Water Barrier Properties Of Films Research Articles

Scalable production of hydrophobic starch/beeswax films by continuous solution casting

AbstractStarch is an appealing natural polymer for the scaled‐up production of biodegradable plastics. However, the low water resistance of starch has made its broad applicability largely doubted. In this study, starch was combined with beeswax (BW) through a pilot scale continuous solution casting (CSC) technique to reduce water affinity while keeping the ensuing films totally biodegradable. The phase morphology, surface wettability, and water vapor permeability (WVP) of films were examined over a broad BW–starch mass ratio (0.3–0.7). Emulsified, surfactant‐free starch/BW films were successfully obtained at a productivity of 0.55 m2 film h−1. The water contact angle increased nearly by 100% at 30 wt% BW, leading to remarkable reductions in WVP. BW droplets well distributed within the starch matrix played a key role in enhancing the water barrier properties of films. CSC of starch/BW films offers a basis to design new hydrophobic formulations for applications that require biodegradable plastics with high moisture resistance.

κ-Carrageenan-essential oil loaded composite biomaterial film facilitates mechanosensing and tissue regenerative wound healing

Polysaccharides κ-carrageenan (κ-Car) have become a predominant source in developing bioactive materials. We aimed to develop biopolymer composite materials of κ-Car with coriander essential oil (CEO) (κ-Car-CEO) films for fibroblast-associated wound healing. Initially, we loaded the CEO in to κ-Car and CEO through homogenization and ultrasonication to fabricate composite film bioactive materials. After performing morphological and chemical characterizations, we validated the developed material functionalities in both in vitro and in vivo models. The chemical and morphological analysis with physical structure, swelling ratio, encapsulation efficiency, CEO release, and water barrier properties of films examined and showed the structural interaction of κ-Car and CEO-loaded into the polymer network. Furthermore, the bioactive applications of CEO release showed initial burst release followed by controlled release from the κ-Car composite film with fibroblast (L929) cell adhesive capabilities and mechanosensing. Our results proved that the CEO-loaded into the κ-Car film impacts cell adhesion, F-actin organization, and collagen synthesis, followed by in vitro mechanosensing activation, further promoting wound healing in vivo. Our innovative perspectives of active polysaccharide (κ-Car)-based CEO functional film materials could potentially accomplish regenerative medicine.

Effects of beeswax emulsified by octenyl succinate starch on the structure and physicochemical properties of acid-modified starchfilms

This work aimed to develop a novel strategy to modulate the distribution of beeswax in acid-modified starch films via tuning octenyl succinate starch (OSS) ratios and to elucidate their structure-property relationships. The apparent viscosity and storage modulus of the film-forming solution decreased with the increase of OSS ratio. Attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy revealed that the hydrogen bond in the film-forming network was cleaved with the presence of OSS. Scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD) demonstrated that OSS ratio had an obvious effect on the formation and distribution of beeswax crystal particles. Uniform distribution of beeswax effectively enhanced the hydrophobicity and water barrier properties of films and performed preferable elongation at break but at the expense of tensile strength and optical properties. The films with higher OSS ratio (>12 %) presented higher thermal stability. This study provides new information on the rational design of emulsified films to obtain desirable physicochemical properties by tuning the distribution of beeswax.

Gelatin Films Activated by Cinnamon Essential Oil and Reinforced with 1D, 2D and 3D Nanomaterials: Physical and Release Controlling Properties

The aim of this study was to assess the effect of sodium montmorillonite (MMT), cellulose nanofibers (CNF) and titanium dioxide nanoparticles (TiO2NPs) on the physicochemical properties and release profile of the gelatin-based film activated with cinnamon essential oil (CEO). The results of FT-IR, XRD, FE-SEM and tensile analysis showed that the incorporation of nanofillers caused to different changes in the morphology, crystalline structure, and mechanical properties of gelatin films that were correlated with their morphology. The water barrier properties of films significantly increased by incorporation of nanofillers and MMT had the highest improving effect. As results of release profile study, MMT incorporated active film exhibited the slowest release rate with the lowest diffusion coefficient (8.67 ± 0.52 × 10−8cm2 s−1 at 25 °C), and highest activation energy (14.87 ± 1.11 kJ mol−1). In conclusion, nanolayers such as MMT were suggested as the best candidate to use as simultaneous reinforcement and release controlling agent in the activated biopolymer-based films.

