Water Vapor Permeability Properties Research Articles

Desiccant Films Made of Low-Density Polyethylene with Dispersed Silica Gel-Water Vapor Absorption, Permeability (H2O, N2, O2, CO2), and Mechanical Properties.

Silica gel is a well-known desiccant. Through dispersion of silica gel in a polymer, films can be made that absorb and desorb water vapor. The water vapor absorption becomes reversible by exposing such films to a water vapor pressure below that of the water vapor pressure during absorption, or by heating the film. The intention of this study was to achieve a better understanding about the water vapor absorption, permeability (H2O, N2, O2, CO2), and mechanical properties of films with dispersed silica gel. Low-density polyethylene (PE-LD) monolayer films with a nominal silica gel concentration of 0.2, 0.4, and 0.6 g dispersed silica gel per 1 g film (PE-LD) were prepared and they absorbed up to 0.08 g water vapor per 1 g of film. The water vapor absorption as a function of time was described by using effective diffusion coefficients. The steady state (effective) water vapor permeation coefficients of the films with dispersed silica gel were a factor of 2 to 14 (8.4 to 60.2·10−12 mg·cm·(cm2·s·Pa)−1, 23 °C) higher than for pure PE-LD films (4.3·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C). On the other hand, the steady state gas permeabilities for N2, O2, and CO2 were reduced to around one-third of the pure PE-LD films. An important result is that (effective) water vapor permeation coefficients calculated from results of sorption and measured by permeation experiments yielded similar values. It has been found that it is possible to describe the sorption and diffusion behavior of water by knowing the permeability coefficient and the sorption capacity of the film (). The tensile stress changed only slightly (values between 10 and 14 N mm−2), while the tensile strain at break was reduced with higher nominal silica gel concentration from 318 length-% (pure PE-LD film) to 5 length-% (PE-LD with 0.6 g dispersed silica gel per 1 g film).

The optimization of physico-mechanical properties of bionanocomposite films based on gluten/ carboxymethyl cellulose/ cellulose nanofiber using response surface methodology

Abstract In the present study, new biodegradable nanocomposite films were produced. The effect of wheat gluten (WG) (1–2.5 wt%), carboxymethyl cellulose (CMC) (0.5–1 wt%) and cellulose nanofiber (CNF) (0-10 wt% based on gluten and CMC biopolymers solid matter in each formula) concentration on water vapor permeability (WVP), mechanical and color properties of the biodegradable nanocomposites were investigated using response surface methodology (RSM). Regression models were also developed for all responses as a function of linear, interaction and quadratic terms of WG/CMC/CNF concentrations. The optimum point with 1 wt% gluten, 0.686 wt% CMC and 8.549 wt% CNF for a maximum desirability of 0.878 was obtained. Furthermore, the microstructure, surface topography and the distribution quality of cellulose nanofiber in the biopolymer matrix were evaluated by scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and X ray diffraction (XRD) analysis.

