Testing of polybutylene succinate based films for poultry meat packaging

Overall evaluation of the newly developed materials based on polybutylene succinate (PBS) and polybutylene succinate-co-adipate (PBSA) derived from renewable resources was carried out. This study was focused on the practical examination of two selected double layer materials - i) PBSA/(90% PBS + 10% PBSA) and ii) PBSA/(80% PBS + 10% PBSA + 10% talc), which were applied for vacuum packaging of raw chicken and turkey meat and smoked turkey meat. Physical, chemical and mechanical properties of these materials were compared with commonly used packaging material based on polyamide/polyethylene (PA/PE). Functional parameters of packaging materials such as the film thickness, water vapour transmission rate, oxygen permeability, tensile strength, transmittance and overall migration were tested. Various values of water vapour transmission rate for PA/PE, i) PBSA and ii) PBSA 2.1, 20.9 and 21.0 g·m^−2·d⁻¹; oxygen permeability 74.7, 115.4 and 85.1 ml (STP)·m⁻²·d⁻¹·0.1 MPa⁻¹ (all at 23 °C, 75% relative humidity) and transmittance 82.6, 15.7 and 6.9% were found, respectively. For the packaged meats only minor changes of pH, water activity, microbiological quality, colour and profiles of volatile compounds during the storage throughout their shelf life were found. Results of all experiments confirm that even if the physical, chemical and mechanical properties of commonly used PA/PE and new PBS packaging materials are not the same, there is no significant limitation in the practical application of PBS based films for raw and smoked poultry meats.     

Influence of the Addition of Lauric Acid to Films Made from Gelatin,Triacetin and a Blend of Stearic and Palmitic Acids

Summary: The objective of this research was to verify the influence of adding increasing amounts of lauric acid on the functional properties of homogenized films made from gelatin, triacetin and a blend of palmitic and stearic acids. The films were characterised with respect to their visual aspect, water vapour permeability (WVP), water solubility, mechanical properties (tensile strength and percent elongation), oxygen permeability (O₂P), opacity (OP) and melting and glass transitions temperatures. The films produced were malleable and macroscopically homogeneous. The addition of 1% of lauric acid to the film of gelatin, triacetin and blend of palmitic and stearic acids (5.84 ± 0.31 gmm · m⁻² dkPa) caused a slight decrease in WVP. The additions of 2.5% (5.70 ± 0.76 gmm · m⁻² dkPa), 5% (5.38 ± 0.64 gmm · m⁻² dkPa) and 10% (4.50 ± 0.55 gmm · m⁻² dkPa) of lauric acid were sufficient to make a significant difference in the WVP at the higher levels used. As compared to the gelatin and triacetin film, the addition of lauric acid at all the concentrations studied resulted in a slight increase in the film solubility. The addition of hydrophobic substances to gelatin/triacetin films (15.26 ± 0.28 cm³ · µm · m⁻² dkPa) favoured an increase in O₂P permeability, this effect being greater in the films made from gelatin, triacetin, blend of palmitic and stearic acids and 10% lauric acid (24.48 ± 0.07 cm³ · µm · m⁻² dkPa). The increasing addition of lauric acid significantly reduced the tensile strength and increased elongation of the films composed of gelatin, triacetin and blend that being more evident at the concentrations of 5% (67.58 ± 1.23 MPa and 11.45 ± 0.57%) and 10% (63.50 ± 1.56 MPa and 12.90 ± 0.57%). The addition of 1% (OP, 27%) and 10% (OP, 28%) of lauric acid induced no visible effect on the opacity of the films. The thermogrammes showed three transitions for the gelatin/triacetin/stearic-palmitic blend/1% lauric acid films (−57.42 °C, 23.74 °C and 44.11 °C) and two for the gelatin/triacetin/stearic-palmitic acids blend/10% lauric acid films (−56.22 °C and 17.35 °C). As observed by DSC, the addition of fatty acids resulted in the appearance of more than one melting peak for all films in relation to the gelatin and triacetin film.     

