Water Vapor Permeability Values Research Articles

Microencapsulation of Carvacrol Using Pectin/Aloe-gel as a Novel Wound Dressing Films.

Recently, Pectin (PEC) and Aloe-Gel (AG) have received great attention for their use in the encapsulation of hydrophobic bioactive compounds such as Carvacrol (CAR). The aim of this study is to assess the physical, chemical and biological properties of a novel PEC/AG film and evaluate its capability to entrap CAR into microencapsulates. For this purpose, the casting method was used to prepare the PEC/AG membranes (70:30 % w/w). The CAR-loaded PEC/AG film was prepared adding different proportions of CAR (0.25%, 0.50% and 1.00% v/v) to the mixture of PEC/AG, previously emulsified with tween 80 (1.0%). The optical properties, Water Vapor Permeability (WVP), ATR-FTIR spectroscopy, microstructure, antibacterial activity and size of microcapsules were evaluated. The PEC/AG membranes loaded with CAR showed yellowish appearance and they were transparent to the UV electromagnetic radiation (190, 200 and 280 nm). The film prepared with the lowest amount of CAR (PC/AG-CAR-0.25%) showed the highest values of WVP (66.2%) and, according to SEM micrograph, the largest microcapsules (≈1005± 39 µm3). The FTIR analysis showed the characteristic absorption peaks located at 1015 cm-1 to 1030 cm-1 and a small shoulder to 990 cm-1 of benzene ring 1:2:4 substituted that suggested the presence of CAR-loaded in the PC/AG film. On the other hand, E. coli O157:H7 showed the highest sensitivity to the PEC/AG-CAR-1.00% film, while S. aureus was not sensitive.

Relationship between dissolution temperature and properties of oil palm biomass based-regenerated cellulose films prepared via ionic liquid

In this article, we described fabrication of regenerated cellulose (RC) films derived from oil palm empty fruit bunch-microcrystalline cellulose (OPEFB-MCC) via ionic liquid 1-butyl-3-methylimidazolium chloride [BMIM][Cl]. The properties of RC films as a function of varied dissolution temperature; 75, 80 and 85 °C were unraveled by means of their water vapor permeability, light opacity, mechanical performance, thermal characteristic and morphology. It was shown that when dissolution temperature was increased, the barrier properties of RC films were enhanced as indicated by increment of opacity values (1.44–1.63) but decline of water vapor permeability values (0.95–1.30 × 10−10 g s−1 m−1 Pa−1). We also observed an improvement in thermal stability of RC films as shown by the increase of their degradation temperatures; T20 = 264–266 °C and Tmax = 273–281 °C. However, the films’ mechanical performances denoted by TS and EAB values were slightly diminished with percentage reduction of 21.7% and 5.2%, respectively. Meanwhile, the films exhibited Tg without Tm, reflecting their highly amorphous structure after regeneration. Microstructural analyses of the films depicted uniform distribution of cellulose fragments on their cross-sectional surfaces thus indicated excellent dissolution of cellulose in the solvent.

MECHANICAL, BARRIER AND ANTIOXIDANT PROPERTIES OF EDIBLE FILMS MADE FROM WHEY PROTEIN ISOLATE INCORPORATED WITH GREEN TEA EXTRACT

