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Gas overruns and explosions often occur in coal mining. To deal with this problem, the spatial structure model of a new non-ventilation excavation system is constructed. Combined with the model, a simulation experiment is conducted and the variations in gas concentration in each area of the system with variations in the amount of gas emission, drainage, and nitrogen curtain outlet velocity are obtained. The effectiveness of the gas barrier by the combined action of the gas drainage and nitrogen curtain is verified. This study provides the experimental basis for solving the problem of gas overruns and explosions, and is of great significance for realizing safe, efficient, and rapid excavation.

Compact stacking of building blocks is essential in order to utilize the impermeable nature of reduced graphene oxide (rGO) for encapsulating barriers in organic electronics. To obtain the desired accumulation characteristic, rGO films were fabricated via spraying process using phase-controlled graphene oxide (GO) dispersion. The rGO laminate prepared from the isotropic-phase dispersion exhibits a more favorable face-on orientation of rGO building blocks than that from the nematic-phase GO, which implies effective stacking of building blocks. As a result, the resulting gas barrier performance of the low-temperature-annealed rGO film is superior to previously reported low-temperature solution-processed materials. Fabricated gas barriers are adopted to seal the polymer solar cell with 57.2 times longer lifetime than that of the unsealed device. A device covered by an optimized rGO/polyethylene naphthalate gas barrier maintains photovoltaic performance as high as 88% of the initial efficiency after 28 days.

Thanks to their remarkable mechanical, electrical, thermal, and barrier properties, graphene-based nanocomposites have been a hot area of research in the past decade. Because of their simple top-down synthesis, graphene oxide (GO) and reduced graphene oxide (rGO) have opened new possibilities for gas barrier, membrane separation, and stimuli-response characteristics in nanocomposites. Herein, we review the synthesis techniques most commonly used to produce these graphene derivatives, discuss how synthesis affects their key material properties, and highlight some examples of nanocomposites with unique and impressive properties. We specifically highlight their performances in separation applications, stimuli-responsive materials, anti-corrosion coatings, and energy storage. Finally, we discuss the outlook and remaining challenges in the field of practical industrial-scale production and use of graphene-derivative-based polymer nanocomposites. Keywords: Graphene oxide, Reduced graphene oxide, Graphene quantum dots polymer, Nanocomposites, Synthesis, Properties of graphene and graphene oxide, Applications

This research is to studies the improvement of gas barrier properties of Polyethylene Terephtalate (PET) by graphene nanoplatelets (GNP). The composite is produced by solvent casting method. The GNP content is varied from 0 wt% to 2 wt%. The optimum tensile properties of PET/GNP nanocomposite is 34.7 MPa and the reduction of gas permeation is about 99% when the PET is mixed with 2 wt% of GNP. The scanning electron microscopy (SEM) revealed that the micropores are induced in PET/GNP nanocomposite. This suggests that PET in conjunction with GNP have the potential for high gas barrier properties in food packaging.

For many years, the inorganic content in nanocomposites has seldom exceeded 10 vol%. Novel fabrication methods have been employed to incorporate high inorganic loading within the polymer matrix. This review reports recent progress in high filler-content nanocomposites with high aspect fillers and the various unique techniques used for their fabrication. This review will also highlight the high filler-content nanocomposites, including mechanical, electrical, gas barrier and flame-retardant properties, with particular emphasis on quantitative information.

Information on the possible correlations between the characteristics of graphene itself or the performance of graphene-based devices and the conditions of its preparation or fabrication is scarce. This study examined how the characteristics and performance of graphene in applications, such as batteries and supercapacitors, conductive electrodes, and gas barrier films, change according to the conditions of the adopted process focusing mainly on graphene derived from GO. The overall aim was to determine the possible relationships between the characteristics and the conditions of the oxidation and reduction processes and the performance of devices based on the graphene prepared. Through a deeper understanding of the chemistry involved in the oxidation and reduction processes, possible routes along which the characteristics of graphene from GO can be tuned to a specific application were suggested. These guidelines will provide insights to those wanting to extend their exploration of graphene to new areas, such as catalysts, semiconductors, and biomedical materials.

In an attempt to enhance the gas barrier property of plastic containers such as poly(ethylene terephthalate) bottles, a hot wire chemical vapor deposition (CVD) technique for a type of SiOC thin film, which has been recently found to be applicable in this field, was further studied using different hot wire and material gas species. As a result, the authors found practically useful coating was possible with specific combinations of the hot wire and material gas species.

