Semitransparent chitosan‐TiO2 nanotubes composite film for food package applications

Semitransparent composite films were prepared made from TiO₂ nanotubes in chitosan (CS) matrix. Hydrothermally synthesized titanium nanotubes (TiNTs) were dispersed in chitosan matrix in order to produce film‐forming solutions at 0.05 and 0.10% w/v. Structural, topological, optical and thermal properties of these films were evaluated. The antimicrobial activity of films against Salmonella enterica serovar Typhimurium, Escherichia coli (Gram‐negatives) and Staphylococcus aureus (Gram‐positive) was also investigated. Fourier transform infrared (FTIR) spectra showed effective site‐selective interactions between chitosan and TiNTs. TiNTs prevented the degradation of films, avoiding the oxidization of the glucosamine ring. Characterizing techniques such as, Scanning electron microscopy–energy dispersive spectroscopy (SEM‐EDS) line profile and atomic force microscopy (AFM) were used to examine the TiNTs dispersion within the film. The morphological analysis indicated that the TiNTs were well dispersed and became clustered proportionally to the weight percentage of TiNTs used in the composites. The UV‐Vis spectra showed that TiNTs increased the film absorption in the UV region and the light barrier properties of films remained stable over the storage period. Photoacoustic spectroscopy (PAS) was used to study these films, nondestructively for their thermal effusivity (e). The films were effective in reducing the microbial concentration in the liquid culture for all bacteria tested. The effectiveness was found to dependent on the bacterial strain and TiNTs content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhancing the mechanical and barrier properties of chitosan/graphene oxide composite films using trisodium citrate and sodium tripolyphosphate crosslinkers

This study investigated the effect of ionic crosslinking on the mechanical, barrier, and optical properties of chitosan (CS) and CS/graphene oxide (CSGO) composite films using trisodium citrate (CIT) and sodium tripolyphosphate (TPP) solutions of different concentrations (0.5, 1.0. 2.0, and 3.0% w/v). Successful crosslinking was confirmed by Fourier-transform infrared spectroscopy. The hydrophilicity and light transmittance decreased significantly (p < 0.05) with the increase in concentration of both crosslinking agents. The CS films crosslinked with 3.0% w/v TPP exhibited significant (p < 0.05) improvements in barrier properties, achieving a 51% decrease of water vapor permeability and 59% decrease in oxygen permeability, in comparison to neat CS film. In addition, TPP-crosslinked CSGO films experienced an 82% and 42% improvement in tensile strength and elongation at break, respectively. Overall, crosslinked CS and CSGO films possess significantly improved properties and have great potential to be further studied as food packaging materials.     

Packaging‐related properties of alkyd‐coated,wax‐coated,and buffered chitosan and whey protein films

Packaging‐related properties of coated films of chitosan–acetic acid salt and whey protein concentrate (WPC) were studied. Chitosan (84.7% degree of deacetylation) and WPC (65–67% protein) were solution cast to films. These films are potential oxygen barriers for use in packaging. Coatings of wax or alkyds were used to enhance the water‐barrier properties. The packaging‐related properties of chitosan films treated in a buffering solution, with a pH of 7.8, were also investigated. The coated films were characterized with respect to Cobb absorbency, overall migration to water, water vapor transmission rate, and oxygen permeability. The creasability and bending toughness were determined. The wax was a more efficient barrier to liquid water and 90–95% relative humidity than the alkyd. However, the alkyd‐coated material had superior packaging‐converting properties. The alkyd‐coated WPC and chitosan–salt films were readily folded through 180° without any visible cracks or delamination. The overall migration from the alkyd‐coated materials was below the safety limit, provided the coat weight was higher than 7.5 mg/cm² on WPC and 2.1 mg/cm² on chitosan–salt. The barrier properties of chitosan film under moist conditions were improved by the buffer treatment. However, the buffering also resulted in shrinkage of the film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 60–67, 2004     

Barrier,rheological, and antimicrobial properties of sustainable nanocomposites based on gellan gum/polyacrylamide/zinc oxide