The aim of this research was to study the effect of adding green tea extract (GTE) on the mechanical, oxygen permeability, water vapor permeability and antioxidant properties of whey protein isolate edible films. Edible films incorporated with the alcoholic extract of green tea showed high antioxidant activity as compared with the standard antioxidant BHA (Butylated hydroxyl anisole), The scavenging values of the film with GTE and the control film were 65.22% and 9.5%, respectively. The mechanical tests, revealed a decreasing in thickness in the control film which was formed without GTE from 181 μm to 169 μm. The tensile strength has been reduced in the film to 7.87 MPa where it was in the control sample 8.29 MPa. However, the elongation rate increased to 117% in the film supported by the extract, which was higher than the elongation rate of the control protein film without GTE (107%). The permeability value of oxygen (OP) and water vapor permeability (WPV) were measured and the properties of film were evaluated. The OP value of the control film was 90.07 ml / m 2 * day, whereas the permeability of the film with (GTE) decreased to 72.45 ml / m 2 * day. The WVP value of the control film was 0.61(gm.mm / hr. m2. mPa), while the permeability value of the film with GTE was 0.22 (gm.mm / hr. m2. MPa). The water solubility of film with GTE was increased to 47.5% as compared to the control film which was 41.2%.In respect to the optical properieties the ∆E value of supported film samples was 29.09%,and (L, a, b) (28.3,-7.41, 51.01) respectively, while for the control Sample ∆E was 9.6% (L, a, b), (6.6,-9.27, 59.15) respectively.

Water vapor and oxygen barrier properties of extrusion-blown poly(lactic acid)/cellulose nanocrystals nanocomposite films

This paper examined the effect of cellulose nanocrystal (CNC) content on water vapor permeability (WVP) and oxygen permeability (OP) of extrusion-blown poly(lactic acid) (PLA) films recorded at various temperatures and relative humidities. While both WVP and OP followed the Arrhenius equation, the WVP decreased with increasing temperature whereas an opposite trend was observed for OP, resulting in negative activation energy (Ep) for WVP but positive Ep for OP, regardless of CNC content. However, the Ep for both WVP and OP increased by adding CNC into PLA matrix. WVP was not affected by the relative humidity agreeing with Fick’s law. Nanocomposite films had lower WVP (∼40%) and OP (∼75%) than neat PLA films because of the tortuosity effect created by the presence of highly crystalline CNCs in the nanocomposites, which increased PLA’s degree of crystallinity. Indeed, the values of WVP and OP negatively correlated with increased crystallinity, irrespective of testing conditions.

Preparation and Identification of Optimal Synthesis Conditions for a Novel Alkaline Anion-Exchange Membrane

The physicochemical and mechanical properties of new alkaline anion-exchange membranes (AAEMs) based on chitosan (CS) and poly(vinyl alcohol) (PVA) polymers doped with unsupported copper nanoparticles (NPs) and copper exchanged over different porous materials were investigated regarding ion-exchange capacity (IEC), OH− conductivity, water uptake (WU), water vapor permeability (WVP), and thermal and mechanical resistance. The influence of the type of filler included in different morphologies and filler loading has been explored using copper exchanged materials such as the layered porous titanosilicate AM-4, layered stannosilicate UZAR-S3, and zeolites Y, MOR, and BEA. Compared to commercially available anion-exchange membranes, the best performing membranes in terms of WU, IEC, OH− conductivity and WVP in this study were those containing 10 wt % of Cu-AM-4 and Cu-UZAR-S3, although 10 wt % Cu-MOR provided better mechanical strength at close values of WVP and anion conductivity. It was also observed that when Cu was exchanged in a porous silicate matrix, its oxidation state was lower than when embedded as unsupported metal NPs. In addition, the statistical analysis of variance determined that the electrochemical properties of the membranes were noticeably affected by both the type and filler loading, and influenced also by the copper oxidation state and content in the membrane, but their hydrophilic properties were more affected by the polymers. The largest significant effects were noticed on the water sorption and transport properties, which gives scope for the design of AAEMs for electrochemical and water treatment applications.

