Low Water Vapor Transmission Rate Research Articles

Smart and in-situ formation electrospun fibrous membrane for the control of antimicrobial efficacy

A smart poly(N-isopropyl acrylamide- N-Methylol acrylamide-acrylic acid) (PNIPAm-NMA-Ac) fibrous membrane with a dual response to thermal and pH was obtained via radical copolymerization and electrospinning technology. Two antimicrobial agents, gatifloxacin hydrochloride (GH) and silver nanoparticles (Ag) were chosen and incorporated into the PNIPAm-NMA-Ac fibres with different methods to achieve controllable antimicrobial efficacy with time. GH was directly mixed and Ag was in-situ formed to fabricate the antimicrobial membrane. The low water vapor transmission rate (23419.4 ​± ​2.5. 8 ​g/m2·24 ​h), high water-contact angles (118 ​± ​1.1°), excellent mechanical properties (tensile strength, 2.09 ​± ​0.53 ​MPa; elongation at break, 20.18 ​± ​1.07%), and good biocompatibility made the membrane have a great advantage on antimicrobial material. More importantly, both GH and Ag max release amounts are higher at 37 ​°C or pH 4.0 than 20 ​°C or pH 10.0 due to the smart thermal and pH responsive PNIPAm-NMA-Ac polymer. Meanwhile, GH and Ag release behavior are different: GH showed burst release behavior (72.72 ​± ​0.8% for 40 ​min), and Ag showed sustained release behavior (64.43 ​± ​2.53% for 3 ​h), which caused by the synergistic effect of two antimicrobial agents. Hence, antibacterial activity of this membrane is controllable with the environment temperature, pH value, and time. According to these results, this smart membrane has better antimicrobial efficacy at higher temperatures, lower pH and/or shorter time. In summary, this smart membrane could control the antimicrobial efficacy and be a potential membrane in harsh conditions.

Use of Lemongrass Leaf Ethanol Extract for Developing Alginate Based Antibacterial Edible Films

Alginates extracted from brown seaweed have a variety of prospective applications such as thickeners, stabilizers, or restructuring agents. Due to its properties as a natural polysaccharide, alginate is very potential to be used as edible films for food packaging purposes. Edible films are developed for food protection being excellent barriers to gases but not to moisture. Incorporation of antimicrobial agents into edible film formulation can extend product shelf life and reduce the risk of pathogenic bacterial growth on food. Therefore, this study was aimed to develop an alginate based antibacterial edible film. Antibacterial agent extracted from lemongrass leaves using ethanol was employed. The study was conducted by varying the addition levels of lemongrass ethanol extract to the alginate based edible films, i.e. 0.5%, 1.0% and 1.5%. Before being added to the alginate based edible films, the lemongrass ethanol extract was investigated for its antibacterial activity. The edible films obtained were analyzed in terms of physical, mechanical and chemical and microbiological parameters, including thickness, water vapor transmission rate (WVTR), brightness, tensile strength, elongation, moisture content, water solubility and antibacterial activity. Results showed that the higher addition levels of lemongrass ethanol extract tended to produce alginate based edible films with lower WVTR and brightness value as well as higher elongation, moisture content and water solubility. Edible film added with lemongrass ethanol extract resulted in this study demonstrated antibacterial activity against Staphylococcus aureus. The addition of lemongrass alcohol extract at 0.5% was considered as a recommended concentration level for producing alginate based antibacterial edible films.

