Water Vapor Permeability Values Research Articles

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.

Effect of squalene rich fraction from shark liver on mechanical, barrier and thermal properties of fish (Probarbus Jullieni) skin gelatin film

Golden carp skin gelatin films incorporated with squalene rich fraction from shark liver (SRF) at various levels (5, 10, 15, 20 and 25%, w/w) were characterized in comparison with palm oil (PO) incorporated film and control film (CON) (without oil addition). PO films exhibited lower tensile strength (TS) but higher elongation at break (EAB) as compared to that of CON film. SRF films added with 25% SRF showed higher EAB as well as TS, compared to both CON and PO films (p < 0.05). SRF films showed significantly lower water vapor permeability (WVP) and lower lightness (L*) value than CON and PO films (p < 0.05). Moreover, SRF films with negligible fishy odor had lower transparency and yellowness than CON and PO films. SEM images showed that CON and SRF films exhibited relatively smoother surface, compared to PO film. Additionally, SRF films had lower oil at the surface of the films than PO film. Moreover, DSC and FTIR spectra results revealed that incorporation of PO and SRF lowered interaction between gelatin molecules with coincidentally disordered structure. Besides, both SRF and PO films demonstrated lower degradation (Td), glass transition (Tg) and melting transition (Tm) temperatures than CON film. Thus, incorporation of SRF could render stronger films with higher TS and enhanced flexibility and also moisture barrier porperty of gelatin films.

The properties of κ-carrageenan and whey protein isolate blended films containing pomegranate seed oil

Abstract In this study, whey protein isolate (W), κ-carrageenan (C), and a mixture of both (W–C, 1:1, w/w) containing pomegranate seed oil (PSO) was developed and characterized by scanning electron microscopy (SEM), water vapor permeability (WVP), solubility, mechanical, optical properties, release tests and antimicrobial activity. Film samples containing PSO showed higher elongation capacity, and lower WVP, solubility and transparency values (p

Polymer blending effects on the physicochemical and structural features of the chitosan/poly(vinyl alcohol)/fish gelatin ternary biodegradable films

Films with appropriate mechanical properties and low permeability are very important for food packages. The aim of this research was to develop and characterize the ternary films made from chitosan (CH), poly(vinyl alcohol) (PVA), and fish gelatin (FG) at different blend compositions (50/50/0, 40/40/20, 35/35/30, 30/30/40, and 25/25/50, CH/PVA/FG) via a simple casting method. Stress-strain curves showed that the incorporation of 20% FG into the films made them tougher as well as making them more elastic; optimum ternary films were obtained using CH/PVA/FG ratio of 40/40/20, giving maximum values of TS and EAB as 41.93 ± 3.24 MPa and 133.13 ± 13.23%, respectively. The water vapor permeability (WVP) values of the ternary films were in the range of 0.686–0.818 g mm/kPa h m2. With increasing FG content, the WVP of the films increased to some extent, whereas the water solubility was reduced up to 23%. Water absorption increased with increasing FG concentration up to 874%. Meanwhile, the ultraviolet–visible-light barrier of the resultant ternary films was significantly improved with the addition of FG; at the same time, an increase in FG concentrations also made the films more opaque and improved their thermal stability. FT-IR spectra showed interactions through hydrogen bonding between the polar groups of FG and hydroxyl moieties of CH and PVA in the blends, which enhanced the compatibility between the three polymers. X-ray diffraction analysis suggested compatibility among the polymeric-blends, and changes of the surface of the films was confirmed by SEM and AFM analyses. The obtained results suggested the effectiveness of blending approach in improving the compatibility of polymers and overall functionality of films.

