Development of a melt‐extrudable biobased soy flour/polyethylene blend for multilayer film applications

Monolayer and multilayer films from biobased linear low‐density polyethylene and milled soy flour were produced through cast film coextrusion processes using conventional thermoplastic processing equipment. Films containing 10 and 20% by weight of soy flour milled to maximum particle sizes of 8, 11, and 22 µm were extruded and characterized as a packaging film material. Water resistance, tensile properties, and gas permeability were measured on each film and analyzed with respects to the soy particle size, soy loading, and layer configuration in the multilayer film structure. Mechanical properties results indicated that ultimate elongation of the soy‐containing films decreased by as much as 14% compared to the control, while tensile strength and maximum load testing did not reveal any identifiable trends. Monolayer soy‐containing film showed high moisture sensitivity, as measured by contact angle and absorption testing, while the multilayer films demonstrated a more hydrophobic nature as indicated by higher contact angle measurements. This increase in hydrophobic properties is due to protective polyolefin skin layers, which are more hydrophobic. Oxygen transmission rates of the multilayer films decreased by 38% due to the presence of soy flour as compared to the control that did not contain any soy flour. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40707.     

Fabrication and characterization of sucrose palmitate reinforced poly(lactic acid) bionanocomposite films

Environmental issues concerning petroleum‐based polymers have begun a growing emphasis to utilize sustainable poly(lactic acid) (PLA) based packaging. However, PLA has its own limitations such as brittleness, high gas permeabilities and slow crystallization rate. With the aim to alleviate these limitations, we made a maiden effort to use a food additive, sucrose palmitate (SP) as eco‐friendly filler for fabrication of PLA based bionanocomposites. FTIR analysis elucidated the presence of hydrogen bonding and intermolecular interaction between PLA and reinforcement. Ordered orientation of the SP in the PLA matrix visualized by TEM analysis revealed uniform dispersion of SP filler into PLA matrix. DSC and XRD results confirmed that the incorporated bio‐filler acted as a nucleating agent and thus partially contributed towards the crystallinity of PLA‐SP bionanocomposites. Enhancement in the tensile strength and elongation at break up to 83 and 56% respectively is obtained. The best positive influence for the oxygen barrier was confirmed for the PLA‐SP bionanocomposite film where the reduction in oxygen permeability by 69% is achieved in comparison to pure PLA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41320.     

A new approach for flexible PBAT/PLA/CaCO3 films into agriculture

The use of flexible films in agriculture has increased intensely in the last 15 years bringing benefits to producers. However, environmental impacts increased due to their incorrect post‐use disposal which leads the degradable films to emerge as an alternative. The production films of poly(butylene adipate‐co‐terephthalate) and poly(lactic acid) reinforced with calcium carbonate (CaCO₃) was studied focusing on producing lower cost materials and flexible films. Four different films (reinforcement compositions) were prepared by melt extrusion with 10 and 20 wt % of CaCO₃. Mechanical and thermal properties, crystallinity, water absorption, and soil degradation, were evaluated. The addition of reinforcement leads to improved compatibility between the polymers in the matrix, which usually presented phase segregation. The films showed better mechanical properties with the addition of CaCO₃. Highly orientated amorphous structures were obtained leading to low water absorption and low degradation in the simulated soil. This low degradation, suggests that the obtained films would be of interest in flexible mulch films manufacturing, particularly for Muridori plantation system, where long‐term plantations are needed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46660.     

Effect of dicumyl peroxide on biodegradable poly(lactic acid)/functionalized gum arabic based films

Blending of poly (lactic acid) (PLA)/functionalized gum arabic (FG) in presence of dicumyl peroxide (DCP) presents a simple process to produce film using melt extrusion (recycle time ~ 4 min, screw speed ~60 rpm) at 180°C with tailored characteristics. The FTIR investigation shows that the confirmation of grafting of PLA chains on FG through formation of new C─C linkage. Properties of fabricated films such as morphological, mechanical, UV barrier and contact angle are examined to develop film with improved interfacial interaction, increased toughness, UV–C blocking effect (~95%) and hydrophobicity (~14%). Polarized optical microscopy (POM) studies reveal that PLA/1FG with and without DCP has more crystal density as compared to PLA at 120°C. This melt extrusion permits straightforward, feasible bionanocomposite film and has great potential as a modification with DCP assists to overcome particular drawbacks of FG.     