Design of an optical sensor for ethylene based on nanofiber bacterial cellulose film and its application for determination of banana storage time

In this work, new ethylene gas sensor was developed on the basis of portable bacterial cellulose (BC) nanofiber film doped with KMnO₄ (K‐BC). The relationship between the concentration of KMnO₄ (8 × 10⁻³, 8 × 10⁻⁴, and 8 × 10⁻⁵ mol L⁻¹) and the optical and morphological properties of ethylene sensor was investigated. The Fourier‐transform infrared results showed that some new interactions have occurred between BC membrane and KMnO₄. The significant reduction in the relative intensity of the characteristic X‐ray diffraction peak of BC in the doped films clearly indicates that the crystalline fraction decreases as a result of KMnO₄ addition. The fabricated K‐BC was used for determination of ethylene concentration. The color, clarity, and absorbance of film at different concentrations of ethylene (10‐2000 μg mL⁻¹) were determined by spectrophotometer. Moisture absorption and water vapor permeability of BC were increased by the addition of KMnO₄. Finally, the ethylene optical sensor was used for detection and determination of ethylene concentration in the bunch banana packages.     

Strength and barrier properties of MFC films

The preparation of microfibrillar cellulose (MFC) films by filtration on a polyamide filter cloth, in a dynamic sheet former and as a surface layer on base paper is described. Experimental evidence of the high tensile strength, density and elongation of films formed by MFC is given. Typically, a MFC film with basis weight 35 g/m² had tensile index 146 ± 18 Nm/g and elongation 8.6 ± 1.6%. The E modulus (17.5 ± 1.0 GPa) of a film composed of randomly oriented fibrils was comparable to values for cellulose fibres with a fibril angle of 50°. The strength of the films formed in the dynamic sheet former was comparable to the strength of the MFC films prepared by filtration. The use of MFC as surface layer (0–8% of total basis weight) on base paper increased the strength of the paper sheets significantly and reduced their air permeability dramatically. FEG-SEM images indicated that the MFC layer reduced sheet porosity, i.e. the dense structure formed by the fibrils resulted in superior barrier properties. Oxygen transmission rates (OTR) as low as 17 ml m⁻² day⁻¹ were obtained for films prepared from pure MFC. This result fulfils the requirements for oxygen transmission rate in modified atmosphere packaging.     

Improvement of mechanical and oxygen barrier properties of cellulose films by controlling drying conditions of regenerated cellulose hydrogels

Mechanical, thermal and oxygen barrier properties of regenerated cellulose films prepared from aqueous cellulose/alkali/urea solutions can be markedly improved by controlling the drying conditions of the films. By pre-pressing followed by vacuum drying under compression, the tensile strength, Young’s modulus, coefficient of thermal expansion and oxygen permeability of the dried films reached 263 MPa, 7.3 GPa, 10.3 ppm K⁻¹ and 0.0007 ml μm m⁻² day⁻¹ kPa⁻¹, respectively. Thus, films produced in this way show the highest performance of regenerated cellulose films with no orientation of cellulose chains reported to date. These improved properties are accompanied by a clear increase in cellulose II crystallinity from 50 to 62% during pre-pressing/press-vacuum drying process. At the same time, the film density increased from 1.45 to 1.57 g cm⁻³, and the moisture content under equilibrium conditions decreased from 14.1 to 9.8%. Hence, the aqueous alkali/urea solvent system has potential applications in producing new and environmentally friendly cellulose films with high performances through control of the drying conditions.     

