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Polymeric Films (polymeric + film)
Selected AbstractsThe Debittering of Navel Orange Juice Using Polymeric FilmsJOURNAL OF FOOD SCIENCE, Issue 4 2007Stéphane C. Fayoux ABSTRACT:, In order to better understand and optimize the sorption of limonin (the major navel orange juice bitter principle) by various plasticized polymeric films, a sorption and plasticizer migration study was carried out using high-performance liquid chromatography (HPLC) and gas chromatography (GC). Low molecular weight (LMW) poly (vinyl chloride) (PVC) plasticized with dioctyl adipate (DOA) gave the best results for both limonin sorption and low DOA migration. Thick films did not significantly sorb more limonin than thin films in the timeframe of our experiments, as the absorption involved rapid surface sorption followed by slow bulk diffusion. The debittering efficiency was a 1000-fold greater than that obtained with current polystyrene divinylbenzene resin beads, with potential for industrial scale debittering. [source] Preparation and Characterization of Nanostructured TiO2/Epoxy Polymeric FilmsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2006Marco Sangermano Abstract Summary: Titania-containing coatings were prepared by cationic photopolymerization of an epoxy resin either by dispersion of preformed TiO2 nanoparticles or by their in-situ generation through a sol-gel dual-cure process. The kinetics of photopolymerization was evaluated by real-time FT-IR, studying the effect of the TiO2 concentration. The properties of cured films were investigated, showing an increase of hydrophilicity on the surface of the coatings with increasing TiO2 content. TEM analysis demonstrated that it is possible to achieve a significantly better control of the dispersion of the inorganic particles within the organic matrix by in-situ generation of TiO2, thus completely avoiding macroscopic phase separation and obtaining homogeneous, transparent coatings. Bright-field TEM micrograph for TIP20 dual-cured film. [source] Inorganic Layers on Polymeric Films , Influence of Defects and Morphology on Barrier PropertiesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2003M. Hanika Abstract Flexible polymeric films are not only widely used in conventional packaging as substitute for glass and aluminum foil packaging but are also proposed as encapsulation for novel products, like flexible solar cells or organic light-emitting devices. The two essential properties of the polymeric packaging are flexibility and good permeation barrier properties against gases and vapors. This article deals with vacuum web coating as a common way of increasing barrier properties of polymeric films and the problems related to this procedure. Defects caused by particles and surface imperfections are found to dominate the permeation rate for such coated polymeric films. Atomic force microscopy, electron and also optical microscopy was used for analysis of the coating layer. Three-dimensional numerical simulations were performed for modeling of the influence of defect size, spacing and film thickness. Results of numerical modeling and of many practical experiments show that the permeability is almost independent of the substrate film thickness when a critical thickness is exceeded. In most cases the defects can be treated as independent of each other. The gas permeability of vacuum web-coated polymeric films can be quantitatively predicted by a simple formula. For gases, like oxygen, it is shown that a statistic analysis of the defect sizes by optical microscopy is sufficient. For water vapor transmission, however, the structure of the coating layer itself has also to be taken into account. [source] Polariscopic imaging and vibrational characterization of hybrid films for packagingPACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2008Iari-Gabriel Marino Abstract Polymeric films (low-density polyethylene and oriented polypropylene) for packaging applications coated with organic,inorganic nanocomposite hybrids have been prepared by sol-gel process. Tetraethoxysilane and two different organic phases, polyvinyl alcohol and a diblock copolymer polyethylene-polyethylene glycol were used as precursors. Information about the hydrolysis and polycondensation degrees was obtained by investigating the vibrational features of the coatings by means of attenuated total reflectance-Fourier transform infrared and Raman spectroscopies. Through a new polariscopic imaging technique, the bi-dimensional maps of the optical anisotropy of the samples, both as-prepared and under mechanical strain, were obtained. The maps showed inhomogeneous retardation and nearly flat azimuth distributions. The anisotropy properties of the samples depended mainly on the substrates and were not influenced by the coatings, while the optical transmission was slightly better for the tetraethoxysilane-polyvinyl alcohol sample. Copyright © 2008 John Wiley & Sons, Ltd. [source] Photolithographic Patterning of Ring-Opening Metathesis Catalysts on