Water Vapor Permeability Rate Research Articles

Whey protein isolate/jujube polysaccharide-based edible nanocomposite films reinforced with starch nanocrystals for the shelf-life extension of banana: Optimization and characterization

The formulation of new bionanocomposite (BNC) films using whey protein isolates (WPI, 3.3–11.7 %)-jujube polysaccharide (JPS, 1.59–18.41 %)/starch nanocrystals (SNCs, 0.32–3.68 %) blends was optimized. The ultrasound-assisted acid hydrolysis produced ~63.1 nm SNCs from native starch with −24.3 mV ζ-potential. The extracted JPS purification led to a single symmetrical peak for galactoarabinan-rich fraction (1.35 × 105 Da). The optimal levels of barrier (oxygen (11.85 cm3 m−2 d−1 atm−1) and water vapor (3.22 × 10−10 g m−1 s−1 Pa−1) permeability rate), optical (opacity index (2.7 AU μm−1), total color difference (18.69), and whiteness index (77.40)), and thermal (glass transition temperature (−8.29 °C) and melting point (110.38 °C)) properties were obtained at 5.0 % WPI, 15.0 % JPS, and 3.0 % SNCs. The film-forming solution of optimal BNCs had a significant antibacterial effect against Staphylococcus aureus and Escherichia coli. The improved crystallinity of BNCs at an optimal SNC level was confirmed by the X-ray diffraction (XRD). The field emission-scanning electron (FE-SEM) and atomic force (AFM) microscopy images confirmed a continuous and uniform network for the optimal BNCs without any pores or cracks accompanied by low surface roughness. The FTIR spectroscopy proved covalent interaction and hydrogen bonding among chemical functional groups of WPI and JPS reinforced with SNCs. The optimal BNC could preserve banana fruits with favorable physicochemical and microbial quality during storage.

Sunflower Oilcake as a Potential Source for the Development of Edible Membranes.

Sunflower oilcake flour (SFOC) resulting from the cold extraction of oil is a rich source of valuable bio-components that stimulated the development of novel, biodegradable and edible films. The films were prepared by incorporating different concentration of sunflower oilcakes (0.1–0.5 g). The obtained films were characterized in terms of physical, water-affinity, antimicrobial and morphological properties. The edible-film properties were affected significantly by the presence and the level of SFOC added. The water vapor permeability and water vapor transmission rate improved with the amount of SFOC added. However, the solubility, oxygen and grease barrier were slightly lower than control film. SEM analysis revealed a rougher but continuous structure with the increases in sunflower oilcake. Moreover, the films with different SFOC levels were opaque, thus presenting good protection against UV radiation. Overall, the SFOC can be use as raw material to produce edible films with suitable properties and microbiological stability for food-packaging applications.

Active Potential of Bacterial Cellulose-Based Wound Dressing: Analysis of Its Potential for Dermal Lesion Treatment.

The use of innate products for the fast and efficient promotion of healing process has been one of the biomedical sector’s main bets for lesion treatment modernization process. The aim of this study was to develop and characterize bacterial cellulose-based (BC) wound dressings incorporated with green and red propolis extract (2 to 4%) and the active compounds p-coumaric acid and biochanin A (8 to 16 mg). The characterization of the nine developed samples (one control and eight active wound dressings) evidenced that the mechanics, physics, morphological, and barrier properties depended not only on the type of active principle incorporated onto the cellulosic matrix, but also on its concentration. Of note were the results found for transparency (28.59–110.62T600 mm−1), thickness (0.023–0.046 mm), swelling index (48.93–405.55%), water vapor permeability rate (7.86–38.11 g m2 day−1), elongation (99.13–262.39%), and antioxidant capacity (21.23–86.76 μg mL−1). The wound dressing based on BC and red propolis was the only one that presented antimicrobial activity. The permeation and retention test revealed that the wound dressing containing propolis extract presented the most corneal stratum when compared with viable skin. Overall, the developed wound dressing showed potential to be used for treatment against different types of dermal lesions, according to its determined proprieties.

