Water Vapor Permeability Research Articles

Preparation and characterization of carvacrol/soybean protein isolate composite film with efficient antimicrobial and antioxidant activities and its application in grape preservation

There is an urgent need for a simple and effective method to enhance the freshness of fruits during transportation. In this study, we developed a composite antibacterial film (CAR film) using carvacrol and soy protein isolate (SPI). The mechanical properties, hydrophobicity, antibacterial activity, and antioxidant capacity of the film were characterized. The results demonstrated that, compared to the soy protein isolate film, the film with 2.5 % carvacrol content exhibited superior mechanical properties (tear strength decreased by approximately 37 %, elongation at break increased by about 108 %), hydrophobicity (water vapor permeability decreased by 38 %), antibacterial activity (inhibition zone diameters against E. coli and S. aureus were 14.21 mm and 11.83 mm, respectively), antioxidant capacity (increased by 5 to 6 times), and biocompatibility (cell survival rate exceeded 90 %). Grape preservation experiments further confirmed that the CAR film effectively prolongs shelf life. Therefore, CAR film is a promising packaging material for fruit preservation.

Hollow fibers with encapsulated ionic liquid for gas dehydration

Membrane technology is a viable alternative for achieving energy savings and sustainability, particularly in dehydration applications. The selective removal of water vapor from gas mixtures by membranes enhances the process efficiency furthermore the industry increasingly prioritizes resource conservation and environmental impact, advancements in membrane technology are crucial for meeting these goals and driving progress toward a sustainable future. Our approach consists of the incorporation of a proline amino acid-based ionic liquid encapsulated in carbon capsules, dispersed in a Pebax®1657 matrix, and coated on polyetherimide hollow fibers. The filled capsules have high sorption capacity for both water vapor and carbon dioxide (CO2) contributing for successful exploration for air dehumidification, as well as flue gas, natural gas and biogas dehydration. The membranes had exceptional water vapor permeance, reaching values up to approximately 10,000 GPU while maintaining an H2O/N2 selectivity of around 124,000. CO2/N2 selectivity as high as 100 and promising results for CH4 purification were demonstrated. Long-term studies using alternative modules to prevent saturation of the encapsulated capsules with water vapor and effective regeneration have been proven.

Freestanding Hydrogen-Bonded Organic Framework Membrane for Efficient Wound Healing.

Hydrogen-bonded organic frameworks (HOFs) are emerging as multifunctional materials with exceptional biocompatibility, abundant active sites, and tunable porosity, which are highly beneficial for advanced wound care. However, a significant challenge involves transforming pristine HOFs powders into lightweight, ultrathin, freestanding membranes compatible with soft biological systems. Herein, the study successfully develops shape-adaptive HOF-based matrix membranes (HMMs) using a polymer-assisted liquid-air interface technique. The HMMs conform seamlessly to tissues of different sizes and shapes, effectively stopping bleeding, and provide high water-vapor permeability. Notably, both in vitro and in vivo studies with mice wound models demonstrated that these tissue-conformable HMMs significantly accelerate wound healing by modulating the inflammatory environment of the injured tissue and promoting rapid re-epithelialization. Furthermore, RNA-seq analysis and mechanistic studies revealed that HMMs effectively reduce inflammation and facilitate the tissue transition from the proliferative stage to the remodeling stage of skin development. This work not only opens up new avenues for advanced wound care materials but also establishes a foundation for hybridizing HOFs with polymers for a wide range of potential applications.

Fabrication of bamboo nanocellulose fibril-based food packaging with dual-antimicrobial property