Starch-based films enriched with nanocellulose-stabilized Pickering emulsions containing different essential oils for possible applications in food packaging

Consumers are increasingly demanding biodegradable food packaging with a minimal amount of synthetic preservatives and, at the same time, worried about potential contaminants, particularly during any pandemic event. Plant essential oils (EO) are natural compounds with remarkable antimicrobial properties. This study aimed to prepare thermoplastic starch films (TPS) containing nanocellulose-stabilized Pickering emulsions (PE) of different essential oils: ho wood (Cinnamomum camphora), cardamom, and cinnamon, and investigate the suitability of biopolymer films as packaging material. The films were prepared via casting method and were characterized concerning chemical interactions by FT-Raman and FTIR, mechanical, crystallinity, thermal, and water vapor permeability properties. PE Ho wood-starch films showed strong chemical interactions, which significantly improved the film's mechanical resistance. The films with cardamom and cinnamon showed low compatibility, with a decrease in tensile strength. All films showed less crystallinity than the pristine TPS, which can be attributed to the starch chain organization's changes. The films showed high thermal stability due to the strong molecular interactions among starch chains and PE, as confirmed by TGA and DSC analysis. The films' thermal stability is an indication that it can be safely applied in the food industry. Besides, the films showed a lower water vapor transmission rate, and the water may act as a carrier for PE, improving the release of the active compounds. This study reveals the differences between three essential oils incorporated into starch-based films. The ho wood films are the most promising PE to be applied as biodegradable active packaging.

A Potential Alternative to Polystyrene: Ring-opening Terpolymerization of Different Epoxides with Phthalic Anhydride Using Metal-free Dual Catalysts

A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of bio-based cyclohexane oxide (CHO)/propylene oxide (PO)/phthalic anhydride (PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 °C to 133 °C. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability (T5% ranging from 306 °C to 323 °C) and high tensile strength (40.21–55.7 MPa) that is comparable with polystyrene (PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.

Attributing the crosslinking density to water vapor transmission rate of an acrylic-melamine automotive clearcoat

In this study, the effect of crosslinking density of an acrylic-melamine clearcoat on water vapor transmission rate was evaluated. Four types of acrylic resins with different OH contents were used as the main polymeric backbone of the acrylic-melamine clearcoat. Also, three different acrylics to melamine–formaldehyde ratios were used in the coating formulations to obtain various crosslinking densities. It was observed that other film properties such as surface hydrophilicity and molecular homogeneity had a crucial impact on the clearcoat water vapor transmission rate together with the crosslinking density. Surprisingly, results showed that samples with acrylic resin with less OH content and lower melamine–formaldehyde crosslinker had the lowest water vapor transmission rate among other samples. These results were in agreement with the water contact angle and the data deduced from dynamic mechanical thermal analysis (DMTA) results of clearcoats.

Improving nisin production by encapsulated Lactococcus lactis with starch/carboxymethyl cellulose edible films

In this study, Lactococcus lactis was embedded in a film of corn starch (NS) and carboxymethyl cellulose (CMC) prepared using a casting method. At a CMC:NS ratio of 5:5, the composite film had the best comprehensive properties. Scanning electron microscopy images clearly showed that L. lactis was effectively embedded. The film with 1.5 % L. lactis showed the best performance and the lowest water vapor transmission rate (5.54 × 10−11 g/m s Pa. In addition, the edible film retained a viable count of 5.64 log CFU/g of L. lactis when stored at 4 °C for 30 days. The composite film with 1.5 % L. lactis showed the highest release of nisin (3.35 mg/mL) and good antibacterial activity against Staphylococcus aureus (53.53 %) after 8 days. Therefore, this edible film is a viable alternative antimicrobial strategy for the active packaging of foods containing low moisture content.

Effect of gamma irradiation on physico‐mechanical and structural properties of basil seed mucilage‐chitosan films containingZiziphora clinopodioidesessential oil and MgO nanoparticles for rainbow trout packaging