Improvement of Gas Barrier Properties for Biodegradable Poly(butylene adipate-co-terephthalate) Nanocomposites with MXene Nanosheets via Biaxial Stretching.

In order to ease the white pollution problem, biodegradable packaging materials are highly demanded. In this work, the biodegradable poly (butylene adipate-co-terephthalate)/MXene (PBAT/Ti3C2TX) composite casting films were fabricated by melt mixing. Then, the obtained PBAT/Ti3C2TX composite casting films were biaxially stretched at different stretching ratios so as to reduce the water vapor permeability rate (WVPR) and oxygen transmission rate (OTR). It was expected that the combination of Ti3C2TX nanosheets and biaxial stretching could improve the water vapor and oxygen barrier performance of PBAT films. The scanning electron microscope (SEM) observation showed that the Ti3C2TX nanosheets had good compatibility with the PBAT matrix. The presence of Ti3C2TX acted as a nucleating agent to promote the crystallinity when the content was lower than 2 wt%. The mechanical tests showed that the incorporation of 1.0 wt% Ti3C2TX improved the tensile stress, elongation at break, and Young’s modulus of the PBAT/Ti3C2TX nanocomposite simultaneously, as compared with those of pure PBAT. The mechanical dynamical tests showed that the presence of Ti3C2TX significantly improved the storage modulus of the PBAT nanocomposite in a glassy state. Compared with pure PBAT, PBAT-1.0 with 1.0 wt% Ti3C2TX exhibited the lowest OTR of 782 cc/m2·day and 10.2 g/m2·day. The enhancement in gas barrier properties can be attributed to the presence of Ti3C2TX nanosheets, which can increase the effective diffusion path length for gases. With the biaxial stretching, the OTR and WVPR of PBAT-1.0 were further reduced to 732 cc/m2·day and 6.5 g/m2·day, respectively. The PBAT composite films with enhanced water vapor and water barrier performance exhibit a potential application in green packaging.

The Physicochemical, Antioxidant, and Color Properties of Thin Films Based on Chitosan Modified by Different Phenolic Acids

Chitosan-based films are promising for consideration as packaging materials. In this study, we modified the chitosan by phenolic acid addition, such as ferulic acid, caffeic acid, tannic acid, and gallic acid. The mechanical and thermal properties were studied, and the water vapor permeability rate was determined. Moreover, the antioxidant activity and film color were considered. The results showed that phenolic acids are effective cross-linkers for chitosan. The addition of phenolic acids improved the mechanical properties and decreased the roughness of surfaces. The enthalpy value was lower for films with phenolic acids than for pure chitosan. Chitosan with ferulic acid showed the highest antioxidant activity and water permeability value. Based on the obtained results, we determined that films obtained from the chitosan/ferulic acid mixture are the most promising for use as packaging material.

Bioinspired Crosslinked Nanocomposites of Polyvinyl Alcohol‐Reinforced Cellulose Nanocrystals Extracted from Rice Straw with Ethanedioic Acid

In this study, cellulose nanocrystals (CNC) were extracted from rice straw and incorporated into polyvinyl alcohol (PVOH) as reinforcement nanofillers. Multiple nanocomposites with different CNC contents were prepared. Extracted CNC appear as long, well‐defined rodlike crystals with a high aspect ratio (41). Nanocomposites with 3 wt% of CNC significantly exhibit improved tensile strength (60.4%) and maximum degradation temperature (287°C). Moreover, they demonstrate a decrease in water vapor permeability rate and in the swelling and solubility indices of PVOH/CNC. Significant improvements were observed when nanocomposites were crosslinked specifically in terms of tensile strength (104.8%) and maximum degradation temperature (364°C). They also demonstrate greatly reduced water vapor permeability rate, swelling, and solubility indices. The optimum CNC amount for both nanocomposites is 3 wt%.