Co-extrusion of multilayer poly(m-xylylene adipimide) nanocomposite films for high oxygen barrier packaging applications

Multilayer packaging films incorporating a montmorillonite layered silicate (MLS)/poly(m-xylylene adipimide) (MXD6) nanocomposite as the oxygen barrier layer and low-density polyethylene (LDPE) as the moisture resistant layer were produced through the co-extrusion process at the laboratory and pilot scale level. Extrusion screw speeds were varied from 30 to 130 rpm in order to produce samples with varying layer thicknesses. The multilayer film structure was scaled up from the laboratory scale to the pilot-level scale based on oxygen transmission data obtained from the laboratory-scale process parameters. Laboratory-scale film results indicated that the film which demonstrated an optimal oxygen transmission rate (OTR) of 0.3 cm³/(m² day) at 60%RH and water vapor transmission rate (WvTR) of 1.4 g/(m² day) at 90%RH had a structure that contained a core barrier film layer of nanocomposite MXD6 that makes up roughly 34% of the total film thickness, with the remainder of the film material consisting of maleic anhydride grafted polyolefin tie layers and LDPE skin layers. The OTR of the films changed as the relative humidity of the test environment was varied from 0 to 90%. However, for the pilot-scale trial it was necessary to reduce the target thickness of the core nylon barrier layer to 22% due to layer-to-layer melt flow instabilities that occurred during processing. The barrier properties of the multi-layer co-extruded films were highly dependant on overall film thickness. The highest performing oxygen barrier pilot-scale film had an OTR of 0.3 cm³/(m² day) (60%RH) and a WvTR of 2.4 g/(m² day) (90%RH) with a core nylon layer of 1.5 mil and a total thickness of 7.7 mil. Correlation of the layer thicknesses to the barrier and mechanical properties of the pilot-scale multilayer films indicated that an increased nanocomposite core layer thickness improved the oxygen barrier performance and decreased film elongation while improving the tear resistance of the films.     

Preparation and characterization of edible films composed of Dioscorea opposita Thunb. mucilage and starch

With the goals of reducing negative environmental impacts and improving the novel food packaging industry, edible films composed of Chinese yam mucilage (DOM) and starch were prepared via a casting method. The films were characterized by analysing the physical, morphological, mechanical and barrier properties, performing a thermal analysis, and finally performing an acute toxicity analysis in rats that ingested the film-forming solutions. Four film samples (F1, F2, F3 and F4) were prepared to evaluate the effects of ultrasound and the addition of sodium carboxymethyl cellulose (CMC) on DOM. DOM films presented a compact and uniform structure without toxicological responses, and the optimal DOM film-forming solution contained 20.0% mucilage, 10.0% starch, 1.0% glycerol, and 2.0% CMC after a 1 h ultrasound treatment. The solubility, swelling degree and water vapour permeability (WVP) of DOM film were 41.11%, 95.03% and 55.30 g mm/m²·d·kPa, respectively. The functional groups analysed by FT-IR and thermal degradation were not affected by the different formulations. Therefore, the non-toxic and bio-degradable films prepared using DOM have the great potential to be used in applications in food packaging.     

Effect of post-deposition annealing temperature on RF-sputtered HfO2 thin film for advanced CMOS technology

Structural and electrical properties of HfO₂ gate-dielectric metal-oxide-semiconductor (MOS) capacitors deposited by sputtering are investigated. The HfO₂ high-k thin films have been deposited on p-type <100> silicon wafer using RF-Magnetron sputtering technique. The Ellipsometric, FTIR and AFM characterizations have been done. The thickness of the as deposited film is measured to be 35.38 nm. Post deposition annealing in N₂ ambient is carried out at 350, 550, 750 °C. The chemical bonding and surface morphology of the film is verified using FTIR and AFM respectively. The structural characterization confirmed that the thin film was free of physical defects and root mean square surface roughness decreased as the annealing temperature increased. The smooth surface HfO₂ thin films were used for Al/HfO₂/p-Si MOS structures fabrication. The fabricated Al/HfO₂/p-Si structure had been used for extracting electrical properties such as dielectric constant, EOT, interface trap density and leakage current density through capacitance voltage and current voltage measurements. The interface state density extracted from the G–V measurement using Hill Coleman method. Sample annealed at 750 °C showed the lowest interface trap density (3.48 × 10¹¹ eV⁻¹ cm⁻²), effective oxide charge (1.33 × 10¹² cm⁻²) and low leakage current density (3.39 × 10⁻⁹ A cm⁻²) at 1.5 V.     