This study was conducted to find the structural features of acyl groups that enhance both the thermoplasticity and gas barrier properties of cellulose esters (CEs). The morphology, thermomechanical properties, and the gas permeability of the membrane of a cellulose ester (CPhP) highly acylated with 3-phenylpropionyl (PhP) group were compared with the alkyl chain type (C2-C8) CE membranes. The glass transition temperature of the CPhP membrane was 48°C, which was lowest among the CE membranes. Although the gas permeability coefficient of the cellulose triacetate (CTA) and CPhP membranes was reversed as the temperature increased, the permeability coefficient of O2 and CO2 for the CPhP membrane at 25°C was 3.0 × 10−16 and 2.2 × 10−15 [mol mm−2 s−1 Pa−1], respectively, which was lower than the CTA membrane. Its thermoplasticity and gas barrier properties were simultaneously improved by the PhP group compared with the alkyl type acyl groups.

Four post-synthetic modification (PSM) reactions to incorporate alkyl chains onto metal-organic frameworks (MOFs) were explored by using various organic transformation reactions. The modified hydrophobic MOFs can reduce the interface voids within the MOF-polymer composites. In this work, it was demonstrated that the decorated hydrophobic MOFs eliminated the interfacial voids in the MOF-polyaniline (PANI) composites and increased the anticorrosion performance. In particular, PAZr-C18-5% composite exhibited significant anticorrosive properties as the corrosion current density was reduced from 71.61 to 0.18 μA/cm2. Furthermore, the doping of hydrophobic MOFs into PANI can also increases the composite's surface hydrophobicity and improve its gas barrier performance.

A green and facile preparation method of GO/NR nanocomposite film was developed, in which self-crosslinking was formed in nanocomposite film under assistance of protein. The self-crosslinking of GO/NR nanocomposite film did not only enhance the crosslinking density of GO/NR nanocomposite film, but also enhanced interfacial interactions between GO and NR matrix. Furthermore, there were no vulcanization ingredients and surface chemical modification in the process. Thereby, the preparation process showed environmentally friendly and green, meanwhile enhanced effectively mechanical properties and barrier property of GO/NR nanocomposite film. This work provides a green and facile method for preparing high-performance GO/NR nanocomposite film for various applications.

Novel poly(lactic acid)-based chain extended triblock copolymers have been successfully synthesized in melt. The new polymers are characterized by a triblock ABA architecture, where A, is poly(lactic acid) and B is an ad hoc synthesized random biobased aliphatic copolyester poly(propylene/neopentyl glycol succinate). PLLA homopolymer has been also prepared for the sake of comparison. The samples under study were deeply characterized from the molecular, thermal and structural point of view. Mechanical and barrier properties and compostability were also investigated, in order to assess the potentiality of these materials in food packaging applications. The results obtained show that copolymerization leads to better mechanical response and barrier properties with respect to poly(lactic) acid homopolymer. Moreover, the presence of the central B block in the main polymer chain facilitates the process of compostability.

Hollow carbon microspheres were successfully fabricated in a convenient fashion by employing polyacrylonitrile (PAN) emulsions as precursors. The obtained hollow carbon microspheres were shown high monodispersity, tunable pore structures—gradient pore diameters and uniform orientation of pores. Through varying the flowing rates of three phases and solidification time, the PAN microspheres with different sizes and densities could be simply synthesized. Besides the relationship between the solidification time and the density of microspheres as well as their gas barrier properties were studied in this paper. These structured microspheres have great potential applications in various areas, including foam targets, carbon molecular sieve, cargo storage, medical instruments and so on.

This communication summarizes the salient features and mechanisms in high-pressure homogenization of wood fibres in order to make nanofibrillar cellulose (NFC). The energy-efficiency of delamination of fibres and the clogging tendency of fibres in high-pressure homogenizers/microfluidizers during delamination are critical and ways to alleviate these problems are reviewed. It is shown that the mechanical properties of NFC-films can be estimated from the Page equation. Usually, the evolution of the tensile strength properties of NFC-films increases with the extent of film delamination to reach a saturation value, which can be deduced from first principles using the Page equation. Finally, the evolution of the rheological features of NFC-gels and the barrier properties are reviewed and the estimation the nanofraction content in NFC-gels is being discussed.

