Films of chitosan and N‐carboxymethylchitosan. Part II: effect of plasticizers on their physiochemical properties

Chitosan (Ch) and N‐carboxymethylchitosan (N‐CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG‐400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1:1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG‐400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N‐CMCh. While the PEG‐400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG‐400 > unplasticized film; this was more pronounced in the N‐CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. Copyright © 2006 Society of Chemical Industry     

Preparation and characterization of starch-based composite films reinforced by apricot and walnut shells

Starch-based biodegradable films were prepared by using solution-casting method and reinforced by agricultural residues [apricot and walnut shell (APS and WNS) powder]. The powder of both shells was added in different ratios (0, 2.5, 5, 7.5, and 10%) to investigate the microstructures and performances (mechanical and thermal properties) of the starch-based film. Different techniques such as impact, tensile testing, scanning electron microscope, optical microscope (OM), X-ray diffraction (XRD), water vapor transmission rate (WVTR), and dynamic mechanical analysis were applied to study the thermomechanical and barrier properties of the composite films. Results showed that the incorporation of both shells significantly improved the WVTR and mechanical properties of starch-based films. The shells powder was significantly increased the Young's modulus and tensile strength of the starch-based films. Both OM and SEM results showed reasonably good compatibility between starch and reinforced shells. OM and XRD indicated that the APS and WNS not only retained their crystalline structure in the film but they also strengthened the peak intensity of the film. This phenomenon can be used to explain the mechanism of mechanical reinforcement. Since all the components used in the preparation of the films are food grade ingredients, it is expected that the films developed in this work will be used for food packaging applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47978.     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

聚乳酸水蒸气阻隔性的改性

聚乳酸(PLA)用于产品包装时不仅要满足所必需的力学性能、化学稳定性、透明性、印刷性以及热封性等,还要满足产品对阻隔性的要求.采用共混、添加助剂的方法以提高PLA对水蒸气的阻隔作用.结果显示:乙烯-乙烯醇共聚物(EVOH)、有机蒙脱土(OMMT)的加入可以降低PLA的水蒸气透过率(WVTR),且随着其含量的增加,WVTR值逐渐减小,当EVOH质量含量达到50％时,WVTR值减小了61％,OMMT含量达到9％时,WVTR值减小了58％;在OMMT/PLA共混物中加入聚癸二酸丙三醇酯(PGS)后,WVTR值增加.     

Mechanical,thermal, and barrier properties of nanocomposites based on poly(butylene succinate)/thermoplastic starch blends containing different types of clay

Nanocomposites based on blends of poly(butylene succinate) (PBS) and thermoplastic cassava starch (TPS) were prepared using a two‐roll mill and compression molding, respectively. Two different types of clay, namely sodium montmorillonite (CloisiteNa) and the organo‐modified MMT (Cloisite30B) were used. The morphological and mechanical properties of the nanocomposite materials were determined by using XRD technique and a tensile test, respectively. Thermal properties of the composite were also examined by dynamic mechanical thermal analysis and thermal gravimetric techniques. Barrier properties of the nanocomposites were determined using oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) tests. From the results, it was found that by adding 5 pph of the clay, the tensile modulus and the thermal properties of the blend containing high TPS (75 wt %) changed significantly. The effects were also dependent on the type of clay used. The use of Cloisite30B led to a nanocomposite with a higher tensile modulus value, whereas the use of CloisiteNa slightly enhanced the thermal stability of the material. OTR and WVTR values of the blend composites containing high PBS ratio (75 wt %) also decreased when compared to those of the neat PBS/TPS blend. XRD patterns of the nanocomposites suggested some intercalation and exfoliation of the clays in the polymer matrix. The above effects are discussed in the light of different interaction between clays and the polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1114‐1123, 2013     

Chia seeds to develop new biodegradable polymers for food packaging: Properties and biodegradability

Chia seeds are a promising raw material for the development of biodegradable and edible polymers due to their composition and properties. This study aimed to evaluate the effects of drying process of chia mucilage (oven and freeze-drying) and the incorporation of chia oil in films for food packaging. The films were formed by casting using chia mucilage and glycerol. The polymers developed were evaluated by physicochemical properties, microstructure, thermal properties, and biodegradation. The drying process of mucilage and oil incorporation in films affected mainly mechanical and color properties. Freeze-dried mucilage resulted in superior mechanical performance. Differences were caused by the effect of drying process in the molecular structure of chia mucilage and the incorporation of oil among the polymer chains. Chia mucilage films were completely soluble in water and biodegraded in a short time in soil. These films are promising biodegradable polymers for the development of eco-friendly food packaging and edible sachets for small pre-measured portions, preventing environment pollution and facilitating product consumption.     

