Search

Engineering keratin plastics from chicken feather wastes is highly attractive from an environmental prospect but challenging due to the influence of extraction routes on the macromolecular keratin features. In this study, the effect of precipitation methods on desired properties of biodegradable keratin films was investigated. Keratin was extracted from an industrial chicken feather waste by sulfitolysis, and further recovered using hydrochloric acid (KHA), citric acid (KCA), sodium chloride (KSC), and acetone (KAT) as precipitating agents. Keratin films containing glycerol at 25 wt% were produced by compression molding. All keratin films were nearly colorless and highly transparent to visible light while exhibiting good UV barrier properties. The KAT and KSC films showed greater ductility (εbreak > 50%) compared with KHA and KCA, which was correlated with broader molecular weight distributions and less crosslinking in the former keratins. Importantly, disulfide bonds created in the processing led to keratin films with low water solubility. Larger surface hydrophobicity was attained from keratin recovered by organic solvent precipitation (KAT). These results advance the understanding of precipitating agents as physicochemical property modifiers of biodegradable keratin films for food packaging and other applications. [ABSTRACT FROM AUTHOR]

A disposable electrochemical immunosensor for on‐site detection of aflatoxin B1(AFB1), one of the most toxic mycotoxins in agri‐food products, was fabricated through a low‐cost cut‐printing method and then modified with zein/polypyrrole(PPy) electrospun nanofibers onto which anti‐AFB1 monoclonal antibodies were immobilized covalently. Fabrication was possible with an innovative and simple approach to adsorb nanofibers onto the working electrode during electrospinning. Electrochemical impedance spectroscopy was employed as the principle of detection, and the data collected with a portable potentiostat were treated with information visualization techniques. The nanostructured immunosensor showed a high sensitivity for AFB1 with a linear detection range from 0.25 to 10 ng mL−1 and a theoretical limit of detection of 0.092 ng mL−1, which is adequate to detect AFB1 in food, according to regulatory agencies. [ABSTRACT FROM AUTHOR]

BACKGROUND Cut flowers require proper postharvest stem hydration to prolong vase life. Nano‐sized chitosan is an effective antimicrobial agent that has several potential agricultural applications. In this study, we compared the efficacies of solutions containing chitosan nanoparticles, regular chitosan particles, citric acid, and distilled and tap water controls in treating cut gerbera inflorescences during postharvest storage. Relative water uptake (RWU), transpiration rate (TR), water balance (WB), ligule color, solution pH, stem bending, stem‐end blockage, and counts of bacteria, mold and yeast were investigated. RESULTS: The solution containing chitosan nanoparticles prevented stem bending, enabled higher RWU (41.8 g kg−1 day−1), established a suitable WB, and controlled microbial growth more efficiently than the other solutions. The chitosan nanoparticle solution strongly inhibited molds and yeasts. CONCLUSION: The results of this study demonstrated that nano‐chitosan is a promising postharvest preservative for cut gerbera inflorescences. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Considerable effort has been devoted to improving the properties of PVDF (polyvinylidene fluoride), arguably the most technologically important piezoelectric polymer. Electrospinning has been found to be a particularly effective method of producing PVDF nanofibers with superior piezoelectric properties due to the resulting exceptionally high fraction of the piezoelectrically active crystalline β‐phase. It is typically assumed that the high external electric fields applied during electrospinning enhance the formation of this β‐phase, with the confused literature offering various unsatisfactory mechanistic explanations. However, by comparing PVDF nanofibers produced by two different processes (electrospinning and blowspinning), we show that the electric field is entirely unnecessary; indeed, the crystallization dynamics are principally driven by the applied mechanical stress, as evidenced by structurally identical 200 nm diameter PVDF fibers produced with and without external electric fields. [ABSTRACT FROM AUTHOR]

A non‐enzymatic sensor for hydrogen peroxide (H2O2) determination based on Ag/δ‐FeOOH nanocomposite immobilized on an all‐plastic disposable carbon‐based electrochemical cell (DCell) is constructed by a rapid prototyping technique. Ag/δ‐FeOOH is synthesized by a simple and reproducible method and its structural and morphological properties characterized by X‐ray diffraction (XRD), Fourier transform‐infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The Ag/δ‐FeOOH is successfully immobilized on the DCell, as revealed by SEM images. The electrochemical investigation indicates that the Ag/δ‐FeOOH/DCell has a good electrocatalytic response for the H2O2 reduction, showing detection limit of 71 μmol L−1 H2O2 at a signal‐to‐noise ratio of 3 and analytical sensitivity of 215.4 μA mM−1 cm−2. Moreover, Ag/δ‐FeOOH/DCell can be used to selectively detect H2O2 in the presence of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Finally, Ag/δ‐FeOOH/DCell can be used to determine H2O2 in fetal bovine serum. The achieved results indicate that the non‐enzymatic Ag/δ‐FeOOH/DCell is a cost‐effective alternative for the determination of H2O2. [ABSTRACT FROM AUTHOR]