In the study reported in this paper, sulfonated graphite oxide (SGO) was chemically reduced and then incorporated into a polyurethane matrix to produce reduced sulfonated graphite oxide/polyurethane (RSGO/PU) composites. Following reduction, the oxygen-containing functional groups attached to SGO had been effectively removed. The thermally conductive and electrical properties of RSGO/PU composites were thereby enhanced. Percolation thresholds of PU composites filled with RSGO were obtained at loadings below 1 wt%. The RSGO/PU composites exhibited improved gas barrier properties as the loading of RSGO was increased. Based on the fracture morphology investigation, the RSGO was evenly distributed throughout the PU composites and strong filler–matrix interactions were observed.

In this work we present the effect of defects in graphene on its potential for application in flexible electronics. We visualize defects at the grain boundaries, transfer defects and local atomic defects. We show that these defects are currently determining the gas barrier properties of graphene. Under strain up to only 2% we show that these defects lead to cracks in the graphene thereby deteriorating its conductivity.

Nanoscale manufacturing has enabled the development of smart packaging systems for the functional and convenient distribution of food products, overcoming the major bottlenecks to the future fabrication of stable, safe, economically feasible, and environmentally friendly food packaging systems. Traditionally, packaging systems have been used to protect products from physical impacts and were designed mainly for storage and transportation. The more recent packaging systems carry out the many additional functions required to maintain, preserve, and sustain the food product. In this review, we describe two nanoscale manufacturing-based approaches (viz., nanomaterials and nanofabrication) for smart food packaging systems and focus on their performance, including their gas barrier, antibacterial, and protective effects. Looking to the future, we summarize the updated information on the incorporation of nanoscale manufacturing-based systems into the food industry and discuss new perspectives of these systems for the smart food packaging industry.

Fabrication of polymer nanocomposite usually requires an extensive high shear mixing and substantial energy input. However, it has been demonstrated that polyvinylpyrrolidone (PVP) and Montmorillonite clay nanoparticles (MMT), will spontaneously form a highly ordered nanocomposite film when applied to a surface utilizing an inkjet printing technique. The as-synthesized nanocomposite prepared by this technique exhibits high barrier properties for oxygen gas. This self-assembly of MMT nanosheets inside the polymer matrix appears to be driven by entropic forces. In this work, an efficient gas barrier based on MMT and polyvinyl alcohol (PVOH) nanocomposite is reported. By adding MMT clay to our PVOH polymer, we solve the problem of sensitivity to humidity observed in pure PVOH films. PVOH is a well-known polymer that exhibits excellent gas barrier properties. However, PVOH is very sensitive to humidity and it must be protected by polymer overcoats such as polypropylene to exclude water. PVOH-MMT nanocomposite prepared in this work solves this problem without the need for polymer overcoating for protection. PVOH and MMT are spontaneously self-assembled into a nanocomposite film that exhibits extremely high oxygen barrier, high transparency, and low sensitivity to humidity which can largely be attributed to constrained polymer effects.

Encapsulation may solve thermal and storage stability issues for vitamins in foods. Here, the role of encapsulation in improving thermal and oxidative stability of vitamin C (encapsulated (EVC) and non-encapsulated (NVC), lipid-soluble vitamins (A & E together, esterified forms) was determined in mashed potato. The product was vacuum packed in four different oxygen barrier films, pasteurized using a microwave-assisted system or conventionally, and then stored at 5 °C for 90 days. We observed 4–5 % losses of NVC, while no losses occurred in EVC, vitamin A & E after thermal processing. At the end of storage, NVC and EVC losses in mashed potato varied between 12–76 % and 13–31 %, respectively depending upon film type, while vitamin A & E remained stable. TPC and pH of mashed potato were stable over the storage period in all selected films, but the color changed significantly in the lowest barrier film. Processing affected the gas barrier, dielectric, and thermal properties of films to a variable extent. This study demonstrated the effectiveness of encapsulation in improving the stability of vitamin C and can help processors in selecting optimal packaging film.

