Barrier Properties Research Articles

Bacterial cellulose production through the valorization of waste apple pulp and stale bread

AbstractIn this work, stale bread and waste apple pulp were used as feedstocks for the production of bacterial cellulose (BC). A glucose-rich solution was prepared from stale bread by dilute acid hydrolysis, while an extract comprising fructose and glucose was obtained from the waste apple pulp, which was used for cultivating Komagataeibacter xylinus DSM 2004, either as sole feedstocks or supplemented with Hestrin-Schramm medium. Supplementation significantly improved BC production: 3.38 ± 0.09 g/L for waste apple pulp extract and 2.07 ± 0.22 g/L for stale bread hydrolysate. There was no significant impact on BC chemical structure or fiber diameter, but the biopolymer produced from waste apple pulp extract had slightly higher crystallinity (CI = 59–69%) and lower thermal degradation temperature (Tdeg = 341–350 ℃) than that of the stale bread hydrolysate (CI = 55%; Tdeg = 316–320 ℃). Moreover, supplementation of the waste apple pulp extract led to the preparation of thicker membranes, with higher Young’s modulus, tension, and deformation at break but lower water uptake capacity and lower permeability to O2 and CO2. These results show that waste apple pulp and stale bread are suitable feedstocks for BC production and the cultivation conditions can be adjusted for tailoring the biopolymer’s mechanical and barrier properties to suit different applications.

Design and Evaluation of pH-Sensitive Pectin Films Infused with Anthocyanin-Rich Extracts from Australian Native Fruits for Intelligent Food Packaging Applications

This study investigates the incorporation of anthocyanin-rich extracts from Mountain Pepper Berry (MPB) and Queen Garnet Plum (QGP) into pectin-based films to develop pH-sensitive indicators. Using glycerol as an extraction solvent, significant differences in anthocyanin composition were identified: MPB extracts contained a diverse range of anthocyanin species, with a total content of 267.13 ± 5.21 mg L⁻¹, compared to the predominantly cyanidin-based QGP extracts, with 222.14 ± 1.61 mg L⁻¹. Differences in anthocyanin structures were elucidated using UPLC-Q-ToF-MS/MS analysis. FTIR and UV-Vis spectroscopy were used to assess the compatibility of the extracts with pectin and the homogeneity of anthocyanins within the film structure. Mechanical testing revealed that MPB films exhibited superior tensile strength (8.53 ± 0.51 MPa), stiffness (2274 ± 158.64 gmm− 1), and energy to failure (141.7 ± 16.23 J m− 3) compared to QGP films, which had lower tensile strength (7.74 ± 0.32 MPa), stiffness (1947 ± 125.82 gmm− 1), and energy to failure (115 ± 18.81 J m− 3). Both film types displayed similar moisture content (MPB: 48.89%, QGP: 48.13%) and water vapour permeability, indicating comparable barrier properties. When exposed to volatile ammonia, QGP films showed a more pronounced colour change, attributed to their anthocyanin profile, with a notable shift from red to brown. This research highlights the potential of glycerol-extracted anthocyanins from Australian native fruits as functional additives in pectin films, offering promising applications for intelligent packaging with enhanced mechanical performance and responsive colour-changing properties.Graphical

The preparation of different types of reclaimed rubber and their applications in tire inner liner

AbstractIn this work, the application of reclaimed ground tire rubber (RGTR) and butyl reclaimed rubber (BRR) in the inner liner rubber were investigated. Carbon black dispersion, rheological, mechanical, tear strength, dynamic compression heat build‐up, aging performance, and gas barrier properties of tire inner liner were evaluated to analyze the effects of reclaimed rubbers on the tire application. It was found that RGTR improves carbon black dispersion and tear strength of tire inner liner, while maintaining comparable tensile strength, particularly with low amount of RGTR. Furthermore, compounds containing lower amounts of RGTR exhibit reduced heat build‐up during dynamic compression tests. Additionally, RGTR with higher reclamation degree demonstrates favorable aging performance, and has superior gas barrier properties at lower amount. These findings suggest promising opportunities for the application of reclaimed rubber to enhance the performance inner liner of Radial Engineering Tires and contribute to the waste management.

Properties of Antioxidant Film Based on Protein Isolate and Seed Coat Extract from Bambara Groundnut.

