Water Vapor Permeability Values Research Articles

The Effect of Kappa Carrageenan Composition on the Characteristics of Chitosan-Kappa Carrageenan Hydrogel Film

Chitosan-Kappa Carrageenan (Chit-KC) hydrogel films have been made using a casting method with different compositions. This research aimed to investigate the effects of different compositions on the chemical, physical, and mechanical characteristics of the Chit-KC hydrogel films. The compositions of the kappa carrageenan in the Chit-KC films were 0%, 16.67%, 33.33%, 50.0%, and 100.0%. The films were characterized using FTIR, SEM, DTA-TGA, and XRD instruments to analyze their functional groups, morphology, thermal properties, and crystallinity. They were also tested for their solubility, swelling, water vapor permeability (WVP), and mechanical characteristics. The results revealed that the addition of kappa-carrageenan induced the formation of a polyelectrolyte complex. The polyelectrolyte complex caused an increase in swelling, crystallinity, and WVP values and a decrease in solubility, tensile strength, elongation, and elasticity. It also caused the formation of film layers and granules on the surface of the hydrogel film. The IR spectra exhibited that the Chit-KC hydrogel films contained O-H, C-H, C=O, S=O, C-O, and C-O-C groups. The DTA-TGA test results revealed that the film began decomposing at around 200°C and re-decomposing at 300°C.

Antibacterial and wound healing stimulant nanofibrous dressing consisting of soluplus and soy protein isolate loaded with mupirocin

Severe cutaneous injuries may not heal spontaneously and may necessitate the use of supplementary therapeutic methods. Electrospun nanofibers possess high porosity and specific surface area, which provide the necessary microenvironment for wound healing. Here in, the nanofibers of Soluplus-soy protein isolate (Sol-SPI) containing mupirocin (Mp) were fabricated via electrospinning for wound treatment. The fabricated nanofibers exhibited water absorption capacities of about 300.83 ± 29.72% and water vapor permeability values of about 821.8 ± 49.12 g/m2 day. The Sol/SPI/Mp nanofibers showed an in vitro degradability of 33.73 ± 3.55% after 5 days. The ultimate tensile strength, elastic modulus, and elongation of the Sol/SPI/Mp nanofibers were measured as 3.61 ± 0.29 MPa, 39.15 ± 5.08 MPa, and 59.11 ± 1.94%, respectively. Additionally, 85.90 ± 6.02% of Mp loaded in the nanofibers was released in 5 days in vitro, and by applying the Mp-loaded nanofibers, 93.06 ± 5.40% and 90.40 ± 5.66% of S. aureus and E. coli bacteria were killed, respectively. Human keratinocyte cells (HaCat) demonstrated notable biocompatibility with the prepared nanofibers. Furthermore, compare to other groups, Sol-SPI-Mp nanofibers caused the fastest re-epithelialization and wound healing in a rat model. The findings of this study present a novel nanofiber-based wound dressing that accelerates the healing of severe skin wounds with the risk of infection.

Transforming Agro-Industrial Waste into Bioplastic Coating Films.

Addressing the environmental impact of agro-industrial waste, this study explores the transformation of banana, potato, and orange peels into bioplastics suitable for thin coating films. We prepared six extracts at 100 g/L, encompassing individual (banana peel, BP; orange peel, OP; and potato peel, PP) and combined [BP/OP, BP/PP, and BP/OP/PP] formulations, with yeast mold (YM) medium serving as the control. Utilizing the spin-coating method, we applied 1 mL of each sample at 1000 rpm for 1 min to create the films. Notably, the OP extract demonstrated a twofold increase in bioplastic yield (860.33 mg/L) compared to the yields of BP (391.43 mg/L), PP (357.67 mg/L), BP/OP (469.40 mg/L), BP/PP (382.50 mg/L), BP/OP/PP (272.67 mg/L), and YM (416.33 mg/L) extracts. Atomic force microscopy analysis of the film surfaces revealed a roughness under 8 nm, with the OP extract recording the highest at 7.0275 nm, whereas the BP/OP mixture exhibited the lowest roughness at 0.2067 nm and also formed the thinnest film at 6.5 nm. With R2 trend values exceeding 0.9950, the films exhibited water vapor permeability values ranging from 3.05 × 10-3 to 4.44 × 10-3, with the OP film being the least permeable and the BP/PP films the most permeable. The OP film demonstrated the lowest solubility in both water and ethanol with values of 64.71 and 1.05%, respectively. The solubilities of all films were above 60% in water and below 4% in ethanol. Furthermore, the films exhibited antimicrobial efficacy against both Gram-positive and Gram-negative bacteria. Our findings confirm the potential of utilizing banana, orange, and potato peels as viable substrates for eco-friendly bioplastics in thin-film applications.