The development of cellulose-based packaging films with excellent antimicrobial properties and biocompatibility has garnered significant attention. In this work, nanocellulose fibrils (NCFs) derived from from bamboo parenchyma cells were utilized to fabricate nanocomposite film with antimicrobial properties. This system exhibited distinct release behaviors for two antimicrobial agents, with the slow release of Ag nanoparticle (AgNP) in the initial stage contributed to delaying food spoilage, while the subsequent pH change in the microenvironment facilitated the release of essential oil of sour orange blossoms (SEO) for secondary antimicrobial activity. Additionally, the composite film demonstrated improved thermal stability and UV blocking capacity. Moreover, AgNP has been proven to enhance the mechanical properties, with the tensile strength of the novel composite film increasing by 34.85 % compared to control group. The water vapor permeability and oxygen permeability of the novel composite film were reduced, which could potentially reduce weight loss and slow down the rate of after-ripening. Following the acidification treatment, the films containing EO@MPN (essential oil encapsulated with metal-polyphenol network) component performed different antimicrobial patterns, indicating their pH-responsive antimicrobial capabilities, and they are effective against both Gram-positive and Gram-negative bacteria. After a 24-h exposure to a food simulant, the release amount of Ag was measured at 67.6 μg/dm2, within the acceptable limit, and the release profile of Ag was characterized. Cytotoxicity and Live/Dead staining tests confirmed that the novel composite film film had no significant toxicity, thus making it safe for application in food preservation. Furthermore, in a 15-day preservation experiment with mangoes, the novel composite film demonstrated the best performance, underscoring its potential as a sustainable antimicrobial packaging material.

Multifunctional electrospun nanofibrous film integrated with cinnamon essential oil emulsion stabilized by dealkali lignin for active packaging material

Cinnamon essential oil (CEO) has good antibacterial properties, but its volatility, hydrophobicity and bad odor limit its use in food preservation. In this study, a dealkali lignin (DAL) stabilized emulsion loaded with CEO was encapsulated into poly (vinyl alcohol) (PVA) and zein using an emulsion electrospinning technique. With the existence of DAL, the PVA/zein/DAL/CEO nanofibrous film (PVA/zein/DAL/CEO NF) exhibited good antioxidant properties. Moreover, higher antibacterial activity was achieved owing to the nanosized structure and enhanced stability compared to DAL/CEO emulsion and pure CEO. Scanning electron microscopy (SEM) revealed uniformly produced PVA/zein/DAL/CEO NF with an average diameter of 295 nm. The interactions among the nanofibrous film's components were confirmed using attenuated total internal reflectance fourier transform infrared spectroscopy (ATR-FTIR). The nanofibrous film demonstrated a low water vapor permeability (WVP) of 5.07 mm∙g/(m2∙h∙kPa), which was beneficial for reducing moisture transfer from the external environment to the interior of the packaging. Additionally, the PVA/zein/DAL/CEO NF also exhibited a marked enhancement in antioxidant activity, neutralizing 94.54 % of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The nanofibrous film also demonstrated potent antibacterial effects, with inhibition zones measuring 19.47 mm for Escherichia coli (E. coli) and 30.37 mm for Staphylococcus aureus (S. aureus), respectively. This study provided a reference for preparing a multifunctional electrospun nanofibrous film integrated with CEO as an active packaging material.

Optimization of novel sustainable Dictyota mertensii alginate films with beeswax using a simplex centroid mixture design

The environmental risks of synthetic polymers drive the need for innovative and sustainable film and packaging solutions. This study optimized the formulation of films composed of alginate derived from the brown seaweed Dictyota mertensii (ADM), glycerol, beeswax, and tween 80, aiming to improve their properties. A simplex-centroid blend design was employed to develop and optimize the composite films. The films were characterized based on their morphological properties, moisture content (MC), contact angle (CA), solubility (S), water vapor permeability (WVP), color parameters (L*, a*, and b*), opacity, tensile strength (TS), elongation at break (EB), and elastic modulus (E). Contour surfaces were plotted from the studied variables, fourth-order polynomial models were predicted, the influence of the blend components was analyzed, and the response variables were subjected to analysis of variance (ANOVA) and the F test with 95% confidence. The predicted conditions were experimentally validated. MC, WVP, solubility, opacity, a*, and b* were minimized, whereas CA, L*, TS, EB, and E were maximized, resulting in MC=6.85%, WVP=16.37 g.mm/h.kPa.m2, S=28.87%, CA=83.86°, Opacity=5.60 AU.nm.mm-1, L*=70.31, a*=4.79, b*=21.00, TS=11.76 MPa, EB=12.70%, and E=96.47 MPa. The overall desirability index was 0.70, resulting in an optimal biopolymer matrix of 75.00% ADM, 5.00% glycerol, 7.50% beeswax, and 12.50% Tween 80. The results highlight the potential of alginate films made from the brown seaweed Dictyota mertensii and the sustainable use of natural marine resources.