Freezing/thawing effects on the exfoliation of montmorillonite in gelatin‐based bionanocomposite

Freezing/thawing is used as a new method to elaborate exfoliated gelatin‐Montmorillonite (MMT) bionanocomposites. The data of X‐ray diffraction and transmission electron microscopy indicate that freezing/thawing is an effective approach to exfoliate the clay for concentrations higher than 5 mass% in gelatin matrix. In addition, after freezing/thawing process to introduce, the crystallinity (triple‐helix content) of gelatin‐MMT bionanocomposites is improved, revealing that freezing/thawing method has the advantages for gelatin molecules to renature into triple‐helix. Specially, the data of Fourier transform infrared indicate that freezing/thawing may be induce more hydrogen bond interactions in gelatin‐MMT bionanocomposites due to the better dispersion of MMT. The mechanical measurements and thermogravimetric analysis show that gelatin‐MMT bionanocomposites prepared by freezing/thawing display enhanced mechanical properties and thermal stability in comparison with the ones prepared by conventional blending at the same clay content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Bioplastic based on 1,8‐octanediol‐plasticized feather keratin: A material for food packaging and biomedical applications

Keratin without plasticizer produces fragile films. 1,8‐Octanediol (OD) was used as a plasticizer to modify keratin films in this study. Two keratins with different structures were extracted from duck feather, including reduced keratin (RK) and native keratin (NK). Formaldehyde was used as the crosslinking agent for RK to prepare crosslinked keratin (CK) films. The addition of OD toughened the CK and RK films. In particular, the plasticized CK films demonstrated good mechanical properties and had satisfactory water resistance. The water vapor permeability varied between 0.106 and 0.808 g/(m s Pa) for CK films without OD and with 0.30 g OD/g keratin, respectively, and the tensile strength decreased from 12.1 to 8.0 MPa and the elongation at break increased from 2.3% to 11.6%. Cell culture experiments suggest that OD‐plasticized NK films are biocompatible. In general, OD‐plasticized keratin films can find applications in food packaging and biomedical materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46516.     

Ultrasonic welding of plasticized PLA films

Poly(lactic acid) (PLA) is a commercially available biobased material that has become an ideal material in packaging applications because of its low toxicity along with its environmentally friendly characteristics. Unfortunately, PLA is rigid and brittle. These characteristics impede its wide application. The flexibility of PLA can be improved by plasticization. In addition, welding polymer films is essential in the packaging production. Therefore, the weldability by means of ultrasonic welding of the neat and with polyethylene glycol plasticized PLA films was analyzed in this study. Moreover, the study examines the influence of the material composition on the processing window, that is, the range of welding parameters which could be used to weld films efficiently, and on the weld quality. This research showed that all examined films can be welded by ultrasonic welding. Furthermore, it was discovered that the addition of a plasticizer has a strong influence on the processing window and on the weld quality. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41351.     

Antibacterial polymer composites based on low‐density polyethylene and essential oils immobilized on various solid carriers

In this study, we investigated the antibacterial modification of polymers with biologically active substances in essential oils [EOs; linalool, 4‐allylanisole (ALY), and trans‐anethole]. These compounds were thermoplastically incorporated into a low‐density polyethylene matrix via solid inert carriers [wood flour (WF) and talc and molecular sieves] with physically immobilized EOs. The concentrations of the antibacterial modifiers on the carriers and in the resulting composites were determined with three chromatographic techniques (gas chromatography with mass spectrometry, pyrolysis and gas chromatography with mass spectrometry, and high‐performance liquid chromatography). The effects of such modifications to the mechanical properties of the prepared composites were studied by stress–strain analysis. Interactions on the polymer matrix carriers were observed by scanning electron microscopy. The prepared composites were also tested for antibacterial activity against both Gram‐negative and Gram‐positive bacterial strains. The highest efficiency of isothermal immobilization was found for systems consisting of ALY and WF. This finding was in accordance with microbiological studies. The phase of immobilizing the EOs did not influence the mechanical properties of the studied composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42816.     