Effect of multiscale structure on the gas barrier properties of poly(lactic acid)/Ag nanocomposite films

Poly(lactic acid) (PLA) is the most suitable for biodegradable packaging film because of its excellent integrated property, but the poor gas barrier property is its weakness. In this study, a nanocomposite film based on PLA incorporated with 0‐, 1‐, 3‐, 5‐, 10‐, or 15‐wt% nano‐Ag was developed. Effect of multiscale structure on the barrier properties of PLA/nano‐Ag films was studied. The PLA nanocomposite film with 5‐wt% nano‐Ag had the lowest water vapor permeability (WVP) value. Oxygen transmission rate (OTR) value for PLA nanocomposites with 3‐wt% nano‐Ag was found to be the lowest among all the samples. Multiscale structure was demonstrated by the scanning electron microscopy, Fourier transform‐infrared spectroscopy, X‐ray diffraction measurement, and differential scanning calorimetry results. The crystallinity of the PLA phase increased with the content of nano‐Ag in the PLA composites. The evolution of the PLA phase crystallinity could improve the barrier properties of PLA/nano‐Ag composite films for food packaging applications. From the view of multiscale structure, it is better to achieve a balance among short‐range conformation in the amorphous region, long‐range‐ordered structure, and ordered aggregated structure to improve the barrier properties of PLA/nano‐Ag composite films.

Time-dependent evolution of properties of fish gelatin edible films enriched with carvacrol during storage

The temporal stability of the physicochemical, antibacterial and antioxidant properties of fish gelatin (FG) films plasticized by glycerol (20% w/w) and supplemented with carvacrol (CRV) obtained by casting and stored at 65% RH and 25 °C, was investigated over 15 days. The level of CRV incorporated into FG film was determined from minimum inhibitory concentration (MIC) values against E. coli and S. aureus. The incorporation of 0.6% w/v CRV reduced the moisture content (MC), and water vapor permeability (WVP) while kept invariable the tensile and light barrier properties, compared to the control. Additionally, CRV increased the in vitro antibacterial and antioxidant effectiveness of films. Upon storage, the sustained loss of moisture and glycerol provoked the drop of MC and WVP values of both films. Control film became stiffer and less stretchable while the active film remained mechanically time-stable. Such difference was ascribed to the increased contribution of triple helical structures in the control, as revealed by ATR-FTIR and XRD. Antibacterial effectiveness (based on disc diffusion assay) decayed from 3.1 ± 0.1 and 2.7 ± 0.3 cm for E. coli and S. aureus, respectively, to undetectable levels for both pathogens. Antioxidant power in terms of radical scavenging activity (RSA) declined to about 2.74 % of the initial value, in line with the decline of CRV level up to 13 % of its initial concentration. Overall this study proves the significance of assessing the stability of the properties of edible films before proposing any technical application.

Development of black and biodegradable biochar/gutta percha composite films with high stretchability and barrier properties

It is necessary to develop biodegradable composite films for reducing environmental pollution. Black and biodegradable biochar/gutta percha composite films were developed by adding different contents of biochar (0, 2, 4, 6 and 8%, w/w) into the gutta percha matrix. The results showed that the biochar effectively improved the hydrophobicity and mechanical properties compared with the control film. Moreover, the biochar/gutta percha composite films showed high stretchability and barrier properties. In particular, the 2% BC film had the highest tensile strength (18.3 MPa) and elongation at break (280.4%) and the lowest water vapor permeability value (0.09 × 10−9 g/m/h/Pa) at 34% relative humidity. However, the melting enthalpy (ΔHm) and crystallinity decreased. In addition, these composite films exhibited little electromagnetic interference shielding with a reflection loss up to −1.79 dB at 8.2 GHz. Finally, the composite films were more biodegradable than PE film after 60 days in soil.

Synthesis and characterization of interpenetrating polymeric networks based bio-composite alginate film: A well-designed drug delivery platform.

This study aimed to develop and characterize the calcium alginate films loaded with diclofenac sodium and other hydrophilic polymers with different degrees of cross-linking obtained by external gelation process. To the formed films different physicochemical evaluation were performed which showed an initial character of the films. The films produced by this external gelation process were found thicker (0.031-0.038 mm) and stronger (51.9-52.9 MPa) but less elastic (2.3%) than those non-cross-linked films (0.029 mm; 39.7 MPa; 4.4%). The lower water vapor permeability (WVP) values of the films were obtained where maximum level of crosslinking occurs. Composite films can be cross-linked in presence of external crosslinking agent to improve the quality of the produced matrices for various uses. The characterization of the film was performed using Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FT-IR) analysis. The Scanning Electron Microscopy (SEM) study showed the morphology of treated composite films. The kinetic release studies showed a sustained release of the drug from the formulated films as it can be prolonged in composite film. The prepared biodegradable Ca-Alginate bio-composite film may be of clinical importance for its therapeutic benefit.