In this study, we used a solution casting method to prepare gellan gum (G)-based ternary nanocomposite films containing polyacrylamide (P) and zinc oxide (ZnO) nanoparticles. All composites were prepared using the chemical cross-linker N,N-methylenebisacrylamide. The nanocomposites were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and scanning electron microscopy. Attenuated total reflectance FTIR revealed strong hydrogen bonding interactions among gellan gum, polyacrylamide, and ZnO, which enhanced the physiochemical, thermal, and mechanical properties of the GPZnO nanocomposites. The addition of ZnO nanoparticles increased the glass transition temperature (T_g: 181.8–196.3°C), thermal stability (T_5%: 87.8–96.5°C), and char yield (23.9–29.1%) of the GP composite films, as well as their the tensile strength (from 33.5 to 43.8 MPa) and ultraviolet (UV) blocking properties (~99.2% protection against UVB [280–320 nm]). ZnO significantly influenced the rheological properties of the GP composite. The prepared GP and GPZnO nanocomposites exhibited shear thinning behavior and their viscosities decreased when there is an increase in shear rate. Storage and loss modulus increased with frequency with the addition of ZnO nanoparticles. The GPZnO films exhibited reduced hydrophilicity, moisture content, and water barrier properties compared with the GP film. The GPZnO nanocomposites exhibited effective antimicrobial activity against six different pathogens. The prepared GPZnO films could be useful in biodegradable packaging applications.     

Preparation and optical properties of nanocomposite film of CdS:Cu with biomacromolecules

Nanocomposite films of CdS:Cu nanoparticles with chitosan and sodium alginate were prepared using spin‐coating method, and characterized by X‐ray diffraction, transmission electron microscopy, atomic force microscopy (AFM), ultraviolet–visible (UV–vis), and photoluminescent spectrum. The CdS:Cu nanoparticles have a cubic structure with an average crystal size of ∼2 nm, which show blue shift in UV–vis absorption spectra compared to bulk CdS. Furthermore, the CdS:Cu nanoparticles are formed steadily with increasing number of composite layers and homogeneously distributed between the chitosan and alginate layer. AFM measurement shows that the average height of a mono‐layered composite film is 25 nm. Emissions ascribed to the electron–hole recombination of CdS and the t₂‐like energy level of Cu was observed for the multi‐layered composite films. POLYM. COMPOS., 35:477–481, 2014. © 2013 Society of Plastics Engineers     

Polymer–gold nanoparticle composite films for topical application: Evaluation of physical properties and antibacterial activity

The biocompatible polymer films show potential as an alternative to gels and patches used for topical delivery of therapeutics and cosmetics. The physical strength and antimicrobial activity of polymer films are important attributes for their topical applicability. Here, we have investigated the physical properties and antibacterial activity of six commonly used film forming polymers before and after formation of nanocomposites with gold nanoparticles (AuNP). The blank and AuNP loaded polymer films were prepared by solvent casting method and characterized for thickness, tensile strength, burst strength, skin adhesion strength, degree of swelling, and porosity. The antibacterial activity of the composite films was evaluated by zone‐of‐inhibition and spectrophotometric growth inhibition method against Staphylococcus aureus and Escherichia coli . The physical characterization showed that chitosan films casted using 1.5% w/w resulted in 76 MPa of tensile strength, while zein films required 40% w/w to show 23 MPa of tensile strength. The AuNP (250 μM; 35 nm) loaded polymer films showed significantly (p < 0.05) greater burst strength and skin adhesion strength compared with respective blank films. Among the polymers tested, only blank films of chitosan and zein showed antibacterial activity. On the other hand, all the AuNP loaded polymer films showed significantly (p < 0.05) greater antibacterial activity. The AuNP loaded chitosan film showed E. coli growth inhibition similar to tetracycline. Taken together, chitosan‐ and zein‐AuNP nanocomposite films showed better physical properties and antibacterial activity. POLYM. COMPOS., 38:2829–2840, 2017. © 2015 Society of Plastics Engineers     

Development and characterization of chitosan bionanocomposites containing oxidized cellulose nanocrystals

In this research, cellulose nanocrystals (CNs) were extracted from corn cobs by 2,2,6,6,‐tetramethylpiperidine‐1‐oxyl radical‐mediated oxidation combined with ultrasonic treatment for the first time. These CNs were then used as a mechanical reinforcement agent and barrier in chitosan‐based bionanocomposite films. Birefringence analyses under crossed polarizers indicated the presence of isolated nanocrystals in suspension, which was later confirmed by TEM analysis. The crystallinity index obtained from X‐ray diffraction was 92.4%. The incorporation of these nanoparticles into a filmogenic matrix of chitosan made it possible to obtain bionanocomposite films with improved properties. The water‐vapor permeability was reduced by 70%, whereas the tensile strength and Young's modulus increased by up to 136 and 224% respectively. The developed films were applied as interleaving of sliced cheese, and the efficiency was assessed by investigation of adhesion between the surfaces and by comparing its properties with two commercial interleaving products (polyethylene (PE), and Greasepel paper (GP)). Concluding, the developed films showed a substantial potential to be exploited as an interleaving film, owing to its excellent mechanical properties, permeability, hydrophobicity, and low surface adhesion compared to pure chitosan, PE, and GP films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43033.     