Sodium alginate edible films incorporating cactus pear extract: antimicrobial, chemical, and mechanical properties

The potential benefits of biodegradable and functional food packaging materials have garnered increasing attention in recent years. Sodium alginate (SA), a commonly utilized polysaccharide, is particularly noteworthy for producing biodegradable films for food packaging. This study aimed to investigate SA-based edible films enriched with various proportions of cactus pear peel extract (CPPE). We assessed the films and extracts for total phenolic content, antimicrobial and antioxidant activities, as well as mechanical properties. Cactus pear peels powder (CPPP) exhibited higher contents of total polyphenols (1243.82 mg GAE/100 g), total flavonoids (18.92 mg QE/100 g), and betalains (2.28 mg/100 g). The main constituents detected were catechol, pyrogallol, catechin, and alpha-coumaric acid, with concentrations of 1013.82, 223.45, 148.21, and 101.02 ppm, respectively, contributing about 45.71%, 9.85%, 6.54%, and 4.46% of the total phenolic compounds. The thickness of the SA films increased from 0.220 mm to 0.265 mm. The tensile strength values ranged from 1.98 to 3.12, while the elongation at break values for SA-CPPE films decreased relative to the plain SA film. Moreover, the inclusion of CPPE improved the barrier characteristics (with water vapor permeability values for SA films with 1%, 2%, and 3% CPPE ranging from 0.72 × 10−5 g·h−1·m−1·Pa−1 to 1.68 × 10−5 g·h−1·m−1·Pa−1) and induced variations in flexibility and resistance. The plain SA film did not exhibit any inhibitory activity against bacteria and fungi. However, the inclusion of CPPE in alginate films showed favorable antibacterial properties, which improved progressively with increasing CPPE concentration. These findings highlight the potential of incorporating active alginate-based films in food preservation.

Preparation and characterization of chitosan-rice starch films incorporating Amomum verum Blackw essential oil for grape preservation

The preservation of perishable food items presents a significant challenge in the food industry. In this study, we investigated the development and characterization of chitosan-starch films incorporated with A. verum essential oil for application in grape preservation. The films were prepared using a solvent casting method, and their physical and antibacterial properties were thoroughly evaluated. The films demonstrated tensile strength values ranging from 21.28 MPa to 27.64 MPa and elongation at break between 71.24% and 84.23%. The water vapor permeability values for chitosan-starch films were from 2.04 kg/Pa·s·m to 2.51 kg/Pa·s·m. In addition, the antibacterial activity of the films was assessed against Escherichia coli and Staphylococcus aureus. The results revealed notable inhibitory effects, with inhibition zones ranging from 14.41 mm to 21.00 mm. The films' efficacy in grape preservation was evaluated through storage experiments at room temperature for 9 days, comparing them with polypropylene film and unwrapped samples. The chitosan-starch films, particularly those containing 1.0% A. verum essential oil, exhibited superior performance in reducing weight loss and maintaining grape firmness compared to common packaging materials. Moreover, grapes covered with these current active bio-based films demonstrated higher antioxidant activity, indicating potential benefits for extending shelf life and preserving fruit quality. Chitosan-starch films incorporated with A. verum essential oil hold promise as effective and environmentally friendly packaging materials for grape preservation.