In the present study, it was aimed to evaluate the effect of gamma irradiation (0, 2.5, and 5 kGy) on physico-mechanical and structural properties of basil seed mucilage-chitosan-based films containing Ziziphora clinopodioides essential oil (ZEO: 0%, 1%, and 2%) and magnesium oxide nanoparticles (MgO: 0%, 0.1%, and 0.2%), and their application on trout fillet´s shelf-life during refrigerated storage for 18 days. The irradiated films under the cobalt-60 source at 5 kGy dose had better tensile strength as well as lower swelling index and water vapor transmission rate compared with other prepared films. Therefore, all films selected to package trout fillets were irradiated at 5 kGy dose. Fillets packaged with films containing ZEO 2% + MgO 0.2% and ZEO 2% + MgO 0.1% had the lowest microbial population (total viable count, psychrotrophic count, Pseudomonas spp., P. fluorescens, H2S producing bacteria, and Enterobacteriaceae) and chemical changes (total volatile base nitrogen content and peroxide value) (p < .05). Practical applications Active packaging has been introduced to increase the shelf-life of fresh fishery products during refrigerated storage. Gamma irradiation is a nonthermal method of food preservation and has recently received great interest in betterment of the physico-mechanical properties of packaging biopolymers. Our findings indicated that irradiation at 2.5 and 5 kGy doses can be used as a tool for improvement of the property of basil seed mucilage-chitosan-based films. The designated films containing Ziziphora clinopodioides essential oil (1% and 2%) and MgO nanoparticles (0.1% and 0.2%) could improve the shelf-life of trout fillets up to 18 days during refrigerated storage condition.

Low Temperature Deposition of High‐Quality Silicon Oxynitride (SiON) for OLED Encapsulation via Conventional PECVD

Thin film encapsulation (TFE) was an efficient way to guarantee the reliability of organic light emitting diodes (OLEDs). To passivate the moisture penetration, the TFE barriers should have low water vapor transmission rate (WVTR). In this study, high quality SiON barrier with good passivability was achieved by adjusting the deposition pressure and power of plasma‐enhanced chemical vapor deposition (PECVD). We successfully achieve a SiON film with few dangling bonds and defects, which showed a WVTR of 1.07×10−4 gm−2d−1 at the thickness of 750 nm.

L-Arginine Grafted Poly(Glycerol Sebacate) Materials: An Antimicrobial Material for Wound Dressing.

This study focuses on the development and evaluation of a novel wound dressing material. l-arginine grafted poly(glycerol sebacate) materials (PGS-g-Arg) are developed by chemical conjugation of l-arginine on poly(glycerol sebacate) chains and the mechanical property, water vapor transmission rate, antimicrobial functions and biocompatibility are investigated. At various l-arginine grafting ratio, the mechanical properties are tunable. It was found that between 7–13% l-arginine grafting ratios, the tensile strengths of PGS-g-Arg were similar to that of natural skin. These materials are shown with a low water vapor transmission rate, 6.1 to 10.3 g/m2/h, which may form a barrier and assist in the closure of wounds. Inhibition in the growth of Pseudomonas aeruginosa and Staphylococcus aureus was observed on PGS-g-Arg, and a series of experiments were conducted to confirm its biocompatibility. In summary, l -arginine grafted poly(glycerol sebacate) may offer a novel option for wound dressing.

Individual and Combined Coatings of Chitosan and Carnauba Wax with Oregano Essential Oil to Avoid Water Loss and Microbial Decay of Fresh Cucumber

The objective of the present study is to evaluate the effect of individual and combined coatings of chitosan (0.008 g·mL−1) and carnauba wax (0.1 g·mL−1) with oregano essential oil (OEO, 0.08 g·mL−1) to reduce dehydration and microbial decay of fresh cucumbers stored at 10 °C. Chitosan-OEO-wax films showed the lowest water vapor transmission rate (0.141 g·m−2·h−1), compared to single chitosan films (0.257 g·m−2·h−1). While chitosan-OEO films completely inhibited the in vitro growth of Alternaria alternata and reduced the growth of Salmonella Typhimurium, Escherichia coli O157:H7, mesophilic bacteria, and fungi isolated from decayed cucumbers. Besides, the infrared analysis of chitosan-OEO-wax films showed shifts in O–H and N–H absorption bands, indicating possible hydrogen bonding between the components. Wax and wax-OEO were the most effective coatings to prevent weight loss in cucumbers during 15 days of storage at 10 °C, while the most effective antimicrobial treatments were chitosan and chitosan-OEO. Therefore, these results showed that carnauba wax and carnauba wax-OEO coatings were the most effective in weight loss, whereas chitosan and chitosan-OEO were the most effective to reduce the microbial load of the treated fresh cucumber.