Transparent low‐density polyethylene/starch nanocomposite films

Low‐density polyethylene (LDPE)/starch nanocomposite films were prepared by melt extrusion process. The first step includes the preparation of starch–clay nanocomposite by solution intercalation method. The resultant product was then melt mixed with the main matrix, which is LDPE. Maleic anhydride‐grafted polyethylene (MAgPE), produced by reactive extrusion, was used as a compatibilizer between starch and LDPE phases. The effects of using compatibilizer, clay, and plasticizers on physico‐mechanical properties were investigated. The results indicated that the initial intercalation reaction of clay layers with starch molecules, the conversion of starch into thermoplastic starch (TPS) by plasticizers, and using MAgPE as a compatibilizer provided uniform distribution of both starch particles and clay layers, without any need of alkyl ammonium treatment, in LDPE matrix. The nanocomposite films exhibited better tensile properties compared to clay‐free ones. In addition, the transparency of LDPE film did not significantly change in the presence of TPS and clay particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The fabrication of flexible and oxygen barrier cellulose nanofiber/polylactic acid nanocomposites using cosolvent system

The main disadvantages of polylactic acid (PLA) for food packaging applications are its brittleness and poor gas barrier properties. The purpose of this study is to evaluate the potential usability of triethyl citrate (TEC) and cellulose nanofiber (CNF) in PLA to obtain bio-based films with optimal properties. The incorporation of CNF as reinforcement fillers in polymer matrix has long been debated due to its difficulties to disperse uniformly in hydrophobic polymer matrix attribute to their hydrophobic nature. In order to overcome this problem, different feeding method for CNF into the mixer was studied, and CNF/PLA nanocomposites were characterized. It was found that CNF was successfully dispersed in the PLA matrix through the TEC-CNF suspension, which greatly improved tensile strength and flexibility of the CNF/PLA nanocomposites. The oxygen barrier property was enhanced up to 47.3% (16.99 cc·mm/m²·day·atm) with the increase loading of 0.25, 0.50, and 1 wt% of CNF. Moreover, the dynamic mechanical analysis showed that the low tan delta peak of CNF/PLA nanocomposites (48.25°C) was shifted to high peak (52.99°C) due to incorporation of TEC; indicates an improved of thermal stability of the composites. Overall, the t-CNF/PLA nanocomposites show a great feasibility for various eco-friendly flexible packaging applications.     

Keratin–polyhydroxyalkanoate melt‐compounded composites with improved barrier properties of interest in food packaging applications

Sustainable biocomposite materials based on the combination of polyhydroxyalkanoates with a keratin additive derived from poultry feathers were successfully developed via melt compounding. Suitable dispersions for low loadings of the additive in the biopolymeric matrix were achieved by the melt‐mixing technique. A good physical interaction between the polymeric matrix and the additive was observed by scanning electron microscopy (SEM). Reductions in water, limonene, and oxygen permeability of the pure polymer to less than a half of its initial value for the composite containing 1 wt % of keratin additive were achieved. This composition was also found to exhibit optimum mechanical performance. As a result, these materials offer significant potential in fully renewable packaging applications based on polyhydroxyalkanoates with enhanced barrier performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39947.     

Reactive modification and compatibilization of poly(lactide) and poly(butylene adipate‐co‐terephthalate) blends with epoxy functionalized‐poly(lactide) for blown film applications

Biodegradable blown films comprising of poly(lactide) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) were produced using epoxy functionalized‐poly(lactide) (EF‐PLA) reactive modifiers for rheological enhancement and compatibilization. The epoxy groups on the EF‐PLA modifiers react with PBAT forming an in situ copolymer that localizes at the blend interphase resulting in compatibilization of the polymer blend components. The EF‐PLA modified polymer blends have improved melt strength and the resultant films showed better processability as seen by increased bubbled stability. This allowed for blown films with higher PLA content (70%) compared to the unmodified control films (40%). The static charge build‐up typically experienced with PLA film blowing was decreased with the inclusion of EF‐PLA yielding films with better slip and softness. The compatibilization effect of the EF‐PLA modifiers resulted in significant improvement in mechanical properties. For example, dart test performance was up to four times higher than the control, especially at higher PLA concentrations. Therefore, the rheological enhancement and compatibilization effects of the EF‐PLA reactive modifiers make them ideally suited to create high PLA content films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43310.     