Silicon,ADVANCED MATERIALS, Issue 1 2005F. Harris Ruthenium-based metathesis catalysts have been successfully covalently bound to a thermal oxide layer on a Si(100) wafer. Selective inactivation of the catalyst is achieved via exposure to UV light using standard photolithographic techniques. Subsequent exposure of the wafer to a suitable monomer results in the formation of a patterned polymeric film that is covalently attached to the oxide layer (see Figure). [source] UV-embossed microchannel in biocompatible polymeric film: Application to control of cell shape and orientation of muscle cellsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Jin-Ye Shen Abstract This article shows that ultra violet (UV) micro-embossing can be successfully used for fabricating biocompatible micropatterned films with microchannels separated by high aspect ratio microwalls. Eight series of micropatterns were investigated; the width of the microwall was either 10 or 25 ,m and that of the microchannel either 40, 80, 120, or 160 ,m. The material investigated was principally polyurethane diacrylate. The UV-embossed micropattern was extracted with methanol, converting the micropatterns from cytotoxic to biocompatible. The typical UV embossing method was modified by using a marginally adhesive polyester substrate, which facilitates demolding but is removable before methanol extraction to avoid fragmentation of the embossed micropatterns. The effect of the micropatterns on A7r5 smooth muscle cells and C2C12 skeletal muscle cells was investigated. The dimensions of both channel and wall have significant effects on the elongation of both muscle cells. In the narrower 40-,m channel, the C2C12 cells merged together to form myofibers. These results indicate that UV-embossed micropatterns may present a useful scaffold for in vitro cell shape and orientation control needed in vascular and muscle tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] How to design perforated polymeric films for modified atmosphere packs (MAP)PACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2001Luciano ZanderighiArticle first published online: 12 APR 200 Abstract Increasing proportions of fresh produce are being sold in modified atmosphere packs (MAP) with the aim of preserving product quality longer and reducing freight costs. A rigorous theoretical analysis was made of the transport phenomena across packaging film (composite, perforated, etc.) in order to find out whether polymeric film will permit a stationary modified atmosphere (MA) inside the pack, and if so when, and to investigate the effect of the size and shape of the holes in the perforated film. The continuity equations of the pack, for all diffusing species, were written and solved for stationary conditions, with the boundary conditions that species not involved in metabolic processes do not diffuse across polymeric film. After a detailed analysis of the transport phenomena across both continuous and perforated film, and of the metabolic rate processes, it transpires that no stationary conditions compatible with any MA can be found for continuous film, owing to the permeation characteristics of the film and the rate of the metabolic processes. With perforated film it is possible to find, at least for certain metabolic process rates, a stationary state where a constant MA is maintained inside the pack. A proposal is given, provided the rate of the metabolic process is known, for the design of a pack in terms of polymeric materials and of the pinhole size. Two case studies, strawberry and cabbage, are presented and discussed, along with the optimization of the polymeric film and the size and length of the pinholes of the packs. Another point raised deals with the advantages of using perforated film and/or of making holes or openings along the edges where the polymeric film is welded. Copyright © 2001 John Wiley & Sons, Ltd. [source] Colloidal Films That Mimic CiliaADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Fang Liu Abstract Cilia are wavy hair-like structures that extend outward from surfaces of various organisms. They are classified into two general categories, primary cilia, which exhibit sensing attributes, and motile cilia, which exert mechanical forces. A new poly(2-(N,N -dimethylamino)ethyl methacrylate- co -n-butyl acrylate- co - N,N -(dimethylamino) azobenzene acrylamide) (p(DMAEMA/nBA/DMAAZOAm) copolymer is prepared using colloidal synthesis, which, upon coalescence, form films capable of generating surfaces with cilia-like features. While film morphological features allow the formation of wavy whiskers, the chemical composition of the copolymer facilitates chemical, thermal, and electromagnetic responses manifested by simultaneous shape and color changes as well as excitation wavelength dependent fluorescence. These studies demonstrate that synthetically produced polymeric films can exhibit combined thermal, chemical, and electromagnetic sensing leading to locomotive and color responses, which may find numerous applications in sensing devices, intelligent