We used soluble graphene derivatives to fabricate gas barrier coatings on the surface of several industrially relevant commodity polymers. The coatings are prepared using electrochemically exfoliated graphene oxide, featuring both monoatomic thickness and micron-scale lateral size, showing better gas barrier performance as compared to films of commercial graphene products. A 74% decrease of oxygen transmission rate is found using loadings as low as 0.4 wt. % (0.2 vol. %). The coating process is performed using a combination of solution processing, filtering, and transfer. It is a robust and versatile approach, working with different transfer processes, different starting graphite materials and a wide range of well-known polymeric substrates: poly(ethylene terephthalate), poly(lactic acid), poly(hexamethylene adipamide), poly(propylene), and poly(vinyl chloride). The use of 2D sheets as surface coatings instead of bulk additives overcomes common issues related to dispersion of graphene in a polymer matrix, and gives a clear advantage in preserving the mechanical properties of the bulk polymer. Furthermore, it is a scalable approach able to significantly improve the barrier properties of polymeric films for large-scale applications.

The specific interface area between filler and matrix is of key importance for the performance of nanocomposites and therefore blending methods that deliver the best possible dispersion quality, while at the same time being technically benign, are sought-after. Transfer batch blending, as proposed here, utilizes an organic separator compound that is highly volatile at melt compounding temperatures allowing for its easy removal, while being solid at room temperature allowing for easy handling and processing. As judged by particle size distributions for redissolved nanocomposites and TEM micrographs, the quality of dispersion achieved by this transfer batch blending is of comparably high quality as the quality achieved by solution blending and is clearly superior to the quality obtained by melt blending. Permeability was chosen as the nanocomposite property used to probe dispersion quality as achieved by the different blending methods. For both fillers applied, organically modified natural montmorillonites and synthetic hectorites, transfer batch blending consistently delivered significantly higher reductions of the permeability suggesting that higher effective aspect ratios are achieved via the improved dispersion quality by transfer blending as compared to melt blending.

The research objective was to evaluate the performance of biobased plastics for modified atmosphere packaging (MAP) both on laboratory and industrial scales. Therefore the shelf-life (4 °C) of rumpsteak, ham sausage, filet de saxe, grated cheese and pre-fried fries that were MAP-packed in poly(lactic acid) (PLA) and cellulose-based multilayer packages was evaluated and compared with their shelf-life when packed in conventional materials. Furthermore, tests were performed on industrial packaging lines. The biobased packages showed sufficient gas-barrier to guarantee the shelf-life of MAP-packed food products, even when materials with lower barrier properties were used, but for rumpsteak and ham sausage, different light permeabilities of the packaging materials led to more discoloration. Furthermore, the biobased materials performed well on the industrial packaging machines, but seemed too brittle to hold larger contents. This study shows promising results toward the application of biobased packaging materials for different food products. Industrial relevance Environmental concerns regarding food packaging have led to the development of more sustainable alternatives. One of these alternatives are biobased materials. This research shows that several biobased plastics can contain and protect the food as well as maintaining its sensory quality. The biobased packages showed sufficient gas barrier to guarantee the shelf-life of the MAP packed food products, even when materials with lower barrier properties were used. Furthermore, case studies at different companies (on industrial packaging lines) show that a successful entrance in the market will not be hindered by technical problems.

A transparent, gas barrier film comprised of poly(vinyl alcohol) (PVA) and graphene oxide (GO) is synthesized through combined methods of solution blending and isothermal recrystallization. The recrystallized PVA/GO film with only 0.07 vol% GO gives an O2 transmission rate

Spatial atomic layer deposition (ALD) is capable to increase film deposition rate dramatically by eliminating the need of traditional pulse/purge steps in ALD process. Numerical simulations offer valuable information on spatial ALD system design and development. In this paper, a numerical study of inline spatial ALD process with a large gap (36 mm) is presented to investigate the effectiveness of precursor isolation using N2 flow as gas barrier in two different geometric designs, namely, top and bottom purge configurations. Bottom purge configuration is shown more effective in preventing precursor intermixing than top design. Higher N2 injecting flow rate and higher relative purging pressure are beneficial to construct an effective gas barrier in spatial ALD system. Evenly assigned precursor dosing pressure is advantageous to further prevent material intermixing. Transient material distributions in the flow field, contour plots of species, velocity field, and material tracelines have confirmed the effective gas barrier built by N2. Precursor intermixing molar fraction is shown as low as 0.0045%, and the intermixing molar concentration is as low as 9.105 × 10−5 mol/m3. The study provides invaluable information in determining geometric and process parameters for system design, and the effectiveness of precursor isolation using N2 as gas barrier in spatial ALD with a large gap is validated.

