Zein‐based ultrathin fibers containing ceramic nanofillers obtained by electrospinning. I. Morphology and thermal properties

This work presents the first results on the development and characterization of novel nanobiocomposite fibers prepared by electrospinning of zein/clay mixtures (from 99/1 to 75/25 wt/wt) from ethanol‐based solutions. To do so, commercial ceramic materials of different nature, such as organomodified and unmodified mica, kaolinite, montmorillonite, and zeolite were employed and compared. A significant decrease in fiber diameter was observed as the clay fraction increased in the hybrid material. The highest clay contents also produced fibers but with extended beaded regions. All fillers nanodispersed well in the fibers at low loadings but unmodified mica particles were also seen excluded from the fibers, most likely due to excessive size. Surprisingly, the ceramic laminar structures, i.e. the phyllosilicates, were all seen to embed within the ultrathin fibers in what appears as an unreported rolled morphology due to the extensional forces generated by the electrospinning process. Electrospun nanobiocomposite fibers with optimal ceramic nanoparticle contents are currently investigated as an adequate procedure to prepare naturally occurring composite additives, coatings, and interlayers with enhanced performance in terms of mechanical, thermal, barrier, and control release properties for packaging, active packaging, biomedical, and pharmaceutical applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical recycling of nanocellulose containing multilayer packaging films

The aim of this study was to demonstrate mechanical recycling of low density polyethylene (LDPE) films coated with a thin layer of cellulose nanofibrils (CNFs). CNF acts as an effective barrier against oxygen and mineral oil residues. Two different CNF grades were tested, and both were applied onto plasma activated LDPE film using a pilot coating line. The coated films were shredded with the help of liquid nitrogen, compacted and compounded with virgin LDPE and compatibilizer, and processed into cast films and injection molded test specimens. The CNF coatings were completely blent as microscale agglomerates in the LDPE matrix. The effect of these agglomerates on the barrier and heat sealing properties was statistically insignificant compared to recycled uncoated LDPE. The mechanical properties were only moderately changed. CNF‐coated LDPE films can therefore be recycled back into films without sacrificing the characteristic properties of the base polymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46237.     

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.     

Morphology,physical properties,silver release,and antimicrobial capacity of ionic silver‐loaded poly(l‐lactide) films of interest in food‐coating applications

In the present study, silver ions were incorporated into a poly‐(l ‐lactide) (PLA) matrix by a solvent casting technique using different solvents and glycerol as plasticizer. The effect of the different formulations on the morphology, thermal, mechanical and color properties were first evaluated. Additionally, a thorough study of the silver ions release to an aqueous environment was also monitored over time by anodic stripping voltammetry and correlated with the antimicrobial performance against S. enterica. The incorporation of silver contents of up to 1 wt % did not affect morphology, thermal or mechanical properties of the films. A sustainable, antibacterial effectiveness was found for the films in liquid medium and a breakpoint of 10–20 μg L^?1 silver was established under the stated conditions, evincing silver ion releasing technologies may be applied to liquid environments while complying with current legislation. This study provides insight into the structure properties relationship of these antibacterial polylactide materials of significant potential in coating applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41001.     

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.     

Mushroom polysaccharides‐incorporated cellulose nanofiber films with improved mechanical,moisture barrier,and antioxidant properties

Mushroom polysaccharides (MP), including white MP, brown MP, and enoki MP, were incorporated into cellulose nanofiber (CNF). Studies on thermal property, structure, crystallinity, and morphology of CNF‐MP films revealed that MP was well interacted with and adsorbed onto CNF. Incorporation of MP significantly (P < 0.05) increased tensile strength and reduced water vapor permeability of CNF film. CNF‐MP films possessed higher antioxidant activity than CNF only or CNF‐chitosan film, and the antioxidant activity of released components from CNF‐MP films immersed in water was higher than that released from films immersed in methanol. Radical scavenging activity and reducing ability were major antioxidant mechanisms of CNF‐MP films. These trends were consistent with the results of total phenolics content released from films and the antioxidant activity of MP themselves. This study demonstrated CNF‐MP films may be used as packaging material for preventing oxidation and/or dehydration of food during storage. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46166.     

