Water Vapor Permeability Values Research Articles

Development of chitosan/tannic acid/corn starch multifunctional bilayer smart films as pH-responsive actuators and for fruit preservation.

The design of intelligent films for pH-responsive actuators fully constructed from natural biopolymers remains challenging. This study used natural biopolymers to develop a new type of smart and multifunctional chitosan/tannic acid/corn starch (CHT/TA/CS) bilayer films, which can be used for pH-responsive actuators and fruit preservation. We studied the microstructural morphology, physicochemical, antioxidant, antimicrobial properties of the films. Compared with the CHT film, the water vapor permeability (WVP) values of the CHT/TA/CS bilayer films were reduced by 3.1 times, and the tensile strength was increased by 4.6 times. The CHT/TA/CS bilayer films also exhibited high 1,1-diphenyl-2-picrylhydrazyl (DPPH) (94.6%) and hydroxyl (OH) (97.5%) radical scavenging activity. The bilayer films had good antimicrobial activity. The CHT/TA/CS bilayer films exhibited different directional deformation behaviors in acid-base solutions and could be used as pH-responsive actuators. By changing the solution's pH, the bilayer films could grab and release heavy objects 21 times heavier than themselves. Furthermore, the CHT/TA/CS bilayer coating prolonged the bananas' storage time from three to six days, and its weight loss was reduced by 14%. The developed CHT/TA/CS bilayer films have potential application in degradable materials, soft robotics fields, and food packaging materials.

Influence of sericin‐g‐PLA as an organic nucleating agent for preparing biodegradable blend films

AbstractHere for the first time, this work indicated that the sericin‐g‐polylactide (SS‐g‐PLA) copolymer can be potentially used as an organic nucleating agent to improve the crystallinity and biodegradability of polylactide (PLA). The properties of blended films containing SS‐g‐PLA mixed with virgin PLA polymer were highly evaluated. The water vapor permeability (WVP), thermal behavior, dynamic mechanical properties, crystal structure, and biodegradability of the PLA/SS‐g‐PLA‐blended films were characterized and compared with a commercial PLA film. The results clearly indicated that the incorporation of SS‐g‐PLA copolymer in the PLA matrix had a significant effect on the properties of PLA/SS‐g‐PLA‐blended films. The WVP values of PLA/SS‐g‐PLA‐blended films were lower than that of commercial PLA film by about 2–3 g·mm/m2·day·atm, and their thermal behaviors (e.g. Tg, Tcc, and Tm) were also decreased. Adding SS‐g‐PLA can increase the crystallinity of PLA. The degree of crystallinity (%χc) of the series of PLA/SS‐g‐PLA‐blended films was increased to about 2–4 times that of the commercial PLA film (3%). Interestingly, biodegradation results revealed that the percent of biodegradability of PLA/SS‐g‐PLA‐blended film was 80% in 43 days under a compost environmental temperature of 58 ± 2°C. This evidence indicated that the SS‐g‐PLA copolymer can improve the biodegradability of PLA.

Greaseproof, hydrophobic, and biodegradable food packaging bioplastics from C6-fluorinated cellulose esters

Tridecafluorononanoic acid (TFNA), a C6-fluorinated carboxylic acid, was esterified with cellulose at different molar ratios (0:1, 1:1, 2:1, and 3:1) in a trifluoroacetic acid (TFA):trifluoroacetic anhydride (TFAA):CHCl3 (2:1:1, v:v:v) solvent mixture. Free-standing films were obtained for all formulations and are presented as alternatives to composites and blends of paper with fluorinated molecules. Mechanical properties were investigated by tensile tests, and a plasticizer effect of fluorinated chains was observed. Interestingly, the wettability of these new cellulose derivatives was similar or even better than other common cellulose derivatives and fluorinated polymers employed in food packaging. Hydrodynamic properties were also improved by addition of TFNA, resulting in materials with water vapor permeability values comparable to other cellulose-based food packaging materials. In addition, films with the higher amounts of TFNA showed the required oil resistance for papers used in food packaging applications, as determined by the Kit Test. Finally, the biodegradation of these C6-fluorinated cellulose esters, assessed by biological oxygen demand (BOD) in seawater, was higher than typical bio-based polymers used in food packaging. The bioplastic synthesized at a molar ratio 1:1 (TFNA:cellulose) showed excellent performances in terms of greaseproof, hydrophobicity, ductility, and biodegradability, representing a sustainable alternative to typical plastics used in food packaging.