Effects of plasticization conditions on the structures and properties of cellulose packaging films from ionic liquid [BMIM]Cl

By using natural softwood pulp with higher degree of polymerization (DP = 1460) as cellulose source, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid as solvent and glycerol as plasticizer, a novel cellulose packaging film was prepared. The effects of plasticization conditions on the structures, mechanical properties, permeability for oxygen and water vapor were measured by Wide-angle X-ray scattering, thermogravimetric analysis, scanning electron microscopy (SEM), and other techniques. The investigations suggested that the glycerol concentration and plasticizing time had great effect on the properties of the regenerated cellulose films. The crystal transformation of cellulose I to cellulose II occurred during the dissolution and regeneration process, combining with the decrease of thermal stability. The tensile strength decreased rapidly with the addition of glycerol and prolongation of plasticizing time. However, elongation at break of the regenerated cellulose films increased at first and then decreased with increasing of glycerol concentration and plasticizing time. The morphologies for the fracture surface obtained from SEM images showed transformation of typical brittle fracture to plastic deformation with increasing of glycerol concentrations. It was also found that both water vapor permeability and oxygen permeability of the regenerated cellulose films decreased slowly with increasing of glycerol concentrations and plasticizing time, but water vapor permeability and oxygen permeability presented an almost opposite trend. The films prepared by using ionic liquid technology would be used in food packaging or other fields as a kind of green packaging material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of UV-cured polyurethane acrylate/ZnO nanocomposite films based on surface modified ZnO

A series of polyurethane acrylate (PUA)/ZnO nanocomposite films with different ZnO contents were prepared via a UV-curing system. To ensure good dispersion in the PUA matrix, ZnO nanoparticles were modified with a silane coupling agent and confirmed by FT-IR analysis. The morphological structures, thermal properties, mechanical properties and water transfer properties of the prepared films were investigated as a function of their ZnO concentration. WAXD and SEM analyses showed that the surface-modified ZnO nanoparticles were homogeneously dispersed in the PUA matrix and the molecular ordering increased with increasing ZnO content. Compared with neat PUA, the hardness and elastic modulus in films increased from 0.03 to 0.056 GPa and from 2.75 to 3.55 GPa, respectively. Additionally, the water uptake and WVTR in the PUA/ZnO nanocomposite films decreased as the ZnO content nanoparticles increased, which may come from enhanced molecular ordering and hydrophobicity in films. UV light below approximately 450 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PUA matrix, indicating that these composite films exhibit good weather ability and UV-shielding effects. The enhanced physical properties achieved by incorporating modified ZnO nanoparticles can be advantageous in various applications, whereas the thermal stability of the composite films should be increased.     

Influence of succinylation on the properties of cast films from red bean protein isolate at various plasticizer levels

The effects of succinylation at three anhydride levels (0.2, 0.4, and 0.6 g g⁻¹) on the properties of cast films from red bean protein isolate (RPI) at three glycerol levels of 0.2, 0.4, and 0.6 g g⁻¹ were investigated. The tested properties included tensile strength (TS) and elongation at break (EB), surface hydrophobicity, moisture content (MC), total soluble matter (TSM), water vapor transmission rate, and permeability (WVTR and WVP), permeability coefficient of oil (PO). The results showed that the succinylation greatly improved the mechanical properties (especially the EB), but decreased the surface hydrophobicity of cast films. The MC, TSM, WVTR, WVP, and PO were considerably increased by the succinylation. The size exclusion chromatography analysis indicated that the succinylation resulted in protein aggregation or association, and transformation of insoluble precipitates (initially present) to soluble protein components. The dependence of the influence of succinylation upon some selected properties on the plasticizer level suggests interactions between introduced anionic succinic moieties and the hydroxyl groups of the plasticizer. These results suggest that the succinylation treatment could be applied to modify the mechanical properties of legume proteins, especially in the case that requires excellent flexibility of cast films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Starch nanocomposite films incorporating grape pomace extract and cellulose nanocrystal