Impact of test parameters on the water vapor permeability of textiles

PurposeUnlike other materials, textiles associate with aesthetic and mechanical properties such as flexibility and removability that allow them to be deployed or folded as required and which make them good candidates for clothing and furnishing but also, eventually, for other applications such as building. Actually, the clothing should ensure appropriate heat and mass transfers between the human body and its environment in order to maintain the thermo-physiological comfort. For that, it is important to determine water vapor permeability (WVP) of textile. Several normalized procedures with variants depending on the nature of the tested material exist to measure the WVP. One of the methods used is the “dish method” described by the British Standard (BS 7209). The purpose of this paper is to determine the influence of the test parameters on the WVP measurements.Design/methodology/approachConsequently, WVP of different textiles was measured while varying several parameters like: nature of fabrics, air layer thickness, vapor pressure gradient and air velocity.FindingsA decrease in the WVP values was observed with an increase in the air layer thickness and the number of textile layers. On the other side, an increase in the water pressure gradient induces an increase in the WVP value. Finally, it was also observed that air velocity has an impact on the WVP measurements.Originality/valueIn addition to intrinsic properties of fabrics, i.e., nature of fiber, woven structure, the influence of the several extrinsic properties, i.e., the influence of the air layer thickness, the number of textile layers, the vapor pressure gradient and the air velocity, on the WVP were investigated. Some researchers have already investigated the impact of these parameters on the WVP measurement separately. However, this study presents a difference from other studies that it takes into account the influence of the both intrinsic and extrinsic properties on WVP. In addition to these, this work combine several extrinsic properties which are presented separately during other studies. The first time, in this study the influence of the air velocity on WVP was investigated. Results on both hydrophilic and hydrophobic fabrics showed a great variation in the results when varying the location of the cups inside the climatic chamber. This is the reason why future studies look at studying more deeply the effect of air velocity on the WVP properties on different types of fabrics by connecting WVP values with air velocity values. It is also planned to make tests with the rotation device and by fixing the value of the temperature and RH. The objective will be to obtain reliable values that do not take into account the effect of air velocity.

Encapsulation of essential oil in emulsion based edible films prepared by soy protein isolate-gum acacia conjugates

Emulsions containing essential oils (EOs) of oregano (OG-EO), lemon (LM-EO), fruit of Amomum tsaoko Crevost et Lemaire (ACL-EO) or grapefruit (GF-EO) were used as dispersed phase and aqueous solution of soy protein isolates-gum acacia (SPI-GA) conjugates was used as continuous phase to produce edible films. The viscosity, oil droplet size distribution, zeta (ζ)-potential, storage and loss moduli and microstructure of film forming emulsions were affected by the type or nature of the EOs used. The microstructure, glass transition temperature (Tg), tensile strength, elongation at break, water vapor permeability, surface hydrophobicity, electrostatic interactions, hydrogen bonds, hydrophobic interactions, disulfide bonds, antioxidative and antibacterial properties as well as the release pattern of EO from the EO containing films were affected by the nature of the EO used. Among these films, the film containing GF-EO showed the best water vapor barrier properties, the highest tensile strength and Tg compared to the films prepared from other EOs. The films containing LM-EO and OG-EO showed the highest radical scavenging activity and antibacterial activity, respectively. The release profiles of EOs from their respective films were fitted well by Peppas model.

Engineering Sustainable Antimicrobial Release in Silica-Cellulose Membrane with CaCO3-Aided Processing for Wound Dressing Application.

The sustained release of antimicrobial therapeutics for wound dressing has become an attractive design strategy for prolonging the timespan of wound dressings and for reducing the risk of chronic wound infection. Recently, cellulose-based membrane has become a preferred option of wound dressings for the treatment of burn wounds and skin ulcers. In this work, novel cellulose membrane incorporated with mesoporous silica particles (SBA-15) was developed as an antimicrobial wound dressing with desirable sustained release functionality for targeting persistent bacterial pathogens. Attributed to a coated layer of calcium carbonate (CaCO3), SBA-15 particles were free from corrosion in alkaline condition during the preparation of cellulose-based composite membranes. SEM, TEM and BET results showed that the morphology, specific surface area, pore size and pore volume of pristine SBA-15 were preserved after the incorporation of CaCO3-coated SBA-15 into the cellulose matrix, while the mesoporous structure of SBA-15 was significantly disrupted without the use of CaCO3 coating. The resultant composite membranes containing 30 wt% SBA-15 (denoted as CM-Ca2-SBA(30%)) achieved 3.6 wt% of antimicrobial drug loading. Interestingly, CM-Ca2-SBA(30%) demonstrated the sustained release property of chloramphenicol for 270 h, driven by a two-stage drug release processes of SBA-15/cellulose. The water vapor permeability (WVTR) and swelling properties of composite membranes were shown to have complied with the primary requirements of wound dressing. Antibacterial assays revealed that strong antibacterial activities (144 h) of the composite membranes against Staphylococcus aureus and Eschericia coli were achieved. All results displayed that the strategy of coating silica with CaCO3 helps to obtain cellulose–silica composite membranes with desirable sustained release profiles and strong antibacterial activities. The antibacterial SBA-15/cellulose composite membranes show potential for the application of wound dressing.