Development and characterization of bamboo fiber reinforced biopolymer films

A paradigm shift from petrochemical based packaging films for food packaging due to its non-renewable and waste disposal challenges has motivated research interest in development and characterization of biopolymer films. In this study, biocomposite films was prepared using bamboo fiber to reinforce modified and unmodified red seaweed SW Kappaphycus alvarezii, resulting in improved mechanical characteristics of 109.1 MPa tensile strength, 55.4 MPa Young’s Modulus and 22.3% stretchability prior to breakage at the optimum value of 15% bamboo fibers loadings for unmodified biocomposite. There was general improvement in the fiber/matrix interface of the modified SW based composite films over the biopolymer films from unmodified SW bamboo reinforced films resulting in improved water vapour barrier as the fiber load increases up to Water vapour permeability value of 5.2 (g/s/m2/Pa)., while the contact angle as high as 91° was obtained. FTIR analysis validates the effective interaction of both the bamboo fibers and the seaweed matrix without any significant biochemical alteration of the seaweed within the frameworks of composite films. SEM characterization and contact angle measurement indicate that heterogeneous surface modification of the biopolymer film increases with the fiber loading. Results demonstrated the potential use of the renewable and biodegradable biopolymer composite films as packaging films useful in the food industry.

Metal ions increase mechanical strength and barrier properties of collagen-sodium polyacrylate composite films

From the previous experiment, it was confirmed that the incorporation of 0.3 wt% sodium polyacrylate (PAAS) into collagen (Co) fibers can improve the mechanical properties and thermal stability of the composite films. In this study, Ca2+, Fe3+ and Ag+ ranging 0.001–0.004 mol/g were used to improve the properties of Co-PAAS blend films based on the rationale of their potential electrostatic interaction with these biopolymers. As expected, Zeta-potential film-forming solutions was decreased to some extent with the addition of metal ions. SEM images presented that the surface of the composites became coarser and internal structure became more stratified as metal ion contents increased. Tensile strength was increased by the addition of these ions with a varied optimal concentration: Ca2+ (0.003 mol/g), Fe3+ (0.002 mol/g) and Ag+ (0.001 mol/g). Water vapor permeability (WVP), solubility and light transmission value of films while causing film thickness no obvious change. In addition, the differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) results indicated that the metal ions improved the thermal stability of the composite film. Therefore, Ca2+, Fe3+ and Ag+ with an appropriate addition amount can be used as a potential alternative to reinforce collagenous composite materials.

Study of Spray System Applications of Edible Coating Suspensions Based on Hydrocolloids Containing Cellulose Nanofibers on Grape Surface (Vitis vinifera L.)

An edible coating is a useful technology to preserve fruit quality by covering them with a protective layer which improves the appearance and provides a semipermeable barrier for gases and water vapor transfer, allowing extension of their shelf life. In this study, edible coatings based on hydroxypropyl methyl cellulose, k-carrageenan, glycerol, and cellulose nanofibers were formulated. The operational conditions of the spray system were studied to obtain a coating with optimal adhesion on grape (Vitis vinifera L.) surface. Furthermore, the physico-chemical properties of grapes covered with edible coatings were evaluated during refrigerated storage. A full factorial 23 experimental design was applied, where liquid suspension flow (1–5 L h−1), air pressure (50–200 kPa), and height of impact (0.3–0.5 m) were evaluated as independent variables, whereas the percentage of coating and thickness of coating was the response variables. Both mechanical and physico-chemical properties were evaluated during 41 days in both coated and uncoated grapes as shelf life criteria. Throughout the storage time, noticeable changes in pH and total soluble solids were not found in grapes covered with edible coatings and they showed the highest stability for the evaluated mechanical properties. Moreover, coated grapes showed final weight loss and water vapor permeability values of approximately 30 and 34% lower, respectively, than uncoated grapes, suggesting a shelf life extension.

Edible Gum-Phenolic-Lipid Incorporated Gluten Films for Food Packaging.

The edible composite film will be produced in industry according to the data provided in our paper; the film can be used as packaging material for seasonings in food production.