actuators, defensive mechanisms, and others. [source] Repairing Polymers Using Oscillating Magnetic FieldADVANCED MATERIALS, Issue 48 2009Cathrin C. Corten Repair of physically separated thermoplastic polymers containing , -Fe2O3 nanoparticles without sacrificing their mechanical properties is achieved by applying an oscillating magnetic field. As , -Fe2O3 nanoparticles oscillate at the frequency of the magnetic field, localized amorphous flow occur, and a permanent repair of physically separated polymeric films is achieved. [source] Orthogonal Transformations on Solid Substrates: Efficient Avenues to Surface ModificationADVANCED MATERIALS, Issue 34 2009Leena Nebhani Abstract The performance of solid substrates is not only governed by their molecular constitution, but is also critically influenced by their surface constitution at the solid/gas or solid/liquid interface. In here, we critically review the use of orthogonal chemical transformations (so-called click chemistry) to achieve efficient surface modifications of materials ranging from gold and silica nanoparticles, polymeric films, and microspheres to fullerenes as well as carbon nanotubes. In addition, the functionalization of surfaces via click chemistry with biomolecules is explored. Although a large host of reactions fulfilling the click -criteria exist, pericyclic reactions are most frequently employed for efficient surface modifications. The advent of the click chemistry concept has led,as evident from the current literature,to a paradigm shift in current approaches for materials modification: Away from unspecific and nonselective reactions to highly specific true surface engineering. [source] Shelf life extension of durum semolina-based fresh pastaINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010Cristina Costa Summary In this work, the combined effects of chitosan, modified atmosphere packaging (MAP) and packaging barrier properties on shelf life of fresh pasta is presented. In particular, all pasta samples were packaged under active and passive MAP in two different polymeric films with high and low barrier properties. In order to assess the influence of the variables described beforehand on the shelf life of pasta, the sensorial and microbiological quality has been monitored during storage. Results confirmed the antimicrobial properties of chitosan. Moreover, the findings recorded in this study suggest that the shelf life of fresh pasta is limited by the sensorial characteristics. Statistically significant differences between the shelf life of pasta packaged in low barrier and high barrier films were found. The best result was obtained for samples packaged in high barrier film, due to the ability of the packaging to maintain the gas headspace conditions during the storage. [source] Effect of packaging conditions on the growth of micro-organisms and the quality characteristics of fresh mushrooms (Agaricus bisporus) stored at inadequate temperaturesJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2000E. González-Fandos Mushrooms were packed in two polymeric films (perforated and non-perforated PVC) and stored at 17 °C and 25 °C. The carbon dioxide and oxygen content inside the packages, aerobic mesophiles, Pseudomonas spp., faecal coliforms, Escherichia coli, anaerobic spores and major sensory factors (colour, texture, development stage and presence of moulds) were determined. The non-perforated packages had the highest contents of CO2 (6,7%), the lowest contents of O2 (0·013,0·17%) and the most desirable quality parameters (texture, development stage and absence of moulds). Pseudomonas spp. counts were around 1 logarithmic unit lower in mushrooms packaged in non-perforated film as the O2 concentrations were lower than in perforated film. The mushrooms themselves were inoculated with an enterotoxin A-producing strain of Staphylococcus aureus, packaged in overwrapped trays and stored at 17 and 25 °C. Staphylococcus aureus did not grow in the samples stored at 17 °C. Only slight growth was observed in mushrooms packaged with non-perforated film after 1 day at 25 °C. No enterotoxin was detected in any package. Faecal coliform counts were <2 log cfu g,1. Escherichia coli was not isolated in any of the samples. At 25 °C, counts of anaerobic spores of around 2 log cfu g,1 were detected in those mushrooms packaged in non-perforated film. [source] Novel bioactive scaffolds with fibronectin recognition nanosites based on molecular imprinting technologyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Elisabetta Rosellini Abstract Biomimetic materials for application in the field of tissue engineering are usually obtained through covalent bonding between the polymer backbone and the bioactive molecules. A totally new approach, proposed for the first time by our research group, for the creation of advanced synthetic support structures for cell adhesion and proliferation is represented by molecular imprinting (MI) technology. In this article, we describe the synthesis and characterization of molecularly imprinted polymers with