coatings comprising polylactic acid-based coating (PLAX) and hybrid nanomaterial lacquer (bioORMOCER®) on commercial base papers for barrier packaging using semi-pilot reverse gravure and industrial-scale rod coaters. One multilayer structure demonstrated a low water vapour transmission rate (WVTR), achieving a WVTR of 12 g/(m2·day) under standard conditions and a 78% reduction of WVTR compared to the substrate under elevated humidity. The other multilayer structure exhibited an excellent oxygen transmission rate (OTR) of 2.3 cc/(m2·day·bar) at dry conditions, which is comparable to conventional high-performance alternatives. Both multilayer coatings enhanced the grease and mineral oil barriers significantly, as heptane vapour transmission rate (HVTR) reductions exceeded 97%. The multilayer coatings demonstrated strong potential for scalable production of sustainable, high-barrier packaging materials. These findings highlight the capability of dispersion coatings to replace traditional fossil-based barriers, advancing the development of environmentally friendly packaging solutions. [ABSTRACT FROM AUTHOR]

Abstract Here the performance of phase change material (PCM)‐coated paper made from unbleached kraft pulp is introduced. The applied PCM consists of a mixture of ethylene glycol distearate (EGDS), a well‐known PCM wax material, and a fully substituted cellulose stearoyl ester (CSE). Transfer of the PCM material onto/into paper is achieved by spray as well as blade coating of EGDS + CSE mixture. It is shown that the kind of coating method used does not interfere with observed PCM properties. The significantly higher melt viscosity of the EGDS + CSE blends ensures that the EGDS wax is not bleeding out of the paper, which avoids the use of further encapsulation processes. The PCM behavior, as observed by thermal load measurements, and the thermal buffering of the coated paper is a function of the applied mass of the PCM material applied. The thermal retention exhibited a quasi‐isothermal behavior at ≈65 °C with EGDS + CSE coatings. These effects can offset fluctuations in temperature, and the PCM papers can be employed to achieve a more uniform temperature setting. PCM‐modified papers are therefore interesting candidates for paper‐based packaging or for use in paper‐based sensors, where overheating can strongly affect reliability of results.

A sodium bentonite product (nanoclay) was added to a polyhydroxybutyrate/ethyl cellulose (PHB/EC) blend coating agent, and the impact of the nanoclay content on the properties of the coated paper was investigated. The organically treated nanoclay exhibited enhanced compatibility with the PHB/EC blend, ensuring uniform dispersion within the coating layer and improving the barrier properties of the coated paper. The mechanical properties of the PHB/EC blend-coated paper with nanoclay demonstrated ductile behavior, reducing the tensile strength and increasing the elongation. However, at higher nanoclay loadings, specifically up to 25%, aggregation among nanoclay particles occurred. This hindered the enhancement of barrier properties, thereby decreasing the degree of elongation. Incorporating nanoclay as a filler in the PHB/EC blend at suitable levels showed potential for further enhancing the barrier properties and ensuring economic feasibility in the production of packaging paper. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) curing is an efficient and environmentally friendly curing method. In this paper, UV-cured polyurethane acrylates (PUAs) were investigated as potential military coatings to serve as barriers against chemical warfare agents (CWAs). Seven UV-cured PUA coatings were formulated utilizing hydroxyethyl methacrylate-capped hexamethylene diisocyanate trimer (HEMA-Htri) and trimethylolpropane triacrylate-capped polycarbonate prepolymer (PETA-PCDL) as the PUA monomers. Isobornyl acrylate (IBOA) and triethyleneglycol divinyl ether (DVE-3) were employed as reactive diluents. Gas chromatography was utilized to investigate the constitutive relationships between the structures of the PUA coatings and their protective properties against simulant agents for CWAs, including dimethyl methylphosphonate (DMMP), a nerve agent simulant, and 2-chloroethyl ethyl sulfide (CEES), a mustard simulant. The glass transition temperature (Tg) and crosslinking density (υe) of PUAs were found to be crucial factors affecting their ability to serve as barriers against CWAs. The incorporation of IBOA units led to enhanced Tg and barrier performance of the PUAs, resulting in a DMMP retention of less than 0.5% and nearly 0 retention of CEES. However, an excessive introduction of polycarbonate chains decreased the υe and barrier performance of the PUAs. These findings may offer valuable insights for enhancing the protection of UV-cured PU coatings against CWAs. [ABSTRACT FROM AUTHOR]

The kinetics of bulk and unidirectional surface hydrogen absorption by a two-phase α + β VT23 titanium alloy (Ti–Al–Mo–V–Fe–Cr) at a temperature of 800°C in the concentration range 0.2–0.8 wt % is studied. Structures from three-phase α + α" + β to single-phase β are found to form in the sample volume when the introduced hydrogen concentration is varied during bulk hydrogenation annealing. The hydrogen penetration depth and, hence, the degree of the α → β transformation are shown to be controlled by changing the hydrogenation conditions and using barrier coatings; as a result, a unidirectional gradient structure, which changes from α" + β on the side of hydrogen introduction to α + β on the opposite side, is formed. The absorption of 0.6 wt % hydrogen during unidirectional surface hydrogenation is found to proceed 20 times slower than that during bulk hydrogenation. During unidirectional surface hydrogenating, the hydrogen content in the near-surface layers is found to be 0.2 wt % higher than the introduced hydrogen concentration calculated per sample volume. [ABSTRACT FROM AUTHOR]