Waterborne epoxy–clay nanocomposites were prepared by encapsulation of organoclays in epoxy latex particles via phase inversion emulsification. The organoclays were exfoliated in the epoxy backbone before compounding with a hardener and subsequently dispersing in water. The encapsulation of clay platelets into the waterborne epoxy latex particle resulted in an exponential increase in particle size, from 5 to 10 times at a clay loading of only 1–2 wt%, respectively. The XRD patterns and TEM images show that clay platelets were well intercalated and exfoliated in the epoxy matrix. The gas barrier performance of the epoxy–clay nanocomposite strongly depended on the kind of organoclay. The best oxygen barrier efficiency was approximately 14% at 2 wt% clay loading.

With modification of layered double hydroxide (LDH) and prescription of additives, optical substrates with good transparency, high antistatic capability, and excellent gas barrier properties have been manufactured by a single-screw extruder and a T-Die. Moreover, we have also applied them for flexible OLEDs. The experimental results reveal that lab-made optical substrates can effectively hinder the invasion of moisture and oxygen in the air into the devices, therefore drastically prolonging the lifetimes.

In many polymer applications such as inner tire liners and fuel hoses, imparting excellent gas barrier property is of prime importance. Researches in this direction had been done based on a judicious choice of polymer type or a blend thereof and the compounding ingredients. Though butyl rubber has been the polymer of choice because of its excellent gas barrier property, yet researches were targeted to improve the same with further modification in the polymer type and variation in compounding ingredients. In this study, a (90:10) blend of chlorobutyl rubber (CIIR) and Epoxdised Natural Rubber (ENR) by weight was used as the base. Four different types of process oil and three different types of zinc oxide (ZnO) at fixed predetermined concentrations were used to optimize the gas barrier and mechanical properties. In this blend, recycled aromatic oil (RAE) and sheet zinc oxide were effective in imparting the best overall combination of properties. Scanning Electron Microscopic (SEM) studies of ZnO were done to understand the structure property relationship.

A new surface modification method by DLC coating with organosilane interlayer was introduced. Some DLC-coated polypropylene (PP) films pretreated with certain types of organosilane interlayers showed marked improvement in the gas barrier property. Among the DLC-coated PP, the PP films modified by organosilane interlayers with an amino group presented an extremely low oxygen transmission rate, which was even comparable to the existing low oxygen transmission rate of commercial DLC-coated PET with very high gas-barrier property. The barrier improvement factor (BIF) of DLC-coated PP by the amino-organosilane interlayer became approximately 300 times higher than that of the untreated neat PP. By observing the DLC surface, it was considered that such gas barrier improvement occurred due to the establishment of flawless DLC on PP with few cracks. In addition, DLC which was deposited onto the organosilane interlayer showed higher sp 3 /sp 2 ratio than an ordinary DLC, indicating a fairly dense DLC structure synthesized on PP with the organosilane interlayer, which was revealed by XPS. Furthermore, the new surface-treatment method for DLC was extensively found to be applicable to several other types of polymers including polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), and polylactide (PLA) which are all important polymeric materials for industry.

Thermal degradation of polyethylene terephthalate (PET) is accelerated in the presence of commercial organoclays, and this remains a challenge for the industry. While a high level of clay delamination is required in polymer nanocomposites, thermal degradation increases furthermore for highly exfoliated morphologies due to an increased exposure of the polymer matrix to silicate nanoplatelets. In this work, two different types of organomodified clay were melt blended with PET in the presence of a multifunctional epoxy-based chain extender, Joncryl® ADR-4368F (Joncryl), to compensate for molecular weight reduction during processing. The chain extender was added via a master-batch approach in order to promote clay delamination before molecular weight increase. The morphological, rheological, mechanical, thermal, and gas barrier characteristics of the nanocomposites were studied using several characterization techniques. A remarkable improvement in viscoelastic properties was observed for samples containing the chain extender due to recoupling of degraded chains. A better clay dispersion, enhanced barrier properties and increased Young modulus were also obtained for nanocomposites containing the chain extender. Compared to neat PET films, the oxygen permeability of nanocomposite films containing 4 wt% Cloisite® 30B and 1 wt% Joncryl decreased by 46%, whereas the corresponding permeability decrease for the Nanomer® I.28E nanocomposite was 40%. A 66% improvement in Young modulus was obtained for nanocomposite films containing 4 wt% Nanomer® I.28E and 1 wt% Joncryl. The improvement of the tensile modulus for the corresponding Cloisite® 30B nanocomposite was slightly less. © 2012 Elsevier Ltd. All rights reserved.