Effect of Tea Polyphenols on Curdlan/Chitosan Blending Film Properties and Its Application to Chilled Meat Preservation

Incorporating phenolic acids into polysaccharide films improves their physical properties, in turn improving their potential commercial applicability as a preservation material for different foods. This study aimed to develop films from curdlan and tea polyphenols, and determine the effect of their contents on the water vapor permeability (WVP) and mechanical properties (tensile strength and elongation at break) of the films. Different ratios of tea polyphenols were incorporated into the curdlan-based films to improve their properties. The results obtained showed that the tensile strength and elongation at break of films were likely to be significantly decreased by adding tea polyphenols, especially at a content of 0.6%, which resulted in a 50% decrease. Meanwhile, the WVP and moisture content of the films was also decreased. However, a low WVP can prevent moisture loss from food. Other film properties, such as antioxidant efficiency, were also investigated. The results showed that the antioxidant potential of the film can be improved by tea polyphenols. The composite films were also applied to the preservation of chilled meat, which resulted in the shelf life being extended by about 3–5 days. Some properties, such as water resistance and DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging capacity of the composite film, were improved.

Ionic Liquids as Delaminating Agents of Layered Double Hydroxide during In-Situ Synthesis of Poly (Butylene Adipate-co-Terephthalate) Nanocomposites.

Currently, highly demanded biodegradable or bio-sourced plastics exhibit inherent drawbacks due to their limited processability and end-use properties (barrier, mechanical, etc.). To overcome all of these shortcomings, the incorporation of lamellar inorganic particles, such as layered double hydroxides (LDH) seems to be appropriate. However, LDH delamination and homogenous dispersion in a polymer matrix without use of harmful solvents, remains a challenging issue, which explains why LDH-based polymer nanocomposites have not been scaled-up yet. In this work, LDH with intercalated ionic liquid (IL) anions were synthesized by a direct co-precipitation method in the presence of phosphonium IL and subsequently used as functional nanofillers for in-situ preparation of poly (butylene adipate-co-terephthalate) (PBAT) nanocomposites. The intercalated IL-anions promoted LDH swelling in monomers and LDH delamination during the course of in-situ polycondensation, which led to the production of PBAT/LDH nanocomposites with intercalated and exfoliated morphology containing well-dispersed LDH nanoplatelets. The prepared nanocomposite films showed improved water vapor permeability and mechanical properties and slightly increased crystallization degree and therefore can be considered excellent candidates for food packaging applications.

Characteristics, Controlled-release and Antimicrobial Properties of Tea Tree Oil Liposomes-incorporated Chitosan-based Electrospun Nanofiber Mats

In this paper, a notable chitosan/poly(ethylene oxide) nanofiber mats containing tea tree oil liposomes (TOL-CENs) were successfully fabricated using electrospinning process. The microstructures and morphology were characterized by scanning electron microscopy. The porosity, fluid absorbability, water vapor permeability and mechanical properties of nanofiber mats were also estimated by ethanol density method, gravimetric method, dish method and tensile test, respectively. Compared to the chitosan/poly(ethylene oxide) composite freeze-dried sponges containing tea tree oil liposomes, TOL-CENs had greater porosity, water absorption, breathability and better mechanical properties. In addition, the controlled-release properties and long-term bactericidal capability of the material were also assessed. From the analysis of the release kinetics and mechanism, it was found that the significant decreased terpinen-4-ol concentration gradient from liposomal surface to the outside of material was the key to the sustained terpinen-4-ol release in virtue of liposomal encapsulation. TOL-CENs exhibited long-term and more excellent microbicidal effects against Staphylococcus aureus, Escherichia coli and Candida albicans than chitosan/poly(ethylene oxide) nanofiber mats. The combination of tea tree oil liposomes and chitosan in nanofiber mats synergistically destroyed cell membrane, prevented cell adhesion and caused the irregular aggregation of cytoplasm, resulting in cell disintegration observed by transmission electron microscope. In summary, TOL-CENs had potential application value as a long-term antimicrobial nonwoven materials.