Organically modified layered silicates can be used as barrier pigments in organic coating systems to reduce the permeation of water vapor and gases, e.g., oxygen as well as harmful gases that promote corrosion. Unmodified layered silicates are not sufficient to reduce the permeation significantly. However, the arrangement and orientation of the particles have an enormous impact on the later performance in the barrier film. In organic solvents or non‐aqueous polymer matrices the non‐modified layered silicates cannot exfoliate adequately. The organic modification influences the layer spacing and the compatibility to organic solvents. Layered silicates are modified with dodecylamine to enhance the spacing layer. The spacing layer is enhanced by 55% caused by the organic modification as it is commonly known. In contrast to previous work freeze drying of the organically modified layered silicates improved the particle distribution and by this barrier properties significantly. The modified particles reduce the diffusion of water and oxygen by ≈99.6% and 97.2%, respectively. The corrosive gas test of electronic circuit boards shows no growth of dendrites and no failure of the electronics in contrast to protective coating without the layered silicates. [ABSTRACT FROM AUTHOR]

Abstract Organically modified layered silicates can be used as barrier pigments in organic coating systems to reduce the permeation of water vapor and gases, e.g., oxygen as well as harmful gases that promote corrosion. Unmodified layered silicates are not sufficient to reduce the permeation significantly. However, the arrangement and orientation of the particles have an enormous impact on the later performance in the barrier film. In organic solvents or non‐aqueous polymer matrices the non‐modified layered silicates cannot exfoliate adequately. The organic modification influences the layer spacing and the compatibility to organic solvents. Layered silicates are modified with dodecylamine to enhance the spacing layer. The spacing layer is enhanced by 55% caused by the organic modification as it is commonly known. In contrast to previous work freeze drying of the organically modified layered silicates improved the particle distribution and by this barrier properties significantly. The modified particles reduce the diffusion of water and oxygen by ≈99.6% and 97.2%, respectively. The corrosive gas test of electronic circuit boards shows no growth of dendrites and no failure of the electronics in contrast to protective coating without the layered silicates.

The effect of the vacuum ion–plasma treatment parameters on the regularities of nitride barrier coating formation on a VT23 titanium alloy (Ti–Al–V–Mo–Cr–Fe system) is studied. The resistance of the formed coating is studied upon subsequent vacuum annealing at 800°C for 1 h. The coating thickness is shown to increase with the titanium nitride deposition time. The formed nitride coating is found to have high resistance to heating in vacuum. [ABSTRACT FROM AUTHOR]

The influence of the parameters of thermal, electrochemical, and microarc oxidation on the laws of formation of oxide barrier coatings on a VT23 titanium alloy (Ti–Al–V–Mo–Cr–Fe system) is studied. The resistance of the formed coatings to the subsequent vacuum annealing at 800°C for 1 h is examined. The coating thickness is shown to increase with the oxidation temperature or voltage. The coatings produced by thermal and microarc oxidation are most resistant to heating in vacuum, but those produced by microarc oxidation contain pores. The anodic oxide coating is completely dissolved upon vacuum annealing. [ABSTRACT FROM AUTHOR]

Cellulose, a sustainable and environmentally-friendly polymer derived from biomass, has shown great potential in many applications as an alternative to petroleum-based polymers. However, its hydrophilic nature limits its integration into packaging systems. This study aims to enhance the water-repellency of cellulose filament (CF) films by plasma deposition of an organosilicon (SiOCH) thin film. Water contact angle and Cobb test measurements reveal that the SiOCH coating deposited by non-thermal dielectric barrier discharge (DBD) at atmospheric pressure decreases the water absorbency of the substrate by about one order of magnitude, resulting in a highly hydrophobic CF film. However, the water vapour (WVTR) and oxygen transmission rates (OTR) of CF remain almost unchanged. Spray coating with 5% carboxymethylcellulose (CMC) sealer effectively decreases the WVTR and OTR of the CF film; however, the water absorbency is increased. Finally, the measurements conducted on a CF film sample coated with a bilayer of CMC/SiOCH reveal that the combined treatment reduces the WVTR and OTR of the film by 95% and 66%, respectively, and lowers the water absorbency by two orders of magnitude. The functionalization methods proposed herein provide an effective approach for the selective tuning of CF film permeation properties. It can be applied in the development of both, wet and dry, sustainable packaging materials. [ABSTRACT FROM AUTHOR]

As established by the conducted studies of brazing dissimilar joints of Kovar with titanium alloy, applying a standard procedure of barrier nickel coating deposition on a titanium alloy by electrolytic method does not ensure its integrity during vacuum heating in the brazing mode. The structure, chemical heterogeneity of brazed joints and surface morphology of the nickel coating are studied by applying the chemical method of producing a barrier nickel coating. Proceeding from the derived investigation results, a 4-stage technology of electrolytic application for the barrier nickel coating is proposed. This coating preserves its integrity during vacuum brazing of the following dissimilar metals: BT1-0 titanium alloy with 29NK precision alloy. A detailed study of the Kovar + BT1-0 brazed joints with the application of electron microscopy and x-ray microspectral analysis confirm the formation of dense brazed seams with full penetration fillet regions with a eutectic rodlike structure, when using silver brazing filler metal. [ABSTRACT FROM AUTHOR]