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.

Efficiency of Novel Photocatalytic Coating and Consolidants for Protection of Valuable Mineral Substrates.

In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility.

Surface texture and barrier performance of poly(lactic acid)–cellulose nanocrystal extruded‐cast films

ABSTRACTIn this study, we assessed the influence of cellulose nanocrystal (CNC) addition level (0.5–2 wt %) on the surface texture, thickness, and barrier properties of poly(lactic acid) (PLA) extruded‐cast films. Regardless of the CNC content, the addition of CNC increased the surface average roughness and maximum roughness of the PLA films in both the machine and cross‐machine directions because of the presence of CNC agglomerates. The increased roughness resulted in films with uneven thicknesses; this affected their accurate measurements with a conventional micrometer. Rather, accurate thickness measurements were obtained through the density method, a more appropriate thickness measurement method for films with rough surfaces. The permeability values were negatively correlated with the increased crystallinity. Both the water vapor permeability and oxygen permeability (OP) values decreased significantly by approximately 26–45 and 25–50%, respectively, as the CNC content increased from 0.5 to 2 wt % because of the tortuosity effect. The OP values of the neat PLA and composite films remained insensitive to changes in the relative humidity (from 0 to 75%) when they were tested at 23 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47594.

Facile preparation of reactive hydrophobic cellulose nanofibril film for reducing water vapor permeability (WVP) in packaging applications

Due to energy crisis and environmental pollution, biopolymer-based packaging materials have been extensively investigated. Cellulose nanofibrils (CNFs), due to their good oxygen barrier performance and excellent mechanical as well as film-forming properties, have emerged as interesting packaging materials. However, the problem of the resulting films is the highly hygroscopic character of the cellulose fibers themselves, which would further lead to a decrease of the films’ mechanical and barrier properties. Herein, a facile preparation of hydrophobic CNF films was carried out by the attachment of 10-undecylenoyl chloride onto CNFs followed by vacuum filtration. The modified CNFs became thicker and rougher compared with the pristine CNFs and were easy to disperse in ethanol. The resulting CNF film showed a higher surface roughness and a tensile strength of (47 ± 4) MPa. Additionally, the modified CNF film was hydrophobic, leading to an obvious barrier improvement with the WVP value decreasing by 62.4% in comparison to the pristine CNF film. Since this hydrophobic CNF film is easy to prepare with a good vapor barrier property, it should be promising for packaging applications. Furthermore, the generated CNF film demonstrated good reactivity with thiol groups, which can be applied for further functionalization to enrich their application fields.

Development of biodegradable coatings for maize seeds and their application for Azospirillum brasilense immobilization.

The objective of this study was to develop biodegradable coatings for agriculture crop seeds based on starch, gelatin, and polyvinyl alcohol (PVA). Developed materials were characterized according to their microstructures, barrier properties, influence on germination of maize seeds, and ability to sustain Azospirillum brasilense Ab-V5 viability in coated maize seeds. The coatings were obtained employing different proportions of starch, gelatin, and PVA, ranging from 0 to 3.0g/100g of each material, respectively. Samples formulated with the pure polymers showed the highest values of water absorption capacity, solubility, and water vapor permeability, and the ternary mixtures showed the lowest values. Single polymer formulations and the binary starch-gelatin mixture (CS50GL50) favored maize seeds germination compared to the uncoated maize seeds. In addition, seed coating obtained from CS50GL50 formulation resulted in A. brasilense Ab-V5 viability in coated seeds up to 15days after bacterial immobilization, being considered a promising low-cost, biodegradable, and renewable source material to be used in agriculture.

Double Cross-Linked Chitosan Composite Films Developed with Oxidized Tannic Acid and Ferric Ions Exhibit High Strength and Excellent Water Resistance.