Development of Chitosan and Polycaprolactone based active bilayer films enhanced with nanocellulose and grape seed extract

In this study, nanocellulose (NC) (2–5%, w/w) and grape seed extract (GSE) (15%, w/w) added chitosan (CH) and polycaprolactone (PCL) based active bilayer films were prepared by either coating with PCL in the form of chloroform solution (C-PCL) or compression of PCL and CH layers (P-PCL). Films were tested by means of scanning electron microscopy (SEM), water vapor permeability (WVP), tensile tests, optical and active properties (antimicrobial, and antioxidant activities), and release studies. The incorporation of NC significantly reduced WVP and opacity of films while GSE addition had an adverse effect. P-PCL films showed higher elastic modulus, tensile strength and WVP values and lower elasticity when compared to C-PCL films (p < 0.05). All film samples showed antimicrobial activity, and GSE retained its antioxidant capacity within CH matrix. The formation of the CH and PCL based bilayer films with NC and GSE improved the suitability of CH films for food packaging applications.

Pectin/Carboxymethylcellulose Films as a Potential Food Packaging Material

The present paper reports on pectin based films modified with carboxymethyl cellulose intended for food packaging. The films are prepared by solvent‐casting method with different carboxymethyl cellulose content and cross‐linker concentration (Ca2+ ions) in the presence of glycerol as a plasticizer. FT‐IR spectra of the prepared films propose that carboxyl group from pectin are mainly involved in interactions with CMC, whereas −OH groups are mainly involved in self‐associated hydrogen bonding of neat polymers. Further, an addition of carboxymethyl cellulose improved mechanical properties compared to pure pectin films, while TGA analysis confirmed satisfying thermal stability regarding their potential application as packaging material. Finally, water vapor permeability values are in the range of 1.32 × 10−7 up to 2.03 × 10−7 g/m h Pa.

Development of plasticized edible films from Opuntia ficus-indica mucilage: A comparative study of various polyol plasticizers

Mucilage polysaccharide was extracted from Opuntia ficus-indica cladodes (Cactaceae) and its composition was determined by sugar analysis using HPLC-RID and its structural features were elucidated by FTIR and 1H and 13C NMR. Films from the extracted mucilage were loaded at 40% (w/w) with glycerol, sorbitol, PEG 200 or PEG 400. The physical, thermal, mechanical and barrier properties of the obtained films were investigated. The highest water vapor barrier properties of plasticized mucilage films were obtained with sorbitol reaching water vapor permeability (WVP) values up to 3 times lower than the other films. The tensile strength (TS) values of films plasticized with PEG 200 and sorbitol were about 2 times higher than those of glycerol-plasticized films. The significant effect of polyol type plasticizers on the different properties of mucilage edible films was related to their structural features that promote different interactions with mucilage polysaccharides as demonstrated by FTIR and thermal properties.

High hydrostatic pressure processing for the preparation of buckwheat and tapioca starch films

Buckwheat starch (BS) and tapioca starch (TPS) films were prepared to compare the effect of different gelatinization methods on the physical, optical, and thermal properties of the films. High hydrostatic pressure processing (HPP) at 600 MPa (20 °C, 20 min) and thermal processing (TP, 90 °C, 20 min) for gelatinization of the starches were used to prepare the films. Consequently, the films prepared using HPP had higher tensile strength and elongation at break than those prepared using TP regardless of the starch type. In particular, the BS films prepared using HPP exhibited lower water vapor permeability (2.10 × 10−9 g/m s Pa) and water solubility (11.67%) values than those prepared using TP (3.10 × 10−9 g/m s Pa, 19.85%). Overall, the application of HPP improved the physical properties and water resistance of both films. Thus, HPP can be used as a method for the preparation of starch films.

Evaluating the fabric performance and antibacterial properties of 3-D piezoelectric spacer fabric