Effects of chain extender and uniaxial stretching on the properties of PLA/PPC/mica composites

Poly(lactic acid) (PLA)/poly(propylene carbonate) (PPC)/mica composites with different amount of chain extender (CE) were melt compounded and then processed via two routes (compression molding and uniaxial stretching) into sheets and films. The tensile, thermal, and oxygen barrier properties of all the samples were investigated. Tensile test showed that the tensile strength and elongation at break of all films were much higher than that of all sheets, especially for PLA/PPC/mica with 0.9‐wt% CE composite (CM₃(CE)_0.9) film. The crystallinity of all films increased significantly after uniaxial stretching of sheet samples. The Fourier transform infrared spectroscopy (FTIR) results proved the chemical reactions occurred between PLA/PPC and CE. Scanning electron microscope (SEM) analysis revealed that compatibility and interfacial adhesion of all samples were improved after adding mica and CE, and they were further enhanced after uniaxial stretching. The addition of CE was not favorable to improve the oxygen barrier performance of PLA/PPC/mica sheet samples. However, the oxygen barrier performance of film samples was significantly improved after uniaxial stretching. In particular, the CM₃(CE)_0.9 film had the lowest oxygen permeability coefficient (1.4 × 10^?15 cm³·cm/(cm²·s·Pa)), and this was the best oxygen barrier properties reported in the literature for PLA‐based composites, which was comparable with PA film. This study demonstrated the high efficiency of uniaxial stretching on improvement of properties of composites, which would promote the application of biodegradable polymers in oxygen sensitive food packaging.     

New methodology for anodic stripping voltammetric determination of methylmercury

A novel procedure for trace methylmercury determinations by anodic stripping voltammetry at a gold film electrode is presented. Measurements were performed in a flow system. For selective determination of methylmercury, the Hg²⁺ ions were masked by complexation with DTPA. Hg-DTPA complex is not reduced at the gold film electrode at the potential of methylmercury reduction to the metallic state. The calibration graph was linear from 5 × 10⁻⁹ to 1 × 10⁻⁷ mol L⁻¹ for an accumulation time 600 s. A detection limit (based on 3σ criterion) for methylmercury was 2.3 × 10⁻⁹ mol L⁻¹. The validation of the proposed procedure was made by analyses of human hair certified reference material.     

Modification of poly(propylene carbonate) with chain extender ADR-4368 to improve its thermal,barrier, and mechanical properties

Melt blending with the application of epoxy compound ADR-4368 as a chain extender was used to chemically modify polypropylene carbonate (PPC). ¹H nuclear magnetic resonance spectroscopy (¹H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tests using a universal material testing machine, a gas permeability tester, a water vapor permeability tester and other instruments were used to assess changes in the chemical structure, thermal and mechanical properties, and barrier efficacy of PPC before and after modification.The epoxy group in ADR-4368 reacted with the terminal hydroxyl group in PPC, considerably enhancing its mechanical properties, thermal stability and barrier efficacy to O₂ and CO₂. With the addition of 1% ADR-4368, the glass transition temperature of PPC was increased from 17 °C to 26.9 °C, while the thermal decomposition temperature (T_−5%) of PPC was increased from 177.3 °C to 240.6 °C. Moreover, the tensile strength of the modified PPC was improved from 3.3 MPa to 20.7 MPa.     