Carboxymethyl cellulose – Polyvinyl alcohol bioactive films loaded with green extracted date seed polyphenols for active packaging of Shiitake mushrooms

This study investigated the use of a natural deep eutectic solvent-based polyphenolic extract (DSE) from date fruit seed as a bioactive and functional component for the development of carboxyl methylcellulose-poly(vinyl)alcohol (CMCPVA) packaging films. The impacts on the physicochemical, structural, water barrier and bioactive properties of the CMCPVA films were studied. Different concentrations of DSE (1.5%, 2%, 2.5%, and 3%) incorporated into CMCPVA film increased the total phenolic content (0.08–0.17 mg GAE/mL), DPPH scavenging activity (4.08–5.11 mmol GAE/mL), and ferric ion-reducing antioxidant power (0.82–1.46 μmol TE/mL) of the films. The antibacterial activities against S. aureus, L. monocytogenes, S. typhimurium, and E. coli were also improved. In particular, a 4–5 log reduction was recorded for CMCPVA film incorporated with 3% DSE. Also, the presence of DSE enhanced elongation at break (25.53%–93.23%) and film thickness (0.10–0.19 mm), whereas tensile strength (6.39–1.40 MPa) and Young's modulus (25.89–2.85 MPa) decreased. Furthermore, UV-shielding performance improved, opacity decreased from 2.93 to 0.86, while the water vapor permeability was not significantly affected which ranged from 3.01 to 5.83 (X 10−10 g/m.s.Pa). The application of CMCPVA film incorporated with 3% DSE (CMCPVA_3) as a bioactive film for preserving sliced and whole shiitake mushrooms at refrigeration temperature for 8–12 days was studied. The CMCPVA_3 film preserved the mushrooms' color, browning degree, and texture compared to the cling film-covered samples. There is a potential for the successful application of NADES-based polyphenolic extract in biopolymer films for food preservation.

Development and application of visual fish freshness indicator film incorporated with anthocyanins encapsulation by whey protein-propylene glycol alginate nanoparticles

Intelligent indicator packaging has gained increased attention in meeting the demand for reducing food waste and mitigating the risk of food poisoning. This study focused on the preparation, characteristics, and application of freshness indicator films based on polyvinyl alcohol (PVA) and anthocyanins (ACNs)-encapsulated whey protein (WP)-propylene glycol alginate (PGA) nanoparticles. The successful encapsulation of ACNs by WP-PGA nanoparticles improved the stability of ACNs and their encapsulation efficiency (EE) reached 95.34 %. The incorporation of nanoparticles into the structure of the PVA films was justified by SEM, XRD, and ATR-FTIR, and resulted in a decrease in water vapor permeability (WVP) from 15.76 (×10−7 g·m−1·Pa−1·h−1) to 8.40 (×10−7 g·m−1·Pa−1·h−1) and an increase in scavenging rate of DPPH radical from 1.47 % to 18.92 %. The light-blocking property and mechanical properties of the films were also improved, and they showed visible color change in response to pH 2–12 and high color stability after 14 days of storage at 4 °C and 25 °C. Furthermore, the freshness indicator films underwent a noticeable transformation from rosy red to gray at bighead carp head spoilage. Therefore, the encapsulation of ACNs using WP-PGA nanoparticles provides a promising non-destructive and real-time freshness indication of aquatic products during both storage and transportation processes.

Characterization of exopolysaccharide/potato starch nanocomposite films loading g-C3N4 and Ag and their potential applications in food packaging