A multi-layer barrier coating technology was developed using nano-fibrillated cellulose (NFC) alongside a hydrophobic, paraffin-free biowax for manufacturing an eco-friendly functional packaging paper. Anionic NFC was prepared by isolating hardwood-bleached kraft pulp (Hw-BKP) using a micro-grinder, and cationic NFC was prepared by the quaternization reaction of the anionic NFC. Thereafter, a three-layer barrier-coated paper was manufactured using cationic and anionic NFCs and biowax. The air permeability and water vapor transmission rate (WVTR) of the three-layer barrier-coated paper were measured, and its coverage and coating layer structure were observed by scanning electron microscopy (SEM). The air permeability of the three-layer barrier-coated paper was more than 15,000 s and those WVTR was 67.1 g/m2/day. Its coverage and surface were considerably uniform and smooth. Thick and effective barrier coating layers were formed as indicated by SEM images. Therefore, it was concluded that a multi-layer barrier-coated paper with considerably high barrier properties could be produced using cationic and anionic NFCs with high gas barrier properties and biowax with high moisture barrier properties. Further, the structure could be used as a functional packaging paper with high barrier properties.

A review on ceramics, glasses and glass–ceramics as thin film protective coatings for solar cells is given. The different preparation techniques and the physical and chemical properties are presented in a comparative way. This study is useful for technologies involving solar cells and solar panel cell development at the industrial scale, because protective coatings and encapsulation play a major role in increasing the lifetime of solar panels and environmental protection. The aim of this review article is to give a summary of existing ceramic, glass, and glass–ceramic protective coatings and how they apply to solar cell technology: silicon, organic or perovskite cells. Moreover, some of these ceramic, glass or glass–ceramic layers were found to have dual functionality, such as providing anti-reflectivity or scratch resistance to give a two-fold improvement to the lifetime and efficiency of the solar cell. [ABSTRACT FROM AUTHOR]

Titanium mesh (Ti‐mesh) for guided bone regeneration (GBR) approaches has been extensively considered to offer space maintenance in reconstructing the alveolar ridge within bone defects due to its superb mechanical properties and biocompatibility. However, soft tissue invasion across the pores of the Ti‐mesh and intrinsically limited bioactivity of the titanium substrates often hinder satisfactory clinical outcomes in GBR treatments. Here, a cell recognitive osteogenic barrier coating was proposed using a bioengineered mussel adhesive protein (MAP) fused with Alg–Gly–Asp (RGD) peptide to achieve highly accelerated bone regeneration. The fusion bioadhesive MAP‐RGD exhibited outstanding performance as a bioactive physical barrier that enabled effective cell occlusion and a prolonged, localized delivery of bone morphogenetic protein‐2 (BMP‐2). The MAP‐RGD@BMP‐2 coating promoted in vitro cellular behaviors and osteogenic commitments of mesenchymal stem cells (MSCs) via the synergistic crosstalk effects of the RGD peptide and BMP‐2 in a surface‐bound manner. The facile gluing of MAP‐RGD@BMP‐2 onto the Ti‐mesh led to a distinguishable acceleration of the in vivo formation of new bone in terms of quantity and maturity in a rat calvarial defect. Hence, our protein‐based cell recognitive osteogenic barrier coating can be an excellent therapeutic platform to improve the clinical predictability of GBR treatment. [ABSTRACT FROM AUTHOR]

In the winter of North China, the use of a large amount of chlorine salt snow - melting agent makes the durability problem of highway concrete guardrail increasingly serious. Aiming at this problme, a simulation model of chloride ion corrosion resistance of concrete guardrail coating of highway bridge was established by COMSOL software using the chloride ion diffusion model as the theoretical basis. Results showed that the coating could significantly reduce the chloride ion concentration in the guardrail and thus improve its durability. As the coating thickness increased, chloride ion concentration decreased sharply first, and the decrease tendency gradually slowed down. With the decline of coating diffusion coefficients, the chloride ion concentration decreased significantly. Compared with the guardrail without coating, the ones applied with chlorinated polyvinyl chloride (CPVC) coating, chlorinated polyethylene (CPE) coating, chloroprene rubber latex (CR) coating and polyvinylidene chloride latex (PVDC) coating, which had different diffusion coeficients, realized a reduction of chloride ion concentration of at least 98%, 28%, 75% and 90%, respectively. Under the as - mentioned environment, CPVC coating possessed a better effect than other coatings. The research results could provide guidance for the actual construction projects.

