Potato protein isolate‐based biopolymers

Thermal processing of two potato protein isolates (PPIs) with glycerol as a plasticizer was explored in this study. The PPIs were pretreated by alkali or alkali under reducing conditions. The PPIs before and after pretreatment were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The effects of plasticizer content and pretreatment on mechanical and thermo‐mechanical properties of the compression‐molded biopolymers were studied. The highest tensile strengths obtained were 20–25 MPa and the biopolymer can be brittle or ductile depending on the plasticizer contents. The molecular weight and protein structure of the PPIs markedly affected the resultant biopolymers’ static and dynamic mechanical properties. The pretreatment of PPIs caused distinctly different changes in the mechanical properties of the two PPIs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42723.     

Characteristics of soy protein isolate‐montmorillonite composite films

Soy protein isolate/montmorillonite (SPI/MMT) nanocomposite films were prepared in which MMT was used as a nanofiller at 0, 3, 6, 9, 12, and 15 wt % relative to SPI dry weight. Effects of MMT on film properties including tensile strength, elongation at break, total soluble matter, water vapor permeability, and oxygen permeability were assessed. X‐ray diffraction patterns were determined, and morphologies of SPI and the SPI‐MMT composite films were visualized by scanning electron microscopy. Mechanical and barrier properties were improved by evidenced increases in tensile strength and modulus, and decreases in permeability to water vapor and oxygen. MMT concentrations of 3%–12% were optimal for improving functional properties of the composite films. X‐ray diffraction and scanning electron microscopy examinations revealed the formation of an intercalated and exfoliated structure on the addition of MMT into the SPI matrix. We conclude that intercalated and exfoliated MMT silicates enhance mechanical and barrier properties of SPI films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Water vapor permeability properties of edible whey protein-lipid emulsion films

The water vapor permeability (WVP) of whey protein emulsion films was investigated. The exponential effect of relative humidity on the WVP of whey protein films was reduced through lipid incorporation. Film orientation had a significant effect on WVP due to emulsion separation during film formation. Heat denaturation of whey proteins lowered emulsion film WVP. Increasing fatty acid and fatty alcohol chainlengths significantly reduced WVP, as did increasing lipid concentration. The WVPs of fatty acids, fatty alcohols and beeswax were compared in whey protein-lipid emulsion films. Scanning and transmission electron microscopy revealed the crystalline microstructure of lipid particles in emulsion films.     

Mechanical and barrier properties of edible starch–protein‐based films

The present investigation dealt with the mechanical properties, water‐vapor transmission behavior at different relative humidity conditions, and DSC thermograms of edible films formulated using various proteins (casein, gelatin, albumin) in combination with starch and nonthermal as well as intense thermal blending. Nonthermal blended film showed in the DSC thermogram a double T_g, indicating poor miscibility of the components and, hence, a poor film‐forming property. However, the DSC thermogram of all the films based on intense thermal blending showed a single T_g, indicating the complete molecular miscibility of the components. Casein‐based film showed a lower water‐vapor transmission rate, water gain at different relative humidity conditions, and higher tensile strength compared to its counterparts containing gelatin and albumin. Since the casein–starch blend gave better film properties, a blend of hydrophobic carnauba wax and casein was prepared to compare the properties of hydrophilic–hydrophilic and hydrophobic–hydrophilic blends. Both these blends compared well with respect to the water‐vapor transmission rate. Wax‐based film showed multiphased behavior in the DSC thermograms and the percent elongation was lower as compared to the casein–starch blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 64–71, 2003     

Preparation and characterization of poly(vinyl alcohol) and 1,2,3‐propanetriol diglycidyl ether incorporated soy protein isolate‐based films

Novel biodegradable films were prepared from soy protein isolate (SPI), poly(vinyl alcohol) (PVA), glycerol, and 1,2,3‐propanetriol diglycidyl ether (PTGE). The mechanical, hydrophilic, and compatible properties of the films were investigated. The influence of PTGE as a crosslinker on the properties of the SPI/PVA/PTGE films was examined with Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), thermogravimetric analysis, mechanical analysis, contact angle measurements, and scanning electron microscopy. XRD and contact angle examination confirmed that the addition of PTGE altered the film microstructure to a crystalline one. The mechanical properties and water resistance of the SPI/PVA/PTGE films increased notably compared with those of the unmodified SPI films. All results indicate that the networks were formed between SPI and PTGE and played an important role in forming a homogeneous structure in the obtained films. The novel biodegradable films provide a convenient and promising way for preparing environmentally friendly film materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42578.     