The interest in nanocomposite films incorporating edible ingredients and active nanoparticles has surged due to their potential to enhance food quality and prolong shelf-life. This research focused on developing innovative exopolysaccharides (EPS)/potato starch (PS) nanocomposite films integrated with g-C3N4 and AgNO3. Extensive analysis was conducted to assess the microstructure, physical attributes and antimicrobial properties of these films. Fourier transform infrared (FT-IR) analysis revealed electrostatic and hydrogen bonding interactions within the film components. X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS) data indicated a high level of compatibility among EPS, PS, g-C3N4, and AgNO3, with no new absorption peaks or characteristic signals of C3N4 and Ag appearing in the nanocomposite films patterns. The thickness, water solubility and water vapor permeability (WVP) of the EPS-PS-C3N4-Ag nanocomposite film increased due to the addition of g-C3N4, reached 0.31 ± 0.03 nm, 36.61 ± 1.76 % and 1.42 ± 0.34 × 10−10 g−1 s−1 Pa−1, respectively. While transparency, swelling degree, and oxygen permeability (OP) significantly decreased, reached 26.18 ± 2.38 %, 63.01 ± 2.51 % and 41.98 ± 1.28 %, respectively. Scanning electron microscopy (SEM) and atomic force microscope (AFM) images depicted an augmented roughness and porosity on the film surface upon integration of g-C3N4 and AgNO3. Moreover, the EPS-PS-C3N4-Ag nanocomposite film displayed enhanced mechanical strength due to the presence of g-C3N4. The melting temperature (Tm) of EPS-PS-C3N4-Ag nanocomposite film was 313.3 °C, the removal rates of DPPH and ABTS was 66.11 ± 2.87 % and 45.09 ± 1.23 % respectively. Significant inhibition of microbial growth was observed in film containing g-C3N4 and AgNO3, which demonstrated no toxicity towards NIH-33 cells, suggesting their potential application as promising active packaging material for food preservation.

Fluorinated B-72 hybrid silver doped modified nanoparticle as a coating for biological corrosion protection of ancient bricks

In this paper, a superhydrophobic organic-inorganic composite coating containing fluorinated B72 hybrid methyl-modified silica/(Ag doped TiO2) by hexamethyldisilazane (HMDS) (H-SiO2/Ag/TiO2) was prepared by means of a mild and an environmental friendly method. Transparency, adhesion, hardness tests and photocatalytic performance were measured to determine the content of Ag in TiO2 which the TiO2/AgNO3 ratio is 0.008 g/mL. The synthesized Ag/TiO2 nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra and transmission electron microscope (TEM). The highest contact angle of coated ancient bricks was 148.66° and the color change value of ΔE⁎ before and after coating was <5 which is within an acceptable range. The physical properties such as apparent porosity and water vapor permeability (ΔMp) were studied. After weathering from acid, alkali, salt, water and ultraviolet radiation, the bricks coated by the composite coatings still have good hydrophobicity that the contact angle were >120° and minor degree of surface corrosion comparing with the ancient bricks. The inhibitory effect of the composite coating on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and that on algae (Chlamydomonas and Dunaliella) were studied through bacteriostasis test and algae comparative experiments, respectively. Finally, the mechanism of the composite coating on antibacterial and anti-algae was studied. The results showed that the appearance of the ancient bricks was not changed after coating, and the anti-weathering, antibacterial and anti-algae properties of the ancient transformation were increased.

The physicochemical, mechanical, and antifungal properties of sodium alginate film containing Japanese rice vinegar and peppermint (Mentha piperita) oil as bio-composite packaging

Sodium Alginate has a high demand and is favored for food packaging; however, this film typically exhibits poor antimicrobial activity. In this study, sodium alginate film containing peppermint essential oil, Japanese rice vinegar, or a combination of both, is used to analyze antimicrobial, mechanical, structural, and optical properties. The scanning electron microscopy (SEM) technique is utilized to observe the film's surface and cross-section homogeneity. The addition of peppermint essential oil and Japanese rice vinegar to the alginate film solution improves fungal growth and spore germination prevention. Unlike the film containing vinegar, the film with peppermint essential oil shows the lowest transparency. It also has the lowest tensile strength and exhibits the highest elongation at break and water vapor permeability. Conclusively, the film containing a combination of vinegar and essential oil indicates moderate values. According to AFM topography, the film with a mix of essential oil and vinegar has a smoother, more homogeneous surface than other films. Our results prove that combining vinegar and oil with sodium alginate film is an ideal choice. This combination significantly improves the performance of food packaging.