Dispersion coating may represent an alternative technology to extrusion coating, currently dominating the market of coated paper-based packaging. Being processed as inks, dispersion coatings can be applied with conventional equipment, achieving lower dry coat grammages. In this work, two styrene-butadiene-based (Tg1 ≅ 0 °C; Tg2 ≅ 15 °C) dispersion coatings filled with different amounts of kaolin were developed and rod-coated on two different paper substrates. The samples were tested for water, moisture, and grease barrier properties. Kaolin-containing formulations showed moisture barrier as low as 15 g/(m2∙day), as well as grease barrier higher than 24 h. The best formulation involved 20% by weight of kaolin, whereas higher amounts were detrimental for water barrier, beneficial for moisture barrier, and slightly detrimental for grease barrier properties. Benchmarked to two commercial grades, kaolin-filled coatings strongly improved grease barrier, yet achieving similar moisture barrier. [ABSTRACT FROM AUTHOR]

A multi-layer barrier coating technology was developed using nanofibrillated cellulose (NFC) alongside a hydrophobic, paraffin-free biowax for manufacturing an eco-friendly functional packaging paper. Anionic NFC was prepared by isolating hardwood-bleached kraft pulp (Hw-BKP) using a micro-grinder, and cationic NFC was prepared by the quaternization reaction of the anionic NFC. Thereafter, a three-layer barrier-coated paper was manufactured using cationic and anionic NFCs and biowax. The air permeability and water vapor transmission rate (WVTR) of the three-layer barrier-coated paper were measured, and its coverage and coating layer structure were observed by scanning electron microscopy (SEM). The air permeability of the three-layer barrier-coated paper was more than 15,000 s and those WVTR was 67.1 g/m² /day. Its coverage and surface were considerably uniform and smooth. Thick and effective barrier coating layers were formed as indicated by SEM images. Therefore, it was concluded that a multi-layer barrier-coated paper with considerably high barrier properties could be produced using cationic and anionic NFCs with high gas barrier properties and biowax with high moisture barrier properties. Further, the structure could be used as a functional packaging paper with high barrier properties. [ABSTRACT FROM AUTHOR]

The interest of the food packaging industry in biodegradable, recyclable, and functional materials has steadily increased in recent years. The use of hydrogels in the food sector holds great potential for use in packaging systems or as carriers for bioactive substances. The synthesis of an oxygen barrier coating of prolaminic silica material and antimicrobial functionalization with fumaric acid for packaging materials described here is an elegant way to meet these requirements. The developed material achieved a significant antimicrobial activity against Escherichia coli and Staphylococcus aureus, two common clinical pathogens. Another pre-requisite of such materials is a high biocompatibility, which can be assessed using human cell models, to help ensure consumer safety. The biocompatibility was determined by luminescence adenosine triphosphate and photometric lactate dehydrogenase assays. No cytotoxic effects on human keratinocytes in vitro were found for the test materials. [ABSTRACT FROM AUTHOR]

Due to the inherent hydrophilic nature and porosity of the paper fibers, hydrophobic polymeric materials, waxes, and inorganic fillers have been widely utilized as coatings and fillers, respectively, on a fiber-based substrate. Coatings also impart oxygen, aroma, and oil barrier properties desirable for food packaging applications. In addition, coatings improve the functional properties and characteristics of paper, including reduced water absorbance, enhanced surface finish, gloss finish, printability, readability, dimensional stability of the substrate, and antimicrobial performance. Such functional properties are highly desirable for consumer packaging applications. However, such coatings may limit the repulpability, recyclability, biodegradability, and compostability of paper and paperboard. In addition, the contamination of the substrate by-product also limits the recyclability of the fiber-based substrates, and the paper, paperboard, or corrugated material ends up in landfill sites. This review focuses on bioderived, biodegradable, compostable, and functional organic, inorganic, and hybrid hydrophobic coatings, which promote the circular economy by improving the repulpability or reduces carbon footprints.

Materials with high barrier properties against oxygen are required for the packaging of many sensitive foods. Since commodity polymers lack these properties, additional barrier materials are used in plastic-based barrier packaging. These are usually more expensive than commodity polymers and, in higher fractions, also make recycling more difficult. Current developments, therefore, aim at barrier layers that are as thin as possible but retain the barrier properties. One approach is to incorporate nanoparticles into these layers. In this study, the barrier properties of nanocomposite coatings, consisting of unmodified polyvinyl alcohol (PVA), and dispersed stick-shaped halloysite (Hal) or platelet-shaped montmorillonite (MMT) silicate nanoparticles, were investigated. The PVA was dissolved in aqueous nanoparticle dispersions, which were prepared by mechanical shearing, to produce the so-called “nanolacquer.” Nanolacquers with nanoparticle concentrations of 7, 30, and 47 vol% with respect to PVA were applied in a single process step with k-bar on a polypropylene substrate film. The integration of 30 vol% platelet-shaped MMT enhances the barrier performance in comparison to pure PVA by a factor of 12 and 17 for oxygen and helium, respectively. Scanning electron microscopy (SEM) shows a homogeneous distribution and a parallel alignment of the nanoparticles within the coated layer. An increase in the crystallinity of PVA was observed due to the nanoparticle integration as demonstrated by x-ray diffraction (XRD) measurements. The investigation by Fourier transform infrared (FTIR) spectroscopy and the activation energy of the permeation coefficient indicate an interaction between the nanoparticles and the PVA. The theoretically calculated values for barrier enhancement accord well with the experimental values, which emphasizes that the gas barrier improvement for oxygen and helium is mainly dominated by the tortuous path effect.