Geosmin (GSM) and 2‐Methylisoborneol (MIB) are substances commonly found in river water and arise due to eutrophication process. Such contaminants affect the organoleptic properties of water, hampering its consumption, and use in beverage industries. As the human perception threshold for these compounds is low, the devices aimed at their detection must be sensitive enough to detect concentrations as low as a few nanogram per liter in order to guarantee the water quality parameters. Due to the experimental simplicity, fast analysis, portability, and capability for on‐site analysis, the use of electronic tongues and electronic noses employing hybrid and composite materials are potential for GSM and MIB determination. In this work, two distinct electronic tongues were applied in the electrical determination of GSM and MIB in pure and river water. The difference between them consisted in the type of polymer processing used in the fabrication of sensing units. The thin films deposited onto gold IDEs were based on polyamide 6, polypirrole, and polyaniline, but fabricated by drop‐casting and electrospinning. The differences in the electronic tongue performances were correlated to the distinct morphologies of the sensitive layers. Both devices were able to discriminate pure water from solutions tainted with GSM and MIB in concentration as low as 25 ng L−1, with high data correlation and a good reproducibility. [ABSTRACT FROM AUTHOR]

Food packaging materials are traditionally expected to contain foodstuffs and protect them from deteriorating agents. Although petroleum-derived polymers have been widely used for this purpose, the rising concern with their nonrenewable and/or nonbiodegradable nature paves the route for the development of greener alternatives, including polysaccharides and polypeptides. The use of these food-grade biomacromolecules, in addition to fruits and vegetables, provides edible packaging with suitable physical-mechanical properties as well as unique sensory and nutritional characteristics. This text reviews the chronological development pathway of films based on fruit and vegetable purees, pomaces, and extracts. Recent advances are extensively reviewed with an emphasis on the role that each film component plays in the resulting materials, whose production methods are examined from a technical standpoint and essential properties are compiled and contrasted to their conventional, synthetic counterparts. Finally, this comprehensive review discusses advantages and limitations of edible films based on fruits and vegetables. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper reports on a facile method for synthesizing gold nanoparticles (AuNps) with diameter around 5 nm encapsulated with water-soluble polythiophene sulfonate poly[2-(3-thienyl)ethyloxy-4-butylsulfonate] sodium salt (PTS) and their physical-chemical characterization. The synthesis of hybrid materials of polythiophene derivatives and gold nanoparticles is a way to improve the polymer properties, mainly in application for chemical and optical sensing platforms. The AuNps were prepared by reducing gold salt with acid aqueous sodium citrate by the Turkvich method in the presence of PTS, and both PTS and citrate helped to stabilize the AuNps. The suspensions of AuNp:PTS presented good chemical and photostability for long period of storage. The nanoparticles encapsulated with the polymer presented smaller diameters than those obtained using only sodium citrate, according to scanning electron microscopy images. The AuNps obtained were used for fabrication LbL films with commercial chitosan, which were characterized by impedance spectroscopy measurements. The results showed that the charge transfer resistance values ( Rct) decrease as the average diameter of the AuNps decreases and the proportion of PTS increases in the nanocomposite. Such increase of the nanocomposite conductivity, given by the low values of Rct, indicates that the novel film architecture developed is promising for chemical sensing applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1245-1254 [ABSTRACT FROM AUTHOR]

ABSTRACT Electrospinning is a powerful technique to produce nanofibers of tunable diameter and morphology for medicine and biotechnological applications. By doping electrospun nanofibers with inorganic and organic compounds, new functionalities can be provided for technological applications. Herein, we report a study on the morphology and optical properties of electrospun nanofibers based on the conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly(methylmethacrylate) (PMMA). Initially, we investigate the influence of the solvent, surfactant, and the polymer concentration on electrospinning of PMMA. After determining the best conditions, 0.1% MEH-PPV was added to obtain fluorescent nanofibers. The optical characterizations display the successful impregnation of MEH-PPV into the PMMA fibers without phase separation and the preservation of fluorescent property after fiber electrospinning. The obtained results show the ability of the electrospinning approach to obtain fluorescent PMMA/MEH-PPV nanofibers with potential for optical devices applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1388-1394 [ABSTRACT FROM AUTHOR]