Bambara groundnut (BG)-based films containing seed coat extract at different concentrations were prepared and characterized. BG seed coat extract (BGSCE) had a total phenolic content of 708.38 mg GAE/g dry extract. BGSCE majorly consisted of quercetin 3-galactoside, rutin, and azaleatin 3-arabinoside. BGSCE exhibited ABTS and DPPH radical scavenging activities (ABTS-RSAs and DPPH-RSAs), a ferric reducing antioxidant power (FRAP), and an oxygen radical absorbance capacity (ORAC) of 66.44, 4.98, 4.42, and 0.91 mmol Trolox equivalent/g dry extract, respectively. When BGSCE at various concentrations (0-8%, w/w, protein content) was incorporated into the BG protein isolate (BG-PI)-based films, film containing 4% BGSCE exhibited higher thickness, tensile strength, elongation at break, water vapor and UV-light barrier properties, and a*-value (redness) than the control film (p < 0.05). Films containing BGSCE had greater ABTS-RSA, FRAP, and ORAC than the control film (p < 0.05). An FTIR analysis elucidated that the proteins interacted with phenolic compounds in BGSCE. Nonetheless, less thermal stability was attained in films added with BGSCE. Hence, the addition of BGSCE possessing antioxidant activity exhibited an important role in properties and characteristics of BG-PI-based film. The developed active film could be applied as packaging material possessing antioxidant property for food applications.

Enhancing barrier and mechanical properties of paper through NMMO/cellulose solution coating

Enhancing barrier and mechanical properties of paper through NMMO/cellulose solution coating

Poly (Butylene Adipate‐Co‐Terephthalate) (PBAT) – Based Biocomposites: A Comprehensive Review

AbstractWith the issue of plastic waste persisting and the need for more sustainable solutions to the ever‐increasing demand for lightweight and durable plastic products, this review has become imminent and compelling. Poly (butylene adipate‐co‐terephthalate) (PBAT) is a biodegradable polymer with exceptional film‐forming ability resembling those of low‐density polyethylene. PBAT has a huge advantage for packaging applications due to its remarkably high elongation at break, giving it a good processing window for its application in packaging. However, certain defiant intrinsic properties stand in the way of its full commercialization. The development of blends and biocomposites of PBAT has, therefore, become imperative for complementing its properties and producing a superior material. This paper focuses on the recent developments in preparing PBAT‐based blends and biocomposites with superior mechanical, barrier, and antimicrobial properties and, most importantly, has also investigated how the development of these blends and biocomposites impacts the biodegradation rate of PBAT. It also highlights the possible synthesis of bio‐based PBAT and the commercialization, market trends, and prospects of PBAT‐based materials for flexible, rigid packaging, and other industrial applications compared with biodegradable alternatives.

A novel ε-polylysine-reinforced pullulan/curdlan-active film for an efficient preservation of fresh-cut fruit and vegetable.

In this study, a novel active film was developed by employing ε-polylysine (ε-PL) as a filler in pullulan/curdlan (P/CD) composite film (P/CD/ε-PL). The results showed that the structure of P/CD films was more uniform and denser compared to pullulan films, due to the good compatibility and intermolecular interaction between them. Among P/CD films, P/CD 6:1 film showed improved hydrophobicity, mechanical and barrier properties, and thermal stability, thereby selecting it for further use. Thereafter, the addition of ε-PL further enhanced the structural and physicochemical properties of prepared P/CD/ε-PL composite films, especially for P/CD/2.5%ε-PL composite film. It exhibited improved ultraviolet barrier (about 80% at 200-400nm), antibacterial activity (>90% against Staphylococcus aureus and Escherichia coli), and anti-fog properties (clearly visible and transparent background). Furthermore, P/CD/2.5%ε-PL composite film exerted its preservation effect on fresh-cut peppers and kiwis during storage, delaying the softening, consumption of soluble solids, and deterioration. Therefore, the developed P/CD/2.5%ε-PL composite film provided promising applications of active packing film. Practical Application: Fresh-cut fruits and vegetables are prone to deteriorate during storage, and active packaging films play a crucial role in retaining their quality. This study was conducted to prepare a composite film by blending pullulan, curdlan, and ε-PL and explore its structural, physicochemical, and functional properties, further verifying the preservation effect on fresh-cut peppers and kiwis. Compared to polyethylene film, the P/CD/2.5%ε-PL composite film delayed the softening, consumption of soluble solids, and deterioration of fresh-cut peppers and kiwis during storage. It provides a new perspective on the preservation of fresh-cut fruits and vegetables.