Sustainable nanocomposite films of improved barrier properties for food packaging applications

Environmentally benign, biodegradable materials derived from renewable resources are gaining great consideration in recent times. Food packaging requires FDA approved, lightweight and low cost materials with superior barrier properties for extended shelf life and good flavor/aroma retention. In the present study, polylactic acid (PLA) modified with triethyl citrate (TEC) as a bioplasticizer was reinforced with copper nanoparticles and tested for possible improvement in mechanical and barrier properties. The increase in TEC content upto 8 wt% improved the toughness, beyond 8 wt% there was a decrease in tensile strength and modulus. A nanocomposite film of PLA/TEC/copper nanoparticle (92/8/3 wt%) displayed better barrier properties and optimum mechanical strength. The water vapor permeability and oxygen permeability rate was drastically decreased upon addition of nanocopper.

Polylactide Films with the Addition of Olive Leaf Extract-Physico-Chemical Characterization.

The aim of this work was to obtain and characterize polylactide films (PLA) with the addition of poly(ethylene glycol) (PEG) as a plasticizer and chloroformic olive leaf extract (OLE). The composition of OLE was characterized by LC-MS/MS techniques. The films with the potential for using in the food packaging industry were prepared using a solvent evaporation method. The total content of the phenolic compounds and DPPH radical scavenging assay of all the obtained materials have been tested. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (FTIR-ATR) allows for determining the molecular structure, while Scanning Electron Microscopy (SEM) indicated differences in the films’ surface morphology. Among other crucial properties, mechanical properties, thickness, degree of crystallinity, water vapor permeation rate (WVPR), and color change have also been evaluated. The results showed that OLE contains numerous active substances, including phenolic compounds, and PLA/PEG/OLE films are characterized by improved antioxidant properties. The OLE addition into PLA/PEG increases the material crystallinity, while the WVPR values remain almost unaffected. From these studies, significant insight was gained into the possibility of the application of chloroform as a solvent for both olive leaf extraction and for the preparation of OLE, PLA, and PEG-containing film-forming solutions. Finally, evaporation of the solvent from OLE can be omitted.

A Study on Application of Infrared Sensor Method in Moisture Permeability Test of Food Packaging Materials

Objective This paper is based on the technical improvement of the infrared sensor devices and has combined with the moisture permeability experiments of various food packaging materials, aiming to explore the application performance and effect of infrared sensor method equipment in the moisture permeability test of food packaging materials. Methods The improvement of the temperature control capacity of the equipment together with the sample clamping device helped to ensure a stable temperature during the test. In addition to the test of film/sheet, vessel type samples, the equipment subject to the referee-cup method principle and the equipment of the infrared sensor principle in this study were utilized to test the leather, PET film, sheet, PP film, PET/AI/PA/CPP film and VMPET film with varying moisture permeability levels respectively for their water vapor permeability rates at two different test conditions: 23°C, 90%RH and 38°C, 90%RH. Results The improved infrared sensor method equipment and cup method equipment share a similar relative uncertainty in the test. The water vapor permeability deviations between materials with distinct levels of moisture permeability are within the allowed range after tests with two methods and at different test conditions. Moreover, the homogeneity of test results of each food packaging material is satisfactory. Also, compared with the previous infrared sensor method equipment, the improved equipment witnessed an increase in both uncertainty and precision. Conclusion Therefore, the improved infrared sensor method test equipment can test the water vapor permeability of food packaging materials with different performances in a more accurate and reliable way.

(Invited) Breathable, Stimuli-Responsive, and Self-Sealing Chemical Barrier Material Based on Selectively Superabsorbing Polymer

The persistent use of chemical warfare agents (CWAs) by rogue states in current conflicts provides a reminder that these hazards remain a real threat. Although hazmat suits made of fully impermeable barrier materials provide an effective means of protecting against CWAs, they also inhibit evaporative cooling which can cause rapid hyperthermia. This conundrum has motivated a search for novel materials that allow water vapor but not CWA permeation. Here we show that, at least for aerosolized CWA, this can be achieved using a highly breathable composite fabric that self-seals only when exposed to target chemicals. Our approach is based on the use of selectively superabsorbing polymer (SAP) microbeads that are dispersed on a highly breathable fabric. Many CWAs, especially nerve and blistering agents, have low vapor pressure and are typically dispersed as a “fog” via aerosolization. We show that upon contact with an example organic aerosol (o-xylene) the proposed SAP microbeads dispersed on a nylon mesh rapidly swell, seal pores in the material, and inhibit passage of the microdroplets. In contrast, the SAP microbeads do not swell on contact with water and provide a water vapor permeation rate of over 10 kg m− 2 day− 1, comparable to a cotton shirt.