Mixed rutile-anatase TiO2 nanoparticles were synthesized by hydrothermal treatment under acidic conditions and incorporated into poly(vinyl alcohol) (PVA). These nanocomposites were electrospun to produce nanofibers of PVA/TiO2, which were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The photocatalytic degradation of Rhodamine B and degradation of the polymer by UV-C lamps were also investigated. The results showed that TiO2 nanoparticles did not change the morphology and thermal behavior of the nanofiber polymer, but were effective in modifying the UV absorption of PVA without reducing its stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

This article studied the applicability of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels as potential delivery vehicle for the controlled-extended release of ammonium sulfate (NH4)2SO4 and potassium phosphate (KH2PO4) fertilizers. PAAm-MC hydrogels with different acrylamide (AAm) and MC concentrations were prepared by a free radical polymerization method. The adsorption and desorption kinetics of fertilizers were determined using conductivity measurements based on previously built analytical curve. The addition of MC in the PAAm chains increased the quantities of (NH4)2SO4 and KH2PO4 loaded and extended the time and quantities of fertilizers released. Coherently, both loading and releasing processes were strongly influenced by hydrophilic properties of hydrogels (AAm/MC mass proportion). The best sorption (124.0 mg KH2PO4/g hydrogel and 58.0 mg (NH4)2SO4/g hydrogel) and desorption (54.9 mg KH2PO4/g hydrogel and 49.5 mg (NH4)2SO4/g hydrogel) properties were observed for 6.0% AAm-1.0% MC hydrogels (AAm/MC mass proportion equal 6), indicating that these hydrogels are potentially viable to be used in controlled-extended release of fertilizers systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Nano and submicrometric fibers of poly( D, L-lactide) (PDLLA or PLA) were spun from solutions using a solution blow spinning (SBS) apparatus. Fiber morphology and diameter were investigated by scanning electron microscopy as a function of polymer concentration, feed rate, and air pressure. A more systematic understanding of the SBS process parameters was obtained, and a quantitative relationship between these parameters and average fiber diameter was established by design of experiments and response surface methodology. It was observed that polymer concentration played an important role in fiber diameter, which ranges from 70 to 2000 nm, and its distribution. Lower polymer concentration tended to increase the formation of bead-on-string structures, whereas smooth fibers were formed at higher concentrations. Fiber diameter tended to increase with polymer concentration and decrease with feed rate. Based on these results, optimal conditions could be obtained for solution-blow spun fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011. [ABSTRACT FROM AUTHOR]

This work evaluates the use of cotton cellulose nanofibers (CCN) as a reinforcing agent to prepare thermoplastic corn starch (TPS) matrix plasticized with 30 wt % of glycerol. The nanocomposites were filled with 0.5-5.0 wt % of CCN on a dry-starch basis. The dried nanofibers were resuspended through the use of an ultrasonicator and then introduced in the fixed water formulation for obtaining TPS. The nanocomposites were compounded in a corotating twin-screw extruder. Scanning transmission electron microscopy (STEM), field emission gun (FEG), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), in air atmosphere, were used to characterize nanofibers, neat TPS, and nanocomposites. The results showed that the nanofibers had needlelike structure with an average length of about 135 ± 50 nm and an average diameter of about 14 ± 4 nm. The addition of CCN was effective to enhance the mechanical properties of neat TPS in compositions above 2.5 wt %, although some agglomeration could be observed. The resulting nanocomposites showed good structural stability, because the amylopectin transcrystallization phenomena on the surface of nanofibers had not occurred. Only a slight decrease in the crystallinity index and a minor increase in the water absorption in relation to neat TPS were observed. An increase in the thermal stability of TPS nanocomposites with respect to neat TPS was verified, but it was independent of the CCN content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Segmented polyurethanes exhibiting shape memory properties were modified by the addition of polyaniline (PANI)-coated cellulose nanofibrils (CNFs). The two-phase structure of the polymer is responsible for the material's ability to 'remember' and autonomously recover its original shape after being deformed in response to an external thermal stimulus. PANI was grown on the surface of the CNFs via in situ polymerization. Modified nanocrystals were added to the segmented polyurethane in concentrations ranging from 0 to 15 wt%. The changes in the material properties associated with the percolation of the coated fibrils appear at higher concentrations than previously observed for non-modified CNFs, which suggests that fibril agglomeration is occurring due to the PANI coating. The shape memory behavior of the composites is maintained at about the same level as that of the unfilled polyurethane only up to 4 wt% of fibrils. At higher concentrations, the rigidity of the nanofibrils as well as their interaction with the hard-segment phase and the increasing difficulty of dispersing them in the polymer collaborate to produce early breakage of the specimens when stretched at temperatures above the melting point of the soft segments. Copyright © 2010 Society of Chemical Industry Segmented polyurethanes exhibiting shape memory properties were modified by the addition of polyaniline-coated cellulose nanofibrils, showing a step change in properties between 4 and 10 wt% nanofibrils. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the effects of monomer, crosslinker and polysaccharide compositions on the morphological characterization of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels. It is stated that the hydrogels were synthesized using the free radical polymerization method showing an increase in hydrophilicity. The formula for the effective or apparent crosslinking density was explained.