The objectives of this study were to prepare starch nanocomposite films incorporating grape pomace extract (GPE) and cellulose nanocrystal (CNC) using a solvent‐casting method, and to characterize the mechanical properties, color, water vapor transmission rate (WVTR), crystalline structure, morphology, thermal stability, phenolic compound release profile and antibacterial activity of the films. Incorporating CNC and GPE significantly (P < 0.05) increased the films’ thickness, mechanical properties, and opacity. Brightness and color were mainly influenced by GPE level, while CNC had a great impact on the reduction of WVTR values of the film. Three characteristic cellulose I crystalline peaks were observed using X‐ray diffraction in CNC‐containing nanocomposite films. However, the effect of CNC levels on thermal stability was not significant. Phenolic compound releases were time and film dependent, and the nanocomposite films incorporating with GPE and CNC exhibited stronger inhibitory effect against Staphylococcus aureus ATCC 29213 compared to Listeria monocytogenes ATCC 7644. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44438.     

Cotton linter nano-fibers as the potential reinforcing agent for guar gum

Cotton linter nano-fibers (CLNFs) were prepared from cotton linters by a refining process. The prepared CLNFs were characterized for morphology, crystallinity and degree of polymerization. CLNF was used as a reinforcing agent in guar gum to improve its performance properties. Guar gum/CLNF nanocomposite films were prepared by a solution-casting process. CLNF was added in concentrations of 0.1, 0.25, 0.5 and 1.0 % (w/w) in guar gum. The prepared guar gum/CLNF nano-composite films were characterized for mechanical, thermal, rheological, crystallinity, water vapor transmission rate (WVTR) and light transparency properties. The enthalpy of melting and melting temperature of guar gum increased with increased concentration of CLNF; but up to 0.25 % (w/w) concentration, above which they started decreasing. Tensile strength and Young’s modulus of guar gum increased by 32 and 35 %, respectively, by 0.25 % (w/w) addition of CLNF; however, it decreased on further increase in the concentration of CLNF. The percentage elongation at break and WVTR decreased by 58 and 57 % for 0.25 % (w/w) CLNF-added guar gum. The observed improvements in the properties were due to better interaction between CLNF and guar gum. CLNF was found to have uniformly dispersed in guar gum on addition up to 0.25 % concentration; however, it started forming aggregates at higher concentration, as evident from scanning electron microscopy. Viscosity increased, whereas transparency decreased with increased concentration of CLNF in guar gum.     

Effects of jackfruit waste flour on the properties of poly(vinyl alcohol) film

A series of biodegradable polymer films based on poly(vinyl alcohol) (PVOH) and jackfruit waste flour (JWF) was prepared in the presence of water and glycerol and cast by a solution casting method. The JWF was introduced as a promoter of biodegradability. The blended films were evaluated for their tensile properties, water absorption, water vapor transmission rate (WVTR), and degradation behavior under different environmental conditions such as natural weathering and natural soil. The tensile strength (1.7–6.4 MPa) and elongation at break (13–108%) of the PVOH/JWF films were lower than those of unfilled PVOH film (26MPa and 238%). However, the Young's modulus values (157–196 MPa) of the PVOH/JWF films were higher than that of unfilled PVOH film (137 MPa). The PVOH/JWF blended films showed higher water absorption and WVTR, which increased with increasing JWF content. Biodegradability tests revealed that the presence of JWF stimulated the degradation rate and caused the weight loss and reduction in tensile properties of the PVOH/JWF blended films. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Hydrophobic nanocomposites of PBAT with Cl-fn-POSS nanofiller as compostable food packaging films