recognition properties toward a fibronectin peptide sequence and their application as functionalization structures. Polymers, in the form of densely fused microgel particles, were obtained by precipitation polymerization. The imprinted particles showed good performance in terms of recognition capacity and quantitative rebinding; moreover, the epitope effect was observed, with the particles able to recognize and rebind not only the specific peptide sequence but also a larger fibronectin fragment. The cytotoxicity tests showed normal vitality in C2C12 myoblasts cultured in a medium that was put in contact with the imprinted particles. Therefore, imprinted particles were used to functionalize synthetic polymeric films by deposition on their surface. The deposition of the imprinted particles did not alter their specific recognition and rebinding behavior. The most remarkable result was obtained by the biological characterization: in fact, the functionalized materials appeared able to promote cell adhesion and proliferation. These results are very promising and suggest that MI can be used as an innovative functionalization technique to prepare bioactive scaffolds with an effective capacity for improving tissue regeneration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polymerization at the gas/solution interface: Preparation of polymer microstructures with gas bubbles as templatesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Maciej Mazur Abstract We report on the chemical polymerization of 2-methoxyaniline at the interface between an aqueous solution and air. The polymer is formed in the interfacial region, whereas the soluble trimer is yielded in the bulk of the polymerization solution. The preferential polymerization of 2-methoxyaniline is discussed in terms of monomer and oligomer accumulation at the interface, which influences the reactivity of these species and allows further polymerization. The phenomenon of polymer growth is employed to selectively deposit polymeric material onto glass slides decorated with gas microbubbles. Because of preferential polymerization at the bubble/solution interface, hemispherical features are produced on the surface of glass. When some polymeric material is mechanically removed, microrings or microholes are obtained. The anomalous polymerization of 2-methoxyaniline is compared to that of 2-methylaniline. This monomer polymerizes uniformly within the entire volume of the reaction mixture; thus, no preferential polymer formation at the gas/solution interface is observed. As a result, deposition on microbubble-decorated glass slides produces polymeric films containing a number of microholes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] AN EMPIRICAL APPROACH FOR ASSESSMENT OF SAFE STORAGE PERIOD FOR BUTTON MUSHROOM (AGARICUS BISPORUS) BASED UPON COLOR CHANGES UNDER MODIFIED ATMOSPHERE PACKAGINGJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2010SHASHI PAUL ABSTRACT White button mushroom accounts for 35,45% of the total mushroom produced in the world. Modified atmosphere packaging or MAP is a technology that, along with low temperature storage, helps in extending the shelf life and maintenance of quality of the produce packaged in polymeric films. The present study mathematically modeled the various transport processes associated with the mushroom under MAP at 15C and 75% relative humidity (RH) using the enzyme kinetics approach. Low density polyethylene (LDPE), polypropylene (PP) and oriented polypropylene (OPP) films were used to pack the mushroom. Numerical solutions to the transient state equations were programed in a computer programing language to predict the in-pack gaseous partial pressures at any instant of time. The model was experimentally validated, and a simple qualitative tool based upon optimum whiteness of mushroom was developed using the predictions to determine the safe period of storage. The predicted and experimental in-pack partial pressures of O2 and CO2 were in fair agreement with each other. In the OPP film packages, the O2 and CO2 levels stabilized around 6.87 and 12.93 kPa, respectively. Whereas, O2 levels decreased drastically in LDPE and PP film packages. A combination of predicted in-pack environment in all the film packages, storage time and whiteness of mushroom led to the conclusion that mushrooms can be stored safely for 32, 44 and 108 h in the gaseous environment available in the LDPE, PP and OPP film packages, respectively. PRACTICAL APPLICATIONS The empirical approach followed in this study through assimilation of various transient state in-pack variables with a single qualitative attribute of mushroom can serve as a measure of assessment of the mushroom's safe storage period under modified atmosphere packaging. Further, the mathematical approach suggested in this study can also serve as a benchmark for its application to other fruits and vegetables, taking into consideration their respective limiting qualitative characteristics. Thus, the results detailed in the study can be easily applied for their