The increasing need of on-demand power for enabling portable low-power devices and sensors has necessitated work in novel energy harvesting materials and devices. In a recent work, we demonstrated the production and suitability of three-dimensional (3-D) spacer all fibre piezoelectric textiles for converting mechanical energy into electrical energy for wearable and technical applications. The current work investigates the textile performance properties of these 3-D piezoelectric fabrics including porosity, air permeability, water vapour transmission and bursting strength. Furthermore, as these textiles are intended for wearable applications, we have assessed their wear abrasion and consequently provide surface resistance measurements which can affect the lifetime and efficiency of charge collection in the piezoelectric textile structures. The results show that the novel smart fabric with a measured porosity of 68% had good air (1855 l/m2/s) and water vapour permeability (1.34 g/m2/day) values, good wear abrasion resistance over 60,000 rotations applied by a load of 12 kPa and bursting strength higher than 2400 kPa. Moreover, the antibacterial activity of 3-D piezoelectric fabrics revealed that owing to the use of Ag/PA66 yarns, the textiles exhibit excellent antibacterial activity against not only Gram-negative bacteria E. coli but they are also capable of killing antibiotic methicillin-resistant bacteria S. aureus.

Preparation and Characterization of Proteinaceous Films from Seven Mexican Common Beans (Phaseolus vulgarisL.)

Bean protein concentrate (BPC) as a protein source from seven varieties of Mexican common beans (alubia,flor de mayo,garbancillo,peruano,pinto,mantequilla, andnegro) was utilized for formulating edible films (EF). EF were prepared with BPC (3% w/w) and glycerol as a plasticizer by the casting method; their thickness, water content, soluble matter, protein solubility, color, puncture strength, elongation, water vapor permeability (WVP), and chemical properties (Fourier transform infrared, FTIR, and spectroscopy) were evaluated. Tested EF had an average thickness of0.045±0.001 mm. Good stability was observed since the studied polymers did not exceed 35% of the total soluble matter while protein solubilities were not greater than 3%. EF made fromperuanobean protein presented a lower value of total matter solubility (25.38±2.24%) than the other tested EF. A low value of WVP (2.06±0.25×10-10 g m/Pa s m2) was observed in films fromnegrobean protein, while EF fromflor de mayobean protein exhibited the highest values of puncture strength (17.35±0.82 MPa) and elongation (38.21±0.64%). Most bean protein EF had reddish or brownish color; however, films fromalubiaandperuanobean proteins displayed light yellowish colors. FTIR spectra of EF revealed that glycerol did not react with the studied bean proteins through covalent bonds.

Development, characterization and application of hydroxypropylmethylcellulose films enriched with cypress seed extract.

The phenolic profile of cypress seed extract (CSE) was investigated by means of liquid chromatography with photodiode array and electrospray ionisation mass spectrometric detection (LC/PDA/ESI-MS). The total phenolic (TP) and flavonoid (TF) contents as well as the antioxidant capacity of CSE were determined. The effects of CSE concentration (0.1, 0.3, 0.5, 1, and 2% (w/v)) on the functional properties of hydroxypropylmethylcellulose (HPMC) films were studied. Results showed that CSE presents a good antioxidant capacity due to its high phenolic/flavonoid contents and particularly the presence of bi-flavonoid compounds including cupressuflavone and amentoflavone derivatives. The incorporation of CSE in HPMC films led to a significant decrease in their water vapor permeability (WVP) and enhanced their mechanical strength. The lowest WVP value, the greatest opacity and the highest antioxidant capacity were obtained with the highest CSE concentration. HPMC films with and without CSE were applied on virgin olive oil to study their effect on the oxidative stability of olive oil during accelerated storage by periodically analyzing changes in FTIR spectra and peroxide values. HPMC-2% CSE films were the most effective in lowering light transmission, and consequently decreasing peroxide formation and delaying oxidation of olive oil.

Development of novel pea flour‐based nanofibres by electrospinning method

AbstractThe aim of this study was to produce pea flour and hydroxypropyl methylcellulose (HPMC)‐based novel nanofibres using electrospinning method. The effects of pH, pea flour and HPMC concentration on apparent viscosity, electrical conductivity of electrospinning solutions and nanofibre characteristics were studied. Solutions were prepared at different pH values (7, 10, 12), with different pea flour concentrations (1%, 2% w/v) and HPMC concentrations (0.25%, 0.5%, 1.0% w/v). For all pea flour concentrations, k values increased significantly with increase in pH and HPMC concentration. It also increased with increase in pea flour concentration for basic solutions. Pea flour concentration increased diameter and water vapour permeability (WVP) values of nanofibres. This study showed that electrospinning was a promising method for fabrication of homogenous pea flour and HPMC‐based nanofibres to be used in packaging industry.