Hygric properties of wheat straw biocomposite containing natural additives intended for thermal insulation of buildings

Straw concrete is a biobased composite developed for thermal insulation of new buildings and thermal rehabilitation of old buildings. It is made of the combination of wheat straw, lime or plaster binder and natural additives (hemoglobin, casein, gelatin). The natural additives are used to improve the thermal and mechanical properties of the material. The characterization of these composites has shown an attractive thermal conductivity and an acceptable mechanical strength. The present paper focuses on the hygric characterization of these materials which have different constituents (straw aggregates, binder and additives). Three properties were experimentally determined, namely, sorption–desorption curves, water vapor permeability and moisture buffer value (MBV). These hygroscopic properties are of great importance when it comes to the comfort of the building. The isothermal water vapour diffusivity was also estimated from the sorption curve and the water vapor permeability. The impact of the sample thickness on the moisture buffer value (MBV) was also highlighted. The results showed that the studied composites have excellent hygric properties which can contribute significantly to ensure hygrothermal comfort in buildings. These hygric performances are competitive with those of other insulating bio-based materials studied in the literature and better than those of conventional materials used in construction.

Production and characterization of bacterial cellulose-alginate biocomposites as food packaging material

Biocomposite of bacterial cellulose-alginate has been developed for use as food packaging material. This study aims to understand the physical and mechanical properties of the biocomposite produced from static fermentation of Gluconacetobacter xylinus InaCC B404 in media supplemented with alginate. The strain was grown in a medium containing alginate at a concentration of 0.4, 0.8, and 1.2% w/v at 30oC for 7 days. The SEM images showed that bacterial cellulose produced in a medium supplemented with alginate had a denser structure of fibril network and a smaller pore size than the control one. The structure change was due to interactions through hydrogen bonds between bacterial cellulose and alginate proven by FTIR spectra, resulting in a decrease in crystallinity and crystallite size of bacterial cellulose. It led to the decrease in tensile and tear strength of the resulting biocomposite. Alginate also causes biocomposite to have higher water vapour permeability values.

Dextran-Based Edible Coatings to Prolong the Shelf Life of Blueberries.

The development of edible films and coatings in the food packaging industry presents one of the modern strategies for protecting food products and ensuring their freshness and quality during their shelf lives. The application of microbial polysaccharides to the development of food package materials, as an alternative option to the commonly used plastic materials, is both economic and environmentally favorable. New edible films were developed using dextran from lactic acid bacterium Leuconostoc mesenteroides T3, and additionally plasticized by different concentrations of polyglycerol. The best tensile strength of the films was obtained using a formulation that contained 10 wt% of polyglycerol, which corresponded to a value of 4.6 MPa. The most flexible formulation, with elongation at break of 602%, was obtained with 30 wt% of polyglycerol. Water vapor permeability values of the films synthesized in this study were in the range of (3.45–8.81) ∗ 10−12 g/m s Pa. Such low values indicated that they could be efficient in preventing fruit from drying out during storage. Thus, the film formulations were used to coat blueberries in order to assess their quality during a storage time of 21 days at 8 °C. The results showed that dextran/polyglycerol films could be efficient in extending the shelf life of blueberries, which was evidenced by lower weight loss and total sugar solids values, as well as a delay in titratable acidity, in comparison to the uncoated blueberries.

Effect of Chitosan Nanoparticles Incorporating Antioxidants from Salvia hispanica L. on the Amaranth Flour Films.