Bio-based antimicrobial packaging from sugarcane bagasse nanocellulose/nisin hybrid films

Bio-based nanomaterials with antimicrobial functions hold promise in replacing petroleum-based packaging for food preservation. A nanocellulose-based hybrid film with antimicrobial properties was developed from sugarcane bagasse and nisin. Cellulose nanofibrils (CNFs) were prepared from sugarcane bagasse pulp by mechanical grinding, and mixed with nisin to prepare CNFs/nisin nanohybrid films. The concentration of nisin has a remarkable influence on the mechanical, light transmission, gas barrier, and antimicrobial properties of these films. CNFs/nisin hybrid films with 1920 mg/L nisin exhibit good light transmission, relatively high tensile strength, low oxygen permeability, and low water vapor transmission rates. This hybrid film was used as a liner of low-density polyethylene plastic packaging for ready-to-eat ham; it completely inhibited Listeria monocytogenes during 7 days of storage at 4 °C. Such novel CNFs/nisin nanohybrid films are expected to expand the application of bagasse nanocellulose in active packaging for food preservation.

Cellulose nanocrystal-coated TEMPO-oxidized cellulose nanofiber films for high performance all-cellulose nanocomposites

High performance biopolymer films are of great interest as effective alternatives to non-biodegradable and petroleum-based polymer films. However, most natural biopolymer films possess weak mechanical and poor gas barrier properties, limiting their applicability. In this work, we developed all-cellulose nanocomposite films through a simple vacuum filtration process, using cellulose nanocrystals (CNCs) and 2,2,6,6-tetramethylpiperidine-1-oxy-oxidized cellulose nanofibers (TEMPO-CNFs). The TEMPO-CNFs were employed to construct a transparent, free-standing substrate matrix and the CNCs were used as a coating material to improve the mechanical and water vapor barrier properties of the final material. We have demonstrated that the top and bottom CNCs-coated TEMPO-CNF substrates (CNC/TEMPO-CNF/CNC) have excellent mechanical and good water vapor barrier properties. The resulting CNC/TEMPO-CNF/CNC films revealed a high tensile strength of 114 MPa and a low specific water vapor transmission rate (SWVTR) of 19 g∙mm/m2∙day. In addition, the CNC/TEMPO-CNF/CNC films were resistant to various solvents including water, ethanol, tetrahydrofuran (THF), and acetone. This type of high performance cellulose nanocomposite can be used as a renewable material for a broad range of potential applications.

Open-Air Plasma-Deposited Multilayer Thin-Film Moisture Barriers.

Emerging moisture sensitive devices require robust encapsulation strategies to inhibit water ingress and prevent premature failure. A scalable, open-air plasma process has been developed to deposit alternating layers of conformal organosilicate and dense SiO2 thin-film barriers to prevent moisture ingress. The in situ low-temperature process is suitable for direct deposition on thermally sensitive devices and is compatible with flexible polymeric substrates. Using optical calcium testing, low water vapor transmission rates on the order of 10-3 g/m2/day at an accelerated aging condition of 38 °C and 90% relative humidity (RH) are achieved. Using moisture-sensitive perovskite devices as a representative moisture-susceptible device, devices retain over 80% of their initial performance for over 660 h in a 50 °C 50% RH accelerated aging environment. The ability of the multilayer barrier to enable device resistance to humid environments is crucial toward realizing longer operating lifetimes.