Machine Learnable Language for the Chemical Space of Nanopores Enables Structure-Property Relationships in Nanoporous 2D Materials.

The synthesis of nanoporous two-dimensional (2D) materials has revolutionized fields such as membrane separations, DNA sequencing, and osmotic power harvesting. Nanopores in 2D materials significantly modulate their optoelectronic, magnetic, and barrier properties. However, the large number of possible nanopore isomers makes their study onerous, while the lack of machine-learnable representations stymies progress toward structure-property relationships. Here, we develop a language for nanopores in 2D materials, called STring Representation Of Nanopore Geometry (STRONG), that opens the field of 2D nanopore informatics. We show that STRONGs are naturally suited for machine learning via recurrent neural networks, predicting formation energies/times of arbitrary nanopores and transport barriers for CO2, N2, and O2 gas molecules, enabling structure-property relationships. The machine learning models enable the discovery of specific nanopore topologies to separate CO2/N2, O2/CO2, and O2/N2 gas mixtures with high selectivity ratios. We also enable the rapid enumeration of unique configurations of stable, functionalized nanopores in 2D materials via STRONGs, allowing systematic searching of the vast chemical space of nanopores. Using the STRONGs approach, we find that a mix of hydrogen and quinone functionalization results in the most stable functionalized nanopore configuration in graphene, a discovery made feasible by expedited chemical space exploration. Additionally, we also unravel the STRONGs approach as ∼1000 times faster than graph theory algorithms to distinguish nanopore shapes. These advances in the language-based representation of 2D nanopores will accelerate the tailored design of nanoporous materials.

Cobalt-doped iron-based Prussian blue analogue cubes anchored to phosphorus‑nitrogen-covered BN surfaces for enhancing the flame retardancy of epoxy coatings

Prussian blue analogue (PBA) is considered to be a very promising inorganic nano-flame retardant material due to its structure enriched with transition metal elements. Here, hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine (p-PDA) were first loaded onto the boron nitride surface (BN/PCP) via a polymerization reaction to impart richer flame retardant characteristics. Then, Co-Fe-based PBA nanoparticles were homogeneously anchored on the BN/PCP surface to obtain the BN/PCP@PBA hierarchical nano-flame retardant. It is worth mentioning that this novel composite flame retardant effectively combined the superior barrier properties of BN, fire retardancy of N, P elements and the accelerated carbon conversion effect of Co-Fe/PBA. The test results showed that the loading of PCP on the BN surface could effectively improve the thermal insulation performance of EP, while Co-Fe/PBA had good catalytic carbon formation effect at high temperature. Specifically, the backside of the BN/PCP@PBA filled EP sample displayed the lowest temperature during flame attack (164.1 °C) compared to the other specimens, proving its best thermal insulation. The BN/PCP@PBA/EP obtained the maximum expansion height and expansion rate values (27.6 mm and 21.07) in the furnace chamber experiments, which are crucial for its fire resistance. In addition, BN/PCP@PBA/EP retained the highest residual char (32.6 %) and achieved the lowest smoke density rating (36.9 %), demonstrating its high carbon conversion and fume suppression. Carbon residue analysis confirmed that the char layer of BN/PCP@PBA/EP was more complete and the metal oxides were uniformly embedded in the carbon residue skeleton, which ensured good flame protection for the substrate.

Effect of surface charge on mechano-bactericidal activity of cellulose nanocrystals constructed chevaux-de-frise and meat preservation