On the use of ball milling to develop poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐graphene nanocomposites (II)—Mechanical,barrier, and electrical properties

In this work, poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) nanocomposites containing functionalized graphene sheets (FGS) were prepared by means of high‐energy ball milling. The crystalline structure, oxygen barrier, mechanical and electrical properties, and biodegradability of the developed nanocomposites were analyzed and correlated with the amount of FGS incorporated and with their morphology, which was reported in a previous study. Addition of FGS into the PHBV matrix did not affect the crystal morphology of the material but led to somewhat enhanced crystallinity. The good dispersion and distribution of the nanofiller within the polymeric matrix, revealed in the first part of this study, was thought to be crucial for the mechanical reinforcing effect of FGS and also resulted in enhanced gas barrier properties at high relative humidity. Additionally, the conducting behavior of the nanocomposites, as interpreted by the percolation theory, displayed a very low percolation threshold set at ～0.3 vol % of FGS, while the materials exhibited an overall significantly enhanced conductivity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42217.     

Mechanical and barrier properties of soy protein isolate films plasticized with a mixture of glycerol and dendritic polyglycerol

Soy protein isolate (SPI) films plasticized with different contents of short and linear glycerol (G) and hyperbranched dendritic polyglycerol (DPG) in the presence of water were prepared for the first time with kneading and compression molding; these were analyzed in relation to their visual, morphological, microstructural, mechanical, and water‐ and oxygen‐barrier properties. It was shown that the film prepared with a mixture of 15G15DPG (where the numbers represent the weight percentage of the respective compound) had a higher tensile strength (∼14.4%), lower elongation at break (∼85.7%), and improved water‐barrier (∼54.6%) and oxygen‐barrier (∼84.1%) properties compared to the SPI film plasticized only with 30G. The attenuated total reflectance–Fourier transform infrared spectra of the plasticized SPI films indicated that such properties were related to the approximately 11.3% higher conversion of SPI from the α‐helical conformation to the intramolecular β‐sheet structures for the 15G15DPG films. This resulted in finer films with lower surface roughnesses and surface areas. On the other hand, further increases in G and DPG revealed an opposite effect and worsened the properties; this was much more pronounced by the increased DPG amount because of SPI unfolding and aggregation and resulted in microporous films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41837.     

Preliminary evaluation of packaging‐content interactions: Mechanical and physicochemical characterization of polylactide bottles

Biodegradable materials as polylactide (PLA) are very interesting for cosmetic packaging application. However, these polymers, under environmental conditions or/and chemical treatments, can undergo “aging,” compromising their performances such as container. The aim of this study was the evaluation of mechanical, physicochemical, and organoleptic properties of PLA bottles present in the cosmetic market. In particular, mechanical tests and thermal analyses were applied to study the PLA container degradation under stressed physicochemical conditions. Calorimetric and morphological analyses were applied to evaluate differences between internal and external surface of containers. Results highlighted that the heating process together with chemical treatment determined a significant modification on polymer, leading to a more resistant and fragile material, whereas the only physical or chemical treatment alone showed a plasticizing effect. In conclusion, this study represents a start point to evaluate content–packaging interactions to optimize the choice of PLA polymer as cosmetic packaging. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40067.     

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.     

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     

Nanostructured membranes based on cellulose acetate obtained by electrospinning. Part II. Controlled release profile and microbiological behavior

Nanofiber membranes of cellulose acetate (CA) were produced with four mixtures of solvents, that is, acetic acid/water, acetone/water, dimethylacetamide (DMAc)/acetone, and DMAc/acetone/water, with the incorporation of the drug gentamicin sulfate at two concentrations. We evaluated the influence of the drug concentration in the electrospinning process. The best membrane produced in this stage was the membrane electrospun with the DMAc/acetone/water solvent mixture, whose process was shown to be viable and did not alter the membrane diameter or aspect with the variation of the drug concentration. Membranes prepared in this way and loaded with 50% of the drug were used for the studies of the release kinetics. Comparisons between the release profiles of the same membranes coated with hydroxypropyl methylcellulose, Eudragit L100, and electrospun CA nanofibers were carried out. The best results on the drug‐release profile were obtained with the membrane coated with nanofibers of CA, which caused a decrease of 9 h in the burst effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2772–2779, 2013     

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.     

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.     

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     

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.     