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     

Dual release kinetics of antimalarials from soy protein isolate‐carbopol‐polyacrylamide based hydrogels

The currently used antimalarials suffer from drug resistance which is hampering the global management of malaria infection. To overcome drug resistance, they are administered as combination therapies which involve combination of two or more antimalarials. In this study, chloroquine diphosphate and curcumin were encapsulated onto prepared soy protein isolate‐carbopol‐polyacrylamide based hydrogels. The hydrogels were pH sensitive and exhibited enhanced swelling capability at pH 7.4. The hydrogels were biodegradable which was observed by their SEM images after drug release. The release mechanisms of both drugs were influenced by the degree of crosslinking of the soy protein isolate in the hydrogel network and the presence of the other drug in the network. The release mechanisms of both drugs from the hydrogel networks followed super case transport II. These results suggested that the hydrogels were potential dual drug delivery systems for antimalarials whereby both drugs could work over different period of time and hence, have the potential to overcome drug resistance that is common with the presently used antimalarials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43918.     

Preparation and characterization of soy protein isolate–carboxymethylated konjac glucomannan blend films

To improve the mechanical and water vapor barrier properties of soy protein films, the transparent films were prepared by blending 5 wt % soy protein isolate (SPI) alkaline water solution with 2 wt % carboxymethylated konjac glucomannan (CMKGM) aqueous solution and drying at 30 °C. The structure and properties of the blend films were studied by infrared spectroscopy, wide‐angle X‐ray diffraction spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, and measurements of mechanical properties and water vapor transmission. The results demonstrated a strong interaction and good miscibility between SPI and CMKGM due to intermolecular hydrogen bonding. The thermostability and mechanical and water vapor barrier properties of blend films were greatly enhanced due to the strong intermolecular hydrogen bonding between SPI and CMKGM. The tensile strength and breaking elongation of blend films increased with the increase of CMKGM content: the maximum values achieved were 54.6 MPa and 37%, respectively, when the CMKGM content was 70 wt %. The water vapor transmission of blend films decreased with the increase of CMKGM content: the lowest value achieved was 74.8 mg · cm^?2 · d^?1 when the CMKGM content was 70 wt %. The SPI–CMKGM blend films provide promising applications to fresh food packaging. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1095–1099, 2003     

Oxygen barrier materials from renewable sources: Material properties of softwood hemicellulose‐based films

The aim of this study was to investigate the film‐forming ability of the hemicellulose O‐acetyl‐galactoglucomannan (AcGGM) and to evaluate its potential as a barrier material. The polymer film was evaluated by measurement of its oxygen permeability (Ox‐Tran® Mocon), thermal properties (differential scanning calorimetry), and dynamic mechanical properties under a humidity scan (humidity‐scan DMA). The AcGGM was isolated from industrial process water obtained from mechanical wood pulping. The self‐supporting films were formed by solution‐casting from water. As expected, a plasticizer was needed to avoid brittleness, and glycerol, sorbitol, and xylitol were compared. However, these additives resulted in higher sensitivity to moisture, which might be less beneficial for some applications. Interesting oxygen barrier and mechanical strength properties were achieved in a film obtained from a physical blend of AcGGM and either alginate or carboxymethylcellulose, both having a substantially higher molecular weight than AcGGM. No phase separation was observed, since all the components used were rich in hydroxyl functionalities. When a plasticizer was also added to the binary mixture, a compromise between (1) low O₂ permeability, (2) high mechanical toughness, and (3) flexibility of an AcGGM‐based film was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2985–2991, 2006     

Mechanical and barrier properties of thermoplastic whey protein isolate/ethylene vinyl acetate blends