Development and characterization of pH-indicator films based on cassava starch and blueberry residue by thermocompression

Due to the concern about the inadequate disposal of synthetic and non-biodegradable plastic packaging, a great number of researches pointing at the substitution of these materials by natural and biodegradable sources have been growing in recent years. Another important category recognizes as intelligent packaging has also received more prominence. The study intended to achieve the matter aforementioned developing starch-based films by thermocompression without and with blueberry residue as pH change indicator. Moisture content, water solubility, water vapor permeability, oxygen permeability, morphology, color, and mechanical properties of the films were analyzed. Moreover, analysis of color change and compounds migration were conduct in the films with blueberry. The residue insertion led to the formation of less compact films with high oxygen permeability. Despite the irregular dispersion of the blueberry residue on the polymer matrix identified by optical microscopy, the films showed equal values of water vapor permeability, hydrophilicity, and mechanical properties when compared to the samples without the residue. In addition, they exhibited visually perceptible color changes in the pH range between 2 and 12, which was confirmed by colorimetric analysis since the ΔE94∗ values between the samples were greater than 3. The compounds migration after film immersion in aqueous simulant solution (acetic acid) showed a higher intensity in comparison to the samples immersed in a fatty simulant solution (ethanol) due to the anthocyanins hydrophilicity. Therefore, the film with blueberry has potential as intelligent packaging. Besides that, it present potential as active packaging due to the migration of phenolic compounds in aqueous solutions.

Incorporation of Oregano Essential Oil Microcapsules in Starch‐Poly (Butylene Adipate Co‐Terephthalate) (PBAT) Films

Summary Cassava starch and poly(butylene adipate‐co‐terephthalate) (PBAT) based films containing microencapsulated oregano essential oil (OEO) and free OEO are produced by blow extrusion. Microcapsules produced by ionic gelation were characterized with respect to average size, morphology, and encapsulation efficiency. The microcapsules were spherical and ranged in size from 20 to 1000 μm. Encapsulation efficiency (EE) is 83%. The films are analyzed in terms of their morphology, mechanical properties, water vapor permeability (WVP) and antibacterial properties. The films containing OEO microcapsules exhibited lower ultimate tensile strength, Young's modulus and elongation at break than the control films and the films containing free OEO. The WVP of films containing free OEO is slightly lower, while that of films containing microencapsulated OEO did not differ significantly from the control films. Scanning electron microscopy (SEM) images showed that the surface of films containing microencapsulated OEO are less homogeneous than those of the control and free OEO films. Films containing free or microencapsulated OEO presented inhibitory activity against Staphylococcus aureus, but not against Escherichia coli.

Development and characterization of biodegradable films based on Pereskia aculeata Miller mucilage

Ora-pro-nobis mucilage (MOPN) is a polysaccharide extracted from the leaves of Pereskia aculeata Miller (Cactaceae family), and is composed of the biopolymer arabinogalactan. The aim of this study was to evaluate the viability of MOPN-based films supplemented with glycerol. The films were developed using the casting technique in five treatments: 1.5% MOPN with 20% glycerol (w/w), 1.5% MOPN with 25% glycerol, 1.8% MOPN with 22.5% glycerol, 2.0% MOPN with 20% glycerol, and 2.0% MOPN with 25% glycerol. The films were characterized according to their rheological, optical, mechanical, thermal, and water vapor permeability (WVP) properties. The film-forming solution presented shear thinning and elastic behavior (G'>G"). Films with 1.5% MOPN and 20% glycerol presented greater elongation (46.10%), higher puncture strength 13.8 N, and lower WVP (8.288 g water·mm·day−1·m-²·kPa−1) than the other evaluated films. Glycerol acted as a cross-linking agent, increasing the bond between the MOPN chains, generating more rigid films. These films presented two glass transition temperatures, below 0 °C and around 60 °C. Thermogravimetry indicated that MOPN contributes to better thermal stability of the films. MOPN is a promising alternative for the use of biodegradable and/or edible packagings, and the best formulation studied was 1.5% MOPN and 20% glycerol.

