Improved Barrier Properties Research Articles

Controlled localization of graphene oxide to improve barrier, biodegradation and mechanical properties of PBAT/EVOH

AbstractIncorporating graphene oxide (GO) with controlled localization into poly(butylene adipate‐co‐terephthalate) (PBAT) blends with poly(ethylene vinyl alcohol) (EVOH) aimed to improve barrier properties, biodegradability, and mechanical strength of PBAT. The PBAT/EVOH/GO nanocomposites containing 0 to 1 wt% of GO were prepared by a reactive mixing process in internal mixer. Microscopic images confirmed that the GO nanoplatelets are mainly localized in PBAT phase and then at the interface, contrary to the thermodynamic affinity of GO toward EVOH. The reactive nature of PBAT/EVOH/GO nanocomposites was confirmed via time‐sweep rheological studies where specific changes were observed in melt viscosity over time. The results of microscopic studies, rheometry, tensile test, and dynamic mechanical thermal analysis (DMTA) confirmed that localizing GO at the interface establishes strong interactions between PBAT and EVOH. By the addition of 0.75 wt% GO, tensile and yield strength were improved by 19% and 45%, respectively. Increasing GO significantly increased the hydrolysis degradation rate of the nanocomposites. Furthermore, the addition of GO considerably decreased the oxygen and water vapor permeability of the blends by up to 40% at 1 wt% GO.

Biopolyurethane coatings with silica-titania microspheres (MICROSCAFS®) as functional filler for corrosion protection

In this work, we studied a biopolyurethane (BioPU) coating derived from a bio-based polyol and isocyanate for the protection of carbon steel against corrosion. The direct utilization of polyols obtained from raw biomass represents a novelty in polyurethane coatings production. The protective properties of these coatings were enhanced by incorporating unique silica-titania (ST) MICROSCAFS®, which are microspheres exhibiting interconnected macro- and mesoporosity. They were loaded with tannic acid (TA), an eco-friendly corrosion inhibitor. Confirmation of TA loading into the ST carriers (therefore called ST\\TA) was achieved through Attenuated total reflectance - Fourier-transform infrared spectroscopy (ATR-FTIR) and Thermogravimetric (TG) analyses. TG analysis revealed that ST\\TA particles contain approximately 34 wt% TA, and their average particle diameter is approximately 25 ± 5 μm, observed by SEM. The TGA shows slightly improved thermal resistance of the coatings modified with the filler MICROSCAFS®. Furthermore, it was observed that the fillers strengthened the coating hardness without negatively affecting the adhesion strength. Electrochemical Impedance Spectroscopy (EIS) results demonstrated that all modified coatings exhibited very good to excellent resistance in mild corrosive environments. The coatings maintained a high impedance modulus (|Z|) at low frequencies and phase angle values close to −90° across a wide frequency range, over an immersion period of 80 days in a 0.05 M NaCl solution. After 80 days of immersion, the best coating, BPU-ST\\TA, displayed |Z| of 3 × 1010 Ω cm2. Scanning Vibrating Electrode Technique (SVET) analysis revealed the inhibitory behaviour of TA. For the BPU-ST\\TA sample, inhibition of both anodic and cathodic activities was clearly visible, with a significant reduction of the current densities starting at 1 h and up to at least 24 h of immersion. In summary, the BioPU coatings modified with tannic acid-loaded MICROSCAFS® exhibit improved barrier properties and notable corrosion inhibition capacity in mild corrosive environments.

Development of Functional Composite Edible Films or Coatings for Fruits Preservation with Addition of Pomace Oil-Based Nanoemulsion for Enhanced Barrier Properties and Caffeine for Enhanced Antioxidant Activity.

The aim of this study was to develop functional composite edible films or coatings for fruit preservation by the addition of bioactive components in combinations that have not yet been thoroughly studied, according to the relevant literature. Edible films were initially composed of (i) chitosan (CH), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5% ratio), and (ii) hydroxypropyl methylcellulose (HPMC), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5% ratio). The bioactive components incorporated (5, 10 and 15% v/v) were as follows: (i) pomace oil-based nanoemulsion (NE) aiming to enhance barrier properties, and (ii) caffeine (C), aiming to enhance the antioxidant activity of films, respectively. Indeed, NE addition led to very high barrier properties (low oxygen and water vapor permeability), increased flexibility and reduced color. Furthermore, the contribution of these coatings to fresh strawberries' preservation under cold storage was investigated, with very promising results concerning weight loss, color difference, and preservation of fruit moisture and quantity of O2 and CO2 inside the packages. Additionally, C addition led to very high antioxidant activity, reduced color and improved barrier properties. Finally, the contribution of these coatings to avocado's preservation under cold storage was investigated, with very encouraging results for color difference, hardness and peroxide value of the fruit samples.