The nanostructured insect wings have inspired the development of antimicrobial surfaces with mechano-bactericidal activity. For the first time, a chevaux-de-frise-like nanostructure was fabricated through the coating of cellulose nanocrystals (CNC) onto regenerated cellulose (RC) films via vacuum filtration and the impact of contact time, temperature, and surface topography on eliminating foodborne bacteria was examined. Herein, our focus is to explore in more detail how the surface charge of CNC affects the mechano-bactericidal activity and the performance of chevaux-de-frise-like nanostructure in meat preservation. CNC with neutral (weak), negative, and positive charges were prepared by hydrochloric acid hydrolysis (HCNC), TEMPO oxidation (TCNC), and amination (ACNC), respectively, and showed similar reinforcing effects on the tensile strength (increased from 74.23 ± 1.20 to about 100 MPa) and water vapor barrier property (reduced from 1.83 ± 0.08 to about 1.20 × 10−7 g m−1 h−1 Pa−1). Among them, RC-ACNC showed the highest log reduction against Escherichia coli (0.83 ± 0.06) and Staphylococcus aureus (0.69 ± 0.04) after 5 min contact, respectively, indicating the important role of attractive force in fast eliminating bacteria upon contact. It was worth noting that, during the meat preservation test, all three CNC-coated RC films exhibited a similar 0.4 log reduction of bacteria after day 4, likely due to the same physical attachment with an extended contact time. Therefore, the construction of chevaux-de-frise nanostructure from CNC on food packaging provides a sustainable strategy to contribute to preventing bacterial growth.

Effect of aminolysis treatment on self-healing properties and printing potentialities of banana peel and edible wax based biodegradable film

Cellulose-based materials are a viable alternative to petroleum-based sources; however, the practical applicability of cellulose films is severely limited by their poor hydrophobicity. This study explores the development of hydrophobic films with self-healing properties through the incorporation of natural wax into a cellulose matrix. Different formulations of films were developed varying the concentration of glycerol (0 % to 3.5 % v/v) and aminolysis treatment. Printability property, rubbing, acid, and water resistance property of the film were also evaluated. The self-healing efficiency of the films varied from around 30 % to 80 % based on variations in glycerol and aminolysis treatment provided. Aminolysis-treated films showed enhanced self-healing properties (Self-healing efficiency ~77 %) compared to the control films. The films were characterized for their physical, mechanical, barrier, and thermal properties and it was found that 1.5 % had superior properties compared to other compositions. Printability properties showed that aminolysis-treated films had better wetting properties (WCA ~ 74.46°) with a peak tact force of 8.1 N. This signifies aminolysis-treated films had better ink absorption and adhesion properties, which confirms the printability nature of the films. This study highlights the potential applications of biodegradable self-healing based film, applications with a scope of resolving environmental problems by replacing petrochemical plastics.

Scale-Up Preparation of Biobased Poly(ethylene furanoate) Biaxial Orientation Films with Enhanced Mechanical and Barrier Properties for Packaging

Scale-Up Preparation of Biobased Poly(ethylene furanoate) Biaxial Orientation Films with Enhanced Mechanical and Barrier Properties for Packaging

Waterborne cellulose acetate pickering emulsion generation mediated by cellulose nanocrystals for paper coating applications

There is a continually increasing demand for alternatives to single-use, non-degradable, and synthetic plastic packaging. Environmentally friendly paper products offer a potential solution, but typically do not meet stringent demands for barrier and other physical property performance unless coated with polymeric films, usually polyolefins. Replacing conventional plastic film coatings with bio-based polymer alternatives, such as cellulose acetate, can provide competitive barrier property performance while also providing sustainability benefits. Furthermore, water can be used as a coating medium for added environmental and coatability advantages. In this study, 10 wt% Pickering emulsions of cellulose acetate dispersed in water and stabilized via cellulose nanocrystals (CNC) were generated. Rheological behavior, particle size, stability, and particle morphology were analyzed, as was the effect of modifying the CNCs using (2-Dodecen-1-yl)succinic anhydride over several weeks. Unbleached kraft paper was coated and compared to polyolefin coated and uncoated paper. Water vapor permeability, grease resistance, water absorption, and wet mechanical properties were all investigated, displaying promising properties for barrier paper coating. The grease kit test yielded a result of 10/12 for the coated paper versus 0/12 for uncoated, and water Cobb value showed a 60 % improvement. Lastly, the performance of the coated paper as a food takeout container coating was explored, with convincing results demonstrating a strong avenue of applicability. Overall, the waterborne cellulose acetate Pickering emulsion formation and its paper coating application yielded promising results for sustainable packaging development.