蛭石/PBAT复合薄膜的制备与性能

使用蛭石（VMT）作为填料,以可生物降解的聚对苯二甲酸-己二酸丁二醇酯（PBAT）作为基体,采用熔融-吹塑法制备出蛭石/聚对苯二甲酸-己二酸丁二醇酯（VMT/PBAT）复合薄膜,并通过添加聚苯乙烯马来酸酐共聚物（SMA）作为相容剂制备了VMT/PBAT/SMA复合薄膜。对纯PBAT薄膜、VMT/PBAT和VMT/PBAT/SMA复合薄膜的热性能、流变性能、水蒸汽阻隔性能、断面微观结构和力学性能进行了测试。结果表明,相比纯PBAT薄膜,蛭石的填充使VMT/PBAT复合薄膜的热稳定性降低,相容剂SMA的添加增强了VMT/PBAT/SMA复合薄膜的热稳定性;蛭石的添加使复合薄膜的结晶度降低了约2%。水蒸汽透过量测试表明,两种复合薄膜水蒸汽阻隔性能符合国家标准;VMT的添加使VMT/PBAT复合薄膜的拉伸强度和断裂伸长率降低,而添加相容剂SMA使VMT/PBAT/SMA复合薄膜的拉伸强度和断裂伸长率相比VMT/PBAT复合薄膜提高约10 %。     

Active packaging material based on buriti oil – Mauritia flexuosa L.f. (Arecaceae) incorporated into chitosan films

Active and biodegradable materials have great potential in food packaging applications, improving the safety and quality of products. The objective of this study was to develop a new material based on buriti oil incorporated into a chitosan film. Different concentrations of buriti oil in dried films (2.1 g/m², 10.4 g/m², 20.8 g/m², and 31.3 g/m²) were added into a chitosan matrix (41.7 g/m²). The chitosan/buriti oil films were characterized by water‐vapor barrier properties, total water‐soluble matter (TSM), tensile properties, thermogravimetric analysis, microstructure, microbial permeation properties, and biodegradation estimation. The higher oil concentration improved the water‐vapor barrier and the buriti oil acted largely as a plasticizer and increased the elongation at break, and decreased the tensile strength (TS) of chitosan films. The total water‐soluble matter of chitosan films decreased in function of the buriti oil concentration, but the biodegradation and thermal stability increased. The chitosan films presented a microbial barrier against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43210.     

Improved mechanical and barrier properties of starch film with reduced graphene oxide modified by SDBS

Starch is regarded as one of the most promising biopolymers to replace the fossil resources. However, due to the poor mechanical properties, high sensitivity to humidity, and low barrier property, the development of starch‐based materials has been limited. In this study, they improved the mechanical and barrier properties of starch film with reduced graphene oxide (RGO) modified by sodium dodecyl benzene sulfonate (SDBS). The hydrophilia of modified RGO (r‐RGO) was improved and result in a good dispersion in oxidized starch (OS) matrix. The tensile strength of the r‐RGO‐4/OS film increased to 58.5 MPa which was more than three times of the OS film (17.2 MPa). Besides, both the water vapor and oxygen barrier properties of r‐RGO/OS film were improved greatly compared with OS and GO/OS films. Moreover, the r‐RGO/OS film could protect against UV light effectively due to its lightproof performance. In conclusion, the r‐RGO/OS composite film has great potential applications in packaging industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44910.     

Physicochemical properties of edible films from chitosan composites obtained by microwave heating

Summary  Chitosan films were prepared by casting, using microwave and dried by air convection. No scientific literature covers the use of microwave heating in the preparation of chitosan films by casting technique. Effects of heating time, molecular weight and plasticizer on structure, thermal behavior, surface, barrier properties and light transmission were investigated. Heating time showed that the microwave heating did not affect the structural composition and thermal decomposition of chitosan films. UV-vis light barrier properties, equilibrium moisture content and water vapor permeability varied significantly with the heating treatment. Surface film analysis revealed no captured differences between different heating treatments.     