Hydrogen (H 2) energy has emerged as a promising alternative in the automotive sector to replace fossil fuel; however, its storage with volumetric efficiency remains a challenge. The latest type IV storage vessel featuring a polymeric liner with composite overwrap incurs hydrogen saturation, which eventually causes failure. To prevent the H 2 dissolution in the liner, we have developed a barrier coating comprised of polyurethane/epoxy semi-interpenetrating network (S-IPN) combined with hyperbranched polyglycerol grafted MXene (h -MXene). The hyperbranched structure facilitated the dispersion of MXene in the coating solution by enhancing the exfoliation and improved the polymer filler interaction by forming covalent and H-bonding through end-terminal hydroxyl groups. Leveraging the dense network of S-IPN combined with the dispersed layer structured h -MXene significantly increased the tortuosity of the spray-coated barrier film applied to the nylon 6 liner. The coating exhibited a 90 % reduction in the H 2 gas permeability at only 2 wt% h -MXene concentration, which further improved to above 98 % at 10 wt% loading. Additionally, the h -MXene considerably improved the adhesion with the liner even in a highly stretched condition, signifying the durability of the coating under cyclic pressurization and depressurization of the storage vessel. [Display omitted] [ABSTRACT FROM AUTHOR]

The interest of the food packaging industry in biodegradable, recyclable, and functional materials has steadily increased in recent years. The use of hydrogels in the food sector holds great potential for use in packaging systems or as carriers for bioactive substances. The synthesis of an oxygen barrier coating of prolaminic silica material and antimicrobial functionalization with fumaric acid for packaging materials described here is an elegant way to meet these requirements. The developed material achieved a significant antimicrobial activity against Escherichia coli and Staphylococcus aureus, two common clinical pathogens. Another pre-requisite of such materials is a high biocompatibility, which can be assessed using human cell models, to help ensure consumer safety. The biocompatibility was determined by luminescence adenosine triphosphate and photometric lactate dehydrogenase assays. No cytotoxic effects on human keratinocytes in vitro were found for the test materials.

A major challenge in the flexible electronics industry is the inability to quickly and accurately assess the mechanical properties of barrier materials used to encapsulate various devices. The feasibility of using a low-cost approach, digital photoelasticity (DP), to determine stress formation in barrier film is analyzed so that inherent weak areas cannot only be identified, but also reinforced. In this experimental study, ethylene vinyl acetate (EVA) is slot die coated onto untreated polyethylene terephthalate (PET) or onto PET treated with indium tin oxide (ITO) or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). An axial stress is imposed on each sample using a universal test machine, and DP was used to obtain the stress and grab profiles. It has been shown that highly concentrated and multilayer EVA coatings withstand higher stress. Also, it has been shown that the locations of delamination happen at the side edge of the encapsulation when EVA was coated on a homogenous surface, but for heterogeneous surfaces, the delamination occurred at the boundary between the PEDOT:PSS and ITO. All these data were depicted using DP in very quick fashion. Therefore, DP is a viable method for quickly and accurately determining stress in barrier films. [ABSTRACT FROM AUTHOR]

This study evaluated, for the first time, the feasibility of using 100% microfibrillated cellulose (MFC) for a barrier coating to preserve the shelf life of bananas. MFC was produced from a commercial bleached kraft hardwood pulp through mechanical milling. Barrier coating was accomplished by dipping bananas into aqueous MFC suspensions. Performance of the barrier coating on the banana peel surface was evaluated from visual observations, weight loss, firmness, and dissolved soluble sugars content of the bananas. The results indicated that coating the banana peel surface with MFC delayed the browning and softening of the banana and the conversion of banana carbohydrates into soluble sugars. Furthermore, the extent of mechanical fibrillation in producing MFC affected MFC suspension wettability of banana peel surface, as well as the effectiveness of banana preservation. Casting-made MFC films were used to understand various factors of MFC barrier coating performance. The extent of MFC fibrillation was found to be more effective than increasing the amount of coating in reducing water vapor permeation for better fruit protection. [Display omitted] • Aqueous microfibrillated cellulose (MFC) suspension for barrier coating of bananas. • Film made of MFC from great extent of fibrillation had a lower water vapor permeability. • MFC barrier coating decreased banana surface color darkening. • MFC barrier coating decreased banana weight loss, firmness, and sugar content. [ABSTRACT FROM AUTHOR]

Highlights • Application of barrier dispersion to linerboard by the flexography was demonstrated. • Drying at temperature higher than 40 °C is required to improve barrier performance. • Insufficient drying creates cracks providing open pathways for moisture penetration. • DMTA shows that higher curing temperature improves film uniformity and stiffness. Abstract The post-application behaviour of aqueous dispersion barrier coatings is investigated. We have adapted a dispersion formulation initially optimised for rod coating, for application to linerboard by a flexographic press. The clay/talc/wax/poly(styrene-butadiene) latex dispersion coatings demonstrated a 60% reduction in water vapour transport rate across the barrier, and a 75% reduction in direct water uptake when the applied film was dried at 75 °C. Multi-layer coatings with a combined application rate of 7 g m−2 exhibited Cobb 120 direct water uptake of 16.3 ± 3.7 g m−2 (120 s water contact duration) and a water vapour transport rate of 140 ± 12 g m−2 d−1 (23 °C, 50% RH). Investigation of the post-coating curing regime demonstrated a decrease in the prevalence of crack defects within the cured film, and corresponding improvement in barrier properties when higher drying temperatures were employed. Dynamic mechanical analysis of the cured films indicated improvements in homogeneity and a greater extent of intermolecular interactions in the coating formulations cured at elevated temperatures. [ABSTRACT FROM AUTHOR]