Crude oil is becoming scarcer and more expensive, resulting in alternative biobased or partially biobased materials gaining importance in the field of plastic packaging and encouraging the development of naturally derived, protein‐based plastics (Endres, 2009; Jones and McClements, Compreh. Rev. Food Sci. Food Safety 2010, 9, 374; Khwaldia et al., Compreh. Rev. Food Sci. Food Safety 2010, 9, 374). A strategy to improve extrusion processing behavior of proteins is the blending with other polymers. In this study ethylene vinyl acetate (EVA) was used for such purpose. The aim of this study was to determine the properties of blends of thermoplastic whey protein (TPP) and ethylene vinyl acetate (EVA). Mechanical and barrier properties were tested. Blends of differing TPP/EVA ratio were produced and extruded into flat films. Morphological analysis of the blends shows immiscibility of the TPP and EVA, greatly influencing the mechanical properties. Young's modulus measurements shows the values approached that of pure EVA with increasing EVA ratios. At values of about 21 MPa, corresponding to EVA ratios of 30% (w/w) and above, continuous extrusion including material take‐off was possible. At higher whey protein ratios in the blends the water vapor transmission rate increased, i.e., the higher water vapor transmission rate of whey protein compared with EVA dominated this property. This study showed that whey proteins can be utilized for extrusion by blending with EVA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41172.     

Mechanical and barrier properties of carbon nanotube reinforced PCL‐based composite films: Effect of gamma radiation

Carbon nanotube (CNT) reinforced (0.05–0.5% by wt) polycaprolactone (PCL)‐based composites were prepared by compression molding. Addition of 0.2% CNT caused a 131% improvement of tensile strength (TS) of PCL films. The tensile modulus (TM) and elongation at break (Eb) of PCL were also significantly improved with the addition of CNT. The water vapor permeability of PCL was 1.51 g·mm/m²·day but 0.2% CNT containing PCL films showed 1.08 g·mm/m²·day. Similarly, the oxygen transmission rate (OTR) of PCL films was found to decrease with the addition of CNT. But, carbon dioxide transmission rate (CO₂TR) of PCL film was improved due to incorporation of CNT. Effect of gamma radiation on PCL films and CNT reinforced PCL‐based composites were also studied. The TS of the irradiated (10 kGy) PCL films gained to 75% higher than control sample. The TS of the 0.2% CNT reinforced composite film was reached to 41 MPa at 15 kGy dose. The barrier properties of non‐irradiated and irradiated (10 kGy) PCL films and composites (0.2% CNT reinforced) were also measured. Both PCL films and composites showed lower values of WVP upon irradiation and indicated better water vapor barrier. The OTR and CO₂TR of the irradiated (10 kGy) PCL films and composites were decreased compared to their counterparts. Surface and interface morphologies of the composites were studied by scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Reinforced soy protein isolate–based bionanocomposites with halloysite nanotubes via mussel‐inspired dopamine and polylysine codeposition

Fully renewable soy protein isolate (SPI)–based film with rigid strength and sufficient water resistance is difficult to attain. In this study, the mussel‐inspired surface chemistry of ?‐poly‐L‐lysine (?‐PL)/dopamine was exploited for codeposition onto halloysite nanotubes (HNTs) to engineer a multinetwork of HNT/SPI bionanocomposite films via physicochemical bonds. A series of ?‐PL/dopamine aqueous solutions at different concentration ratios were employed. The ?‐PL with abundant cationic amine groups could prevent the overoxidation of dopamine on HNT surfaces, thus maintaining sufficient free catechol groups for highly active reactions that improve the biphase interfacial adhesion. Moreover, HNTs surface entangled by ?‐PL chains could be more compatible with peptides. This codeposition of ?‐PL/dopamine on HNT (DLHNT) surfaces was analyzed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. Compared to the control SPI film, the tensile strength of the nanocomposite film (DLHNTs0.5/SPI) was increased from 5.9 MPa to 8.25 MPa, the Young's modulus was improved by 166.4%, and the moisture absorption was reduced to 56.1% (87.2% of the control). In summary, a facile and mild bioinspired surface chemistry of ?‐PL/dopamine codeposition onto HNT surfaces was performed to prepare SPI‐based nanocomposite films with improved interfacial adhesion and benign compatibility. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46197.     