Antibacterial nanocomposite films of poly(butylene adipate-co-terephthalate) (PBAT) incorporated with different weight percentage of octakis(3-chloropropyl)octasilsesquioxane (chloropropyl functionalized POSS [Cl-fn-POSS]) nanofiller were prepared. The mechanical, thermal, morphological, barrier, and antimicrobial properties were examined. The mechanical properties of the nanocomposite films were enhanced by the addition of Cl-fn-POSS nanofiller. An optimum filler loading of 3 wt% is identified to be best suited for maximum enhancement in tensile strength (24 MPa for 3 wt% filled PBAT vs 11 MPa for neat PBAT) while a 1 wt% filler loading was adequate to double the tensile strength. The barrier properties (WVTR and oxygen transmission rate) of PBAT was improved by the presence of Cl-fn-POSS. A volume of 3 wt% filler loading results in 50% reduction of water permeation and 10% reduction in oxygen transmission. The thermogravimetric analyses of the nanocomposites indicated that the filler enabled the enhancement of thermal stability of PBAT. The nanocomposite films revealed antimicrobial activity with this activity increasing with increasing filler content. PBAT is compostable under suitable conditions and with a low weight percentage of filler that is largely made of silicon dioxide these nanocomposite films can find application as biodegradable food packaging material given their flexibility.     

Structure and mechanical properties of soy protein materials plasticized by Thiodiglycol

Thiodiglycol (TDG) is a relatively nontoxic compound from organic wastes. By using TDG as a plasticizer with weights from 2.5 to 40%, we prepared soy protein isolate (SPI) films by a compression‐molding technique at 140°C and 15 MPa. The TDG‐plasticized films (SPI–TDG films) were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, thermogravimetric analysis, optical transmittance, and water uptake experiments. The SPI–TDG film plasticized with 25% TDG exhibited good mechanical properties, such as a tensile strength and modulus of 20.3 and 582 MPa, respectively, whereas the SPI–glycerol film with 25% glycerol had a tensile strength and modulus of 16.2 and 436 MPa, respectively. The results from the thermogravimetric analysis and water uptake experiments indicated that the thermal stability and water resistance of the TDG‐plasticized SPI materials were higher than that of the glycerol‐plasticized one. The improvements in the mechanical properties, water resistance, and thermal stability of the SPI–TDG films could be attributed to the strong intermolecular hydrogen bonding between soy protein and TDG and the presence of fewer hydroxyl groups in TDG, as compared structurally with glycerol. This study provided a new plasticizer for the preparation of soy protein materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

棉秆塑木复合材料的制备及性能研究

以棉秆粉和回收聚乙烯为原料、钛酸酯为偶联剂,采用热压法制备了棉秆塑木复合材料,利用正交试验法探讨了棉秆粉含量、热压温度和保温时间对塑木复合材料性能的影响,并通过物理力学性能测试单独考察了棉秆粉含量对塑木复合材料性能的影响。正交试验法的结果表明:棉秆粉含量对复合材料的弯曲强度、弹性模量和吸水率影响最大,热压温度和保温时间对复合材料的弯曲强度和弹性模量影响较大,对吸水率影响不大;当棉秆粉含量为40%、热压温度为160℃、保温时间为10 min时,塑木复合材料具有最优的综合性能。物理力学性能测试结果表明:复合材料的弯曲强度和弹性模量随棉秆粉含量的增加均呈现先增大后减小的趋势,在棉秆粉含量为40%时均达到最大值;吸水率随棉秆粉含量的增加而增大。     

Effect of starch on thermal,mechanical, and barrier properties of low density polyethylene film

Low‐density polyethylene (LDPE) with different quantities of starch was compounded using a twin screw extruder and blown into films by a Konar K, blow‐film machine. Mechanical properties, namely percent elongation, tensile, bursting, and tear strength, as well as barrier properties, such as water vapor and oxygen transmission rate, of the filled LDPE film were studied. Thermal properties of the films were studied using DSC and DMA. Master curves at reference temperature of 30°C were obtained using software linked to DMA. Incorporation of 1% starch in LDPE has marginally affected the thermal, barrier, and mechanical properties; however, that of 5% starch filled LDPE has affected the properties to a great extent. The mechanical properties, such as percent elongation, tensile, tear, bursting, and seal strength, decreased by 19.2, 33.6, 3.60, 10.8, and 22.12%, respectively. Similarly, water vapor and oxygen transmission rate increased to 32.5 and 18.3%, respectively. Other physical properties, namely migration and thermal properties, were also affected in 5% starch filled LDPE; however, the film can still be used as packaging material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3355–3364, 2006     