Abstract: A novel silicone release liner was prepared from porous base paper with a simple biogenic polymeric pre-coat. The introduced method does not require the typical complex pretreatment processes for a paper sheet, such as calendering or pre-coating with clay. Biogenic polymers, hydroxyethyl cellulose and methylcellulose, were used to close the pores of the paper sheet. In addition, we used polyvinyl alcohol (PVA), a commonly used barrier coating with known film-forming capabilities, as a reference to close the pores and prevent silicone penetration into the base paper. In particular, hydroxyethyl cellulose showed promising barrier properties similar to those of PVA coatings. Methyl cellulose is less appropriate for release liner production due to poor film stability and insufficient adhesion to the underlying base paper. Barrier-coatings should be applied by a blade coater rather than a roller coater to obtain homogenous coatings. When a thin silicone layer was applied to the barrier-coated papers, the measured release forces were significantly reduced from 6.5 N/25 mm, for siliconized papers without any pre-coat, to less than 1 N/25 mm after pre-coating, particularly with hydroxyethyl cellulose.Graphical abstract: [ABSTRACT FROM AUTHOR]

Handling acidic chemicals is a challenge in the chemical industry, requiring a careful choice of contact material. Certain thermoset organic coatings are applicable in low pH environments, but when particulate erosion is also present the performance demand is increased. This is the case in, e.g., stirred tanks for agitated leaching of copper ore, where sulfuric acid is mixed with an erosive slurry. A pilot-scale agitated leaching tank was designed and constructed to explore the performance of selected thermoset coatings in such an environment. For reference, simple immersion experiments were conducted. Coating durability was estimated by observing the film thickness change during exposure. It was found to be a function of film swelling and film contraction, due to chemical exposure, as well as the “polishing” caused by erosive wear. Film reduction rates varied with radial position in the tank bottom-placed coating samples. Maximum rates were found about halfway between the reactor center and wall. Polishing rates also varied significantly with acid concentration, most likely due to chemical reactions taking place between the acid and the coatings, damaging surface mechanical properties, similar to the erosion/corrosion-type phenomena found in metals. A vinyl ester-based coating was the most resistant to the simultaneous erosive/acidic exposure, with a maximum polishing rate of 3.24±0.61μm/week, while novolac epoxy and polyurethane coatings showed high polishing rates of 11.7±1.50 and 13.4±0.57μm/week, respectively. [ABSTRACT FROM AUTHOR]

Creating efficient water-borne dispersions based mainly on renewable materials for coating of flexible packaging paper was the aim of this study. The effects of an ethylene modified poly(vinyl alcohol) grade and a standard poly(vinyl alcohol) on the oxygen and water vapor barrier performance of corn starch and potato starch coatings was studied. The results showed that a coating composition with a high fraction of a renewable polymer was effective in keeping the oxygen barrier at a technically and commercially applicable level. An ethylene modified poly(vinyl alcohol) grade was found to provide lower oxygen transmission rates at high relative humidity, as compared to a standard poly(vinyl alcohol) grade. The oxygen barrier properties of blends of starch and poly(vinyl alcohol) were similar to that of the pure modified poly(vinyl alcohol) in the range from 0% starch to 60% starch. This was observed with both hydroxypropylated and octenyl succinate modified starch grades. The drying conditions of the mixed starch:poly(vinyl alcohol) coatings were based on drying trials with pure poly(vinyl alcohol) coatings. Drying at moderate temperatures indicated the possibility to slightly decrease water vapor transmission rate by higher drying temperature. Several secondary effects of increased drying temperature such as coating hold-out and formation of defects may also be of importance. [ABSTRACT FROM AUTHOR]

The degradation of corrosion preventative coatings contributes to the high cost and time requirements for maintaining structures in harsh environments. However, the development of new hydrophobic coatings holds the promise of extending the usable life of structures in marine environments. In this work, we quantify the barrier properties and corrosion resistance of two novel highly hydrophobic polysiloxane formulations and the legacy silicone alkyd topcoat used on the topside of Navy's ships, all with haze gray pigmentation. Based on FTIR-ATR and EIS measurements of the pristine coatings, both the single- (1K) and the two-component (2K) polysiloxane provide significantly improved barrier characteristics (lower water diffusion coefficient and capacitance) than the silicone alkyd. These results were confirmed through a 3-month-long immersion corrosion test, which also showed that the 1K and 2K polysiloxane coatings had comparable degradation characteristic and remained highly hydrophobic. [ABSTRACT FROM AUTHOR]