Weather Resistance Performance of Backsheets with Various Structures

Backsheet is the key element to ensure the power generation of PV modules during their whole life cycle. To continually decrease the LCOE, backsheets of new structures are gradually applied. Currently, the evaluation of module product performance is mainly on the module scale, while the assessment of each single material is rare. This paper is aimed at the evaluation of each single backsheet’s reliability when applied in different climatic environments for the widely used new backsheet structures (BS1-BS5). Through comparative research, the backsheet based on thicker PET was found to have a better mechanical performance and BS3 exhibited good resistance performance in hot and humid condition, which could be attributed to the low water vapor transmission rate of the PO film.

Multifunctional hybrid polymer nanocomposites for automotive‐battery packaging

AbstractGlobal sales of new electric vehicles (EV) already passed a million units last year. Lithium‐ion battery packs are composed of cells and assembly of modules. Nevertheless, the development of light‐weighted with high oxygen and moisture barrierability remains one of the untouched issues in battery technology. This study aimed to fabricate multifunctional hybrid nanocomposites for barrier films for Li‐ion battery packs on electric vehicles applications. The synthesized carbon supported MgO nanoparticles (hereafter referred to as CSMO) were dispersed in high density polyethylene (HDPE) polymer to satisfy several requirements for EV battery packs. The loading amount of MgO was achieved up to 22 wt % of carbon, and the size distribution was in the range of 50 to 100 nm. The hybrid nanocomposites were characterized by water‐vapor transmission rate (WVTR), various spectroscopic methods, thermo‐gravimetric analysis and elemental analysis. Mechanical properties were also tested. The extremely low WVTR value of CSMO/HDPE composites below 0.5 mgm−2 day−1 is the lowest value among any other gas barrier films reported in the literature. Suitable mechanical properties were also achieved. The newly proposed multifunctional hybrid nanocomposites would be very promising for barrier films on automotive packaging applications.

Process design of acetylated sago starch-based edible film

Starch has potential as a material of edible film packaging. However, the use of native starch has a limitation due to the hydrophilic character. Native starch produces brittle edible film and low physical, mechanical properties. This research modified the sago starch with acetylation to produce more hydrophobic starch and improve the film characteristics. The experiments investigated the effect of sago acetylated starch (3%, 4%, and 5%) on the physical and mechanical properties of edible film. The acetylated starch films showed improved physical-mechanical properties compared to the edible film made from native starch. Edible film made by 4% acetylated starch presented lower thickness (0.14 mm), moisture content (7.43%), solubility (26.891 %) and water vapor transmission rate (0.87 g/hour.mm2). This edible film also had higher transparency and tensile strength (87.84%, 1.99 MPa). Characteristics of the edible film were improved and affected by the acetylated starch that used.

Selective Infiltration in Polymer Hybrid Thin Films as a Gas-Encapsulation Layer for Stretchable Electronics.

The infiltration depth and water vapor transmission rate (WVTR) were explored in a variety of Al2O3-polymer hybrid layers as thin gas barrier films by filling the free volumes of polymers in the subsurface region with Al2O3 using the atomic layer infiltration (ALI) method. Among all, the prepared Al2O3-polyethylene terephthalate (PET), Al2O3-polyimide, and Al2O3-Nylon 6 hybrid thin layers with the infiltration depth in the nanometer ranges showed extremely low WVTR values (<10-6 g m-2 day-1) in a Ca dot corrosion test. Furthermore, we observed selective infiltration among the two polymers [perfluoroalkoxy alkane (PFA) and PET] by a preferential growth of Al2O3 in the PET polymer that might be based on effective functional group anchoring in the ALI process. Then, we demonstrated a novel strategy by employing such a selective infiltration procedure and encapsulating individual segments of 144 Ca dots by Al2O3-PET hybrid thin films on the PFA polymer substrate rather than wrapping the whole thing together for the stretchable gas-encapsulation film. Regardless of stretching, it showed an extremely low WVTR (<10-7 g m-2 day-1) and is proposed as a highly promising hermetic sealing alternative in stretchable, flexible, and foldable electronic display technologies.