Combined effect of isophthalic acid and polyethylene glycol in polyethylene terephthalate polymer on thermal,mechanical, and gas transport properties

The objective of this article is to study the combined effect of isophthalic acid (IPA) and polyethylene glycol (PEG‐400) in PET polymer and film on thermal, mechanical, and gas transport properties. The purpose of developing this material is to reduce the melting point, improve mechanical, thermal, and gas barrier properties. The chosen raw materials, namely, IPA and PEG for copolyester synthesis will replace partially the acid and diol monomers of PET. The molar concentration of comonomers (IPA and PEG‐400) were varied from 2 to 50% and the result shows that the gas barrier properties (namely O₂, CO₂, N₂, and water vapor transmission rate), mechanical, and thermal properties were lesser than that of PET polymer. On improving the crystallinity of PET‐isophthalate‐PEG (PET‐IP) copolymer, barrier properties are improved than that of PET polymer. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Utilization of lentil flour as a biopolymer source for the development of edible films

Lentils are one of the cheapest and most nutritional protein sources for vegetarians. Our objective in this study was to evaluate the feasibility of using lentil flour as a raw material for the development of edible films and to investigate the effects of the glycerol concentration (C_g = 1%, 1.5%, and 2%) and process temperature (T_p; 70 and 90 °C) on the physical properties of these films. The films were characterized via their density; water solubility; thermal, morphological, and chemical characteristics; water vapor permeability (WVP); and tensile and optical properties. The lentil flour films were highly transparent and had lower water solubility values yet similar WVPs and mechanical properties compared to most other biodegradable films. An increase in C_g led to the formation of more flexible films with increased hydrophilicity. A T_p of 90 °C resulted in yellower, more transparent films with increased stiffness compared to a T_p of 70 °C. In this study, lentil flour was shown to be an ideal source for edible film production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46356.     

Preparation of gelatin-based films modified with nanocrystalline cellulose

Gelatin is a natural biological macromolecule derived from the collagen in the connective tissue of the skin, bone and other tissues. It has been widely used in medicine, food and industrial production and other fields for easy molding, excellent compatibility and biodegradability. However, physical and chemical disadvantages impede its further application, seriously. Therefore, modification of the gelatin films becomes more and more important. In this study, the gelatin/nanocrystalline cellulose (NCC) composite films were prepared by casting method with 4% glycerol as plasticizer. The effect of NCC on the properties of the composite films was investigated by the characterization of its morphology and mechanical, thermal, and optical properties and water adsorption. The results showed that mechanical, thermal stability and water absorption properties of the gelatin/NCC composite film were obviously improved. The composite films showed the highest tensile strength (13.56?±?0.25 MPa) when the mass concentration of NCC was 0.6%. Adding NCC to gelatin benefited the thermal stability of composite films. The gelatin/NCC composite film of 0.4% NCC had the highest melting transition temperature (138.9 °C). The composite films exhibited the lower water absorption (271.1%) when mass concentration of NCC was 1.0%. Thus, these results indicated that NCC could affect the properties of gelatin-based composite films, and showed it has potential for application in food packing.     

D‐isosorbide and 1,3‐propanediol as plasticizers for starch‐based films: Characterization and aging study

In the present work, D‐isosorbide and 1,3‐propanediol are proposed as alternative plasticizers obtained from renewable resources. Plasticized starch films were prepared by solvent casting method. The influence of using different “green” plasticizers in the final properties of starch‐based films was analyzed. Besides, the characterization of the films was also performed after storage time in order to evaluate the effect of the plasticizer on aging. UV‐spectrophotometry results showed better optical properties for both glycerol and D‐isosorbide films with higher transparency. The thermal and mechanical properties resulted influenced by the nature of the plasticizer. It was demonstrated that water vapor permeability was governed by the starch‐water interactions, whereas the oxygen permeability depended on the plasticizer's nature. The storage time affected the surface, mechanical, and thermal properties of the plasticized starch films. Atomic force microscopy results concluded that the topography of the films changed due to aging. The use of D‐isosorbide as plasticizer reduced the evolution of the mentioned properties and enhanced the reliability of the material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44793.