Spatial distribution of lipids modulated by phase separation in emulsified films and the effects on structure-function relationships

The aim of this work was to develop a novel strategy to modulate the spatial distribution of paraffin in emulsified films via tuning phase separation behaviors among zein/gelatin (ZG) matrix, and to elucidate their structure-function relationships. Three phase separation behaviors within ZG matrix, namely, the zein-dominated, gelatin-dominated and ZG-macro phase separation, were developed. When the ZG matrix was tuned to ZG-macro or gelatin-dominated phase separation, the successive or partial bilayer films can be developed due to the spatial distribution of paraffin as the floating layer. While, when zein-dominated phase separation was created, paraffin uniformly distributed as dispersed phase, forming films with monolayer structure. Surface distribution of paraffin, detected by AFM, revealed that distinct interactions between paraffin and zein or gelatin drove the distribution pattern. The bilayer structure more effectively enhanced water barrier properties of films and performed preferable mechanical properties but at the expense of optical properties, whereas the release property of oregano essential oil and tea polyphenol was dominated by the chemistry nature of film matrixes rather than the spatial distribution. This study adds new knowledges to the rational design of emulsified films by tuning the spatial distribution of lipids.

Development of hydroxypropyl methylcellulose/sodium alginate blend active film incorporated with Dracocephalum moldavica L. essential oil for food preservation

The present study aimed to fabrication and characterization the hydroxypropyl methylcellulose (HPMC) films containing different concentrations of sodium alginate (0.5, 1, and 3% v/v) and Dracocephalum moldavica L. essential oil (DEO; 1, 3 and 5% v/v) as a biodegradable active packaging system. FTIR analysis confirmed the interaction of alginate groups with the hydroxyl group of HPMC. SEM images indicated that the addition of alginate decreased the size and number of the cracks. As a result, the incorporation of alginate and DEO significantly (p < 0.05) improved the water barrier properties of films and the lowest values of water vapor permeability (.38 × 10-10 g/m.h.Pa), moisture content (6.30 ± 0.08%) and water solubility (29.49 ± 0.04%) were related to the sample containing 1.5% alginate and 5% DEO. Additionally, blending with alginate significantly (p < 0.05) improved the mechanical properties of the films and the blended film sample with 0.5% alginate showed the highest tensile strength (16.13 MPa). The blend films showed high thickness and whiteness Index. Also, the antioxidant activity of the films was enhanced by incorporation DEO and the highest DPPH scavenging activity (74.58 ± 2.31%) was attributed to the samples incorporated with 5% DEO. In conclusion, the fabricated blend film showed considerable potential for active food packaging.

Structure, physical and antioxidant properties of chitosan-gum arabic edible films incorporated with cinnamon essential oil

Active films based on chitosan (CS) and gum arabic (GA) incorporated with cinnamon essential oil (CEO) have been developed, and the effect of CS/GA ratios on the film structure, physical and antioxidant properties were investigated. Possible interactions among CS, GA and CEO was evaluated using rheological studies, Fourier transform infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD). These results showed that there existed electrostatic interactions between CS and GA, which led to the formation of entangled structure. The addition of GA enhanced the water barrier properties of films, while it became less resistant to breakage and stretching. Confocal laser scanning microscopy (CLSM) results confirmed the higher CEO retention in films. Greatly enhanced antioxidant effectiveness were observed when the ratio of CS/GA changed from 1:0 to 1:2. However, when the ratio reached 1:4, the antioxidant capacity quickly decreased, which could be attributed to the negative influence of maximal interactions between CS and GA, leading to the loss of CEOs.

Enhanced Water Barrier Properties of Surfactant-Free Polymer Films Obtained by MacroRAFT-Mediated Emulsion Polymerization.