Incorporation of Nano-Zinc Oxide as a Strategy to Improve the Barrier Properties of Biopolymer-Suberinic Acid Residues Films: A Preliminary Study.

Finishing coatings in the wood-based composites industry not only influence the final appearance of the product but also serve to protect against fungi and molds and reduce the release of harmful substances, particularly formaldehyde and volatile organic compounds (VOCs). Carbon-rich materials, such as those derived from birch bark extraction, specifically suberin acids, can fulfill this role. Previous research has demonstrated that adding suberin acid residues (SAR) at 20% and 50% by weight significantly enhances the gas barrier properties of surface-finishing materials based on poly(lactide) (PLA) and polycaprolactone (PCL), particularly in terms of total VOC (TVOC) and formaldehyde emissions. This study aims to explore whether these properties can be further improved through the incorporation of nano-zinc oxide (nano-ZnO). Previous research has shown that these nanoparticles possess strong resistance to biological factors and can positively affect the characteristics of nanofilms applied as surface protection. The study employed PLA and PCL finishing layers blended with SAR powder at 10% w/w and included 2% and 4% nano-zinc oxide nanoparticles. The resulting blends were milled to create a powder, which was subsequently pressed into 1 mm-thick films. These films were then applied to raw particleboard surfaces. TVOC and formaldehyde emission tests were conducted. Additionally, the fungal resistance of the coated surfaces was assessed. The results showed that PLA/SAR and PCL/SAR composites with the addition of nano-zinc oxide nanoparticles exhibited significantly improved barrier properties, offering a promising avenue for developing biodegradable, formaldehyde-free coatings with enhanced features in the furniture industry. Furthermore, by utilizing SAR as a post-extraction residue, this project aligns perfectly with the concept of upcycling.

Chitosan Extracted from the Biomass of Tenebrio molitor Larvae as a Sustainable Packaging Film.

Waste from non-degradable packaging materials poses a serious environmental risk and has led to interest in developing sustainable bio-based packaging materials. Sustainable packaging materials have been made from diverse naturally derived materials such as bamboo, sugarcane, and corn starch. In this study, we made a sustainable packaging film using chitosan extracted from the biomass of yellow mealworm (Tenebrio molitor) shell waste. The extracted chitosan was used to create films, cross-linked with citric acid (CA) and with the addition of glycerol to impart flexibility, using the solvent casting method. The successful cross-linking was evaluated using Fourier-Transform Infrared (FTIR) analysis. The CA cross-linked mealworm chitosan (CAMC) films exhibited improved water resistance with moisture content reduced from 19.9 to 14.5%. Improved barrier properties were also noted, with a 28.7% and 10.2% decrease in vapor permeability and vapor transmission rate, respectively. Bananas were selected for food preservation, and significant changes were observed over a duration of 10 days. Compared to the control sample, bananas packaged in CAMC pouches exhibited a lesser loss in weight because of excellent barrier properties against water vapor. Moreover, the quality and texture of bananas packaged in CAMC pouch remained intact over the duration of the experiment. This indicates that adding citric acid and glycerol to the chitosan structure holds promise for effective food wrapping and contributes to the enhancement of banana shelf life. Through this study, we concluded that chitosan film derived from mealworm biomass has potential as a valuable resource for sustainable packaging solutions, promoting the adoption of environmentally friendly practices in the food industry.