Barrier, Mechanical and Morphological Properties of Biodegradable Films Based on Corn Starch Incorporated with Cellulose Obtained from Pineapple Crowns

ABSTRACT This work aimed to develop biodegradable composites formed from corn starch-based films and cellulose extracted from pineapple crown residue. Fibers obtained from the crowns underwent alkaline treatment, followed by bleaching. Cellulose was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These analyses verified that the process was effective in isolating cellulose fibers. The biocomposites were then produced via casting and with cellulose of different concentrations (5%, 10%, 15%). These biocomposites were less soluble in water than the pure starch film, and the film with 15% cellulose had lower water vapor permeability rate (WVPR) compared to pure starch film. In terms of the thermal characterization, there were no significant variations in the melting and gelatinization temperatures of the films. When analyzing the mechanical properties, it was seen that the Young’s modulus of the biocomposites increased in relation to the starch film, in which the composite with a 15% increase of 377.76%. Regarding the tensile strength, there were no differences between preferences, probably due to the dispersion of the fibers.

An in vitro evaluation of Genipin‐crosslinked and Hypericum perforatum incorporated novel membranes for skin tissue engineering applications

AbstractIncorporating medicinal plant extracts in membranes have a great potential as scaffolds for tissue engineering applications or vehicles for delivering therapeutic agents. Herein, Hypericum perforatum oil (0.25, 0.50, % vol/vol) loaded membranes were developed with Polyvinyl alcohol and chitosan polymer, where Genipin works as a chemical crosslinker to obtain a wound dressing material with acceptable characterization properties. Chemical groups, surface morphology, water uptake capacity, water vapor permeability rate, hydrophilicity, and mechanical properties of membranes were thoroughly investigated. Increasing oil concentration had a significant effect on the water uptake, surface morphology. and water vapor permeability rate of the membranes. Cytocompatibility of the membrane was also investigated with mouse embryonic fibroblasts (MEF) by 3‐(4,5‐dimethylthiazoyl‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay for direct and indirect cell culture studies. SEM was used to investigate the cell morphology on the membranes. The MTT assay findings prove that Genipin crosslinked H. perforatum oil loaded scaffolds are highly biocompatible and enhance the adhesion and proliferation of MEF cells. In addition to this, the genotoxicity test was performed to show DNA fragmentation. Results showed that the H. perforatum oil loaded polyvinyl alcohol‐chitosan membrane presents suitable properties for potential skin tissue engineering applications.

Water barrier and mechanical properties of sugar palm crystalline nanocellulose reinforced thermoplastic sugar palm starch (TPS)/poly(lactic acid) (PLA) blend bionanocomposites

Abstract The disposal of non-biodegradable synthetic plastic wastes is linked with air, land, and marine pollutions. Incineration of plastic wastes released toxic substances into the air while recycled plastics end up accumulated in landfill and dumped into the ocean. In this study, novel sugar palm starch reinforced with sugar palm crystalline nanocellulose was blended with poly(lactic acid) (PLA) with various formulations to develop alternative materials potentially substituting conventional plastics. X-ray diffraction analysis demonstrated broad amorphous scattering background with minor diffraction peaks at 2θ of 19.4° and 22° associated with VH-type and B-type crystal structure for all blend bionanocomposites samples. Higher solubility rates were observed for PLA20TPS80 (96.34%) and PLA40TPS60 (77.66%) associated with higher concentration of plasticizers providing extra space in the polymer chains to be penetrated by water molecules. Increasing PLA content was not necessarily enhancing the water vapor permeability rate. Dynamic mechanical analysis presented a significant increment in storage modulus (E′) for PLA60TPS40 (53.2%) compared to the trivial changes of PLA70TPS30 (10%) and PLA80TPS20 (0.6%). However, significant improvement in impact strength occurred only at PLA40TPS60 (33.13%), and further addition showed minor improvement between 12 and 20%. Overall, it is noted that PLA60TPS40 demonstrated adequate functional properties to be used in food packaging application.