Microencapsulation of capsanthin by soybean protein isolate‐chitosan coacervation and microcapsule stability evaluation

Although capsanthin possesses excellent coloring performance and healthcare functions, its application in the food industry is limited due to its susceptibility to humidity, heat, and light. The purpose of this research was to microencapsulate capsanthin by soybean protein isolate (SPI)‐chitosan coacervation and evaluate whether the microencapsulation improved the stability of capsanthin against the adverse conditions mentioned above. The results indicated that the optimum conditions for capsanthin microencapsulation were emulsification speed 10,000 rpm, emulsification temperature 45°C, wall concentration 15 g/L and core to wall ratio 1:2 (w/w). Under these conditions, the droplets in the emulsion were even in size distribution without agglomeration and the microencapsulation efficiency and microencapsulation yield reached 90.46% and 86.69%, respectively. Microencapsulation increased the stability of capsanthin against low/medium moisture, heat, and especially light, but was less effective in protecting capsanthin microcapsules in high moisture. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39671.     

Nanocomposites‐based polyolefins as alternative to improve barrier properties

This work investigates the influence of some ammonium quaternary compounds as coupling agent in polyethylene/clay nanocomposites to improve the performance of polyethylene used as packaging barrier material. The 3 wt % of vermiculite used as a nanofiller was added to linear low‐density polyethylene (LLDPE) and to linear low‐density polyethylene grafted with maleic anhydride (LLDPE‐g‐MA). The analysis results revealed that the influence of both the clay exfoliation in a polymer matrix and the coupling agents on the barrier properties were significant. Among the coupling agents used, cetylpropyldimethylammonium chloride yielded the best result for vermiculite exfoliation. A reduction of up to 18% in the oxygen‐permeability coefficient was observed in the nanocompounds with exfoliated vermiculite. The nanocomposite produced with vermiculite did not prove to be efficient as a moisture barrier against according to the analysis performed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermomechanical properties of styrene‐butyl acrylate/organo‐silica nanocomposite films prepared by seed emulsion polymerization

Organo‐silica nanoparticles were prepared by sol–gel technique of triethoxyvinylsilane (VTES) in aqueous solution. The vinyl groups located on the surface of organo‐silica were used to induce the polymerization process and the encapsulation into styrene‐butyl acrylate copolymer emulsion. The prepared latex samples were characterized using FTIR, ¹HNMR, UV–visible, thermal analysis, field emission‐SEM and TEM. Results of TGA revealed that nanosilica has retarded the decomposition of nanocomposite polymers with at least 10°C higher than that of pure emulsions. DSC has shown an increase in the nanosilica ratio up to 5% which leads to a dramatic decrease in the glass transition (T _g) of nanocomposite polymer due to the formation of silica nanoparticles homopolymer. DMTA results indicated that the storage modulus of pure polymer is less than nanocomposite, which proves the reinforcing role of nanosilica in the matrix of polymer. Water resistance and UV‐blocking ability have improved by introducing the nanosilica into the matrix of prepared polymer. POLYM. COMPOS., 38:61–67, 2017. © 2015 Society of Plastics Engineers     

Tensile properties,barrier properties,and biodegradation in soil of compression—Molded gelatin‐dialdehyde starch films

Glycerol (Gly)‐plasticized gelatin (Ge) films crosslinked with dialdehyde starch (DAS) as environmentally friendly crosslinking agent were successfully produced by compression molding, demonstrating the capacity of gelatin of being transformed into films by using thermoplastic processes. The effect of DAS content on the color, light transmission, total soluble matter (TSM), water uptake (WU), water vapor permeability (WVP), oxygen permeability (OP) as well as biodegradability during soil burial was investigated. The addition of up to 10 wt % DAS (Ge‐10DAS) generated transparent films, with reduced TMS, WU, WVP, and OP values but higher extensivity than the uncrosslinked counterpart. Further incorporating DAS into plasticized‐gelatin matrix conducted to phase separation with detrimental effect of transparency and tensile properties. DAS‐containing films degraded at slow rate than the uncrosslinked counterpart, suggesting that biotic attack during soil burial is restricted by covalent crosslinking points induced by DAS. Ge‐10DAS films lost about 28% of their initial mass within the first 8 days of exposure to degrading medium; therefore, the material can be classified as rapidly degradable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyethylene‐based nanocomposite films: Structure/properties relationship