Pullulan‐based films and coatings for food packaging: Present applications,emerging opportunities,and future challenges

Societal and industrial demands for lower environmental impact, cost effectiveness, and high‐performance goods and services are increasingly impacting the choice of technologies which are developed and deployed in consumer products. Like many other sectors, food packaging is moving to new technologies; the use of biopolymers is one of the most promising strategies toward an optimized use of traditional packaging materials (e.g., oil‐based plastics) without impairing the goal of extending shelf life. Among other food packaging materials, pullulan is attracting much attention due to its unique features. The goal of this review is to provide an overview of current and emerging applications of pullulan within the food packaging sector. In particular, the functional properties of interest for the food packaging industry will be discussed in light of the physicochemical attributes of this exopolysaccharide. Future challenges that may dictate the successful penetration of pullulan in the food packaging market are also outlined. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40539.     

Improvement of water barrier properties of soybean protein isolate films by poly(3-hydroxybutyrate) thin coating

The aim of this work was to study the preparation of bilayer films formed by soy protein isolate (SPI) and polyhydroxybutyrate (PHB). This was done using the lowest possible concentration of PHB to improve the functionality of SPI films as food packaging or for agricultural uses, specially reducing their water vapor permeability (WVP). SPI films are environmentally friendly since they are biodegradable and come from renewable sources but they are brittle and have high water permeability. Even for the lowest concentration analyzed, PHB managed to form a homogeneous layer that successfully covered up the SPI film surface. All bilayers films showed a significant reduction of WVP of SPI films, and those with the highest PHB content showed the highest elastic Young's modulus and mechanical strength while maintaining a good elongation and low T_g value, similar to that of SPI. Despite of their hydrophobicity differences, a good adherence of both layers was achieved, which allowed to improve the mechanical and barrier properties of the SPI coated films with respect to films formed by both biopolymers separately. The combination of both SPI and PHB seems to be a good alternative to prepare a biodegradable material taking advantages of the best properties of each component.     

Humidity regulation by stretched PP and PLA films with dispersed CaCl2

Polymer materials that regulate the relative humidity in their environment are relevant for applications in the packaging and building sectors. By integration of salts in polymer structures, such materials are able to absorb and desorb high amounts of water vapor. In this study, films of polylactic acid and polypropylene with dispersed calcium chloride (2 and 4 wt %) were produced and biaxially stretched to induce the formation of cavities. The resulting cavities in these films account up to 10 vol % and are able to contain emerging calcium chloride solution formed by water vapor absorption. These films absorb reversibly up to 15 wt % water vapor at 75% relative humidity at 23 °C. This absorption behavior is described by effective diffusion and effective sorption coefficients. Using a simple model, the effective water vapor diffusion coefficient of these films can be estimated from the permeation coefficient of the polymer and the sorption coefficient of the absorber. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45713.     

Orange peel‐derived pectin jelly and corn starch‐based biocomposite film with layered silicates

Orange peel‐derived pectin jelly/corn starch‐based biocomposite films with and without layered silicates (LSs) were prepared using melt extrusion followed by film die casting. To enhance interfacial compatibility, corn starch and LSs were chemically modified. Regardless of chemical modification or LS weight content, different pectin jelly‐to‐starch weight ratios (63/37, 60/40, 57/43, and 54/46) were considered to formulate the ingredients of biocomposite films in light of Taguchi‐based predictions. X‐ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), scanned electron microscopy (SEM) and transmission electron microscopy (TEM) were systematically used to characterize corn starch, LSs, and biocomposite films. Among all the films considered, pectin jelly/modified (15%) starch‐based biocomposite film (54/46 w/w) containing 0.25 wt % of pristine LSs was found to be the most promising in terms of texture structure and mechanical integrity. Furthermore, creep recovery, hydrophobicity, and water vapor and oxygen gas transmission rates of the most promising biocomposite film were experimentally determined. Based on the findings obtained, the overall performance of the biocomposite film was evaluated and weighed against the overall performance of a low‐density polyethylene film. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40654.     