Photocatalytically active coatings for cement and air lime mortars: Enhancement of the activity by incorporation of superplasticizers

Coatings made with water dispersions of different nano-particles of photocatalytic additives (titania and titania doped with iron and vanadium) were prepared with diverse superplasticizers, SPs, to optimize the atmospheric NO removal efficiency when applied onto cement- and air-lime mortars. The use of different polycarboxylate-based superplasticizers (52IPEG, 23APEG and 45PC6) prevented nano-particles from agglomeration. The steric hindrance, provided by a large density and length of side chains, was ascertained as the most effective repulsion mechanism and 52IPEG was the most efficient SP. In PC- and air-lime mortars, the coatings with polycarboxylate-based SPs improved the NO removal rates as compared with the SP-free coating: an average increase of NO degradation by 15% under UV and by 76% under solar light was found. This finding was related to the drop in the agglomeration of the photocatalysts, with more exposed active sites and a decrease of the electron-hole recombination rates. Capillary water absorption and water vapour permeability values showed that the coatings did not alter the performance of the mortars. SEM examination showed that the use of SPs enhanced the distribution of the photocatalysts yielding thinner coating layers and boosting the percolation of the active material within the mortars. Accelerated weathering showed a moderate reduction of NO removal efficiency. Coating with 52IPEG was the most efficient in preserving the activity. Measurements of Ti content showed a low washout of the TiO2 nano-particles, supporting the long-run activity of these coatings.

Preparation and characterization of nanocrystalline cellulose/Eucommia ulmoides gum nanocomposite film

The nanocomposite films were prepared using Eucommia ulmoides gum (EUG) matrix reinforced with nanocrystalline cellulose (NCC) at different concentrations. Subsequently, the obtained films were characterized by Raman spectra, AFM, XRD, TGA, and DSC. Meanwhile, the wettability, mechanical, and water vapor barrier properties of these films were analyzed. AFM noticed that the average sizes of NCC were 81.95×50.17×13.06nm, while the size of molecular chain for EUG was 2530×57.33×1.28nm. In comparison with control film, a certain amount of NCC obviously improved elongation at break and enhanced their crystallinity and ΔHm. More importantly, NCC/EUG nanocomposite films presented lower thermal stability, glass transition temperature (Tg), melting temperature (Tm), and water vapor permeability (WVP) values, especially the WVP values of 4% NCC film were the lowest as 0.28×10−9, 0.30×10−9, and 0.58×10−9g/m/h/Pa at RH 34%, 55%, and 76%, respectively.

The properties of potato and cassava starch films combined with cellulose fibers and/or nanoclay

The aim of this study was to develop and evaluate films produced from potato and cassava starches, reinforced with cellulose fibers and/or nanoclay. The films were elaborated with 4% starch, 30% glycerol, 20% cellulose fiber, and/or 5.0% nanoclay. The films were evaluated by physical, mechanical, and water vapor barriers, and morphological properties. The addition of nanoclay and cellulose simultaneously increased the tensile strength from 12.03 to 17.75 MPa and decreased the elongation from 13.81 to 0.94% of the potato starch films when compared to films without addition of these reinforcements. The addition of cellulose fibers and/or nanoclay increased the tensile strength of the cassava starch films. The water vapor permeability (WVP) of the films decreased with the addition of reinforcing agents, and the lowest WVP values were presented when cellulose and nanoclay were added simultaneously to the starch films. A synergistic effect between the cellulose and the nanoclay in the constitution of the film promoted a lower WVP value. The addition of cellulose increased the water solubility from 14.7 to 19.6% of the potato starch films. The addition of reinforcement agents in potato starch films produced more resistant films with a moderate solubility, thus can be used as a biodegradable sachet to release systems.