There is tremendous scientific interest in developing biodegradable films through facile and versatile strategies. Although extensive studies on the preparation of chitosan films have been conducted, the reported results commonly present low mechanical strength and weak water resistance. In the present study, high strength and significantly water resistance single-cross-linked chitosan-oxidized tannic acid (SC-CS/OTA) composite films and double cross-linked chitosan/oxidized tannic acid/FeIII (DC-CS/OTA/FeIII) composite films were created through a Schiff base reaction and metal coordination. As a result, the optimal tensile strength of SC-CS/OTA composite films and DC-CS/OTA/FeIII composite films was 35.92 and 209 MPa, respectively. Notably, when compared with other chitosan-based films, the tensile strength of DC-CS/OTA/FeIII composite films was approximately three times stronger. Moreover, the water vapor permeability (WVP) values of the films with FeIII(0.66 ± 0.03 × 10-10 g/m·h·Pa) was lower than that of films without FeIII (1.33 ± 0.01 × 10-10 g/m·h·Pa). More importantly, WVP values of the DC-CS/OTA/FeIII composite films were 3-4 orders of magnitude lower than those of chitosan films previously reported. The SC-CS/OTA composite films (96.69%) and DC-CS/OTA/FeIII composite films (99.06%) also presented high DPPH radical scavenging activity. Furthermore, SC-CS/OTA and DC-CS/OTA/FeIII hydrogels were also prepared. This work can be widely applied in the food, biomedical science, and wastewater treatment fields.

Corn starch and gelatin-based films added with guabiroba pulp for application in food packaging

Abstract The guabiroba pulp (GP) has natural antioxidant compounds, such as phenolic compounds and ascorbic acid. The aim of this work was to produce an active biodegradable film based on blends of gelatin (GEL) and corn starch (NCS) and activated with GP, for application as package for extra-virgin olive oil, as a sachet. For that, the effect of blends composition was first evaluated in passive films, and then, a formulation was chosen to produce the active film with guabiroba pulp. The effect of the incorporation of GP on the barrier, mechanical and optical properties of these films was studied, and the antioxidant effect on the storage of extra virgin olive oil was verified in a specific test. Blends with GEL (5 and 10%) and NCS (2 and 4%) were prepared, in the different ratios. The film with 5% GEL and 2% NCS in the 1:1 ratio, was selected for the addition of GP (10 and 20%). The addition of GP caused a reduction in tensile strength and increased elongation values. The film with 10% GP was selected for the preparation of the sachet, due to its lower value of water vapor permeability. At the end of the storage period (15 days), the values of acidity index and peroxide index of the extra-virgin olive oil did not reach the maximum limit allowed by the current legislation. It can be concluded that the results obtained may be useful for future studies and applications using active and biodegradable packaging.

Effect of bio-chemical chitosan and gallic acid into rheology and physicochemical properties of ternary edible films

The ternary edible films based on commercial or bio-chemical chitosan (CCh or BCh) and starch (S) with different concentration of gallic acid (GA) were produced by casting. This work analyzed the effect of different type of Ch and GA concentrations (1.25 mg/gTB and 2.5 mg/gTB) on the rheological properties of the film-forming solutions, as well as physicochemical (thickness, moisture content, swelling index, water vapor permeability (WVP), tensile strength, microstructure, opacity, and color) and antioxidant properties of the edible films themselves. The chemical cross-linking between the GA and Ch into the edible films of biopolymers could form of ester linkages between the carboxyl groups of GA and the hydroxyl groups of Ch. Results showed that the ternary edible films of BCh-S-GA5.0 resulted with a positive effect on their rheological (η0, λ, and p), physicochemical (WVP, swelling, tensile strength, microstructure) and antioxidant properties. The greatest incorporation of polyphenol into the BCh-S-GA5.0 films greatly reduced WVP and swelling values in approximately 61.01% and 23%, respectively also the tensile strength value increased to 37.372 MPa. The ternary edible films developed in this study showed many desirable characteristics, which could potentially be used as bioactive packaging films for food applications.

Composite Film Based on Pulping Industry Waste and Chitosan for Food Packaging.