Green nanotechnology for the enhancement of antibacterial properties in lining leather: MgO-chitosan nanocomposite coating

Antimicrobial nanomaterials have received a lot of interest in recent years due to their potential to fight against microbial degradation, a common problem in leather products. In this study, a nanocomposite was synthesized with MgO nanoparticles prepared by Aloe vera leaf extract and chitosan (CS), as an innovative solution to this problem. Three nanocomposite samples (C1, C2, and C3) were formulated with varying ratios of MgO and chitosan and evaluated for antimicrobial efficacy against Escherichia coli and Bacillus subtilis. Leather treated with MgO/Chitosan nanocomposite (MgO/Chitosan-1:1) exhibited substantial inhibition zones of 13 mm and 12 mm against E. coli and B. subtilis, respectively. Characterization of MgO nanoparticles, chitosan, and MgO/CS nanocomposite was performed through FTIR, XRD, SEM, TGA, and cytotoxicity tests. The average particle size and crystallite size of MgO nanoparticles were found as 136 nm and 10.3 nm, respectively and a weight loss of 67 % for MgO/CS nanocomposite in thermogravimetric analysis. FTIR confirmed the successful incorporation of MgO nanoparticles into the chitosan matrix, evidenced by the presence of characteristic functional groups. Application of nanocomposite onto lining leather via spraying resulted in finished leather with improved color rub fastness, perspiration fastness, and thermal stability compared to untreated leather. In comparison to dry color rub fastness, wet color rub fastness was notably improved by the MgO/CS nanocomposite, with gray scale ratings ranging from 4/5 to 5. Perspiration fastness was marginally enhanced by the MgO/CS coating, with gray scale ratings ranging from 4/5 to 5 for both grain and flesh samples. Specifically, the coated leather exhibited a water vapor permeability (WVP) of 9.94 mg cm−2.hr−1 that was lower than both uncoated (12.37 mg cm−2.hr−1) and PVA-coated (11.22 mg cm−2.hr−1) leather. This study presents a promising solution to the challenge of microbial degradation in leather products and highlights the potential of natural sources for synthesizing functional nanocomposites with diverse applications in materials science and biotechnology.

Antioxidant films loaded with β-cyclodextrin-quercetin for enhancing food preservation

As the improvement of consciousness of environment, a considerable effort has been made to shift from petroleum-based plastics to biodegradable alternatives, especially in the food packaging industry. In this work, we develop an innovative food packaging film by encapsulating quercetin (Que) within β-cyclodextrin (β-CD) to create β-CD-Que inclusion complexes, which are then dispersed in a matrix of tragacanth gum (TG) and carboxymethyl chitosan (CMCS) using a solution casting technique. β-CD-Que inclusion complexes were characterized using various methods, including 1H NMR, 2D ROESY and phase solubility testing, to elucidate the interaction between Que and β-CD. ATR–IR, X-ray diffraction, and SEM were employed to confirm the uniform dispersion of β-CD-Que within the macromolecular substrate. The incorporation of β-CD-Que considerably improves the mechanical properties of films, increasing the elongation at break from 13.68 % to 25.74 %. Rheological tests demonstrate that the viscosity of the film-forming complex solution became larger. The films were demonstrated to reduced water vapor and oxygen permeability, possessing remarkable antioxidant capability evidenced by DPPH and ABTS radical scavenging rates of 78.01 % and 99.59 %, respectively. The TG/CMCS/β-CD-Que composite film shows excellent potential for food packaging and preservation applications.

Rice starch-agar composite film decorated with green synthesized silver nanoparticles with superior properties

In this study glycerol-plasticized rice starch/agar-based eco-friendly composite film incorporated with Ocimum tenuiflorum and Murraya koenigii mixed leave extract (15 % v/v) and green synthesized silver nanoparticles (AgNPs) of concentration 1 mM were fabricated and evaluated the physical, mechanical, structural, antimicrobial and biodegradable properties. Sustainable packaging ought to lessen its ecological footprint and its effect on the environment. Boiled rice water, typically regarded as waste, is one of the best sources of starch. We used this boiled rice water to prepare the film directly. The aqueous leaf extract was also used for the synthesis of AgNPs via a simple, cost-effective and green approach. TEM analysis revealed an average particle size of 11.46 nm. Integration of the plant extract and AgNPs into the film matrix introduces antimicrobial properties against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria along with enhanced mechanical and barrier properties. SEM images displayed uniform and smooth surface of the films. The film containing AgNPs has the highest tensile strength of 11.4 ± 0.91 MPa with 56.8 ± 4.51 % elongation and the lowest water vapor permeability and water solubility (17.32 ± 2.20 %). This reveals that the prepared films can be employed as a promising, environmentally benign food packaging material to prolong the shelf life of the food. However, an increase in the concentration of AgNPs up to 2 mM, does not cause any significant improvements to the film’s overall properties. The fabricated films were utilized for wrapping green grapes, which show a reduction in weight loss and browning indicating the expansion of shelf life up to 12 days.