The presence of low-molar-mass surfactants in latex films results in detrimental effects on their water permeability, gloss, and adhesion. For applications such as coatings, there is a need to develop formulations that do not contain surfactants and have better water barrier properties. Having previously reported the synthesis of surfactant-free latex particles in water using low amounts (<2 wt %) of chains synthesized by controlled radical polymerization (Lesage de la Haye et al. Macromolecules 2017, 50, 9315-9328), here we study the water barrier properties of films made from these particles and their application in anticorrosion coatings. When films cast from aqueous dispersions of acrylate copolymer particles stabilized with poly(sodium 4-styrenesulfonate) (PSSNa) were immersed in water for 3 days, they sorbed only 4 wt % water. This uptake is only slightly higher than the value predicted for the pure copolymer, indicating that the negative effects of any particle boundaries and hydrophilic-stabilizing molecules are minimal. This sorption of liquid water is 5 times lower than what is found in films cast from particles stabilized with the same proportion of poly(methacrylic acid) (PMAA), which is more hydrophilic than PSSNa. In water vapor with 90% relative humidity, the PSSNa-based film had an equilibrium sorption of only 4 wt %. A small increase in the PMAA content has a strong and negative impact on the barrier properties. Nuclear magnetic resonance relaxometry on polymer films after immersion in water shows that water clusters have the smallest size in the films containing PSSNa. Furthermore, these films retain their optical clarity during immersion in liquid water for up to 90 min, whereas all other compositions quickly develop opacity ("water whitening") as a result of light scattering from sorbed water. This implies a remarkably complete coalescence and a very small density of defects, which yields properties matching those of some solvent-borne films. The latex stabilized with PSSNa is implemented as the binder in a paint formulation for application as an anticorrosive barrier coating on steel substrates and evaluated in accelerated weathering and corrosion tests. Our results demonstrate the potential of self-stabilized latex particles for the development of different applications, such as waterborne protective coatings and pressure-sensitive adhesives.

English

Synergistic effects of additive amount, reaction time and temperature of transglutaminase on properties of WPI-NaCas composite protein films were discussed by orthogonal experiments. Results indicated that transglutaminase (TGase) modification decreased D50 and D90 of film-forming solution particles, resulting in decrease in water solubility and increase in both mechanical and water barrier properties of films under most conditions. Compared with control sample, scanning electron microscope analysis indicated that cross-section of enzyme modification sample was denser and more impermeable. However, there was no significant difference in both thermogravimetric analysis and solution apparent viscosity changes for all samples. Orthogonal experiment results also showed that TGase reaction time was the most effective factor on tensile strength&nbsp; (TS) &nbsp;and water vapor permeability (WVP) properties of film, and the secondary, tertiary factors were reaction temperature, TGase additive amount respectively. Films modified by 0.1 mg/ml TGase at 50&deg;C for 30 min exhibited the optimum mechanical and water barrier performance. &nbsp; Key words: Transglutaminase (TGase), mechanical properties, water vapor permeability (WVP), scanning electron microscopy analysis.

Influence of ethanol and glycerol concentration over functional and structural properties of zein–oleic acid films

This study was performed in order to determine the effect of the addition of different concentrations of glycerol and ethanol over functional and structural properties of zein–oleic acid films. Films were prepared from zein and oleic acid formulations, containing: 0, 10, 20 and 30% (w/w) of glycerol as plasticizer and 75, 80, 85, 90 and 95% (v/v) of ethanol as zein solvent. Water vapor permeability (WVP) at 4 and 24 °C, opacity, water solubility and structural behavior of the film were assessed. The film water barrier properties, WVP and water solubility, were increased when higher ethanol concentration and lower glycerol concentration were used. Furthermore, WVP at 4 °C was lower than WVP at 24 °C due to the crystalline solid state of oleic acid at lower temperatures. Likewise, opacity, homogeneity and structure of the composite film were improved as ethanol increased and glycerol lowered.

Influence of transglutaminase or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on the properties of fish-skin gelatin films

The effect of cross-linking of fish-skin gelatin with transglutaminase (TGase) on solubility, mechanical and barrier properties of prepared films was determined. For comparison, parallel experiments were made with films chemically modified with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The solubility at pH 3 and 6 of TGase-modified films was decreased from 100% to 30% and that of films modified with TGase in the presence of dithiothreitol or cysteine to 5% and 15%, respectively. Under the same conditions, the solubility of chemically modified films amounted to about 10%. The water barrier properties of films were not improved by cross-linking of gelatin either with TGase or with EDC. Glycerol at concentrations up to 30% did not increase the solubility of enzymatically and chemically modified films. Water vapor permeability of TGase-modified films slightly increased with the increase in glycerol concentration. Plasticization of films cross-linked with EDC affected water vapor permeability into a higher degree. Elongation of enzymatically modified films containing 22.5% of glycerol was about 42%. However, simultaneously, tensile strength decreased from 19.5 to about 8 MPa. Lower concentrations of glycerol were needed to plastify chemically modified films.