Effect of TiO2 Nanoparticles on Barrier and Mechanical Properties of PVA Films

Nanocomposites made of nanoparticles embedded in the matrix of polymer membranes have been used in the food packaging industry due to their enhanced barrier and mechanical properties. In this study, nanocomposite films made of polyvinyl alcohol (PVA) and titanium dioxide nanoparticles (size = 20 nm, 1 and 2 wt%) were prepared by the solvent casting method and their mechanical, physical, and barrier properties were determined. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were performed for characterizing the morphology of PVA/TiO2 nanocomposite films. Water vapor permeability (WVP) and oxygen transmission rate (OTR) were measured for mixed matrix PVA films for two concentrations of TiO2 nanoparticles. The results revealed that OTR and WVP decreased with increasing TiO2 nanoparticle concentration. Elongation at the break point and Young’s modulus both increased whereas strength decreased. XRD measurements confirmed the completely dispersed structure formed in the TiO2 nanocomposites. SEM micrographs showed an identical distribution at 1 and 2 wt% levels of TiO2 nanoparticles.

Modified TiO2@graphene oxide and montmorillonite synergistically enhanced multifunctional nanocomposite films

AbstractThe application of polymers in packaging is still limited due to the problems of poor gas barrier and flame retardant properties. Herein, a modified TiO2 (m‐TiO2)@graphene oxide (GO)/montmorillonite (MMT) filler‐reinforced polyvinyl alcohol (PVA)‐based nanocomposite films with excellent gas barrier, flame retardant, and mechanical properties is fabricated through a simple method of solution casting. In this system, GO and MMT act as bricks, PVA sticks them together like glue, and they together form a brick‐wall structure. By adding these fillers, the oxygen permeability rate (Po2) of this film is 0.48 × 10−18 cm3•cm/(cm2•s•Pa), less than that of pure PVA film by 97%, and the water vapor permeability rate () of the nanocomposite film is 1.21 × 10−13 g•cm/(cm2•s•Pa), less than that of pure PVA film by 86%. In addition, the flame retardant properties of m‐TiO2@GO/MMT/PVA nanocomposite films are excellent, which self‐extinguishes as long as the flame taken away, different from pure PVA film, which is completely burned. Moreover, the thermal stability and mechanical properties of the nanocomposite films are also significantly improved. The nanocomposites with environment‐friendly raw materials, simple manufacturing processes, and excellent performance should have good applications in the packaging and coating industries.

Cellulose Nanocrystals and Corn Zein Oxygen and Water Vapor Barrier Biocomposite Films.

Cellulose nanocrystals (CNC) are well-suited to the preparation of biocomposite films and packaging material due to its abundance, renewability, biodegradability, and favorable film-forming capacity. In this study, different CNC and corn zein (CZ) composite films were prepared by adding CZ to the CNC suspension prior to drying, in order to change internal structure of resulting films. Films were developed to examine their performance as an alternative water vapor and oxygen-barrier for flexible packaging industry. Water vapor permeability (WVP) and oxygen transmission rate (OTR) of the biocomposite films decreased significantly in a specific ratio between CNC and CZ combined with 1,2,3,4-butane tetracarboxylic acid (BTCA), a nontoxic cross linker. In addition to the improved barrier properties, the incorporation of CZ benefitted the flexibility and thermal stability of the CNC/CZ composite films. The toughness increased by 358%, and Young’s modulus decreased by 32% compared with the pristine CNC film. The maximum degradation temperature increased by 26 °C, compared with that of CNC film. These results can be attributed to the incorporation of a hydrophobic protein into the matrix creating hydrophobic interactions among the biocomposite components. SEM and AFM analysis indicated that CZ could significantly affect the CNC arrangement, and the film surface topography, due to the mechanical bundling and physical adsorption effect of CZ to CNC. The presented results indicate that CNC/CZ biocomposite films may find applications in packaging, and in multi-functionalization materials.