Corrosion behavior of combination of laser beam welded UNS S32304 + SS304L in 3.5% NaCl solution

This study investigates the corrosion behavior of laser beam-welded UNS S32304 and SS304L in 3.5% NaCl solutions, focusing on the effects of temperature. The primary objective is to enhance the understanding of corrosion resistance in welded materials and inspire advancements in corrosion mitigation strategies. The methodology involves assessing corrosion resistance under varying temperatures and comparing the performance of laser beam welding (LBW) with that of the base metals. Scanning electron microscopy analysis reveals effective passivation, while quantitative analysis indicates differences in chloride ion coverage between the weld metal and base metals. Tafel plots and electrochemical impedance spectroscopy demonstrate enhanced corrosion potential and improved barrier properties for the weld metal. Results indicate a marginal reduction in corrosion resistance at 50 °C for both base metals. LBW metals corrosion resistance demonstrates superior performance, with only 5% reduction in breakdown potential compared to 10% in base metals. Compared to the base metal, it exhibits a substantial reduction in corrosion rate, ranging from 60 to 75%. This supports enhanced corrosion resistance and material stability. Additionally, similar results are observed after the analysis with scanning electron microscopy images, reinforcing the efficacy of LBW in improving corrosion resistance of LBW UNS S32304 and SS304L. These findings underscore the potential of LBW for applications requiring robust corrosion performance. By contributing to the understanding of the corrosion behavior of laser beam-welded materials, this study addresses a critical research gap in material science and corrosion engineering. Future research may explore long-term durability and corrosion resistance under diverse environmental conditions to further elucidate the mechanisms driving the observed differences in corrosion behavior.

Investigation of novel organic-based anti-microbial agents with polyolefins

This study investigated the anti-microbial efficacy of Nouvex N950-9010 MB, an organic-based master batch, when integrated into polypropylene (PP) and high-density polyethylene (HDPE). The focus centers on its effectiveness against two common bacterial strains: E. coli K-12 MG1655 and S. aureus ATCC 6538P. The master batch was compounded at a 5 wt.% loading concentration with PP and HDPE, and was utilized to create monolayer and multilayer films. The findings reveal significant anti-microbial activity at both 4-hour and 24-hour intervals. SEM analysis confirmed homogeneous mixing and optimal adhesion within the films. Thermal stability, assessed via DSC and TGA, remained consistent, with variations within experimental error margins. Surprisingly, FTIR results indicated no substantial differences between modified and unmodified materials, suggesting that Nouvex N950-9010 MB. preserves material integrity. Mechanical properties, including Izod impact and tensile strengths, remained stable in the modified materials. Moreover, the modified PP and HDPE exhibited improved oxygen and water vapor barrier properties (OTR and WVTR) compared with their neat counterparts. UV spectra validated the non-leachability of Nouvex N950-9010 MB, aligning with the manufacturer’s claims. A groundbreaking revelation from the study is that this master batch functions via reactive oxygen species (ROS), marking a pioneering discovery in the field of novel anti-microbial agents. The research demonstrates Nouvex N950-9010 MB’s potential as a powerful and safe solution for antimicrobial applications, opening new avenues for further exploration and practical implementation.

Novel pullulan-sodium alginate film incorporated with anthocyanin-loaded casein-carboxy methyl cellulose nanocomplex for real-time fish and shrimp freshness monitoring

This study fabricated novel smart colorimetric film from pullulan (P) and sodium alginate (SA) incorporated with anthocyanin (ACNs) loaded casein carboxymethylcellulose (CAS-CMC-ACNs) nanocomplex for the freshness monitoring of the fish and shrimp. The ACNs loaded nanocomplex exhibited large particle size (176.902 ± 4.641 nm) than CAS-CMC (155.454 ± 4.152 nm) nanocomplex without ACNs, and can be loaded in P/SA film with uniform distribution. The P/SA film incorporated with CAS-CMC-ACNs nanocomplex had a more compact structure, improved barrier properties, mechanical strength, and thermal stability than P/SA film incorporated with free ACNs, which could be attributed to hydrogen bonding among the components in the film matrix, as confirmed by SEM micrographs and FT-IR. Intriguingly, the composite film exhibited antibacterial effect against gram-negative bacteria E. coli (Escherichia coli) and gram-positive bacteria S. aureus (Staphylococcus aureus) with inhibition zone of 7 ± 0.283 mm and 8.6 ± 0.141 mm, and antioxidant effect. The composite film demonstrated a visible response to CO2 and pH buffer. Furthermore, the composite smart film demonstrated the potential to monitor the freshness of fish and shrimp stored at 25 °C for 24 h via a visual color change from pink to dark grey. The findings revealed that the fabricated film is an effective tool for evaluating the freshness of fish and shrimp.