Date seed extract encapsulated-MCM-41 incorporated sodium alginate/starch biocomposite films for food packaging application

In this study, we developed active bio-composite films using a sodium alginate/starch (1,1) matrix incorporating date seed extract encapsulated mesoporous silica (DSE@MCM-41) up to 7.5 wt%. Incorporating DSE@MCM-41 significantly improved the films' properties, enhancing antioxidant efficacy and UV-blocking capabilities. Notably, the films exhibited a 29.5 % increase in tensile strength, a 34.81 % decrease in water absorption, and a reduction in water vapor permeability to 1.76 × 10−8 g m−1.h−1.pa−1 at 5 wt% DSE@MCM-41 concentration. These enhancements, coupled with sustained DSE release, effectively extended the shelf life of black grapes by up to 16 days. These results demonstrate the potential of DSE@MCM-41-incorporated bio-composite films to improve food preservation and extend shelf life, making them suitable candidates for advanced food packaging systems.

Fabrication and characterization of long-lasting antifungal film containing cinnamaldehyde-loaded complex coacervation microcapsules based on gelatin and gum Arabic

A novel long-acting antifungal active film was successfully created, as an alternative to conventional chemical food preservatives. The antifungal films incorporated with cinnamaldehyde (CA) microcapsules achieved long-lasting antifungal activity, mitigated yellowing caused by the direct addition of CA, and showed improved flexibility properties. CA multinuclear microcapsules were produced using gelatin with a Bloom value of 200 and gum arabic, resulting in increased encapsulation efficiency (99.86 %), good dispersibility and enhanced antifungal ability (inhibition zone diameter of 32 mm). These microcapsules can be incorporated into films as a sustained-release antifungal agent. Compared to unencapsulated CA, the addition of 1 % CA microcapsules reduced the ultraviolet transmittance (<36.40 %) of the film while maintaining visible-light transmittance (36.40 %–65.20 %), and improving its elongation at break (23.49 %). The water vapor permeability of the film was not affected by the inclusion of CA microcapsules below 0.25 %. Moreover, microcapsules can enhance the thermal properties of the film. Antifungal films incorporated with 0.5 %–2 % microcapsules may offer better long-acting inhibition against A. brasiliensis. This study presents a new promising pathway for food storage.

Self-assembled nanoflower-mediated interfacial polymerization through tunable intra- and inter-layer channels to boost total heat exchange performance

Total heat exchange membranes (THEMs) are vital for minimizing energy consumption and enhancing indoor air quality in energy recovery ventilation (ERV) systems. Manipulating the surface morphology of polyamide (PA) membranes via nanofiller-mediated interfacial polymerization is key to advancing total heat recovery performance. This study presented the fabrication of PA thin-film nanocomposite (TFN) membranes by integrating self-assembled poly(amic acid-imide) nanoflowers (P(AA-I)-NFs) with intertwined nanosheets into the organic phase. This facile approach effectively eliminated nonselective interphase voids and defects, owing to the superior polymer affinity of the organic nanoflowers. The finely tuned intra- and inter-layer channels within P(AA-I)-NFs significantly impacted monomer mass transfer, facilitated the shuttle effect, expanded the interfacial polymerization zone, and led to the formation of a rougher, thicker PA layer with enhanced surface area. The optimized P(AA-I)-NFs/PA TFN membranes exhibited outstanding performance, including CO₂ permeability of 0.51 GPU, water vapor permeability of 656.59 GPU, and an enthalpy exchange efficiency of 71.47 %, surpassing the trade-off limitations typically observed in commercial and other advanced THEMs. These findings underscored the potential of P(AA-I)-NFs-mediated TFN membranes as highly competitive candidates for next-generation ERV systems.