Stage-1 cationic C60 intercalated graphene oxide films

A “stage-1” intercalated film has been made by the ion exchange of pyrrolidinium-functionalized C60 (C60(Py)n+) into centimeter-wide, micrometer-thick air-dried graphene oxide (G-O) films composed of tens of thousands of layers of stacked/overlapping G-O platelets, denoted [C60(Py)n+]G-O films. Spontaneous intercalation by ion exchange of one layer of C60(Py)n+ between adjacent G-O layers expands the interlayer spacing of the films from 0.74 nm to 1.46 nm. The films remain intact in water and various organic solvents, which is likely due to a strong affinity between C60(Py)n+ and G-O. Membranes made of the films showed a 6.8 times faster water vapor permeation rate (allowing the vapor to transport through the membrane almost freely) and a 10.5 times faster liquid water permeation rate than G-O membranes. Heating the films at 2000 °C under applied pressure or at 2700 °C without physical confinement converted them into highly graphitized structures.

Polyvinyl Alcohol Food Packaging System Comprising Green Synthesized Silver Nanoparticles

Green synthesis of silver nanoparticles (AgNPs) using aqueous Moringa extract and their incorporation in polyvinyl alcohol (PVA) as food packaging materials have been performed. The prepared nanoparticles were characterized via Ultraviolet-visible spectra and transmission electron microscope, and the results revealed the formation of silver nanoparticles in a semi-spherical shape with an average size ranged from 2 to 5 nm. The addition of different ratios of the nanoparticles onto the PVA matrix and their crosslinking via citric acid to obtain nanocomposite sheets were performed. The nanocomposite sheets were characterized using FT-IR, UV-Vis, and TGA. In addition, their mechanical properties were evaluated. Water vapor permeability rate and water content were also determined. The composite sheets showed good thermal and optical performance. Antibacterial activities of the prepared nanocomposite sheets were evaluated, and the results exhibited good resistance to bacterial growth.

Physicochemical properties and antibacterial activity of corn starch-based films incorporated with Zanthoxylum bungeanum essential oil

Herein, corn starch-based films were prepared by casting method and different concentrations of Zanthoxylum bungeanum essential oil (ZYO) were added to evaluate the morphological, optical, mechanical, and barrier properties of the resultant films. Additionally, structural analysis was carried out via atomic force microscopy and the antibacterial activities against Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes were assessed. We found that the elongation at break was significantly increased (P < 0.05), whereas tensile strength, moisture content, solubility in water, and water vapor permeability rate were significantly decreased (P < 0.05) in films incorporated with ZYO compared with oil-free films. Furthermore, incorporation of ZYO increased the opacity and decreased the gloss of films. Incorporation of ZYO appears to increase the surface roughness and the antibacterial activity of the films. In sum, ZYO can potentially be used in food packaging, particularly food intended to be protected from light and susceptible to spoilage by microorganisms.

Preparation of novel stable microbicidal hydrogel films as potential wound dressing

This work aimed to prepare a hydrogel film with antibacterial activity and excellent stability in enzymes as potential wound dressing. Using hyaluronic acid, carboxylated chitosan and gentamicin, antibacterial film HA-CC-GS was prepared through intermolecular covalent bonding. Surface morphology of film was evaluated by scanning electron microscope images. The film exhibited good water absorption capacity and appropriate water vapor permeation rate (WVPR), outstanding mechanical properties and remarkable resistance to enzymatic hydrolysis. The biocompatibility of the film was tested by CCK-8 assay, and the results showed that the viability of NIH3T3 cell was not affected by coculture with hydrogel film. In vitro antibacterial test indicated that the synthesized hydrogel film had obvious antibacterial properties. In addition, in vivo studies showed that antibacterial hydrogel film could protect wound from infection and promote wound healing. These results indicated that the prepared antimicrobial hydrogel films by cross-linking had great potential application in skin/tissue repair, suggesting as a hopeful wound dressing.