Effect of clays incorporation on properties of thermoplastic starch/clay composite bio-based polymer blends

In this study, thermoplastic starch (TPS) biofilms were developed using starch isolated from the seeds of Melicoccus bijugatus (huaya) and reinforced with bentonite clays at concentrations of 1%, 3%, and 5% by weight. Novelty of this research lies in utilizing a non-conventional starch source and enhancing properties of TPS through clay reinforcement. FTIR analysis verified bentonite’s nature of clays, while SEM analysis provided insights into morphology and agglomeration behavior. Key findings include a notable increase in biofilm thickness and elastic modulus with higher clay content. Specifically, tensile strength of biofilms improved from 2.5 MPa for pure TPS to 5.0 MPa with 5% clay reinforcement. The elastic modulus increased from 25 MPa (TPS) to 60 MPa (5% clay). Thermal stability also showed enhancement, with initial degradation temperature increasing from 110 °C for pure TPS to 130 °C for TPS with 5% clay. Water vapor permeability (WVP) tests demonstrated a decrease in WVP values from 4.11 × 10−10 g m−1 s−1 Pa−1 for pure TPS to 2.09 × 10−10 g m−1 s−1·Pa−1 for TPS with 5% clay, indicating a significant barrier effect due to clay dispersion. These results suggest that biofilms based on huaya starch and reinforced with bentonite clay have considerable potential for sustainable food packaging applications, offering enhanced mechanical and barrier properties.

Development of active edible films from coffee pulp pectin, propolis, and honey with improved mechanical, functional, antioxidant, and antimicrobial properties

This study examined the impact of propolis and honey on the physicochemical, structural, antioxidant, and antibacterial properties of coffee pulp pectin-based edible films. The films were made from pure pectin (P) and mixtures of pectin-glycerol (PG), pectin-propolis-glycerol (PPG), and pectin-honey (PH). Pectin solutions were prepared by varying the pectin-to-water ratio between 1 % and 5 % (wpectin/vwater). Propolis, glycerol, and honey were then added to the solution, with the ratio of these ingredients to pectin ranging from 0 % to 60 %. The films were characterized for their physicochemical, structural, antioxidant, and antibacterial properties. The results showed that films made from 2 % pectin (P), 2 % pectin with 20 % propolis and 20 % glycerol (PPG), 2 % pectin with 20 % honey (PH), and 2 % pectin with 20 % glycerol (PG) exhibited higher elongation at break and better tensile strength. Higher pectin, honey, and glycol concentrations increase the film thickness. Similarly, Young's modulus increased with rising pectin concentration. The tensile strength of the films increased with glycerol concentration up to 20 %, after which it decreased. Young's modulus decreased with increasing glycerol concentration. Tensile strength and elongation at break improved with honey-to-pectin ratios up to 20 %, then declined with further increases. The water vapor permeability (WVP) values of the edible films ranged from 3.154 to 3.437 × 10−10 g/m·s·Pa. The films were fully degraded in soil within 9 days. The results suggest that adding honey and propolis enhanced the antioxidant and antibacterial properties of the films.

A novel biodegradable film based on chicken gelatin and κ-carrageenan cross-linked with oxidized phenolic compounds.

Natural and renewable polymers are gradually replacing petroleum-based plastics, mostly as a result of environmental concerns. Moreover, upcycling industrial food waste into new added-value products is a creative approach that is crucial for cleaner and more sustainable manufacturing. The aim of this study was to obtain an environmentally friendly biodegradable film using a combination of k-carrageenan (KCAR) and chicken gelatin (CGEL), which obtained from poultry by-products. The effects of varying concentrations of KCAR (0-2%) on the physical, permeability, textural, thermal, and microstructural properties of CGEL/KCAR composite films were evaluated. The findings demonstrated that an increase in KCAR enhanced the lightness and opacity levels of the films. Water vapor permeability (WVP) values reduced as the KCAR concentration increased. The lowest WVP value (0.0012g.mm/h.m2.kpa) was seen in the treatment with 2% KCAR. Tensile strength (TS) values increased with increasing KCAR. The films' thermal stability was increased by the addition of KCAR. Microstructure assessments revealed a more compact and smooth structure in the KCAR-containing treatments, indicating improvements in WVP, thermal stability, and TS. Compared to the commercial cattle gelatin film, the CGEL film had higher TS and lower water solubility (WS). Overall, this study showed that the physical, mechanical, barrier and thermal and microstructural qualities of gelatin-based films may be enhanced by combining CGEL and KCAR to create an effective biodegradable film. Moreover, the comparison study between commercial cattle and chicken gelatin films revealed that cross-linked chicken gelatin films would be a suitable alternative for bovine gelatin films in the production of biodegradable film.