Waste paper recycling and its application in modification of the green biodegradable material

Waste paper is a significant waste resource that is part of waste polymer materials in vast quantities, and there is now a lot of focus on the development of high-value conversion and use technologies for waste paper. High-quality waste paper fibers (WF) were extracted in this work from the deinked waste paper pulp by mechanical process. Then, waste paper fiber/polylactic acid (WF/PLA) composites were synthesized using hybrid forming technique to investigate the modification impact of WF on WF/PLA composites. The results showed that a certain additive amount of WF could improve barrier property of WF/PLA composites. When WF was added of 3.5 %, a water vapor transport rate was only of 59 g/(m2d), and the barrier property was increased by 82.8 %. Besides, WF/PLA composites also possessed good thermal stability. With the additive WF ranging from 3 % to 4 %, the initial decomposing temperature of WF/PLA composites increased by 19℃. Importantly, the transparency of PLA was slightly improved with a certain addition of WF. Hence, this work realized the performance enhancement of WF/PLA composites by a small addition of WF, and reduced the production cost of PLA to some extent, which had a good application prospect.

Aluminum-Doped Indium Oxide Electron Transport Layer Grown by Atomic Layer Deposition: Highly Efficient and Damage-Resistant Interconnection Solution for All-Perovskite Tandem Solar Cells with 25.46% Efficiency.

In fabricating high-efficiency all-perovskite tandem solar cells (APTSCs) with a p-i-n configuration, the electron transport layer (ETL) plays a critical role in facilitating the transport of photogenerated electrons from the front cell to the recombination layer and protecting the front cell from damage during rear cell fabrication. This study introduces aluminum-doped In2O3 (AIO) films grown by atomic layer deposition (ALD) as a promising ETL for high-efficiency APTSCs. ALD-grown AIO films with an optimized Al concentration exhibit superior charge transport characteristics, excellent transparency, and damage-resistant barrier properties against solution infiltration compared with conventional SnO2 ETLs and undoped ALD In2O3. Using an ALD SnO2/3 at.% AIO bilayer as the electron transport layer, an efficiency of 18.33% is achieved from single-junction wide bandgap perovskite solar cells. Furthermore, the use of ALD SnO2/3 at.% AIO ETL enables the reliable fabrication of APTSCs with negligible solution damage to the front cell and minimized power loss. Consequently, APTSC employing the ALD AIO-based ETL exhibit an excellent photoconversion efficiency of 25.46%, outperforming APTSCs with the ALD SnO2 ETL.

Synthesis and Applications of Nanocomposites in Food Packaging Industry: A Review

The current review focuses on the applications of polymer nanocomposites in the packing industry. Nanocomposite fabrication may be carried out through several synthetic techniques based on the type of material required. Basically, it is the composite formation of polymeric matrix and a reinforcing nanofiller. The nanoclay used for the modification of nanocomposites acts as a reinforcement or filler. Montmorillonite (MMT) is the most frequently used clay material to obtain the desired properties of nanocomposite. Clay reinforcement enhances the food packing properties of the material because of its properties as flame retardant, tensile features, barrier properties, and biodegradability. Among bottom-up and top-down techniques, sol-gel synthesis, self-assembly, and polymerization are the most common techniques used for the synthesis of nanocomposites. Nanocomposites derived from bio-polymers make the material biodegradable which, in turn, is one of the most desirable features for their future use. Owing to improved characteristics, clay nanocomposites form a superior class of materials for food packaging, yet much finer dispersion of nanofillers and compatibility may be devised.

Unveiling the Potential of Halloysite Nanotubes: Insights into Their Synthesis, Properties, and Applications in Nanocomposites

AbstractHalloysite nanotubes (HNTs) have attracted considerable attention due to their unique properties and wide range of applications. This review explores HNT‐based nanocomposites, focusing on their preparation methods and improvements in mechanical, thermal, and barrier properties. Various synthesis techniques, including solution mixing, melt compounding, in situ polymerization, and surface modification, are discussed, along with their benefits and limitations. The role of HNT characteristics such as aspect ratio, dispersion, and surface chemistry in enhancing nanocomposite properties is examined. HNTs significantly boost mechanical properties, including tensile strength, Young’s modulus, and toughness, due to their reinforcement effects. Improved dispersion and interfacial adhesion between HNTs and the polymer matrix enhance these properties. HNTs also act as thermal barriers, improving heat resistance and dimensional stability, while enhancing barrier properties against gases and moisture. These synergistic effects allow for the customization of nanocomposites for specific applications in packaging, automotive, electronics, and biomedical fields. Future research should focus on optimizing synthesis methods and processing techniques to further improve HNT‐based nanocomposites’ performance. This review provides a comprehensive overview of HNT‐based nanocomposites, offering valuable insights for advancing nanomaterials science and engineering.