Development and characteristics of biodegradable Aloe‐gel/egg white films

The use of synthetic nonbiodegradable polymers has led to environmental damage. This has encouraged the interest to the development of new renewable and biodegradable matrices. The potential of egg white (EW) protein for the development of bioplastic materials has been published. However, the mixture of EW with Aloe‐gel (AG) for film formation has not been documented. In this study, films with different EW and AG combinations are manufactured and their properties are analyzed. In general, the AG/EW films are homogeneous, smooth, with no pores and with cumulus of protein on the surface with better extensibility, plasticity, and low tensile strength. In addition, they are yellow colored, UV‐light blocker, with high solubility (2.2 times) and high Water Vapor Permeability (4.17 times) compared with the control (EW film). The AG/EW films showed higher percentage of soluble protein and antibacterial activity than the control. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44067.     

Antioxidant and physicochemical properties of blended films based on gelatin‐sodium caseinate activated with natural extracts

Blend films of pigskin gelatin (GEL) and sodium caseinate (SCas) with boldo (B), guarana (G), cinnamon (C), or rosemary (R) extracts added were studied. SCas and extracts addition in blend films significantly increased the gloss and better UV barrier of GEL100 films. Extracts incorporation significantly decreased the rigidity and elongation of GEL100 films, which were significantly improved in GEL75:SCas25 blend films with extracts (EM = 295.69 ± 21.75 MPa and EB = 11.60 ± 3.43%). SCas addition not affected the TS parameter. The water vapor permeability of GEL100 films was reduced in blended films with extracts, showing the lowest value for GEL75:SCas25 + R (0.99 ± 0.07 × 10¹⁰ g s^?1 m^?1 Pa^?1). FTIR and microstructure analyses showed good compatibility for all components. The antioxidant activity of GEL100 was significantly increased with SCas and extracts addition (GEL50:SCas50 + R = 4.31 ± 0.11 mM ), suggesting the application of these films as an active food packaging material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44467.     

Preparation and characterization of poly(vinyl alcohol)/gum tragacanth/cellulose nanocomposite film

The effects of gum tragacanth obtained from two species of Astragalus Gossypinus (GT-G) and A. Parrowianus (GT-P) at two levels of 10% and 30% combined with cellulose nanofibers (CNF; 5%) on the physico-mechanical and structural properties of polyvinyl alcohol (PVA) nanocomposite film were investigated in this study. The water solubility and water vapor permeability of the films decreased with increasing the content of both gums, especially in the film containing 30% GT-P. The highest values of the tensile strength (39.3 MPa) and elongation at break (445%) belonged to the treatment containing 10% GT-P (90/10P/0). The FTIR and DSC analyses confirmed good interactions between GT and PVA in the 90/10P/0 treatment. SEM images indicated the dense structure of this film as the optimum treatment. Although the presence of CNF in the films containing GT-G improved some properties, especially the Young modulus, it impaired all the functional properties of nanocomposite GT-P film.     

Crosslinkable poly(lactic acid)‐based materials: Biomass‐derived solution for barrier coatings

The demand for biobased barrier packaging alternatives is constantly growing. Poly(lactic acid) (PLA)‐based polymers are one of the most extensively studied biomass‐derived synthetic polymers; however, they typically lack water‐barrier properties. We synthesized a copolymer of d ,l ‐lactic acid, 1,4‐butanediol, and itaconic acid [poly(d ,l ‐lactic acid–1,4‐butanediol–itaconic acid) (PLABDIA)] via bulk polycondensation. The radical crosslinking reactions of the synthesized polymer were investigated with bulk crosslinking trials to find a formulation that was suitable for a rapidly crosslinkable barrier coating. The crosslinking efficiency was tested with methacrylate and acrylate crosslinkers together with peroxide radical initiators. Poly(ethylene glycol) diacrylate (number‐average molecular weight = 250 g/mol) together with dilauroyl peroxide proved to be the best crosslinker–initiator combination. An aqueous dispersion of PLABDIA was prepared with a thermomechanical method and applied to commercial boxboard on a pilot‐scale line coater. With a coating weight of 10 g/m², a water vapor transmission rate of 22.8 g/m²d was achieved, and this coating outperformed commercial extruded PLA coatings. The samples also showed very good grease resistance and would, therefore, be a good solution for the packaging of dry and fatty goods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44326.