SUMMARYResearch backgroundAmaranth (Amaranthus hypochondriacus) flour produces films with excellent barrier properties against water vapor, allowing food preservation, but the mechanical properties are poor compared to synthetic films. One strategy to improve these properties is the incorporation of nanoparticles. The particles can also serve as a vehicle for the addition of antioxidant agents into the films. The objective of this work is to optimize the formulation for the preparation of amaranth flour films treated with antioxidant chia (Salvia hispanica L.) extract-loaded chitosan particles using response surface methodology (RSM).Experimental approachChitosan nanoparticles with the extract were synthesized by ionic gelation, and the films were made by the casting method. Three independent variables were assigned: amaranth flour (4-6%), glycerol (25-35%) and chitosan nanoparticles loaded with the chia extract (0-0.75%). We then evaluated the physical (thickness), mechanical (tensile strength, Young´s modulus and elongation), barrier (water vapor permeability, moisture and water solubility) and antioxidant properties of the films. The experimental results of the properties were analyzed using a Box-Behnken experimental design generating 15 runs with three replicates at the central point.Results and conclusionsSecond and third order polynomial models were obtained from the ANOVA analysis of the evaluated responses, and high coefficients of determination were found (0.91–1.0). The water vapor permeability of the films was 0.82−2.39·10-7 (g·mm)/(Pa·s·m2), tensile strength was 0.33−1.63 MPa and antioxidant activity 2.24−5.65%. The variables had different effects on the films: glycerol negatively affected their properties, and the permeability values increased with increased amaranth flour content. The nanoparticles improved the mechanical, barrier and antioxidant properties of the films compared to the films without nanosystems. The optimal formulation was 4% amaranth flour, 25% glycerol and 0.36% chitosan nanoparticles. The optimized films had better mechanical (1.62 MPa) properties, a low water vapor permeability value (0.91·10-7 (g·mm)/(Pa·s·m2)) and moderate antioxidant activity (6.43%).Novelty and scientific contributionThe results show the effect of chitosan nanoparticles on the properties of amaranth flour films for the first time. The resulting equations are useful in the design of food packaging.

Improving moisture barrier and functional properties of active film from genipin‐crosslinked chitosan/astaxanthin film by heat curing

SummaryThis research aimed to improve moisture barrier and functional properties of genipin‐crosslinked chitosan/astaxanthin film by heat curing. The effect of heat curing (25, 80 and 105 °C) on film properties was investigated by measuring water vapour permeability (WVP), contact angle, tensile strength (TS), elongation at break (EAB), Young’s modulus (YM), opacity, chemical structure and antioxidant activity. Results showed that genipin‐crosslinked chitosan/astaxanthin film and heat cured at 105 °C (CAG‐105) have the lowest (P < 0.05) WVP value which decreased by 55% while a contact angle increased from 50.2° to 74.6°, when compared to CAG‐25 film. Heat curing affected the chemical‐crosslinked interaction between chitosan and genipin with the establishment of new chemical bonds, leading to the improvement of TS and YM by 55% and 42%, respectively, for CAG‐105 film. However, EAB and antioxidant activity of the CAG‐105 slightly decreased. Moreover, heat curing changed the colour of genipin‐crosslinked chitosan/astaxanthin film from light brown to reddish brown and increased the film opacity which can lower light transmission through the film. The developed film not only had better water barrier, TS and YM but, due to its opacity, could also provide light protection, and thus would be appropriate for packaging material of foods that degrade when exposed to moisture or light.

Fabrication and the barrier characterization of the cellulose nanofibers/organic montmorillonite/poly lactic acid nanocomposites

AbstractThe hydrophobic modification of cellulose nanofibers (CNF) was carried out via free radical polymerization using methyl methacrylate (MMA) as the monomer to improve the compatibility between CNF and poly lactic acid (PLA). Followed by the preparation of the novel nanocomposites in combination of the organic montmorillonite and the substrate. The resulting nanocomposites were then coated on paper surface using a cast‐coating process in an attempt to improve the barrier properties towards water vapor and oxygen. In addition, the composite films are prepared via a solution casting method. The water vapor transmission rate (WVTR), water vapor permeability (WVP), oxygen transmission rate (OTR), and tensile strength of the as‐prepared films were systematically measured. The corresponding results demonstrated that the WVTR, WVP and OTR decreased with the addition of a certain content of MCNF in coatings. 0.2 wt% MCNF is the optimum content, showing the best gas resistance and tensile performance. The lowest value of WVTR and WVP are 10.30 g/(m2⋯24 h) and 3306.58 g⋯μm/(m2⋯24 h) for films with 0.2 wt% MCNF added, which is 88.23% and 26.05% lower than that of PLA composite film without NFC.