Carrageenan and Garlic Essensial Oil Edible Film as Protective Coating on Catfish Sausage

The edible film based on carrageenan containing garlic essential oil (GEO) at different concentration (0%; 0,2%; 0,4%; and 0,6%) were added into carrageenan edible film (CEF) then applied on sausage, chilled storage for 10 days. The antioxidative allicin prevention on product determined its chemical characteristics such as TBA, TVBN, Aw, and pH. The addition of garlic essential oil on carrageenan based edible film was not significantly different on tensile strength. CEF with 0,6% of garlic essential oil produced the highest elongation value and the lowest Water Vapor Transmission Rate with the amount of 3,970% and 0,673%; respectively. The catfish sausage coated with 0,4% CEF produced TBA and TVBN value during chilled storage with the amount of 0,870 mg malonaldehyde/kg and 17,223 mgN/100g; respectively and not significantly different to CEF 0,6%. The result indicated that edible film containing garlic essential oil able to retard the oxidation process. Indicated from FTIR test, 0,2%; 0,4%; and 0,6% CEF containing garlic compound illustrated with S-S, N-H, C=O and C-H functional group with the wavelength of 408,91 cm-1, 925,83 cm-1, 1543,05 and 2931,8 cm-1.; respectively.

Dual modification of sweet potato crosslinking-hydroxypropylation as biodegradable film materials

Sweet potato starch as the base material for the biodegradable film has a hydrophilic nature that makes the mechanical properties produced less good. To overcome this weakness, modifications were made to starch with a double method of hydroxypropylation and crosslinking. This research was conducted in two stages, namely: modification and characterization of crosslinking–hydroxypropylation and then the making and characterization of biodegradable films. Biodegradable film modified sweet potato starch has a lower water vapor transmission rate (WVTR) than native sweet potato starch films. The tensile strength and percent elongation values of the entire modified starch films have higher values than natural sweet potato starch films. Transparency value has decreased, which indicates that the film is in good clarity. The solubility value is obtained lower because the high solubility value of the film indicates a decrease in the quality of the film to be used as a food packaging material because the film easily dissolves in water and increases the possibility of damage to packaged products, especially for products that are easily affected by moisture content.

STABILITAS EDIBLE FILM PATI SAGU (METROXYLON SAGU ROTTB.) ASETAT SELAMA PENYIMPANAN PADA BERBAGAI SUHU

The degree of stability of starch-based edible films during storage varies greatly compared to synthetic films. This work aimed to study the effect of storage temperatures on the stability of sago starch acetate edible film during storage. Edible films produced by casting and storage at 5, 30 and 40 oC temperatures for 34 days. The observed characteristics were crystallinity, contact angle, physical, mechanical and barrier (WVTR) film properties. Sago starch acetate edible films presented lower relative crystallinity (10,10%) and highest contact angle (51,04o) when compared with native starch edible films. The results indicated that sago starch acetate edible films were relatively stable when stored at low (5 oC) and high (30 and 40 oC) temperatures. Storage temperatures did not affect physical properties (solubility, transparency) and mechanical (elongation at break / EAB) of sago starch acetate edible films except tensile strength (TS) and water vapor transmission rate (WVTR). TS values ​​increased at temperatures 30 and 40 oC and WVTR values ​​increased at temperature 30 oC. Changes in physical and mechanical properties occur at the beginning of storage, but then tend to be stable until the end of storage. Sago starch acetate edible films had low physical and mechanical characteristics, that was TS (2.25–4.90 MPa), elongation at break (29.65–89.62%), solubility (15.01–29.61%),&nbsp; transparency (0.91–1.87)&nbsp; and very low WVTR value (0.07–0.33 g/m2.hour) and Ea (-8.6E-04 kJ/mol). Sago starch acetate edible films had good physical and mechanical properties and resistant to moisture, can be used for applications as edible films and coatings for foods that contain high water content. Keywords: edible film, mechanical and physical properties, sago starch acetate, water vapor transmission rate