Preparation of h-BN@ZnO composite epoxy coating for improve durability and antibacterial properties of concrete

Microbiological corrosion is a significant concern because it causes the deterioration of concrete structures in marine and sewage environments. Based on a hybrid antibacterial strategy, a novel antibacterial coating with h-BN@ZnO as filler was successfully prepared to improve the durability and antibacterial properties of concrete structures in harsh environmental conditions. The properties of h-BN@ZnO were characterized, with a focus on investigating its potential antibacterial mechanisms. Furthermore, three types of composite coatings were prepared by incorporating ZnO, h-BN and h-BN@ZnO as fillers. The microstructure, thermal stability, breathability and antibacterial performance of these composite coatings were thoroughly characterized. Immersion test and pull-off test were conducted to evaluate the effectiveness of these composite coatings in improving the durability of concrete structures. The results demonstrated that h-BN@ZnO exhibited excellent antibacterial activity, primarily attributed to the presence of ZnO. Moreover, the unique structure of ZnO on h-BN sheets contributed to enhancing the dispersion stability of h-BN@ZnO. As filler within the coating, h-BN@ZnO demonstrated significant improvements in antibacterial performance and barrier properties. With 2 wt% h-BN@ZnO, the composite coating achieved an impressive 99 % anti-adhesion rate against Escherichia coli and Staphylococcus aureus. In comparison to pure coatings, this coating demonstrated a 50 % reduction in the penetration depth of sulfate ions. It was also observed that a high content of h-BN@ZnO led to further improvements in the barrier properties and antibacterial adhesion rates of the coating. These findings contribute to understanding the potential of incorporating h-BN@ZnO filler into coatings to improve the durability of concrete structures.

Innovative edible film for fresh fruit packaging: Formulation and characterization

Edible packaging films are gaining attention as an innovative and sustainable solution for food preservation, providing a protective barrier against physical damage, microbial contamination, and environmental factors. This study aimed to develop an advanced edible packaging film by incorporating galactooligosaccharides (GOS) to strengthen intermolecular interactions and improve film integrity. The composite film, consisting of chitosan (CS), zein, and GOS, was carefully optimized and thoroughly characterized for its physicochemical properties. The impact of GOS incorporation on the film's mechanical strength, barrier properties, and performance in food preservation was systematically investigated. The resulting CS-Zein-GOS film, fabricated with a 1 % (w/v) concentration using the solvent casting technique, exhibited enhanced light-blocking capabilities, improved hydrophobicity, and significantly improved barrier properties against water vapor and oxygen permeability compared to the CS counterpart. Moreover, the composite film displayed thermal stability up to 303.91 °C and superior flexibility, as indicated by elongation at break and tensile strength values. Application tests showed that the CS-Zein-GOS coating effectively extended the shelf life of strawberries and cherries at room temperature by up to three days. Analytical techniques revealed the interaction between the components and confirmed the potential of this novel water-soluble, edible film in food packaging applications, particularly for fresh produce, to extend shelf life and reduce plastic waste. These findings highlight the promising prospects of edible packaging films in addressing sustainability challenges in the food industry.

First-principles investigation of Cu/Ti-TM/Si (TM=W, Ru) interfaces: Role of Ti-TM binary alloys as diffusion barrier layers

This study employs first-principles calculations to investigate the role of Ti-TM (TM=W, Ru) binary alloys as diffusion barrier layers in Cu/Ti-TM/Si interfaces, which are critical for enhancing the performance and reliability of microelectronic devices. The calculated results reveal that TiRu and Ti4W12 alloys exhibit exceptional stability and low contact resistance, outperforming traditional Cu/Si interfaces. The introduction of these alloys into the interface structure results in a reduced Cu s-d coupling effect, which is pivotal for inhibiting Cu diffusion. Additionally, the presence of pseudogap features and enhanced electron distribution at the interface indicate strong atomic interactions, contributing to the formation of covalent bonds and further improving barrier properties. The findings suggest that TiRu and Ti4W12 alloys are promising candidates for diffusion barrier layers, offering a balance of low contact resistance, thermal stability, and effective Cu diffusion inhibition. Therefore, from the results, it is concluded that the formation of the new interface structure will improve performance in various aspects, and thus the strategy can be applied in various directions, such as new energy materials, electronic materials, and so on. In addition, the combination of the previous work and the present work suggests that Ti-based alloys have the potential to be used as diffusion barrier materials.