Investigating the Effects of PU-Based Back-Coating with Boric Acid and Titanium Dioxide Additives on Flame Retardancy Levels and Comfort Properties of 100% Cotton Denim Fabric

Abstract This study aimed to develop a cost-effective and resource-efficient application to enhance the thermal stability, flame retardancy, self-cleaning, and antibacterial properties of cotton denim fabrics through a single-step, flexible, and simple polyurethane (PU) based back-coating method, ultimately increasing the use of denim fabrics in daily and work clothes thanks to the increased functionality. This method utilizes boric acid (H3BO3) and a binary composite of H3BO3-titanium dioxide (TiO2) as functional additives while considering comfort parameters. Limiting oxygen index (LOI) and vertical burning tests were conducted to explore the thermal stability and flame retardancy of the samples, while assessments of air permeability, water vapour permeability, thermal resistance, and thermal absorptivity were performed to investigate the comfort properties. Comparing two kinds of back-coated denim fabrics, H3BO3-TiO2 back-coated cotton fabric showed the best flame retardancy with the lowest char length (45 mm) and highest LOI (27%). The air permeability values of back-coated fabrics decreased by approximately half compared to the untreated denim fabric. Although the water vapour permeability values decreased, they were less affected by the coating. Coating application reduced thermal conductivity and thermal absorbency, resulting in more thermally resistant denim fabric. This study demonstrates the potential utility of a PU-based coating incorporating TiO2 and H3BO3 on traditional cotton denim fabrics to enhance flame resistance while minimizing any adverse effects on the overall thermal comfort of the fabric.

Development of Polymeric Films Based on Sunflower Seed Proteins and Locust Bean Gum.

Most polymeric food packaging materials are non-biodegradable and derived from petroleum, thus recent studies have focused on evaluating alternative biodegradable materials from renewable sources, with polysaccharides and proteins as the main types of employed biopolymers. Therefore, this study aimed to develop biopolymeric films based on sunflower proteins and galactomannans from locust bean gum. The influence of the galactomannan amount (0.10%, 0.30%, 0.50%, and 0.75% w/v) on the physicochemical, thermal, and mechanical properties of cast sunflower protein-based films was studied. Sunflower proteins gave rise to yellowish, shining, and translucid films. With the incorporation of locust bean gum-derived galactomannans, the films became more brown and opaque, although they still maintained some translucency. Galactomannans significantly changed the proteins' secondary structures, giving rise to films with increased tensile resistance and stretchability. Nevertheless, the increase in the galactomannan amount did not have a significant effect on the film's thermal stability. The protein/galactomannan-based films showed values of water vapor and oxygen permeability that were slightly higher than those of the pristine materials. Overall, blending locust bean gum galactomannans with sunflower proteins was revealed to be a promising strategy to develop naturally colored and translucid films with enhanced mechanical resistance while maintaining flexibility, fitting the desired properties for biodegradable food packaging materials.

The enhancement in antifungal efficacy of konjac glucomannan films with attapulgites immobilized of AgNPs

The objective of this study was to enhance the water barrier properties and antifungal efficacy of KGM film by incorporating (attapulgites-Ag nanoparticles, APTs-AgNPs) composites. The X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), and Energy dispersive X-ray (EDS) analyses indicated that the successful fabrication of APTs-AgNPs composites. Water vapour permeability (WVP), moisture content (MC), water solubility (WS) and water absorption (WA) values decreased by 19.15%, 12.50%, 74.96% and 41.74% respectively, while the water contact angle (WCA) increased by 134.74%. These results demonstrated that the water barrier property of KGM/APTs-AgNPs films was superior to that of pure KGM films. The Rheological properties, fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD) patterns and Scanning electron microscopy (SEM) images results indicated that hydrogen bonds formed between homogeneous APTs-AgNPs (1.5 wt%) and KGM, which enhanced the water barrier properties of the KGM/APTs-AgNPs films. The KGM/APTs-AgNPs composite films possessed excellent oxygen permeability, Mechanical properties, UV barrier properties, opacity properties and thermostability. Moreover, KGM/APTs-AgNPs films slowly released Ag+ and exhibited long-acting antifungal efficacy against Aspergillus niger, as the inhibition circle diameter was 20.70 ± 0.32 mm for 10 days. Therefore, KGM/APTs-AgNPs films could be a potential alternative to petroleum-based films.