Elevated ductility,optical, and air barrier properties of poly (butyleneadipate‐co‐terephthalate) bio‐based films via novel thermoplastic starch feature

It is important to develop high performances biodegradable polymers to eliminate the “white pollution” evoked by petroleum‐based polymer. Thermoplastic starch (TPS) with nano‐ellipse configuration was fabricated to reinforce the performances of poly (butylene adipate co‐terephthalate) (PBAT) biocomposites. Effects of tartaric acid (TA) (0.5% wt) on the structure of TPS and compatibility for PBAT were evaluated by Fourier‐transform infrared spectroscopy (FTIR), viscosity and rheological measurement, dynamic mechanical analysis (DMA) and scanning electron microscope (SEM), respectively. They revealed that TA reduced the molecular weight of starch and shear viscosity of TPS were beneficial for TPS dispersing in PBAT matrix with 184‐nm averaged diameter. PBAT/TPS‐TA (70:30 wt%) biocomposite films were blew with different blow‐up ratio. The morphology of films presented that nano‐TPS‐TA wrapped in the PBAT matrix and deformed from ball to capsule feature without agglomeration. Compared with those of PBAT film, the increment in elongation at break of PBAT/TPS‐TA film was 100%. The air permeability and UV‐VIS transmittance of PBAT/TPS‐TA films decreased from 6.92 × 10^?9 to 3.72 × 10^?9 cm³·cm·cm^?2 s^?1 Pa^?1 and 47.6% to 23.5%, respectively. This study proposed a facile approach to fabricate low‐cost PBAT films with significant improved mechanical, optical, and air barrier properties for commercial application. Mechanism for nanoparticles of TPS‐TA motivated the elevated performances was proposed, synchronously.     

Influence of chemical surface modification of cellulose nanowhiskers on thermal,mechanical, and barrier properties of poly(lactide) based bionanocomposites

In the aim of producing fully organic bionanocomposite based on poly(lactide) (PLA), cellulose nanowhiskers (CNW) were grafted by n-octadecyl-isocyanate (CNW-ICN) applying an in situ surface grafting method. The compatibilizing effect of the long aliphatic grafted chain was investigated by thermal, mechanical and permeability analysis of solvent cast nanocomposite films. The grafted CNW-ICN could be successfully dispersed in the polymer matrix. The gained compatibility brought about a nucleating effect, decreasing the half time of isothermal crystallization from 25 min for the neat PLA to 8.4 min for the nanocomposite including 2.5 wt% CNW-ICN, e.g., tensile strength was improved by 10 MPa for the same 2.5 wt% CNW-ICN/PLA composite. Mechanical reinforcement was also effective in the rubbery state of PLA and increased the tensile modulus of the rubbery plateau providing thereby thermal resistance to the polymer. Oxygen barrier properties did not change significantly upon the inclusion of CNW-ICN, even when the quantity of CNW-ICN was increased to 15 wt%. More interestingly, the water vapour permeability of the CNW-ICN nanocomposite was always lower than the one of ungrafted CNW composites, which led to the conclusion that the hydrophobic surface graft and improved compatibility could counteract the effect of inclusion of hydrophilic structures in the matrix on water vapour transport. In conclusion, the surface grafting of CNW with isocyanates might be an easy and versatile tool for designing fully organic bionanocomposites with tailored properties.     

Permeation studies on transparent multiple hybrid SiO<Subscript>2</Subscript>-PMMA coatings-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> barriers on PEN substrates

In this work we report the performance of permeation barriers based on organic/inorganic multilayer stacks. We have used PMMA-SiO₂ (poly methyl methacrylate-silica) hybrid films synthesized through a sol–gel route as organic–inorganic components, whereas Al₂O₃ thin films were used as the inorganic component. The hybrid layers were deposited by dip coating and the Al₂O₃ by atomic layer deposition (ALD), films were prepared on polyethylene naphthalene (PEN) substrates. The permeability of the films and stacks is evaluated using helium as the diffusion gas in a custom made ultra-high vacuum system. The results show that permeability for PEN is reduced from 5 × 10⁻³ g/m²-day to about 9 × 10⁻⁵ g/m²-day for the best multiple barrier evaluated. Increased barrier properties are due to the increasing in the path and hence the lag-time of the permeating gas. In particular, we report the surface roughness of the different layers and its impact on the barrier performance. The hybrid layers reduced notably the roughness of the bare PEN substrate improving the quality of the Al₂O₃ layer in the barrier. The optical transmittance of the barriers in the visible region is higher than 80% in all the studied cases.     