Maleic acid crosslinked starch/polyvinyl alcohol blend films with improved barrier properties for packaging applications

Incorporating starch, which is a potential biodegradable substitute for petroleum-based polymers, into conventional polymers is challenging owing to limitations in processability and weak-performing resulting materials. Herein, corn starch/polyvinyl alcohol (PVA) blend films (starch: PVA ratio of 50:50) were prepared via the solvent casting method using glycerol as a plasticizer and with varying concentrations of maleic acid as the crosslinking agent. Fourier transform infrared spectroscopy revealed the molecular interactions of the maleic acid crosslinker with the polymeric network of starch and PVA through an ester linkage. The properties of the films were strongly dependent on the maleic acid concentration. An increasing maleic acid concentration imparted hydrophobicity to the film; therefore, water swelling was significantly reduced, and water resistance was enhanced. The film containing 20 wt% maleic acid exhibited excellent barrier properties, with the lowest oxygen and water vapor transmission rates of 0.5 ± 0.2 cc/m2⋅day and 232.3 ± 5.4 g/m2⋅day, respectively. Moreover, the mechanical properties of the film improved with increasing crosslinking. This study demonstrates that the addition of maleic acid leads to an improvement in the overall performance of starch/PVA blend films. Therefore, maleic acid-crosslinked films can be used as barrier materials in food packaging applications.

The use of supporting materials in the process of making food containers from a mixture of PLA-starch and testing the quality of the coating: A review

The fulfillment of the food packaging industry’s needs for the use of non-petrochemical, biodegradable plastics from renewable sources that are also economically viable can be achieved through the utilization of polylactic acid-starch (PLA-starch). However, the perceived limitations of PLA-starch in terms of long-term food packaging have prompted recent innovations in which research is conducted on supportive materials that extend the shelf life of food packaging while still considering the health value of the added substances. This innovation provides significant advantages in using more durable food packaging materials that do not have adverse effects on food and human health. The utilization of ferulic and cinnamic acid compounds has been studied to reduce the environmental impact of food packaging while extending the shelf life of food. A three-layer film of PLA/starch/PLA (PSP) was designed based on the complementary barrier properties of the polymers, resulting in a film system with improved barrier properties. Electrospinning was effective in producing fibrous mats that encapsulated the acids, while film spraying resulted in the formation of crystalline structures of the active compounds strongly adhered to the surface. The electrospinning- and spray-coated films exhibited effective inhibition against the growth of E. coli and L. innocua. The TPScf-PLAes blend showed good antioxidant capacity when used in meat packaging and reduced microbial counts during cold storage. Silane-doped bilayer films demonstrated higher thermal stability compared to PPS. Therefore, the bilayer films and supporting materials have significant potential to extend the shelf life of food, maintaining its quality and safety for a longer period.

Effect of stearic acid modification on properties of pearl millet starch

AbstractThe present study aims Pennisetum glaucum (commonly known as pearl millet) starch modification with stearic acid at various concentrations (2.4, 2.6, and 4.8%) to improve starch functionality. The interaction of stearic acid and starch was verified by X-ray diffractogram which showed peaks at 15.1°, 23.2°, and a doublet with peaks at 17.1° and 18°confirming that an A-type crystalline starch was successfully isolated from pearl millet. The crystallinity pattern of the starch-stearic acid complex was similar to native starch, but there was a slight increase in peak intensity, and an additional peak at 21.42° (SSA3) was recorded, which might be due to aggregates of stearic acid. The surface of the starch granules was slightly dented and punctured as a result of the stearic acid modification, which SEM confirmed. DSC pattern showed that compared to native starch, the starch-stearic acid complex had higher peak temperatures of 123.21 °C (SSA3), demonstrating greater thermal stability. Complex formation was also interpreted from the FTIR spectrum, which showed a small peak at 1698 cm−1 in starch-stearic acid composite samples, which might be due to the stretching vibration of C═O of stearic acid. The complexing index of the sample increased from 26.81 to 90.32% on increasing the stearic acid concentration from 2.4 to 4.8%, respectively. This characterization confirmed the reaction between the hydroxyl group of starch and stearic acid, which showed an increase in thermal stability and can also help improve hydrophobicity, which implies that this complex has the potential for usage in food packaging with improved barrier properties. Graphical abstract

Improving the Barrier and Mechanical Properties of Paper Used for Packing Applications with Renewable Hydrophobic Coatings Derived from Camelina Oil.