Preparation of multi-functional active packaging film of Galla chinensis waste CDs/pullulan

In this study, multifunctional green carbon dots (CDs) have been synthesized using Galla chinensis waste (GCW) via hydrothermal method for the first time. An active packaging film has been developed in this work by combining CDs and pullulan (PL), using the solution-casting method. The microscopic morphology revealed that the CDs that were prepared using GCW exhibited good compatibility with PL. In addition, it also led to improvement in the toughness of the PL film (14.01 % to 20.26 %), along with its water vapor permeability value [1.31 to 0.53 (g·mm)/(kPa·h·m2)]. The composite films consisting of CDs exhibited good UV blocking rates for the UVA (90.41 %–7.87 %), UVB (87.76 %–0.08 %), and UVC (83.39 %–0 %) spectral ranges. The composite films exhibited strong antioxidant activity, and the clearance of ABTS and DPPH were obtained to be 93.61 % and 86.30 %, respectively. In addition, the composite films showed good antibacterial activity for E. coli and S. aureus, with a high antibacterial rate of up to 99.99 %. Finally, the non-contact preservation of strawberries over a duration of 10 d at room temperature confirmed that the prepared composite film can help preserve the quality of strawberries, as well as extended their shelf-life.

Preserving plum perfection: Buckwheat starch edible coating with xanthan gum and lemongrass essential oil

The research focused on the fabrication of composite coatings using buckwheat starch (BS) and xanthan gum (XG) with incorporation of lemongrass (Cymbopogon citratus) essential oil (LEO) with varying concentration (0.75 %, 1.0 % and 1.25 % (w/v). BS was extracted from buckwheat groats (Fagopyrum esculentum) and its physico-chemical characteristics were determined. BS showed spherical and polygonal morphology and its XRD pattern was similar to starch extracted from other cereal sources. The amount of reducing sugar, starch and amylose content in extracted BS were 0.99 ± 0.33 %, 86.32 ± 0.22 % and 21.02 ± 1.89 % respectively, which indicates that BS is a suitable base material for the formation of edible coatings. XG was mixed with BS in different ratios (1:1, 2:1, 3:1 and 4:1) to optimize the best ratio of combination for composite coatings. The coating with a ratio of 2:1 was very smooth and was chosen for incorporation of LEO and the coatings physical, functional, mechanical, thermal and micro-structural characteristics were examined. The coating S5 with 1.25 % (w/v) concentration of LEO showed the best results with least moisture content (MC), minimum water vapor permeability (WVP) and maximum contact angle value. Moreover, the S5 formulation had the highest antioxidant (73.3 %) ability and maximum antimicrobial efficiency with inhibition zones of 22.09 ± 0.06 mm and 28.65 ± 0.14 mm against S. aureus and E. coli respectively. The coatings were then coated on plum fruit, and various parameters like weight loss, pH, shrinkage and TSS were calculated every 4th day during the 20 days of refrigeration period. The coated plums' ripening pace was delayed by the S5 formulation which improved moisture retention, maintained the plums' TSS value and overall pH. Therefore, composite coatings made up of BS, XG and 1.25 % (w/v) can be used as a cost-effective bio-active coating material for plum preservation under refrigeration conditions.

Investigation of polypropylene yarns containing silver nanoparticles: Fiber characteristics, yarn properties, and fabric performance analysis