Water Barrier Properties of Zein‐Oleic Acid Films

ABSTRACTFree‐standing films were prepared from zein formulations containing 30, 40, 50, 60, 70, and 80% oleic acid (OA). Zein/OA formulations were also used as coating films for rodent diet bars. Water vapor permeability (WVP) of films and moisture loss rate (MLR) of coated rodent diet bars were measured at 4 and 25°C. Temperature affected the water barrier properties of films and coatings. At 4°C, WVP of films decreased with OA concentration while it increased at 25°C. WVP behavior was attributed to oleic acid phase changes due to temperature. At 4°C, OA is a crystalline solid that limits water diffusion through the films. At 25°C, liquid OA increased the system free volume and allowed for water diffusion. The effect was more pronounced the higher the OA concentration in films. Differential scanning calorimetry (DSC) of zein/OA films showed endothermic peaks at 12–18°C, confirming the melting of OA in that temperature range. MLR of coated rodent diet bars was also affected by temperature and OA concentration in coating formulations. In this case, formulations containing 40, 50, and 60% OA were better moisture barriers than coatings with higher OA content at both 4 and 25°C. Moisture losses were reduced at 4°C due to OA solidification.

Effect of surfactants on water sorption and barrier properties of hydroxypropyl methylcellulose films

Moisture sorption isotherms and water barrier properties of films made from hydroxypropyl methylcellulose (HPMC) containing surfactant mixtures of sorbitan monostearate (SPAN 60) and sucrose palmitate (sucrose ester P-1570) were evaluated at 10 °C. The effect of hydrocolloid/surfactant ratio ( H/ S) (0.5, 1.0 and 1.5) and the hydrophilic/lipophilic balance of the mixture (HLB: 4.7, 6.0 and 8.0) was analysed. GAB and BET sorption models were tested to fit the experimental data. The equilibrium moisture content of films increased dramatically above a w=0.6. Films with greater H/ S ratio have greater water binding capacity. For a specific hydrocolloid/surfactant ratio, equilibrium moisture content of the coatings decreased as the HLB of the surfactant mixture increased. Equilibrium moisture contents of the composite films could be predicted from the corresponding values of pure compounds and the respective component mass fractions by a linear model, in the water activity range of 0.11–0.75. At the high relative humidity at which water permeability of the films was evaluated, the water vapour barrier was effective when the films reached a critical amount of surfactants ( H/ S=0.5).

Physical properties of edible films made from mixtures of sodium caseinate and WPI

Abstract The physical properties of thin films (25–30 μm) made from mixtures of sodium caseinate (NaCas) and whey protein isolate (WPI) were investigated. Films were formed by mixing solutions of NaCas (2.5% w/w protein), plasticised with glycerol (NaCas–gly) at a glycerol:protein ratio of 0.32, with WPI solutions (2.3% w/w protein), plasticised (WPI-gly) at a glycerol:protein ratio 0.37. Tensile and water barrier properties of films formed from mixtures of NaCas–gly and WPI-gly were similar to films containing NaCas–gly only. Films containing only WPI-gly had higher maximum load and elastic modulus values than the mixed films. Increasing the NaCas–gly content of the films from 25 to 100% greatly increased solubility. This increased film solubility may increase the number of food applications for protein-based films.

Effect of thermal treatments on functional properties of edible films made from wheat gluten fractions

The effect of thermal treatments on selected properties of films based on gliadins and glutenins prepared from commercial wheat gluten was studied. Gliadin- and glutenin-rich films were heat cured at 40, 55, 70, 85, 95 and 115 °C for 24 h. The effect of heat curing on moisture content, colour, total soluble matter in water, water vapour permeability, tensile strength and elongation at breakpoint of the films was evaluated. Mechanical and water barrier properties of films changed sharply in the range of 55–75 °C. Films became stronger and less extensible with lower water vapour permeability. No changes in the equilibrium moisture content at 50% relative humidity of films associated with thermal treatments were observed. From 70 °C, gliadin films kept their integrity in water whereas film disintegration was observed in other cases. Films became darker with a yellow-brown coloration with the increase of temperature treatment; so in order to preserve the film appearance temperature no higher than 70–75 °C for gliadin and glutenin, respectively, will be recommendable. Thermal treatment can effectively be applied to optimize the use and application of gliadin- and glutenin-rich films.