Structural and physiochemical characterization of novel hydrophobic packaging films based on pullulan derivatives for fruits preservation

Pullulan acetate (PLAc), pullulan propionate (PLPr) and pullulan butylate (PLBu) with various degrees of substitution (DS) were synthesized from pullulan and different carboxylic anhydrides (acetic anhydride, propionic anhydride and butyric anhydride). The structure of PLAc, PLPr and PLBu were determined by Fourier Transform Infrared Spectrometer (FT-IR) and 1H Nuclear Magnetic Resonance Spectroscopy (1H-NMR) spectroscopy. Pullulan ester films were obtained by solvent casting. The water vapor permeability, oxygen permeability, surface hydrophobicity, color and mechanical properties were investigated. Compared with native pullulan, all pullulan esters film showed a lower TS. TS and EAB declined with the increase of DS. PLBu3 achieved the lowest water vapor permeability property at 0.792 × 10−11 g/m s Pa and lowest oxygen permeability property of 0.625 × 10−3 g/m2 s. The onset of ripening was monitored in terms of reduction in flesh firmness loss and weight loss. Package fruits with pullulan ester films delayed the ripening and senescence and hence could be used as an effective edible coating for extending their shelf life.

Bio-on presents method to convert waste oils into biopolymer raw material

Edible films based on plasticized wheat gluten protein were prepared by intensive mixing followed by compression molding. The effects of water and glycerol, which were selected as plasticizers for the wheat gluten, as well as the processing conditions (mixing time and molding temperature) on the physical and mechanical properties of the films were evaluated. The resulting films were characterized in terms of moisture sorption, total soluble matter, water vapor permeability, dynamic mechanical and tensile properties. It was found that plasticizer type and concentration had a dominating effect on mechanical properties and WVP, while other physical properties remain almost non-affected. Moreover, the effect of the added plasticizer (glycerol) on the film properties strongly depends on natural presence of water in commercial gluten (9% as is). On the other hand, the pressing temperature affected the final properties of the films more than the mixing time because the former influences the final cross-linking degree of the protein network. Processing temperatures higher than 100 °C led to darker films that would be discarded by consumers if they were used as food packaging.

Mechanical, thermal, and water vapor barrier properties of regenerated cellulose/nano-SiO2 composite films

Bionanocomposite films were fabricated by reinforcing regenerated cellulose (RC) with 3-aminopropyl-functionalized silica nanoparticles (nano-SiO2). The composite films were prepared by dissolving cotton linter RC in a 7% NaOH/12% urea solution followed by the addition of nano-SiO2 and 5% H2SO4 solution. The effects of nano-SiO2 concentration (1–5 wt% with respect to RC) on the morphology, water vapor permeability (WVP), thermal properties, and mechanical properties of the RC/nano-SiO2 composite films were evaluated. Morphological studies indicated uniform dispersions of the low-concentration nano-SiO2 particles in the RC matrix. The tensile strength and modulus were increased by 26% and 15%, respectively, in the presence of 2 wt% of nano-SiO2 relative to the values of neat RC film. The WVP of the RC/nano-SiO2 composite films decreased by 22% after reinforcement with 2 wt% nano-SiO2. The results revealed that there is a potential interaction between RC and nano-SiO2, resulting in improved thermal and mechanical properties of the RC/nano-SiO2 composite films compared to those of neat RC film. Bionanocomposite films were fabricated by reinforcing regenerated cellulose (RC) with 3-amino propyl functionalized silica nanoparticles (nano-SiO2). The effects of nano-SiO2 (1–5 wt% with respect to RC) on the morphology, water vapor permeability (WVP), and thermal and mechanical properties of the RC/nano-SiO2 composite films were evaluated. This study highlights the potential of organically modified nano-SiO2 to enhance the properties of RC owing to the ability of nano-SiO2 to interact with the RC matrix at very low concentrations (2 wt%).