AbstractThis study focuses on the development of antimicrobial technical textiles using silver‐infused polypropylene fibers to meet the escalating demand for enhanced protection against pathogens in medical settings. Various polypropylene‐based fibers with different silver concentrations and cross‐sections were produced through spinning experiments, resulting in six distinct fiber types. Comprehensive analyses, including differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐Ray diffraction (XRD), were conducted to evaluate thermal and structural properties. Physical strength and morphological characteristics were examined to determine optimal compositions. Subsequently, selected fibers were spun into yarns and knitted to create textile surfaces. Evaluation encompassed physical attributes, color, morphology, water vapor permeability, and antimicrobial efficacy against Gram‐negative bacteria, particularly E.coli. The results demonstrated over 99% antibacterial activity across all samples, highlighting their potential utility in medical textiles and other applications. Additionally, the study revealed that the water vapor permeability values were higher in fabric samples without silver nanoparticle additives, with a negligible decrease observed in samples with higher silver nanoparticle concentrations. The antibacterial activity was found to increase with higher silver concentrations in trilobal cross‐section samples. Round cross‐section samples exhibited higher antibacterial activity at the same silver concentration. These findings provide valuable insights for future antibacterial‐based fiber production studies and literature.

Effect of Soybean Oil on the Improvement of the Functionality of Edible Membrane-Type Food Packaging Films Based on Caseinate-Carboxymethyl Chitosan Compositions.

Edible film biopolymers are gaining attention to tackle problems of plastic waste and food safety to alleviate environmental problems associated with plastic products in food packaging. In this study, caseinate-carboxymethyl chitosan (CA-CMCH) composite films were made with the incorporation of soybean oil (SO) using a casting technique. The influence of different soybean oil concentrations at 0, 0.5, and 1% (w/w) on physical, mechanical, barrier, and surface characteristics of films composed of caseinate-carboxymethyl chitosan (CA-CMCH) was evaluated. The brightest film (L* value of 95.95 ± 0.30) was obtained with the edible film made from the control group of samples with sodium caseinate (NaCA-100; 100% NaCA). The results also indicated that samples with 1% SO in NaCA-75 and CaCA-75 had lower water vapor permeability (WVP), while those with NaCA-50 and CaCA-50 showed higher values of WVP. For mechanical properties, this study found that incorporating soybean oil into the caseinate-carboxymethyl (CA-CMCH) composite films led to an enhancement of both tensile strength and elongation at break. The morphological structures, determined using SEM, of control and composite films showed compact and homogenous surfaces. Overall, the addition of soybean oil contributed to the improvement of the functional properties of the edible films, offering potential solutions to the environmental issues associated with plastic packaging and enhancing the safety and performance of food packaging.

Comfort Properties and Antimicrobial Activity of Cotton and Nylon/PU Knits Treated with Microcapsules Containing Sea Buckthorn Oil

This study was performed to investigate comfort properties and antimicrobial activity of cotton and nylon knits treated with microcapsules containing sea buckthorn fruit oil reported as having antimicrobial efficacy depending on concentration of microcapsules and treatment types. Chitosan-arabic gum microcapsules containing sea buckthorn fruit oil were prepared and they were treated on cotton and nylon/PU knit respectively by an experimental design of 2 different treatment types (bath immersion method and screen printing method) Χ 5 different concentration levels of microcapsules (20, 30, 40, 50, and 60% on the weight of fabric). As comfort properties, stiffness, water-vapor permeability, and air permeability were measured objectively. Antimicrobial activity was evaluated by calculating the percentage reduction of the bacterium. As results, stiffness values of the treated knits were slightly higher than those of untreated ones, which was thought not to affect touch in wear. The values of water-vapor permeability and air permeability of both cotton and nylon after the treatment were not significantly decreased. These results means that microcapsules loaded on the knits might not worsen their wear comfort. As for antimicrobial activity, more than 90% of bacterial reduction rates against S. Aureus were shown in cotton jersey by screen printing even after repeated laundry while those was found in nylon/PU tricot by bath immersion. From these results, it was concluded that chitosan-arabic gum microcapsule containing sea buckthorn fruit oil could be utilized for textiles to provide antimicrobial activity.