Methylation of tin(II) by methyl iodide: influences of different environmental factors on the efficiency and reaction kinetics

The methylation reaction of Sn(II) with methyl iodide (MeI) in water has been studied using sensitive GC-QSIL-FPD technology. The pH value, amount of MeI and salinity (S) are the three important factors that influence the methylation reaction in an aquatic environment. In all experiments, monomethyltin (MMT) is the only methylation product of the tin(II) reacting with MeI observed. At the 95% confidence level, the pH, MeI and S are significant for the MMT yield. The concentration of MMT in the reactor increases with increase in pH within the selected pH range of 4–9 because four different species of Sn(II)–Sn²⁺, SnOH⁺, Sn(OH)₂⁰ and Sn(OH)₃⁻–have different reaction activities with MeI. The methylation activity of Sn(II) was found to be highest at a salinity of 0.1 M at three different pH levels: 5, 7 and 9. Higher concentration of Cl⁻ (as a relatively weak nucleophilic ion) will obstruct nucleophilic attack of Sn(II) on MeI. MMT production also increases with rising volume of MeI. Moreover, first-order reaction rates have been calculated at different pH, salinity and MeI, and found to be in the range 0.0018–0.0199 h⁻¹. The reaction rate also varies largely under different reaction conditions. One probable mechanism for the methylation reaction of Sn(II) with MeI is a S_N2 nucleophilic attack on the methyl group of MeI by Sn(II), via a process of oxidative methyl-transfer. Copyright © 2006 John Wiley & Sons, Ltd.     

Improvement of the mechanical and barrier properties of methylcellulose-based films by treatment with HEMA and silane monomers under gamma radiation

Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol and 0.025% Tween^®-80. Puncture strength (PS), puncture deformation (PD) and water vapor permeability (WVP) of the films were found to be 147 N/mm, 3.46 mm, and 6.34 g mm/m² day kPa, respectively. The monomer, 2-hydroxyethyl methacrylate (HEMA) (0.1–1%, w/w) was incorporated into the MC-based solution and films were prepared by casting. Films were then exposed to gamma radiation (5–25 kGy) and it revealed that 1% HEMA containing films showed the highest PS values (282 N/mm at 10 kGy). Silane monomer (3-aminopropyl tri-ethoxy silane) (0.1–1%, w/w) was also added into the MC-based films and were found to improve the strength of the films significantly. In comparison between HEMA and silane treatment onto MC-based films, it was observed that silane performed better strength and barrier properties. Surface morphology of the monomer treated films was examined by scanning electron microscopy and suggested better appearance than MC-based film.     

Development and Characterization of Novel Composite Films Based on Soy Protein Isolate and Oilseed Flours

The possibility of using oilseed flours as a waste source for film-forming materials with a combination of soy protein isolate in preparation of edible films was evaluated. Physical, mechanical and barrier properties were determined as a function of the oilseed type: hemp, evening primrose, flax, pumpkin, sesame and sunflower. It was observed that the addition of oilseed flours increased the refraction and thus the opacity of the obtained films from 1.27 to 9.57 A mm⁻¹. Depending on the type of flours used, the edible films took on various colors. Lightness (L*) was lowest for the evening primrose film (L* = 34.91) and highest for the soy protein film (L* = 91.84). Parameter a* was lowest for the sunflower film (a* = −5.13) and highest for the flax film (a* = 13.62). Edible films made of pumpkin seed flour had the highest value of the b* color parameter (b* = 34.40), while films made of evening primrose flour had the lowest value (b* = 1.35). All analyzed films had relatively low mechanical resistance, with tensile strength from 0.60 to 3.09 MPa. Films made of flour containing the highest amount of protein, pumpkin and sesame, had the highest water vapor permeability, 2.41 and 2.70 × 10⁻⁹ g·m⁻¹ s⁻¹ Pa⁻¹, respectively. All the edible films obtained had high water swelling values from 131.10 to 362.16%, and the microstructure of the films changed after adding the flour, from homogeneous and smooth to rough. All blended soy protein isolate–oilseed flour films showed lower thermal stability which was better observed at the first and second stages of thermogravimetric analysis when degradation occurred at lower temperatures. The oilseed flours blended with soy protein isolate show the possibility of using them in the development of biodegradable films which can find practical application in the food industry.     