This study looked at using modified camelina oil to develop sustainable coatings that could replace those derived from petroleum-based materials for use in packaging and other industrial sectors. Solvent-free synthesis of maleic anhydride grafted camelina oil (MCO) was carried out at two different temperatures (200 and 230 °C) to obtain sustainable hydrophobic coating materials for paper substrates. Maleic anhydride grafting of camelina oil was confirmed with attenuated total reflectance-Fourier transform infrared and NMR spectroscopic techniques, and up to 16% grafting of maleic anhydride was achieved, as determined by the titration method. MCO, obtained at different reaction temperatures, was coated onto cellulosic paper and evaluated for its hydrophobicity, mechanical, oxygen, and water vapor barrier properties. Scanning electron microscopy indicated the homogeneous dispersion of coating material onto the paper substrate. MCO-coated papers (MCO-200C paper and MCO-230C paper) provided a water contact angle of above 90° which indicates that the modified oil was working as a hydrophobic coating. Water vapor permeability (WVP) testing of coated papers revealed a reduction in WVP of up to 94% in comparison to the uncoated paper. Moreover, an improved oxygen barrier property was also observed for paper coated with both types of MCO. Analysis of the mechanical properties showed a greater than 70% retention of tensile strength and up to a five-fold increase in elongation at break of coated versus uncoated papers. Overall, the results show that camelina oil, a renewable resource, can be modified to produce environmentally friendly hydrophobic coating materials with improved mechanical and water vapor barrier properties that can serve as a potential coating material in the packaging industry. The results of this research could find applications in the huge paper packaging industries, specially in food packaging.

Development and Physicochemical Characterization of Edible Chitosan-Casein Hydrogel Membranes for Potential Use in Food Packaging.

The increasing global concern over plastic waste and its environmental impact has led to a growing interest in the development of sustainable packaging alternatives. This study focuses on the innovative use of expired dairy products as a potential resource for producing edible packaging materials. Expired milk and yogurt were selected as the primary raw materials due to their protein and carbohydrate content. The extracted casein was combined with various concentrations of chitosan, glycerol, and squid ink, leading to the studied samples. Chitosan was chosen due to its appealing characteristics, including biodegradability, and film-forming properties, and casein was utilized for its superior barrier and film-forming properties, as well as its biodegradability and non-toxic nature. Glycerol was used to further improve the flexibility of the materials. The prepared hydrogels were characterized using various instrumental methods, and the findings reveal that the expired dairy-based edible packaging materials exhibited promising mechanical properties comparable to conventional plastic packaging and improved barrier properties with zero-oxygen permeability of the hydrogel membranes, indicating that these materials have the potential to effectively protect food products from external factors that could compromise quality and shelf life.

Synergistic effect of α-alumina integrated silica ceramic nanocomposites prepared using waste beverage cans and rice husk for corrosion protection application

In this study, we investigated the synergistic effect of α-alumina-integrated silica nanocomposites as a promising material for corrosion protection. We synthesized these nanocomposites in different proportions (90 wt% silica:10 wt% alumina (AS-1) and 70 wt% silica:30 wt% alumina (AS-2)) via ball milling using rice husk and waste beverage cans as the precursor source. XRD, FTIR and EDX analysis of α-Al2O3 integrated silica nanocomposites revealed distinct peaks corresponding to both silica and α-Al2O3 components, confirming the successful formation of the nanocomposites. FESEM and TEM analyses showed that the α-alumina and silica nanoparticles were agglomerated and inhomogeneous, with sizes ranging from 150 nm to 250 nm. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests showed that pure silica, AS-1, and AS-2 had corrosion rates of 1.7648, 0.4396, and 0.0610 mm/yr, respectively. AS-1 and AS-2 exhibited higher charge transfer resistance (Rct) values of 34.54 KΩ and 48.60 KΩ, respectively, compared to pure silica (24.4 KΩ). Nyquist and Bode plots revealed the improved corrosion resistance of α-alumina-integrated silica nanocomposites compared to pristine silica-based protective coatings on mild steel. It is noted that the amount of α-alumina content enhances the corrosion resistance efficiency of the nanocomposites. The synergistic effect of the α-alumina-integrated silica nanocomposites can be attributed to the improved barrier properties and forming a protective layer on the metal substrate, effectively mitigating the corrosion process.