Use of Edible Film Incorporated with Parijoto Fruit Extract (Medinilla speciosa Blume) to Inhibit Microbiological and Oxidative Damages of Sausages

Background and Objective: Edible film is one of the solutions for food packaging that carry antimicrobial and antioxidant compounds, usually found in Medinilla speciosa fruits. The objective of this study was to assess effects of Medinilla speciosa fruit extract on physical, chemical and bioactivity of edible films as well as effects of coating on sausage quality during storage. Material and Methods: The edible film included 2% w w-1 chitosan, 2% w w-1 sorbitol and Medinilla speciosa fruit extract. Variations of Medinilla speciosa extract included 0, 2.5, 5 and 10% (w w-1), while the storage temperature included 4 and 27 oC. Seven parameters of edible film characteristics were assessed, including tensile strength, elongation, water vapor permeability, antimicrobial and antioxidant activities, surface microstructure and Fourier-transform infrared response. Parameters assessed in storage treatment included total plate count, yeast mold count and thiobarbituric acid reactive substances. Data were analyzed using Kruskal-Wallis test. Organoleptic characteristics were analyzed using Friedman test and SPSS Software. Results and Conclusion: Results showed that the higher the concentration of Medinilla speciosa extract was, the higher the value of tensile strength, water vapor permeability and antioxidant activity and lower the elongation value were. The film control with 0% Medinilla speciosa extract was the only film that met Japanese standard for the water vapor permeability value, including 6.74 gm-2 h-1. Furthermore, shelf life of sausages coated with edible films revealed that the higher the concentration of Medinilla speciosa extract was, the lower the total plate count, yeast mold count and thiobarbituric acid reactive substances values were. Study demonstrated that the Medinilla speciosa extract edible film inhibited microbiological and oxidative damages. ​Oon Day 15 of storage, sausages coated with edible films with 10% Medinilla speciosa extract included lower total plate count, yeast mold count and thiobarbituric acid reactive substances values, respectively including 2.4 ±0.02 log CFU g-1, 1.3 ±0.08 log CFU g-1 and 13.38 ±0.22 mg malonaldehyde kg-1 sausage, compared to the control film. Organoleptic assessment showed no major differences in consumer acceptance. In conclusion, edible film with 10% Medinilla speciosa extract is the best physical, chemical and bioactivity film. Moreover, this film extends the sausage shelf life. Conflict of interest: The authors declare no conflict of interest.

Sustainable Chitosan-Dialdehyde Cellulose Nanocrystal Film.

In this study, we incorporated 2,3-dialdehyde nanocrystalline cellulose (DANC) into chitosan as a reinforcing agent and manufactured biodegradable films with enhanced gas barrier properties. DANC generated via periodate oxidation of cellulose nanocrystal (CNC) was blended at various concentrations with chitosan, and bionanocomposite films were prepared via casting and characterized systematically. The results showed that DANC developed Schiff based bond with chitosan that improved its properties significantly. The addition of DANC dramatically improved the gas barrier performance of the composite film, with water vapor permeability (WVP) value decreasing from 62.94 g·mm·m−2·atm−1·day−1 to 27.97 g·mm·m−2·atm−1·day−1 and oxygen permeability (OP) value decreasing from 0.14 cm3·mm·m−2·day−1·atm−1 to 0.026 cm3·mm·m−2·day−1·atm−1. Meanwhile, the maximum decomposition temperature (Tdmax) of the film increased from 286 °C to 354 °C, and the tensile strength of the film was increased from 23.60 MPa to 41.12 MPa when incorporating 25 wt.% of DANC. In addition, the chitosan/DANC (75/25, wt/wt) films exhibited superior thermal stability, gas barrier, and mechanical strength compared to the chitosan/CNC (75/25, wt/wt) film. These results confirm that the DANC and chitosan induced films with improved gas barrier, mechanical, and thermal properties for possible use in film packaging.