Flexible cellulose nanofibers/MXene composite films for UV-shielding packaging

Cellulose nanofibers (CNF) based films are promising packaging materials, but the lack of special functions (especially UV-shielding property) usually restrict their further applications. In this work, MXene was incorporated into the CNF film by a direct solvent volatilization induced film forming method to study its UV-shielding property for the first time, which avoided the using of a vacuum filtration equipment. The composite films containing glycerin could be folded repeatedly without breaking, showing good flexibility. The structure and properties of MXene/CNF composite films (CMF) were characterized systematically. The results showed that MXene distributed uniformly in the CNF film matrix and there was strong hydrogen bonding interaction between CNF and MXene. The tensile strength and Young's modulus of the composite films could reach 117.5 MPa and 2.23 GPa, which was 54.1 % and 59.2 % higher than those of pure CNF film, respectively. With the increase of MXene content, both the UVA and UVB shielding percentages increased significantly from 17.2 % and 25.5 % to 100.0 %, showing excellent UV-shielding property. Moreover, CMF exhibited a low oxygen permeability (OP) value of 0.39 cc μm d−1 m−2 kPa−1, a low water vapor permeability (WVP) value of 5.13 × 10−11 g−1s−1Pa−1 and a high antibacterial rate against E. coli (94.1 % at 24 h), showing potential application in the packaging field.

Water vapour permeability of inorganic construction materials

Water vapour permeability (WVP) data on brick, stone, plaster and cement-based materials from some seventy publications are reviewed and assessed. Almost all sources use standard cup-test methods or close variants. Comparisons of WVP values from different sources on similar materials confirm that reproducibility between different laboratories is poor. Some deficiencies of cup-test methods are discussed, including uncertainties arising from the use of saturated-salt humidistats and desiccants. There is evidence that the water vapour resistance factor decreases as volume-fraction porosity increases, and data support a simple porosity–tortuosity relation. Data also show that the resistance factor decreases with increasing mean relative humidity across the test specimen, with the wet-cup value consistently lower than the dry-cup values for a given material. The contribution of liquid film flow to mass transfer is discussed. It is shown how film thickness and film-flow permeability may be estimated from the water-vapour sorption isotherm; and a related regression equation is developed It is concluded that available data are inadequate to establish the fundamental physics of WVP; vapour-only permeability data for engineering purposes should be obtained in dry-cup tests at low humidity; and research studies should aim to integrate the WVP into the framework of unsaturated flow theory.

Thermal Comfort Properties of 100% Cashmere Knitted Fabrics

The purpose of this research is to investigate the effects of knitting type (plain, rib, purl), knitting tightness (three different loop lengths), and plied-yarn (single-ply, two-ply and three-ply) on the thermal comfort properties of cashmere knitted fabrics. Thermal comfort properties of the sample fabrics were measured using Alambeta, Permetest, Textest 3300. Subsequently, the results were statistically evaluated with SPSS program. The findings of this research revealed that the knitting type, knitting tightness and plied-yarn usage significantly affect certain thermal comfort properties of cashmere knitted fabrics. Specifically, the plain knitted fabric exhibits the lowest thermal resistance value and the highest relative water vapor permeability value. The loose knitted fabric demonstrates the highest air permeability, while the fabric knitted with single-ply yarn has the lowest thermal conductivity and thermal resistance values, as well as the highest relative water vapor permeability and air permeability values.

Intelligent double-layer films based on gellan gum/mica nanosheets/anthocyanin/konjac glucomannan/carrageenan for food real-time freshness monitoring

In this work, double-layer intelligent films were designed and synthesized based on Broussonetia papyrifera fruit anthocyanin (BPFA), mica nanosheets (MN), konjac glucomannan (KG), carrageenan (CA) and gellan gum (GG) using layer-by-layer casting strategy for real-time and in situ food freshness monitoring. The KG/CA/BPFA layer served as the indicator layer, while the GG/MN layer acted as the protective outer layer. It was observed that the water vapor permeability value of the GG-MN/KG-CA-BPFA double-layer film was reduced by 4.7 times, and the tensile strength was increased by 4.1 times compared with the GG film, which could be related to the reinforcing effect and proper barrier property of MN. Notably, the double-layer film blocked most of UV-light and oxygen, and its water contact angle reached 102.4° ± 1.18°. In particular, the films showed favorable visually detectable colorimetric responses to different pH buffer solutions and volatile ammonia. More importantly, visual assessment using shrimps as test specimens demonstrated distinct color alteration from red to blue-grey on spoilage. The color change of the film was also highly correlated with TVB-N (R2 = 0.964) and pH (R2 = 0.999). In conclusion, the newly designed double-layer film exhibited excellent performance, which guides an innovative approach for advanced food-packing material development.