Nanocellulose‐polypropylene composites with novel antimicrobial complex salt

AbstractPolypropylene composites with different contents of zinc‐ammonium salts (3, 5 and 7 wt%) and nanocellulose (1 wt%) after enzymatic bioconversion were characterized by structural, dispersion‐morphological, thermal, antimicrobial and mechanical analysis. It was shown that the use of a newly synthesized salt significantly affected the formation of the supermolecular structure of the polymer matrix and increased the nucleation activity, thermostability and flexibility of the composite materials. Moreover, the addition of the inorganic filler allowed to obtain composites with very good antimicrobial properties against Staphylococcus aureus, Escherichia coli and Candida albicans. An interesting relationship between the degree of filler dispersion in the polymer matrix and the formation of polymorphic varieties was elucidated in the study, which contributes to the improvement of final performance characteristics of composite materials. It is noteworthy that a hybrid filler in the form of nanometric cellulose and a biocidal additive containing zinc‐ammonium complex salt was used for the first time. Research has shown that such polymer composites can find application during the manufacture of smart packaging materials with enhanced barrier properties against oxygen and water vapor as well as improved biocidal characteristics, which will notably extend food storage time. At the same time, the presented process of obtaining the innovative composite materials is an excellent example of sustainable technologies for the design of antimicrobial treatments, while guaranteeing the possibility of further processing of these composite materials through material recycling.Highlights Zinc‐ammonium complex with antimicrobial properties was obtained The strength properties and thermal stability of the composites were improved Degree of filler dispersion in polymer affects formation of polymorphic varieties The composites can be applied in the production of smart packaging materials

Visible-light-driven Fe-catalyzed alkylation for synthesizing functionalized polyolefin elastomers as advanced encapsulants in photovoltaic modules

Polyolefin elastomer (POE) has emerged as a promising encapsulant for photovoltaic modules, attributed to its exceptional water vapor barrier properties, robust weather resistance, and enhanced anti-potential induced degradation (anti-PID) capabilities. Despite these advantages, the interfacial adhesion of POE remains a significant challenge, particularly its suboptimal bonding with glass and solar cells, which impedes its broader application within the photovoltaic industry. This study introduced glycidyl methacrylate (GMA) monomers into POE through a photo-induced iron-catalyzed alkylation reaction, developing a novel polyolefin encapsulant for photovoltaic modules. The encapsulant was designed to possess high light transmittance, enhanced adhesion, and elevated resistivity. The modified POE boasts an impressive light transmittance nearing 98% and an adhesive strength of 28.3 N cm−1, both superior to traditional ethylene-vinyl acetate copolymer (EVA) materials. Additionally, this work delves into the correlation between crystallization behavior and light transmittance, elucidating the influence of GMA incorporation on the adhesion and insulation properties of POE through gaussian simulations.

Tuning Barrier Properties of Low-Density Polyethylene: Impact of Amorphous Region Nanostructure on Gas Transmission Rate

This work focused on determining the factors that are of key importance in the oxygen barrier properties of low-density polyethylene (LDPE). It has been shown that, depending on the type and amount of the low-molecular-weight compound (tetracosane, paraffin wax, paraffin oil) introduced into the LDPE matrix, it can contribute to the improvement or deterioration of barrier properties. Tetracosane and paraffin wax incorporated into the LDPE matrix caused a reduction in oxygen permeability parameters compared to neat polyethylene. As their content increased, the barrier properties of the samples towards oxygen also increased. A completely opposite effect was achieved with paraffin oil. The results of comprehensive studies provide evidence that in the case of LDPE blends, two mechanisms are responsible for changing/controlling their transport properties. The first mechanism is associated with changes in the molecular packing in the interlamellar amorphous regions, while the second is related to the crystallinity of the samples. In cases where there are no changes in crystallinity, the density of the amorphous phase becomes the decisive factor in barrier properties, as clearly shown by results assessing chain dynamics.