direct practical application during storage as well as for further academic exercises. [source] The Debittering of Navel Orange Juice Using Polymeric FilmsJOURNAL OF FOOD SCIENCE, Issue 4 2007Stéphane C. Fayoux ABSTRACT:, In order to better understand and optimize the sorption of limonin (the major navel orange juice bitter principle) by various plasticized polymeric films, a sorption and plasticizer migration study was carried out using high-performance liquid chromatography (HPLC) and gas chromatography (GC). Low molecular weight (LMW) poly (vinyl chloride) (PVC) plasticized with dioctyl adipate (DOA) gave the best results for both limonin sorption and low DOA migration. Thick films did not significantly sorb more limonin than thin films in the timeframe of our experiments, as the absorption involved rapid surface sorption followed by slow bulk diffusion. The debittering efficiency was a 1000-fold greater than that obtained with current polystyrene divinylbenzene resin beads, with potential for industrial scale debittering. [source] Monitoring ultrathin film photopolymerization of tetra-alkylepoxyporphyrin by UV-Vis spectroscopyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2009Kalle Lintinen Abstract Cationic photopolymerization is a convenient in situ polymerization method for organic thin film preparation. In this work, the polymerization mechanisms is applied for highly viscous cross-linking monomers, using tetra-alkylepoxyporphyrin (TAEP) as a case study. By comparing the UV-Vis spectra of the polymerized sample before and after the unreacted monomers have been dissolved, it is possible to estimate the polymerization yield. An IR spectrum of a reference thick film confirms full polymerization. Scanning fluorescence lifetime microscopy and AFM show the uniformity of the polymer. It was shown that photopolymerization is highly dependent on the substrate nature and requires at best case a 10 min illumination at 90 °C. Thermal polymerization of the same sample requires 10 min heating at 150 °C in dark. It was also shown that TAEP works as a self-sensitizer for cationic photopolymerization. The proposed method is a mild and versatile technique for in situ preparation of thin polymeric films directly from chromophore monomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6095,6103, 2009 [source] Physicochemical properties and application of pullulan edible films and coatings in fruit preservationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2001Tony Diab Abstract The effects of water, sorbitol and a sucrose fatty acid ester (SE) on the water sorption behaviour and thermal and mechanical properties of pullulan-based edible films as well as the physiological responses of fruit coated with pullulan have been studied. Incorporation of sorbitol or SE in pullulan films resulted in lower equilibrium moisture contents at low to intermediate water activities (aw), but much higher moisture contents at aw,>,0.75; estimates of monolayer values (within 4.1,5.9,gH2O,kg,1 solids) were given by application of the Brunauer,Emmett,Teller (BET) and Guggenheim,Anderson,DeBoer (GAB) models. A single glass,rubber transition (Tg), attributed to the polysaccharide component, was detected by calorimetry and dynamic mechanical thermal analysis (DMTA) at a sorbitol level of 15,30% DM. With both tests the strong plasticising action of water and polyol was evident in the thermal curves, and the Tg vs moisture content data were successfully fitted to the Gordon,Taylor empirical model. Multifrequency DMTA measurements provided estimates for the apparent activation energy of the glass transition in the range of , 300,488,kJ,mol,1. With large-deformation mechanical testing, large decreases in Young's moduli (tensile and three-point bend tests) were observed as a result of water- and/or polyol-mediated glass-to-rubber transition of the polymeric films. In the moisture content range of 2,8%, increases in flexural modulus (E) and maximum stress (,max) with small increases in moisture content were found for films made of pullulan or pullulan mixed with 15% DM sorbitol; a strong softening effect was observed when the water content exceeded this range. Addition of sorbitol increased the water vapour transmission rate of the films, whereas addition of SE had the opposite effect. Application of a pullulan/sorbitol/SE coating on strawberries resulted in large changes in internal fruit atmosphere composition which were beneficial for extending the shelf-life of this fruit; the coated fruit showed much higher levels of CO2, a large reduction in internal O2, better firmness and colour retention and a reduced rate of weight loss. In contrast, similar studies on whole kiwifruits showed increased levels of internal ethylene, which caused acceleration of fruit ripening during storage. © 2001 Society of Chemical Industry [source] Large Enhancement in Conductivity of Polyaniline Films by Cold StretchingMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 10 2010Hong-Mei Xiao Abstract The hot-stretching method has been well