Slot-die coating of cellulose nanocrystals and chitosan for improved barrier properties of paper

Cellulose nanocrystals (CNCs) and chitosan (Cht) have been studied extensively for oxygen and water vapour barrier coatings in biodegradable, compostable or recyclable paper packaging. However, rare studies have been performed by using scalable, inexpensive, and fast continuous slot-die coating processes, and none yet in combination with fast' and high-throughput near-infrared (NIR) light energy drying. In this frame, we studied the feasibility of a moderately concentrated (11 wt%) anionic CNC and (2 wt%) cationic Cht coating (both containing 20 wt% sorbitol related to the weight of CNC/Cht), by using plain and pigment pre-treated papers. The effect of coating parameters (injection speed, dry thickness settings) were investigated on coating quantity (dry weight, thickness) and homogeneity (coverage), papers' structure (thickness, grammage, density), whiteness, surface wettability, barrier (air, oxygen and water vapour) properties and adhesion (surface strength). The coating homogeneity was dependent primarily on the suspensions' viscosity, and secondarily on the applied coating parameters, whereby CNCs could be applied at 1–2 times higher injection speeds (up to 80 mL/min) and versatile coating weights, but required a relatively longer time to dry. The CNCs thus exhibited outstanding air (4.2–1.5 nm/Pa s) and oxygen (2.7–1.1 cm3 mm/m2 d kPa) barrier performance at 50% RH and 22–33 g/m2 deposition, whereas on top deposited Cht (3–4 g/m2) reduced its wetting time and improved the water vapour barrier (0.23–0.28 g mm/m2 d Pa). The balanced barrier properties were achieved due to the polar characteristic of CNCs, the hydrophobic nature of Cht and the quantity of the applied bilayer coating that can provide sustainable paper-based packaging.

Synthesis of Silane Functionalized LDH-Modified Nanopowders to Improve Compatibility and Enhance Corrosion Protection for Epoxy Coatings.

Novel modified Zn-Al LDH/epoxy coatings are synthesized and applied to steel substrates, providing active corrosion protection and improved barrier properties. This protective coating is made by combining Epon 828 as a polymer matrix with modified layered-double-hydroxy (LDH) nanoparticles acting as corrosion inhibitor containers. To synthesize the coatings, nitrate was intercalated into Zn-Al-LDH layers through an aqueous co-precipitation method to obtain Zn-Al LDH-NO3, and decavanadate replaced nitrate within the LDH layers through an anion exchange process to obtain Zn-Al LDH-(V10O28)6-. The intercalated LDH was functionalized by silanization with (3-aminopropyl)triethoxysilane (APTES) to increase the compatibility of the LDH inhibitor nanocontainers with epoxy resin and produce a protective coating. To protect the mild steel substrate, functionalized LDH nanopowders were dispersed into the epoxy resin, mixed with a polyamide hardener (Epikure 3571), and applied and cured to the metal surface. Surface morphology, structure, and chemical composition were determined for the modified LDH nanopowders using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Corrosion protection of the coating system was studied using long-term immersion testing and potentiodynamic polarization studies in a 3.5 wt.% NaCl solution.

Recent Progress of Biodegradable Polymer Package Materials: Nanotechnology Improving Both Oxygen and Water Vapor Barrier Performance.

Biodegradable polymers have become a topic of great scientific and industrial interest due to their environmentally friendly nature. For the benefit of the market economy and environment, biodegradable materials should play a more critical role in packaging materials, which currently account for more than 50% of plastic products. However, various challenges remain for biodegradable polymers for practical packaging applications. Particularly pertaining to the poor oxygen/moisture barrier issues, which greatly limit the application of current biodegradable polymers in food packaging. In this review, various strategies for barrier property improvement are summarized, such as chain architecture and crystallinity tailoring, melt blending, multi-layer co-extrusion, surface coating, and nanotechnology. These strategies have also been considered effective ways for overcoming the poor oxygen or water vapor barrier properties of representative biodegradable polymers in mainstream research.