This paper presents a study of the effect of moisture on the gas permeability of polyvinyl alcohol (PVOH) and PVOH-kaolin dispersion barrier coatings. The oxygen permeability was measured at different humidity levels, and the material properties were characterized under the same conditions: polymer crystallinity, kaolin concentration, and kaolin orientation were all evaluated. The experimental results revealed that the water plasticizes the PVOH material of the coatings, and the presence of kaolin filler is unable to affect such behavior significantly. The PVOH crystallinity was affected drastically by the humidity, as water melts polymer crystallites, which is a reversible process under removal of water. The permeability data were analyzed using a thermodynamic-based model able to account for the water effect on both the solubility of the gas and the diffusivity coefficients in the polymer and composite. The results showed good agreement between the model's predictions and the experimental data in terms of the overall permeability of the material. [ABSTRACT FROM AUTHOR]

Starch and poly(vinyl alcohol) based barrier coatings for flexible packaging papers were studied. Both octenyl succinate modified and hydroxypropylated corn and potato starches were blended with regular and ethylene modified poly(vinyl alcohol) to increase the water vapor barrier properties and enhance the flexibility of the starch coatings, in order to accomplish superior barrier performance. Phase separation between starch and poly(vinyl alcohol) was studied in detail, both in the solution and in dry draw-down coatings on paper. The barrier performance of the coated paper was evaluated with respect to water vapor transmission rate. Conditions for the creation of a thin surface layer consisting of only one of the pure polymers were identified and discussed in terms of phase separation in solution migration of poly(vinyl alcohol) to the uppermost surface layer. The phase separation promoted low water vapor transmission rates also with a rather high fraction of starch in the coatings. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) are widely used on different components of gas turbine engines especially in the combustion chamber where so much thermal energy is expended. During thermal cycling, stresses develop and this directly affects the durability of the coatings. In this study, an experimental procedure was followed in finding the λ, coefficient of thermal conductivity of the TBC-an important parameter in calculating the values of stresses, deformations and the temperature field along the thickness of the TBC coating, the finite element method (FEM) implemented in the ANSYS application package, was used. [ABSTRACT FROM AUTHOR]

Layer-by-layer assembly (LbL) of trilayer coatings of polyelectrolytes and nanoclays (NC) were produced on poly(lactic acid) based (PLAb) films. The focus of this study was on the optimization of the wetting properties of the PLAb substrate, and the adhesion properties of the prepared coating. Coatings produced by an optimized method, by combining UVC-treatment of the substrate and adjusting surface tension of the coating solutions, were compared to coatings made by typically used water-based solutions. Even though LbL-coatings with a high adhesion strength to its substrate is of outmost importance for most applications, this is often not evaluated. In this study, the adhesion of the coatings on the PLAb substrate was assessed using the cross-cut test according to ISO 2409, in which the adhesion is classified on a scale between 0 and 5, where a lower number reflects better adhesion. The coating prepared by the optimized procedure was categorized as class 0, while the control film was classified as 4. These results reveal the importance of the optimization of both the surface free energy of the substrate, and the surface tension of the dipping solutions. The surface morphology and roughness properties of the optimized films were further investigated with scanning electron microscopy (SEM), confocal optical microscopy (COM) and atomic force microscopy (AFM), showing a uniform distribution of NC on the substrate with increasing number of trilayers. X-ray photoelectron spectroscopy (XPS) confirmed the homogenous surface composition of polyelectrolytes and NC. Finally, the oxygen transmission rate (OTR) decreased considerably (by 99.7%), from 97.2 cc/(m2·day) for pristine PLAb substrate to 0.3 cc/(m2·day) for the 20-trilayer coated substrate. [Display omitted] • Greatly improved oxygen barrier properties of a poly(lactic acid) based material. • Surface evaluations on nano- and microscale reveal a uniform barrier coating. • The optimized coating has a superior adhesion strength. [ABSTRACT FROM AUTHOR]

Four commercial barrier coated boards (i.e., internally-sized uncoated board, one-side polyethylene coated board, double-side polyethylene coated board, and multilayer laminated board) were examined for biodegradation using a soil burial approach on a laboratory scale. It was observed that the base-boards were fully biodegradable in a matter of weeks or months, and the degradation process could be accelerated either by sample size modification or enrichment of the soil microbial population. Freezing pretreatment of boards or the fiber directionality of boards had no influence on the rate of degradation. The boards were also found to be recyclable following a simple procedure of re-slushing and screening. The base-boards became almost fully separated from the polyethylene coated material without any special pretreatment.

The application of stainless steels in hostile environments, such as concentrated acid or hot sea water, requires additional surface treatments, considering that the native surface oxide does not guarantee sufficient corrosion protection under these conditions. In the present work, silica-like thin-film barrier coatings were deposited on AISI 316L grade austenitic stainless steel with 2B surface finish from Hydrogen Silsesquioxane (HSQ) spin-on-glass precursor and thermally cured to tailor the film properties. Results showed that curing at 500 °C resulted in a film-structure with a polymerized siloxane backbone and a reduced amount of Si-H moieties. The coatings showed good substrate coverage and the average thickness was between 200 and 400 nm on the rough substrate surface, however, film thicknesses of > 1400 nm were observed at substrate defects. Deposition of these films significantly improved the barrier-properties by showing a 1000 times higher modulus while an ionic transport over the coating was also observed. [ABSTRACT FROM AUTHOR]