The article focuses on a study which examined the characteristics of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels as a novel adsorbent material for removal of the paraquat pesticide. It notes a free-radical polymerization method was used in synthesizing PAAm-MC hydrogels with various acrylamide and MC levels. Results of the study showed that the morpholigical, hydrophilic, and adsorption properties of the hydrogels were influenced by the entrapped MC in PAAm chains.

The article presents a study which examines the use of solution blow spinning technique for the delivery of polymer solution to an apparatus with concentric nozzles. The study analyzes that its process of pressure difference and shearing at the gas/solution interfaces with multiple strands of polymer solution through the collector. Result shows that the fiber production rate and/or fiber morphology was affected by the gas flow pressure, working distance, and injection rate.

The article presents a study which prepared ultrafine fibers of blends of polyaniline doped with p-toluene sulfonic acid and poly(L-lactic acid). The presence of polyaniline reduced the formation of beads in the fibers. The resulting nanofibers also had a lower degree of crystallinity in comparison with cast films.

The article examines the content of unripe coconut fibers used as fillers in a biodegradable polymer matrix of starch/ethylene vinyl alcohol (EVOH)/glycerol on the mechanical, thermal, and structural properties. It was shown that adding coconut fiber into starch/EVOH/glycerol blends lessened the ductile behavior of the matrix by making the composites more brittle. At low fiber content, blends exhibited greater flexibility, with higher tensile strength than at higher fiber levels.

This work involved a study of the effect of processing variables (temperature, water content, rotor speed, and time) on the mechanical properties of starch:gluten:glycerol mixtures in the weight ratio of 40:40:20. The properties of the materials were affected by the processing variables. The torque decreased with water content, indicating that water facilitates the plasticization of mixtures, whereas the increase in temperature accelerated the evaporation of water, thus increasing the torque. Ultimate tensile strength was achieved at the lowest temperature (110°C) and the highest water content (20%), whereas maximum elongation was achieved for the material processed at the highest temperature, 150°C, and the fastest rotor speed, 70 rpm. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Solution blow spun polystyrene (PS) nanofibers were produced from 20 to 30 wt % PS solutions using toluene (industrial solvent) and orange oil (green solvent). The latter being composed of d‐limonene (97.06%) as determined by gas chromatography–mass spectroscopy. The rheological behavior and volatility of the solvents and polymer solutions were correlated with fiber morphology, accessed by scanning electron microscopy. Thermal analysis was used to determine the thermal behavior of fibers. The antimicrobial activity of orange oil was tested for potential applications of the spun mats in active food packaging. Results showed that the nanofibers spun from orange oil solutions had average diameters of 306 ± 74 nm as opposed to 441 ± 110 nm for toluene. Moreover, when compared with fiber spun from toluene solutions, orange oil yielded more flexible fibers with slightly lower contact angles and better antimicrobial properties due to the presence of residual oil confirmed by Fourier‐transform infrared spectroscopy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47337. Polystyrene nanofibrous mats with green solvent (orange oil) by the technique of solution blow spun (SBS). [ABSTRACT FROM AUTHOR]

An artificial taste sensor based on different types of ultra-thin films of conducting polymers (a special class of plastics that can conduct electricity) and their mixture with a lipid-like material has been able to mimic the human palate. In addition, this "electronic tongue" has been successfully employed in the analysis of tastants, suppression effects, and commercial beverages throughout AC measurements (impedance spectroscopy) in a relatively low-cost, simple, and efficient way.