Processing and properties of polypropylene‐based composites containing inertized fly ash from municipal solid waste incineration

This article reports for the first time the results about the use of inertized fly ash from municipal solid waste incineration as a filler for polypropylene (PP). An innovative process based on the stabilization with colloidal silica has been used for fly ash inertization. Polymer–filler composites containing different filler amounts up to 30 wt % have then been formulated and prepared by means of melt compounding process. Structural, morphological, mechanical, and thermal characterization of their properties has been performed and discussed in detail. Remarkable enhancements of tensile (+ 93%) and flexural (+ 107%) elastic moduli if compared to pristine PP, together with enhancements of flexural resistance (+ 36%) and deflection temperature under load (+ 50%), have been observed when adding filler 30 wt % in suitable processing conditions. Moreover the filler has been shown to interact with polymer crystalline structure and positively influence the thermal‐oxidative stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4157–4164, 2013     

Impact of the starch source on the physicochemical properties and biodegradability of different starch‐based films

Concern about environmental issues has motivated research into the development of biodegradable packaging from renewable sources. Natural polymers such as starch constitute a good alternative for diminishing the use of nonbiodegradable and nonrenewable components in the packaging industry. However, depending on the botanical source, films with different properties are formed. The aim of this study was to evaluate the film‐forming capacity of different starch sources (cassava, corn, potato, and wheat) by casting with starch contents from 2 to 6%. Principal component analysis methodology was used to evaluate the correlation between the formulations and their physicochemical and mechanical properties. It was not possible to produce continuous films based on potato starch, probably because of its very low amylose content (10%). The corn‐, cassava‐, and wheat‐starch‐based films were characterized by their thicknesses (0.06–0.22 mm), moisture contents (19–26%), water solubilities (13.7–26.5%), water‐vapor permeabilities (WVPs; 0.19–0.48 g mm h^?1 m^?2 kPa^?1), wettabilities (35–106°), biodegradabilities in soil, and thermal and mechanical properties (tensile strength = 1.9–6.7 MPa, elongation = 41–166%, and Young's modulus = 8–127 MPa). The wheat starch films presented higher WVPs and lower mechanical properties. The cassava starch films presented lower wettabilities and good mechanical properties; this suggested that their use in packaging for products, such as fruits and vegetables, with higher water activities could be feasible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46564.     

Mechanical,thermal, and water absorption properties of melamine–formaldehyde‐treated sisal fiber containing poly(lactic acid) composites

The present study focuses on the melamine–formaldehyde (MF) coating ratio and silanization of PLA/sisal composites. Poly(lactic acid) (PLA) was melt blended with short sisal fiber with and without MF resin coating. MF was applied at different weight ratios (sisal:MF = 1:1; 1:3, and 1:5) to coat the untreated or silanized sisal fibers which were incorporated up to 20 parts per hundred resin (phr) amount in PLA. PLA/sisal composites were produced by compression molding. It was found that the sisal:MF coating ratio at 1:1 by weight improved the tensile strength and tensile modulus of the composite with 10 phr sisal by 4% and 57%, respectively, compared to the virgin PLA. The initial and final decomposition (T_i) and (T_f) of PLA with untreated sisal were changed from 330.8 and 367.1 to 336.2 and 370.4 °C, respectively, after MF‐coating (sisal:MF weight ratio = 1:1). This enhancement in thermal stability was attributed to the strong interaction between the MF and sisal fiber. The water absorption of PLA/MF–sisal composites slightly decreased with increasing sisal:MF ratio. This is due to the fact that the MF‐coating substantially reduced the hydrophilic properties of sisal. Moreover, FTIR spectra and SEM images proved that sisal fibers were coated by MF resin successfully. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45681.     

Thermal,mechanical, and gas barrier properties of ethylene–vinyl alcohol copolymer‐based nanocomposites for food packaging films: Effects of nanoclay loading

For the application of single‐layer food packaging films with improved barrier properties, an attempt was made to prepare ethylene‐vinyl alcohol (EVOH) copolymer‐based nanocomposite films by incorporation of organically modified montmorillonite nanoclays via a two‐step mixing process and solvent cast method. The highly intercalated tactoids coexisted with exfoliated clay nanosheets, and the extent of intercalation and exfoliation depended significantly on the level of clay loadings, which were confirmed from both XRD measurements and TEM observations. It was revealed that the inclusion of nanoclay up to an appropriate level of content resulted in a remarkable enhancement in the thermal, mechanical (tensile strength/modulus), optical, and barrier properties of the prepared EVOH/clay nanocomposite films. However, excess clay loadings gave rise to a reduction in the tensile properties (strength/modulus/elongation) and optical transparency due to the formation of clay tactoids with a larger domain size. With the addition of only 3 wt % clay, the oxygen and water vapor barrier performances of the nanocomposite films were substantially improved by 59 and 90%, respectively, compared to the performances of the neat EVOH film. In addition, the presence of clay nanosheets in the EVOH matrix was found to significantly suppress the moisture‐derived deterioration in the oxygen barrier performance, implying the feasibility of applying the nanocomposite films to single‐layer food packaging films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40289.