Polyethylene (PE) is the most used thermoplastic commodity as a consequence of its convenient cost‐processing‐performance relationship and it can be used in the form of films for food, goods and farming packaging. On the other hand, sepiolite is a high surface area and porosity hydrated magnesium silicate with both remarkable adsorptive and absorptive properties. Thus, PE and sepiolite can combine their properties synergetically to obtain new materials with enhanced properties. In this work, a systematic study of final properties of PE‐sepiolite nanocomposite films was performed to investigate the influence of the sepiolite content and modification on the PE properties. Nanocomposites films with 1, 3, 5 and 10 wt % of sepiolite, with and without surface modification, were prepared by cast film extrusion and tested. The filler dispersion and distribution were evaluated by Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), whereas the film crystalline morphology was analyzed using Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC) and X‐ray Diffraction (XRD). Final properties as mechanical ones, oxygen permeability and transparency were also studied and related with the film structure. Mechanical properties, crystallization and oxygen permeability were increased maintaining good film translucency. POLYM. ENG. SCI., 54:1931–1940, 2014. © 2013 Society of Plastics Engineers     

Microstructural and mold resistant properties of environment‐friendly oil‐modified polyurethane based wood‐finish products containing polymerized whey proteins

Environmental concerns associated with the level of volatile organic compounds used in surface coatings have stimulated increased scientific research toward novel methods of developing environment‐friendly coatings. Prototype wood finish products containing polymerized whey proteins (PWP) were formulated. The microstructural characteristics of dry films prepared from environment‐friendly wood finishes containing PWP were examined using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The susceptibility of the coatings to microbial degradation was also examined using an accelerated mold test. AFM analysis revealed that increased addition of PWP resulted in films with increased surface roughness, decreased number of voids, and increased void size due to excessive aggregation among polymer components. CLSM analysis showed that the PWP distribution in the films is enhanced by homogenization of the coating mixes. There was no significant increase (P > 0.05) in mold growth between panels coated with finish containing PWP and those without PWP. Test panels coated with formulation containing PWP and low levels of biocide (0.3%) resulted in a significant decrease in mold growth in comparison to commercially available water‐based polyurethane coatings (P < 0.05). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3519–3530, 2006     

Gas transport properties in chlorosulfonated polyethylene‐acrylate based adhesives

The permeability and diffusivity properties of four gases—oxygen, nitrogen, carbon dioxide and methane—have been obtained for membranes prepared by the photocrosslinking of a mixture of chlorosulfonated polyethylene, acting as a binder, and a series of acrylic and methacrylic monomers. These measurements have been performed in the range 20°C to 50°C, and the activation energies have also been determined. These data are presented in comparison with those previously obtained in a crosslinked system in which the binder was not chlorosulfonated polyethylene but an aliphatic polyurethane. Both polymeric systems show similar permselectivities for the gas pairs O₂/N₂ (near 5) and CO₂/CH₄ (near 12), though overall permeability is about three times lower in the chlorosulfonated polyethylene—based polymer because of the smaller diffusion coefficients. The permeation and diffusion results are discussed in terms of the final structure of the photocrosslinked polymeric system, and it is concluded that it is the binder which is mostly responsible for the gas transport properties of these crosslinked materials.     

PLA/functionalized‐gum arabic based bionanocomposite films for high gas barrier applications

The present work focuses on the microwave synthesis of lactic acid‐grafted‐gum arabic (LA‐g‐GA) by polycondensation reaction and its influence as an additive to improve the gas barrier properties of poly(lactic acid) (PLA) films, prepared by solution casting method. It is observed that during the synthesis of LA‐g‐GA, hydrophilic gum is converted into hydrophobic due to grafting of in situ grown hydrophobic oligo‐(lactic acid). Subsequently, PLA/LA‐g‐GA bionanocomposite films are fabricated and characterized for structural, thermal, mechanical and gas barrier properties. Path breaking reduction in oxygen permeability (OP) of ～10 folds is achieved in case of PLA films containing LA‐g‐GA as filler. However, water vapor transmission rate (WVTR) is reduced up to 27% after 5 wt % addition of filler. Reduction in OP of this order of magnitude enables the PLA to compete with PET in term of enhancing shelf life and maintaining the food quality. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43458.