Aqueous-processed aluminum oxide phosphate (AlPO) dielectric films were studied to determine how water desorbs and absorbs on heating and cooling, respectively. In-situ Fourier transform infrared spectroscopy showed a distinct, reversible mono- to bidentate phosphate structural change associated with water loss and uptake. Temperature programmed desorption measurements on a 1-μm thick AlPO film revealed water sorption was inhibited by an aqueous-processed HfO 2 capping film only 11-nm thick. The HfO 2 capping film prevents water resorption, thereby preserving the exceptional performance of AlPO as a thin-film dielectric. [ABSTRACT FROM AUTHOR]

There is little published literature on the geometry of fillers used in barrier dispersion coatings. Published information is normally restricted to average values or distributions of length, thickness and general measures of filler shape. For modelling the performance of barrier dispersion coatings, further information is required to accurately represent filler particle geometry. The aim of this investigation was to characterise the geometry of fillers in such a way as to be able to generate geometries suitable for predicting barrier dispersion coating performance. The analysis involved characterising filler particle length, thickness, and shape from light and scanning electron microscopy images of three kaolin clays widely used in the industry. The results indicated that, of the shape description models investigated, the Fourier shape descriptor was best able to quantitatively represent a distribution of filler particles. The easier to implement elliptical shape description model was also acceptable. The methods described in this work can be used to generate geometries that can be used in the modelling and design of barrier dispersion coatings for performance optimisation. [ABSTRACT FROM AUTHOR]

The influence of barrier coating defectiveness on the overall permeating flux through a bilayer film is considered with particular attention to the effect of spatial defect distribution. To that aim, the diffusion equations for the permeating species have been solved in a large number of 3D geometries, built to simulate a bilayer structure with defects randomly distributed on the coating surface. A numerical approach based on finite volume method was used and, for each value of defectiveness considered, ranging from 0.25 to 10%, a minimum number of 200 different geometries were analyzed, in order to obtain statistically meaningful results. The numerical simulations results, which for regular arrays of defects also compares rather well with data available in the open literature, showed that the average flux obtained for each different defectiveness is not a fixed value, but rather shows substantial variations due to the randomness of the defect distribution. In particular, when few defects are present on the surface, differences higher than 10% have been observed in the flux calculated, while deviation lower than 3% with respect to the average value were obtained when the defects fraction on the surface was about 10%. Interestingly, the random distribution of defects on the surface gives average flux which are always smaller than the corresponding ordered geometry and does not result in a Gaussian distribution of the permeate flux. Distributions close to the normal one were indeed observed only for higher defectiveness while, for lower defect fractions, flux distributions with a clear tail towards the lower permeation rates were obtained. [ABSTRACT FROM AUTHOR]

The effect of ion irradiation and deposited yttrium-oxide layers on deuterium desorption from titanium deuteride is studied. The features of deuterium desorption during the interaction of hydrogen ions with a titanium-deuteride layer are revealed. It is shown that gas desorption decreases both under hydrogen-ion irradiation with energies of <1000 eV and the deposition of an yttrium oxide layer. [ABSTRACT FROM AUTHOR]

In this study oxygen permeability in dispersion barriers produced from poly(vinyl alcohol) (PVOH) and kaolin clay blends coated onto polymeric supports was investigated. To determine the oxygen permeability, two measurement methods were used: the oxygen transmission rate (OTR) and the ambient oxygen ingress rate (AOIR). It was found that with increasing kaolin content the oxygen permeability increased, up to about 5 wt% kaolin, whereafter the oxygen permeability decreased, as was expected. The increased (> 5%) kaolin loading lowered the diffusion because of an increased tortuosity. Structural information about the dispersion-barrier coatings, such as kaolin orientation and polymer crystallinity, was obtained from Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Kaolin orientation was influenced by the drying temperature, the thickness of the samples, and the kaolin concentration. The polymer crystallinity increased in thicker samples. The drying temperature did not show any clear effect on the crystallinity of thin samples, while for the thicker barriers, combined with a kaolin concentration lower than 20 wt%, a higher crystallinity was achieved at lower drying temperatures. This study demonstrates the strong influence of chemical and physical structures on the permeability of the investigated coatings. [ABSTRACT FROM AUTHOR]

The residual stress in a thin film can have a major impact on the durability and reliability of the coated device. After deposition and upon exposure to a new environment, a coated material is subjected to various external factors that might affect its stress and thus its overall performance. To identify a protocol to measure stress in a proper and repeatable manner for films deposited on polymeric substrates, we performed ex-situ profilometry measurements on thin dielectric and metallic films (30 nm) deposited on polycarbonate substrates that were stored under different environments over a 1–2 days aging period. We observed a significant tensile transition in the film stress, characterized by an extremum and a return to an equilibrium value within the first 24 h upon atmospheric exposure. Our analyses further revealed that this phenomenon was reversible and dependent on both the relative humidity and the integrity of the thin film. The moisture uptake and subsequent water vapor diffusion within the substrate, which induces an inhomogeneous volume change in the PC and results in extrinsic bending stresses, appears to be the cause of the stress evolution. A precise control of the post-deposition environment is required to measure the residual stress of thin films deposited on polymeric substrates. [ABSTRACT FROM AUTHOR]