Preparation of self‐regulating/anti‐adhesive hydrogels and their ability to promote healing in burn wounds

Few burn dressings can self-regulate the optimal humidity levels that are required for wound healing, while also providing good anti-adhesive properties to prevent damage that can occur when wound dressings are changed. Consequently, a water-soluble carboxymethylcellulose sodium/sodium alginate/chitosan (CMC-Na/SA/CS) composite hydrogel has been developed as a potential burn wound dressing, with orthogonal testing revealing an optimal ratio of CMC-Na, SA, and CS as 2, 3, and 1 wt % for hydrogel preparation, respectively. The resultant hydrogel has been formulated into composite wound dressings that were then used for the treatment of deep second degree burn wounds in Sprague-Dawley (SD) rats. Analysis of the physical properties of this dressing revealed that it exhibits good water vapor permeability properties that promote the healing of deep second-degree burn wounds. The pro-healing mechanism of the dressing has been investigated Vascular endothelial growth factor (VEGF) expression was upregulated and basic fibroblast growth factor (bFGF) expression was downregulated in the early periods of wound healing, with upregulation of bFGF then occurring at a later stage of wound healing. At the same time, the wound dressing decreased the levels of tumor necrosis factor-α and interleukin-6, thus validating its beneficial effect on the wound healing process at a biomolecular level. In conclusion, this new hydrogel dressing was shown to exhibit excellent self-regulatory and anti-adhesive properties that synergistically promote the healing of burn wounds in rats, thus providing promising results that may have clinical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1471-1482, 2019.

Okra mucilage and corn starch bio-based film to be applied in food

Okra mucilage/corn starch films to apply in food were developed by casting and then characterized to know its main requirements for packing material. The film was submitted to an acute toxicity analysis in rats by ingesting the filmogenic solution. An okra mucilage material obtained by precipitation was analyzed by thermal analysis, Fourier Transformed Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive Spectroscopy. Okra mucilage and corn starch films presented compact and uniform structure, low water vapor permeability (1.32–2.84 g/m s Pa), low solubility (around 15%), good thermal and mechanical properties, swelling capacity (about 95%), and no toxicological responses. The precipitated material presented similar characteristics to those of polysaccharides. Thus, okra mucilage differed in view of its improvement in film properties because of high quality intermolecular bonds. The film obtained with okra mucilage has excellent potential to be applied in food packaging.

Study of the Barrier and Mechanical Properties of Packaging Edible Films Fabricated with Hydroxypropyl Methylcellulose (HPMC) Combined with Electro-Activated Whey

The aim of this work was to study the effect of composition and aging time on the physico-chemical, light barrier and color properties, water vapor permeability, mechanical and thermal properties of biodegradable packaging films made of hydroxypropyl methylcellulose (HPMC) incorporated with glycerol (G), non-electro-activated whey (NW) and electro-activated whey (EAW). The films were prepared from the solutions at pH 7 by pouring 6 g of each in the petri-dishes. These films were then stored for aging in a pre-conditioned experimental chamber at 23 ± 0.5 °C and 50% relative humidity (RH) during 30 days. All the films containing G, NW and EAW showed significant increase in film thickness and increase in moisture content (MC) as function of composition. The control film had a thickness of 49.00 ± 7.28 μm and the addition of 1% of whey and electro-activated whey did not decrease the film thickness which had the values of 42.86 ± 9.99 and 42.14 ± 5.24 μm, respectively. Addition of 2, 3 and 4% both whey and electro-activated whey induced significant increase of the film thickness to a maximum value of ≈ 85 μm. The significant increase in MC affected the mechanical properties causing a significant increase in color change (ΔE) values and a decrease in both tensile strength (TS) and Young modulus (YM). The water barrier properties were also affected due to this increase in moisture content (MC). After aging under controlled conditions, the MC of the films containing G, NW and EAW was constant which gave no change in the films properties. Scanning electron microscopy (SEM) images revealed significant microstructural differences between the control HPMC films and those incorporated with G, NW and EAW.