Development of blown film linear low-density polyethylene–clay nanocomposites: Part A: Manufacturing process and morphology

In this study, linear low-density polyethylene (LLDPE)/clay nanocomposites with different clay contents were prepared by melt intercalation using two different compatibilizers: maleic anhydride grafted styrene–ethylene–butylene–styrene and maleic anhydride grafted polyethylene (PE-g-MA). Melt intercalation was achieved by twin extrusion and nanocomposite films were produced by blown film extrusion. Effects of clay and compatibilizer fractions and type of compatibilizer on the structure, permeability, and the barrier properties of the nanocomposite films were investigated. PE-g-MA was shown to notably improve the dispersion of clay layers in the polyethylene matrix, and this was examined by atomic force microscopy and X-ray diffraction. The latter tests have also highlighted the importance of the screw configuration: the presence of mixing elements favors the dispersion and distribution of nanoclay. Moreover, differential scanning calorimetry results have shown no significant effect of the clay on the crystallinity of the composite while thermogravimetric analysis tests have demonstrated a decrease of onset and peak of decomposition temperatures. Finally, barrier properties toward water vapor transmission were measured. It was proven that not also clay, but the compatibilizer participated in decreasing the permeability of the film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48589.     

New Active Packaging Based on Biopolymeric Mixture Added with Bacteriocin as Active Compound

The objective of this work was to develop a chitosan/agar-agar bioplastic film incorporated with bacteriocin that presents active potential when used as food packaging. The formulation of the film solution was determined from an experimental design, through the optimization using the desirability function. After establishing the concentrations of the biopolymers and the plasticizer, the purified bacteriocin extract of Lactobacillus sakei was added, which acts as an antibacterial agent. The films were characterized through physical, chemical, mechanical, barrier, and microbiological analyses. The mechanical properties and water vapor permeability were not altered by the addition of the extract. The swelling property decreased with the addition of the extract and the solubility increased, however, the film remained intact when in contact with the food, thus allowing an efficient barrier. Visible light protection was improved by increased opacity and antibacterial capacity was effective. When used as Minas Frescal cream cheese packaging, it contributed to the increase of microbiological stability, showing a reduction of 2.62 log UFC/g, contributing a gradual release of the active compound into the food during the storage time. The film had an active capacity that could be used as a barrier to the food, allowing it to be safely packaged.     

Preparation,characterization, antibacterial properties,and hemostatic evaluation of ibuprofen‐loaded chitosan/gelatin composite films

Ibuprofen‐loaded chitosan/gelatin (CS/GE) composite films were fabricated in this work. The morphology of the composite film was investigated using scanning electron microscopy. The functional groups of the composite film before and after crosslinking were characterized using Fourier transform infrared spectroscopy. Meanwhile, the mechanical properties, antibacterial performance, cytocompatibility, and hemostatic activity of the composite films were investigated. The results show that the amount of CS affected the mechanical properties and liquid uptake capacities of the composite films. The composite film showed better bactericidal activity against Staphylococcus aureus than Escherichia coli. In vitro drug‐release evaluations showed that crosslinking could control the drug‐release rate and period in wound healing. Both types of CS/GE and drug‐loaded CS/GE composite films also showed excellent cytocompatibility in cytotoxicity assays. The hemostatic evaluation indicated that the composite film crosslinked by glutaraldehyde in rabbit livers had a dramatic hemostatic efficacy. Therefore, ibuprofen‐loaded CS/GE composite films are potentially applicable as a wound dressing material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45441.     

Preparation,physical, and mechanical properties of soy protein isolate/guar gum composite films prepared by solution casting

Guar gum (GG) was incorporated into soy protein isolate (SPI) films using a blending solution casting method to form SPI/GG composite films. The effects of SPI and GG contents on the transparency, water susceptibility, mechanical, and gas‐barrier properties of SPI/GG composite films were analyzed. The results showed that SPI/GG composite films with added GG were much more tensile‐resistant, water‐resistant, gas‐barrier properties but less deformable property than SPI control film. The presence of GG also improved film barrier to the light. The analysis results of contact angle measurement, Fourier transform infrared spectroscopy, and scanning electron microscope indicated that GG induced increased network compactness of the composite films which resulted from strong intermolecular interactions, such as hydrogen bonding, that existed between SPI and GG. Findings indicate that GG may be used as a natural means to improve specific properties of SPI films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43382.     