Interactions, structures, and functions of pomegranate peel reinforced starch film

This work aimed to exploit the effects of pomegranate peel (PP) addition (10 %) and homogenization process (0–12,000 rpm) on the film-forming behavior and interactions of starch film to improve its microstructures and properties. Microrheology results showed that the viscosity of the film suspension was reduced by homogenization, and the amylopectin aggregation was restricted by PP particles under film formation. This helped improve the accessibility of starch and PP, increasing the hydrogen bond energy in the composites from 18.12 to 19.35 kJ/mol and promoting the ester bonds as confirmed by the FTIR results. As a result, the starch film reinforced by PP and homogenization showed a uniform and compact microstructure with reduced water activity, increased UV-blocking capacity (from 67.46 % to 90.11 %), enhanced mechanical resistance, and reduced water vapor permeability (from 4.70 to 2.21 × 10−10·g·m−1·s−1·Pa−1). Additionally, the starch film with 10 % PP also presented superior antimicrobial properties and antioxidant activity with rates of over 86 %, providing an effective strawberry preservation function.

Influence of copper ion cross-linked CMC-PVA film on cell viability and cell proliferation study

In this study, films composed of carboxymethyl cellulose and polyvinyl alcohol were fabricated using the solution casting method. Citric acid (4 %) was employed as a cross-linking agent, while glycerol (3 %) as a plasticizer. Cupric chloride (CuCl2·2H2O) was used for cross-linking at concentrations 0.5 %, 1 %, and 3 % over different times. The cross-linking with copper ions led to a noticeable reduction in elasticity, with the breaking strain ranging from 17.9 %–52.9 %. The ion hydration phenomenon increased the contact angle and swelling ratio. Fourier-transform infrared (FTIR) spectroscopy confirmed esterification reactions and copper ion cross-linking with sodium carboxymethyl cellulose (Na-CMC). The films showed antibacterial activity against Staphylococcus aureus and Escherichia coli. The ion-released mechanism followed was the non-Fickian super case-II type. The concentration and duration of cross-linking significantly influenced cell viability and proliferation. FE-SEM analysis revealed that effective concentrations of CuCl2.2H2O were 0.5 % and 1 %, and cross-linking times were 5–15 min, facilitating cell attachment and proliferation. Films are non-adhesive with water vapor permeation 800–900 g/m2/day. These results indicate the potential use of the films in treating second-degree burn wounds with low to medium exudate levels. This study provides valuable insights into the development of copper-infused materials for advanced wound healing applications.

ADHESIVE ABILITY OF GYPSUM-CONTAINING PLASTER COMPOSITIONS

The traditional material for the construction of buildings in the Northern Black Sea region is a cheap local stone ‒ limestone-shell rock. Most of the buildings in the central part of the city of Odesa, which are of historical and architectural value, are constructed of this material. With proper care and maintenance, these structures can perform their functions for hundreds of years, but as a result of shell rock moisture due to negligent operation and a number of other reasons, the supporting structures are damaged, followed by the collapse of the building. In many cases, the direct cause of the destruction of load-bearing walls is the damage or absence of the outer plaster layer. Repairing walls with cement compounds exacerbates the problem. The article discusses some aspects of the possible use of gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. The requirements for the repair composition are formulated. The expediency of using gypsum as a binder for the repair plaster mixture for exterior repairs is substantiated. An ash-gypsum-cement composition was used to increase the water resistance of the plaster. Sufficient water resistance and vapor permeability of the proposed composition were confirmed. This paper presents the results of studying the adhesive strength of the contact of the developed composition with the surface of various materials. Methods and measuring equipment developed at the ODABA were used. The adhesion strength of the proposed mixture with the surface of shell rock is close to the standard strength. The use of the adhesive additive Ceresit CC 81 increases the adhesive strength of the joint of the proposed composition with shell rock by 1.5 ‒ 2 times. The optimal amount of the adhesive additive to be introduced will be determined by the results of a multifactorial experiment to study the effect of a complex of chemical additives of different functional purposes on the properties of the proposed repair composition.