Preparation and Optimization of Starch/Poly Vinyl Alcohol/ZnO Nanocomposite Films Applicable for Food Packaging

Pollution and destruction of the environment due to the accumulation of non-degradable plastics are some of the most important concerns in the world. A significant amount of this waste is related to the polymers used in food packaging. Therefore, experts in the food industry have been looking for suitable biodegradable alternatives to synthetic polymers. Preparing biocompatible and biodegradable films based on starch is a good choice. In this study, various factors affecting films of starch/polyvinyl alcohol (PVA)/containing ZnO nanoparticles such as the amount of starch, PVA, glycerol, and ZnO were evaluated by response surface methodology (RSM). Film formation by solvent casting method, mechanical properties, swelling, solubility, and water vapor permeability (WVP) were selected as responses of RSM. The results showed that hydrogen bonding interactions between polyvinyl alcohol and starch improved the film formation. The effect of glycerol and PVA content on the mechanical strength was contrary to each other. As the amount of PVA increased, the tensile strength first decreased and then increased. The value of WVP was for all Runs from 0 to 6.77 × 10− 8 g m− 1 s− 1 Pa− 1. Finally, films with high film formation, maximum tensile strength, and high elongation at break, minimum solubility, permeability, and swelling were optimized.

Non-isothermal cold crystallization, melting, and moisture barrier properties of silver-loaded kaolinite filled poly(lactic acid) films

Silver-loaded kaolinite (AgKaol), an antibacterial agent along with a barrier enhancer, was incorporated into poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT) and tetrabutyltitanate (TBT) blend resulting in the formation of polymer composite. The introduction of AgKaol could improve the barrier and the crystallization properties of PLA/PBAT/TBT blend. The barrier property of composite polymer was investigated by water vapor permeability (WVP) to study the influence of AgKaol content (0.0, 1.0, 2.0, 3.0 and 4.0 phr) in polymer matrix. The values of WVP decreased with increasing AgKaol content and amount of crystallite in PLA composite. The cold crystallization property of this PLA/PBAT/TBT composited with 0.0, 2.0 and 4.0 phr of AgKaol was completely investigated by the non-isothermal differential scanning calorimetry (DSC) technique. From the non-isothermal DSC analysis, the crystallization rates (dX(T)/dt) of PLA composite increased with increasing of the heating rate and AgKaol content. The Avrami, Ozawa and Liu models were applied to describe the non-isothermal crystallization kinetics and determine crystallization parameters for PLA/PBAT/TBT/AgKaol composite. The crystallization mechanism of PLA/PBAT/TBT/AgKaol composite was proposed thorough the nucleation and three dimension growths. The activation energies of crystallization (Ea) were determined by the Kissinger-Akahira-Sunose (KAS) isoconversional method. The determined Ea for the crystallizations of PLA/PBAT/TBT with 4.0 phr of AgKaol were lower than 2.0 and 0.0 phr, respectively. Polarized optical microscopy (POM) showed more and larger spherulites with a nanocrystal structure of PLA/PBAT/TBT/AgKaol composite than neat PLA. The nucleating effect of AgKaol on PLA/PBAT/TBT blend might be useful for preparation of PLA composite as a gas barrier protection material in the future. Corresponding to the melt flow index (MFI) results, PLA composites could produce as a film with promising antibacterial packaging due to silver nanoparticles in AgKaol.

Chitosan/acetylated starch composite films incorporated with essential oils: Physiochemical and antimicrobial properties

Due to increasing environmental concerns regarding plastic waste, the development of edible and biodegradable films from natural polymers and food additives is gaining more attention. In this study, chitosan/acetylated starch composite films containing cinnamon and clove essential oils were fabricated via a solution-casting technique. The effects of essential oil concentration on the physical, mechanical, barrier, microstructural, and antimicrobial properties of the films were evaluated. Films incorporated with the essential oils were darker, redder and yellower than control films without essential oils. The moisture content and water solubility of the films decreased by 22.7% and 21.6%, respectively, with the incorporation of 2.50% of essential oils. The incorporation of 2.00% of essential oils decreased the tensile strength and elongation at break of the films by 25.6% and 40.4%, respectively. All the films incorporated with essential oils displayed enhanced light, water vapor, and oxygen barrier characteristics. As the essential oil concentration increased to 2.50%, the film opacity increased by 795.8%, while the water vapor permeability and peroxide value decreased by 35.5% and 52.6%, respectively. Fourier Transform Infrared spectroscopy and scanning electron microscopy results demonstrated well-dispersed essential oils in the polymer matrix. The films incorporated with essential oils exhibited excellent antibacterial activity against spoilage bacteria and the pathogen, Escherichia coli O157:H7, on beef. In conclusion, the films incorporated with essential oils displayed excellent barrier and antimicrobial properties and have a good potential to be used for edible food packaging applications.