accepted for enhancing the electrical conductivity of conducting polymer films. High temperature is the prerequisite to soften the polymer to highly align and elongate the polymeric molecular chains. In this study, the cold-stretching method is proposed for the first time to enhance the conductivity of conducting polymeric films. Polyaniline (PANI) films are stretched at room temperature to different strain levels. It is observed that the applied strain has significant effects on the morphology, molecular chain structure, crystallinity, and crosslinking of the PANI films. As a result, the conductivity of PANI films is effectively increased by the cold-stretching process. Particularly, a maximum conductivity with an 18.4-fold increase in the direction parallel to the stretched direction is obtained when the elastic limit strain is applied. Compared to hot stretching, cold stretching is unique due to the extremely low dimensional change and very high efficiency achieved. [source] Simple universal permeation apparatusPACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2003Tareq Al-Ati Abstract A number of methods and commercial apparatuses for measuring the permeability of polymeric films and sheet materials have been successfully developed. Generally, the equipment is complex, expensive and specific to certain permeants, but all operate on similar basic principles. Because of our interest in a wide range of permeants, including fixed gases and organic vapours, we have built an inexpensive apparatus that can measure permeation to gas, moisture and organic vapours. We also require outputs that can provide not only permeability data but also proved solubility and diffusion coefficients. The apparatus is built around a commercially available thermal conductivity detector. Copyright © 2003 John Wiley & Sons, Ltd. [source] How to design perforated polymeric films for modified atmosphere packs (MAP)PACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2001Luciano ZanderighiArticle first published online: 12 APR 200 Abstract Increasing proportions of fresh produce are being sold in modified atmosphere packs (MAP) with the aim of preserving product quality longer and reducing freight costs. A rigorous theoretical analysis was made of the transport phenomena across packaging film (composite, perforated, etc.) in order to find out whether polymeric film will permit a stationary modified atmosphere (MA) inside the pack, and if so when, and to investigate the effect of the size and shape of the holes in the perforated film. The continuity equations of the pack, for all diffusing species, were written and solved for stationary conditions, with the boundary conditions that species not involved in metabolic processes do not diffuse across polymeric film. After a detailed analysis of the transport phenomena across both continuous and perforated film, and of the metabolic rate processes, it transpires that no stationary conditions compatible with any MA can be found for continuous film, owing to the permeation characteristics of the film and the rate of the metabolic processes. With perforated film it is possible to find, at least for certain metabolic process rates, a stationary state where a constant MA is maintained inside the pack. A proposal is given, provided the rate of the metabolic process is known, for the design of a pack in terms of polymeric materials and of the pinhole size. Two case studies, strawberry and cabbage, are presented and discussed, along with the optimization of the polymeric film and the size and length of the pinholes of the packs. Another point raised deals with the advantages of using perforated film and/or of making holes or openings along the edges where the polymeric film is welded. Copyright © 2001 John Wiley & Sons, Ltd. [source] Compatibilized Ny6-based blends as innovative packaging materials: determination of some important properties relevant to food contact applicationPACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2001P. Laurienzo Abstract Chemical physical analysis, photo-oxidative stability and lipid oxidation of innovative polymeric films based on blends of nylon 6 and ethylene-co-vinyl alcohol for use in food packaging have been investigated. Thermal mechanical analysis showed that the presence of an interfacial agent in the blend stabilized the films towards the action of permeants. Synergistic effects of the interfacial agent are reported with respect to UV photostability. Peroxide value (PV) was used to follow the oxidation of the olive oil, and for this parameter also the influence of the interfacial agent was clearly detected. Copyright © 2001 John Wiley & Sons, Ltd. [source] Poly(4-hydroxyphenylacetic acid): A new material for immobilization of biomoleculesPOLYMER ENGINEERING & SCIENCE, Issue 10 2008Tatiana A.R. Silva The electrochemical modification, surface analysis, and electrochemical impedance spectroscopy of graphite electrodes modified with polymeric films derived from 4-hydroxyphenylacetic acid (4-HPA) were investigated. The electrooxidation and optimization of the immobilization of adenosine monophosphate (AMP) and guanosine monophosphate (GMP) onto poly(4-HPA) films at different pH values was carried out. Variation of the experimental conditions that influenced the electrode reaction, particularly the pH of the electrolytic solution, showed that the oxidation potentials of the immobilized AMP or GMP onto the modified electrodes decreased with increasing pH of the electrolyte. Higher oxidation current was obtained for AMP in phosphate buffer (pH 7.50) solution and GMP in acetate buffer (pH 4.50) solution. Film surface morphology and roughness in the absence or presence of AMP or GMP have been characterized by atomic force microscopy. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Toward the synthesis of strongly photoluminescing polyesters by entropically driven ring-opening polymerizationsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008Richard T. Williams Abstract A range of strongly fluorescent polyesters incorporating distyrylarylene moieties have been prepared. The polyesters have the potential to be prepared from the corresponding macrocyclic oligomers (MCOs) by entropically driven ring-opening polymerizations (ED-ROP). This reactive macrocyclic oligomer approach to the polymers has the advantage of allowing the deposition of conjugated materials by solution deposition techniques, such as ink-jet, since the macrocycles after deposition can be converted directly on the substrate, in the absence of any external initiator, into solvent intractable thin polymeric films. Copyright © 2008 John Wiley & Sons, Ltd. [source] Reduction of diabetes-induced renal oxidative stress by a cantaloupe melon extract/gliadin biopolymers, oxykine, in miceBIOFACTORS, Issue 2 2005Yuji Naito Oxidative stress is implicated as an important mechanism by which diabetes causes nephropathy. Oxykine is the cantaloupe melon extract rich in vegetal superoxide dismutase covered by polymeric films of wheat matrix gliadin. In this study, we examined whether chronic oral administration of oxykine could prevent the progression of diabetic nephropathy induced by oxidative stress using preclinical rodent model of type 2 diabetes. We used female db/db mice and their non-diabetic db/m littermates. The mice were divided into the following three groups: non-diabetic db/m; diabetic db/db, and diabetic db/db treated with oxykine. Blood glucose level, body weight, urinary albumin, and urinary 8-hydroxydeoxyguanosine (8-OHdG) were measured during the experiments. Histological and 8-OHdG immunohistochemical studies were preformed on 12 weeks from the beginning of treatment. After 12 weeks of treatment, the levels of blood glucose and the body weight were not significantly different between the oxykine-treated group and the non-treated db/db group, however both groups kept significantly high levels rather than db/m mice. The relative mesangial area calculated by mesangial area/total glomerular area ratio was significantly ameliorated in the oxykine treated group compared with non-treated db/db group. The increases in urinary albumin and 8-OHdG at 12 weeks of treatment were significantly inhibited by chronic treatment with oxykine. The 8-OHdG immunoreactive cells in the glomeruli of non-treated db/db mice were more numerous than that of oxykine-treated db [source] Inorganic Layers on Polymeric Films , Influence of Defects and Morphology on Barrier PropertiesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2003M. Hanika Abstract Flexible polymeric films are not only widely used in conventional packaging as substitute for glass and aluminum foil packaging but are also proposed as encapsulation for novel products, like flexible solar cells or organic light-emitting devices. The two essential properties of the polymeric packaging are flexibility and good permeation barrier properties against gases and vapors. This article deals with vacuum web coating as a common way of increasing barrier properties of polymeric films and the problems related to this procedure. Defects caused by particles and surface imperfections are found to dominate the permeation rate for such coated polymeric films. Atomic force microscopy, electron and also optical microscopy was used for analysis of the coating layer. Three-dimensional numerical simulations were performed for modeling of the influence of defect size, spacing and film thickness. Results of numerical modeling and of many practical experiments show that the permeability is almost independent of the substrate film thickness when a critical thickness is exceeded. In most cases the defects can be treated as independent of each other. The gas permeability of vacuum web-coated polymeric films can be quantitatively predicted by a simple formula. For gases, like oxygen, it is shown that a statistic analysis of the defect sizes by optical microscopy is sufficient. For water vapor transmission, however, the structure of the coating layer itself has also to be taken into account. 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