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.

Effect of plasticizers on physicochemical properties of cellulose nanocrystals filled alginate bionanocomposite films

AbstractIn this work, the effect of various polyol‐based plasticizers, including glycerol (GLY), diethylene glycol (DEG), and polyethylene glycol (PEG), on the properties of alginate (ALG)‐based films and cellulose nanocrystals (CNC)‐filled ALG‐based bionanocomposite films was investigated. The CNC used as nanoreinforcing fillers were extracted, at nanometric scale, from sugarcane bagasse fibers using sulfuric acid hydrolysis process, and their morphology and structure were characterized. Plasticized ALG films and plasticized ALG‐CNC bionanocomposite films were prepared by solvent casting method. Before the casting process, the steady shear viscosity of film‐forming solutions of all studied formulations was studied and compared. The obtained ALG‐based films were successfully characterized in terms of their structure, transparency, water vapor permeability (WVP), moisture uptake (MU), thermal, and mechanical properties. It was found that all studied plasticized films keep the same transparency level of neat ALG films, thus suggesting that the selected plasticizers are compatible with the ALG biopolymer, and the CNC are well dispersed within the bionanocomposite films. The elastic modulus and tensile strength of neat ALG films were largely decreased after the addition of different plasticizers, while the elongation at break was significantly increased. However, these selected mechanical parameters were simultaneously improved when CNC are incorporated into plasticized ALG bionanocomposite films. The WVP and MU properties of ALG films were decreased when different plasticizers and CNC were added. Herein, the steps to form new eco‐friendly ALG films were described by taking advantage of the combination of plasticizers and CNC with ALG biopolymer. The as‐produced films exhibited good optical transparency while reducing the WVP and enhancing tensile properties, which are the main properties required for packaging applications.

Physicochemical properties of novel pectin/Aloe gel membranes

Nowadays, an increased interest on the development of novel biomaterials for different applications has been observed. The biopolymers such as proteins, lipids, polysaccharides or their combinations have been used for the manufacturing of novel membranes. The pectin is a polysaccharide that previously has been used only or combined with polymeric matrices, but the formulation of PEC/AG has not been evaluated yet. The aim of this work was to evaluate the physicochemical properties of a novel PEC/AG membrane. A mixture of pectin citric (PEC)/Aloe gel (AG) was prepared to manufacture membranes at 100/0 (control), 90/10, 80/20, 70/30, 60/40 and 50/50 proportions (% v/v) by casting method. Water vapor permeability (WVP), solubility, ATR-FTIR spectroscopy, microstructure, mechanical and optical properties were assessed for the produced membranes. The PEC/AG membranes showed a yellowish color, low UV light transmission at 200 nm and no significant changes in the opacity values. In addition, the microstructure by scanning electron microscopy (SEM) showed changes on the surface appeared as differently sized structures. An analysis of the total area of the 3284 cm−1 showed rearrangement of hydrogen bonds of the polysaccharide macromolecules, suggesting an enhanced interaction between the PEC and AG chains. In addition, all the membranes of PEC/AG showed high solubility (100%), low WVP and better toughness, extensibility and plasticity as compared with the control. The assessed physicochemical properties of the produced membranes suggested that they may be used as biomaterial for multiple applications in the medical, pharmaceutical, cosmetic or food industries.