Evolution of crystalline structure in SnS thin films prepared by chemical deposition

Crystal structure and morphology undergo significant evolution in thin films of tin(II) sulfide prepared by chemical deposition, over a narrow interval of bath temperature of 20–40 °C, but has not been recognized in previous studies. The chemical bath is constituted using tin(II) chloride, triethanolamine, ammonia(aq.) and thioacetamide. At bath temperature of 20 °C, the deposition rate of the film is 10 nm/h; and at 24 h, a film of thickness 260 nm is obtained. This film is compact and with a predominantly cubic (Cub-) crystalline structure. At 40 °C, the deposition rate is 25 nm/h, and a film of 600 nm in thickness is deposited in 24 h. However, this film has evolved into vertically stacked platelets of orthorhombic (OR-) crystalline structure. The transition from compact-to-platelet morphology as well as from Cub-to-OR-crystalline structure is observed near a deposition temperature, 35 °C. The Cub-SnS has a characteristic high optical band gap, 1.67 eV (direct gap; forbidden transitions) with an electrical conductivity, 10⁻⁷(Ω cm)⁻¹; both properties being un-affected when films are heated at 300 °C in a nitrogen ambient. In OR-SnS, the band gap is 1.1 eV (indirect gap; allowed transitions). The electrical conductivity of such films is notably higher, 10⁻⁴ (Ω cm)⁻¹, which increases further by an order of magnitude when the films have been heated at 300 °C in nitrogen.     

Enzyme microsensor for glucose with an electrochemically synthesized enzyme-polyaniline film

An enzyme microsensor for glucose was fabricated by the electrochemical polymerization method. A glucose oxidase-entrapped polyaniline (GOD-polyaniline) film was deposited on the top of a platinum fibre (50 μm in diameter) by the electrochemical oxidative polymerization of aniline in a pH 7 buffer solution in the presence of glucose oxidase. The GOD-polyaniline films retained GOD activity and oxygen permeability but prevented large molecules from permeating. Glucose was auperometrically determined with the electrochemically fabricated microsensor in the concentration range 10⁻⁴ to 5 × 10⁻³ M.     

Antimicrobial,mechanical, barrier,and thermal properties of bio‐based poly (butylene adipate‐co‐terephthalate) (PBAT)/Ag2O nanocomposite films for packaging application

Bio‐based nanocomposites of poly (butylene adipate‐co‐terephthalate) (PBAT)/silver oxide (Ag₂O) were prepared by the composite film casting method using chloroform as the solvent. The prepared Ag₂O at different ratios (1, 3, 5, 7, and 10 wt%) is incorporated in the PBAT. The PBAT nanocomposite films were subjected to structural, thermal, mechanical, barrier, and antimicrobial properties. The electron micrographs indicated uniform distribution of Ag₂O in the PBAT matrix. However, the images indicated agglomeration of Ag₂O particles at 10 wt% loading. The thermal stability of the nanocomposite films increased with Ag₂O content. The tensile strength and elongation of the composite films were found to be higher than those of PBAT and increased with Ag₂O content up to 7 wt%. The PBAT‐based nanocomposite films showed the lower oxygen and water vapor permeability when compared to the PBAT film. Antimicrobial studies were performed against two food pathogenic bacteria, namely, Klebsiella pneumonia and Staphylococcus aureus.