Synergistic effects of (3-mercaptopropyl)trimethoxysilane and citric acid on the improvement of water vapor barrier performance of polyvinyl alcohol/xylan packaging films

The application of polysaccharide-based films is limited due to core problems, such as poor water vapor barriers and flexibility. From this perspective, silane coupling agents have recently attracted particular interest because of their insensitivity to moisture. However, it may cause poor mechanical properties due to the aggregation of silane coupling agents within the materials. Here, we report a collaborative modification protocol to reduce water vapor transmission capacity and to improve the flexibility of xylan-based films. Xylan from sugarcane bagasse was firstly modified with (3-mercaptopropyl) trimethoxysilane (MPTMS) to obtain MPTMS-modified xylan (MSMX), and then blended with polyvinyl alcohol (PVA) using citric acid (CA) as a cross-linker. The PVA/MSMX/CA films were found to be highly impermeable to water vapor and to have robust solvent resistance. With an optimized mass ratio (PVA/MSMX, 2:1), the water vapor permeability (WVP) value was 2.79 × 10−13 (g/cm−1·s ∙Pa), significantly lower than that of previously reported PVA/xylan-based films. The excellent barrier properties were attributed to the “torturous path effect”. Meanwhile, the elongation at break increased up to 480 %, showing a 2-fold enhancement compared to that of PVA/xylan films. This study revealed a great potential of using the PVA/MSMX/CA films as packaging materials for moisture susceptible drugs, food, and electronic components.

Properties of chitosan–papain biopolymers reinforced with cellulose nanofibers

There is currently a strong tendency toward the use of biodegradable packaging produced from biopolymers containing active substances. Papain can be used in active packaging. The aim of this paper was to study the effect of cellulose nanofibers (CNF) and papain on the structural, mechanical, and thermal properties of films of chitosan. The experiment was performed with CNF and papain concentrations ranging from 0%–8% and 0%–10%, respectively. The CNF increased the water solubility of films. Lower water vapor permeability values were observed for the films with 4% CNF and papain concentrations up to 6%. Films reinforced with CNF and without papain were rigid and more resistant. Films incorporated with papain and with or without CNF reduced the tensile strength, the percentage of elongation, and the resistance to perforation. The addition of papain improved thermal stability. The films with 2% papain and 4% CNF presented the best results for the parameters studied. Practical applications There is a tendency toward the use of biodegradable packaging produced from biopolymers containing active substances. Papain can be used in active packaging. The aim of this studied was to analyze the properties of chitosan films with cellulose nanofibers (CNF) and papain. The incorporation of papain reduced the mechanical properties of the films with and without CNF and improved thermal stability. The addition of papain allowed to obtain films with good properties that allow them to be applied as active films.

Design of Chitosan and Alginate Emulsion-Based Formulations for the Production of Monolayer Crosslinked Edible Films and Coatings.

This study aimed to develop edible monolayer emulsion-based barriers with polysaccharides as film-forming components (chitosan and sodium alginate), soy lecithin as a surfactant and olive oil as a hydrophobic barrier. Monolayer barriers in the form of films were prepared by casting filmogenic emulsions composed of 2% w/v chitosan (dissolved in lactic acid 1% v/v) or 1% w/v sodium alginate, with different lipid contents (25, 50 and 100% w/w biopolymer basis) and different surfactant concentrations (5, 10 and 25% w/w, lipid basis). Glycerol was used as a plasticizer (25 % w/w, biopolymer basis). After the emulsion drying process, the obtained stand-alone films were sprayed with a crosslinking solution, achieving an optimized crosslinker content of 3.2 mgCa2+/cm2 alginate film and 4 mg tripolyphosphate/cm2 chitosan film. The effect of oil and lecithin contents, as well the presence of crosslinking agents, on the film’s water vapour permeability (WVP), water vapour sorption capacity, mechanical properties and colour parameters, was evaluated. The results have shown that the lowest WVP values were obtained with formulations containing 25% lipid and 25% surfactant for chitosan films, and 100% lipid and 25% surfactant for alginate films. The application of the crosslinking agents decreased even further the WVP, especially for chitosan films (by 30%). Crosslinking also increased films’ resistance to deformation under tensile tests. Overall, the films developed present a good potential as polysaccharide-based barriers with increased resistance to water, which envisages the use of the designed formulations to produce either edible/biodegradable films or edible coatings.