Graphene oxide–polyoctahedral silsesquioxane–chitosan composite films with improved mechanical and water-vapor-transport properties

Graphene oxide (GO) and ball-milled maleamic acid–isobutyl polyoctahedral silsesquioxanes (MAIPSs) were incorporated simultaneously into chitosan (CS) via solution blending to evaluate their combined effects on the structures and properties of composite films. GO and MAIPS aggregates were homogeneously dispersed in CS and affected the crystallinities of the composite films. The binary addition of GO and MAIPS resulted in synergistic enhancements of the tensile strength and elongation at break of the composite films. Composite films containing 3% w/w MAIPS and 0.25% w/w GO (CS–GO–MAIPS-3) exhibited the highest strength and modulus, which were 48 and 42.2% higher, respectively, than the values of the CS film. The water-vapor-sorption isotherms revealed that monolayer sorption sites decreased with the addition of GO or/and MAIPS, but the dissolution process was not significantly influenced. The water-vapor permeability reached its lowest value for the CS–GO–MAIPS-3 film because of hindered diffusion with the presence of impermeable nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47748.     

Effects of vanillin and plasticizer on properties of chitosan‐methyl cellulose based film

Chitosan‐methyl cellulose based films which incorporatate vanillin as an antimicrobial agent and polyethylene glycol 400 (PEG) as a plasticizer were developed in this study. The effects of vanillin and plasticizer concentration on mechanical, barrier, optical, and thermal properties of chitosan‐methyl cellulose film were evaluated. When the vanillin concentration was increased at a given PEG level, film flexibility decreased while tensile strength increased slightly. Vanillin increased the barrier to oxygen but not water vapor. Increasing vanillin content resulted in less transparency and a more yellowish tint. The bulky nature of vanillin reduced film crystallization. When PEG concentration was increased at a given vanillin level, it resulted in greater film flexibility but reduced film strength. Water vapor permeability (WVP) and oxygen permeability (OP) increased with increase in PEG content. PEG contributed less to the opacity, yellowness, and crystallization of the film than did vanillin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of high-performance deproteinized natural rubber/chitosan composite films via a green and sulfur-free method

To solve the environment and health issues arose from the sulfur vulcanization, a facile and completely eco-friendly method of latex-assembly and in situ cross-linking is developed to prepare fully bio-based and high-performance rubber films. The films are featured by a “reinforced concrete” structure composed of dynamically cross-linked chitosan framework and unvulcanized deproteinized natural rubber (DPNR) matrix. The self-assembly of DPNR latex particles and chitosan, as well as the in situ cross-linking of chitosan in the film forming process are confirmed by transmission electron microscope and dynamic light scattering. As green rubbers without vulcanization, the as-designed composite films possess excellent mechanic properties comparable to those of the sulfur vulcanized DPNR film, whose tensile strength and toughness reach 15.2 MPa and 77.6 MJ m⁻³ respectively. Moreover, the films exhibited appropriate permeability to moisture and achievable reprocessing, which have potential applications in wearable devices.     

Preparation and properties of poly(propylene carbonate) and nanosized ZnO composite films for packaging applications

A series of polypropylene carbonate (PPC)/ZnO nanocomposite films with different ZnO contents were prepared via a solution blending method. The morphological structures, thermal properties, oxygen permeability, water sorption, and antibacterial properties of the films were investigated as a function of ZnO concentration. While all of the composite films with less than 5 wt % ZnO exhibited good dispersion of ZnO in the PPC matrix, FTIR and SEM results revealed that solution blending did not lead to a strong interaction between PPC and unmodified ZnO. As such, poor dispersion was induced in the composite films with a high ZnO content. By incorporating inorganic ZnO filler nanoparticles, the diffusion coefficient, water uptake in equilibrium, and oxygen permeability decreased as the content of ZnO increased. The PPC/ZnO nanocomposite films also displayed a good inhibitory effect on the growth of bacteria in the antimicrobial analysis. The enhancement in the physical properties achieved by incorporating ZnO is advantageous in packaging applications, where antimicrobial and environmental‐friendly properties, as well as good water and oxygen barrier characteristics are required. Furthermore, UV light below ～ 350 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PPC matrix. ZnO nanoparticles can also improve the weatherability of a PPC film. In future research, the compatibility and dispersion of the PPC matrix polymer and the inorganic ZnO filler nanoparticles should be increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Bio‐hybrid nanocomposite coatings from sonicated chitosan and nanoclay

Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio‐hybrid coatings were applied onto argon–plasma‐activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV‐light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (≤1 μm), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were “generally recognized as safe” (GRAS) and the calculated total migration was in all cases ≤6 mg/dm², thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio‐hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010