Wood auto-hydrolysates (WAH) are obtained in the pulping process by the hydrothermal extraction, which contains lots of hemicelluloses and slight lignin. WAH and chitosan (CS) were introduced into this study to construct WAH-based films by the casting method. The FT-IR results revealed the crosslinking interaction between WAH and CS due to the Millard reaction. The morphology, transmittance, thermal properties and mechanical properties of composite WAH/CS films were investigated. As the results showed, the tensile strength, light transmittances and thermal stability of the WAH-based composite films increased with the increment of WAH/CS content ratio. In addition, the results of oxygen transfer rate (OTR) and water vapor permeability (WVP) suggested that the OTR and WVP values of the films decreased due to the addition of CS. The maximum value of tensile strengths of the composite films achieved 71.2 MPa and the OTR of the films was low as 0.16 cm3·μm·m−2·24 h−1·kPa−1, these properties are better than those of other hemicelluloses composite films. These results suggested that the barrier composite films based on WAH and CS will become attractive in the food packaging application for great mechanical properties, good transmittance and low oxygen transfer rate.

Gas barrier and wetting properties of whey protein isolate‐based emulsion films

The aim of this research was to investigate the effect of rapeseed oil concentration (1–3% w/w) on the water vapor, oxygen and carbon dioxide permeability, water vapor sorption and surface properties of whey protein isolate emulsion‐based films. The water contact angle as affected by oil content, film side and time was analyzed. The effect of temperature (5 and 25°C) on the water vapor permeability (WVP), water vapor sorption kinetics and diffusion coefficient was also studied. The results showed that the incorporation of a lipid phase to whey protein film‐forming solutions was able to decrease the WVP, water hydrophilicity (increasing water contact angle) and water transfer of whey protein films. However, the films containing oil were more permeable to oxygen and carbon dioxide. Significantly higher values of WVP and diffusion coefficient were obtained at 5°C than at 25°C, indicating that storage temperature should be taken into account when designing the composition of edible films and coatings for food applications. POLYM. ENG. SCI., 59:E375–E383, 2019. © 2018 Society of Plastics Engineers

Cassava bagasse as a reinforcement agent in the polymeric blend of biodegradable films

ABSTRACTThe objective of this work was to develop biodegradable films using fibrous residue from the extraction of cassava starch and to investigate its effect as a reinforcement agent in polymeric films. Micrographs (SEM) showed that the obtained films presented smooth surfaces with no cracking. The addition of fibers affected the properties of the films significantly (p &lt; 0.05), reducing water vapor permeability values (from 8.63 ± 0.15 × 10−11 g.m.m−2.s−1.Pa−1 to 3.33 ± 0.16 × 10−11 g.m.m−2.s−1.Pa−1) and increasing the maximum tensile strength (from 1.23 ± 0.15 MPa to 7.78 ± 0.83 MPa). These results encourage the use of cassava bagasse as a reinforcement in the production of green composites as packaging. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47224.

Elaboration and Characterization of Active Apple Starch Films Incorporated with Ellagic Acid

Apple starch films were obtained from apples harvested at 60, 70, 80 and 90 days after full bloom (DAFB). Mechanical properties and water vapor permeability (WVP) were evaluated. The apple starch films at 70 DAFB presented higher values in the variables of tensile strength (8.12 MPa), elastic modulus (3.10 MPa) and lower values of water vapor permeability (6.77 × 10−11 g m−1 s−1 Pa−1) than apple starch films from apples harvested at 60, 80 and 90 DAFB. Therefore, these films were chosen to continue the study incorporating ellagic acid (EA). The EA was added at three concentrations [0.02% (FILM-EA0.02%), 0.05% (FILM-EA0.05%) and 0.1% (FILM-EA0.1%) w/w] and compared with the apple starch films without EA (FILM-Control). The films were characterized by their physicochemical, optical, morphological and mechanical properties. Their thermal stability and antioxidant capacity were also evaluated. The FILM-Control and FILM-EA0.02% showed a uniform surface, while FILM-EA0.05% and FILM-EA0.1% showed a rough surface and insoluble EA particles. Compared to FILM-Control, EA modified the values of tensile strength, elasticity modulus and elongation at break. The antioxidant capacity increased as EA concentration did. EA incorporation allowed obtaining films with higher antioxidant capacity, capable of blocking UV light with better mechanical properties than film without EA.