Films based on mixtures of zein, chitosan, and PVA: Development with perspectives for food packaging application

This work aims at the production and characterization of promissory food packaging films based on chitosan (CS), zein (ZN), and poly (vinyl alcohol) (PVA). CS and ZN are biodegradable, biocompatible, and extracting from natural-sources and renewable. Although PVA is a synthetic polymer, it is also considered biocompatible and present water-solubility. From binary and ternary macromolecule mixtures based on CS/ZN/PVA, were obtained films solvent-free. In this facet, extrusion of the macromolecule mixture following by a hot compression to acquire the films' solvent-free. The films were characterized by several techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), prioritization query based on critical packaging requirements which underwent visual and sensorial (smell), mechanical properties, scanning electron microscopy (SEM), and barrier property analysis. Our findings showed that a higher proportion of ZN led to yellowish films with lower transparency and/or higher opacity. Therefore, PVA high content is interesting for our proposal since it allows films with translucency, handling, absence of rupture, and odor. The mechanical tests showed that the ZN effect is associated with reduced tensile strength, increasing elongation, and Young's modulus. Thus, ZN's presence, even if in a smaller proportion to PVA, allows the formation of more rigid films. The morphological analysis indicates the formation of compact films and homogeneous surfaces. However, films with higher amounts of CS and ZN presented greater roughness, globular clusters' presence, and heterogeneity (films' cross-section) that may have influenced water vapor permeability values and better barrier property due to tortuosity that decreases as the PVA content is increased. This finding can be associated with the higher crystallinity of the film when the film's formulation presents significant CS and ZN concentrations. Finally, we demonstrate the feasibility of using films based on the mixture of CS, ZN, and PVA as proposals for a food pack.

Cellulose‐Reinforced Starch Biocomposite: Optimization of the Effects of Filler and Various Plasticizers using Design–Expert Method

AbstractIn this study, the effect of cellulose as a reinforcement agent and different ratio of glycerol/sorbitol as plasticizers to improve properties in starch biocomposite are optimized with Design–Expert method for the first time. Thermoplastic starch granule is produced with plasticized and cellulose‐reinforced starch by a twin extruder. After conditioning, the starch granule, is molded into sheet using a hot press with thick plates. Dynamic mechanical thermal analysis show that cellulose increases the glass transition temperature to 120 °C. Optimum point of the starch composite obtained by Design–Expert software 7.1.5, is run with 5 wt% cellulose, 17.5 wt% glycerol and 17.5wt% sorbitol that has water vapor permeability value equally of 7.81E‐10g s−1 m−1 Pa−1, tensile strength of 0.85 MPa, Young´s modulus equally of 377.65 MPa, and elongation at break of 7.08%. Field emission scanning electron microscopy of the optimized biocomposite shows uniform distribution of cellulose in the matrix. Hydroxyl stretching vibrations at 3286 cm−1 is a result of new hydrogen bonding between cellulose and starch molecules and peaks at 3366 and 1702 cm−1 are attributed to glycerol and sorbitol, respectively in the Fourier transform infrared spectra.

Hydrolyzed collagen on PVA‐based electrospun membranes: Synthesis and characterization

AbstractPhysicochemical, structural, and thermal properties of electrospun membranes depend on process conditions and the type and concentration of the raw materials used to produce them. In this work, the electrospinning technique (ES) is used to synthesize membranes with hydrolyzed collagen (HC) and polyvinyl alcohol (PVA) at two different distances. The characterization of these membranes is then carried out by X‐Ray diffraction, Raman spectroscopy, differential scanning calorimetry, water vapor permeability (WVP), microscopy techniques, and porosity measurements. Results show that the morphology of the ES membranes depends mainly on the polymer/solvent system's physicochemical properties and the distance to the collector. Thicker samples (68–86 μm) are formed when using the furthest distance (10 cm), having fiber diameters smaller than 1 μm, porosity percentages up to 90%, and WVP values close to or in the recommended range for wound dressing commercial products. Moreover, the presence of HC results in samples with a less crystalline structure. To the best of our knowledge, this is the first report in which PVA and HC membranes are successfully synthesized by electrospinning and physicochemically characterized.