The properties as well as cut growth behaviour of natural rubber (NR) vulcanizates filled with different mineral clay types, namely devolite and calcined, were studied. The effect of partial replacement of clays with carbon black on the properties was also elucidated while the hardness level of the vulcanizates was kept constant. It is found that 2 phr of devolite clay or calcined clay can be replaced by 1 phr of carbon black (N330) to maintain the hardness value. At similar hardness, the cure retardation and resilience of the samples tend to reduce when decreasing the clay/carbon black ratio while torque difference, strength and thermal ageing resistance show the opposite trend. Compared to devolite clay, calcined clay gives NR vulcanizates with lower gas barrier property as well as scorch and cure time, but higher crosslink density, modulus, tear strength and cut tensile strength. The results also reveal that the cut growth behaviour of the vulcanizate changes from a simple lateral growth to oblique crack with partial replacement of the clay with carbon black, corresponding to its higher cut tensile strength.

This work was aimed to investigate the potential of PuOC protein isolate (PuOC PI) in preparation of biodegradable films at different pH values (2–12) and plasticizer content (0.3–0.6 g glycerol/g PuOC PI). Results showed that films could be formed in a wild range of pH, except at pH = 4–8. Films with 0.4 and 0.5 g glycerol/g PuOC PI were suitable for further analysis. The pH of film-forming solutions influenced all examined film’s characteristics. The amount of added glycerol significantly affected (p

In this study, atomic layer deposition (ALD) has been applied to deposit aluminum doped zinc oxide (AZO) films as gas barriers, successfully. Diethylzinc and trimethylaluminum were used as precursors and water as oxidant. Sequential deposition steps of 400 ALD cycles have been adopted to prepare AZO films. Influences of deposition temperatures on electro-optical properties have studied by using Hall-effect measurement and transmittance spectrometer. AZO film deposited at 130 oC has a low resistivity of 5×10-3 Ω-cm. Water vapor transmittance rate has been carried out by using Mocon Permatran-W 3/61. The WVTR performances of ALD barriers, which highly related to the physical conditions of interfaces between nanolaminated structures, have been measured as 0.001 – 2 g/m2*25oC*day.

Diamond-like carbon (DLC) can be effectively coated on polymer surfaces in order to modify polymers for highly functionalized materials. DLC films have been widely used for many industrial applications due to their outstanding physical properties such as high hardness, wear resistance and biological compatibility. Polymers, on the other hand, can create soft, flexible, highly absorbent and cost-effective materials by selecting or controlling their molecular structures. The DLC films coated on such polymer substrates have been investigated and extensively used because recently, quite a few applications of the polymer–DLC composites to e.g. gas barrier films and biocompatible medical devices have been proposed. In this article, we discussed the barrier properties, especially the gas barrier properties and the biocompatibility of DLC-coated polymers, after summarizing the fundamentals of DLC and polymers, followed by the explanation as to the adhesion and fracture behavior of DLC and polymers, which is crucial for the creation of a new polymer–DLC composite.

UV-curable organic/inorganic hybrid composites with gas barrier and heat-dissipating capability have been successfully fast synthesized with microwave irradiation and utilized for the encapsulation of top-emitting organic light-emitting diodes (TEOLEDs). Experimental results manifest that lab-made organic/inorganic hybrid composites can effectively not only obstruct the invasion of moisture as well as oxygen in the atmosphere into the device but also lower the temperature of device. Therefore, the lifetimes of TEOLEDs with their encapsulation are 2.2 folds longer than those without encapsulation.

Ultra-thin (10–500 nm) photo-polymerized γ-methacryloxypropyltriethoxysilane (MPMS) and vinyltrimethoxysilane (VTS) layers applied to SiO2 coatings on polyethylene terephthalate films improved the oxygen barrier performance of the oxide coated films by more than two-fold, and the coating strain to failure from 1.5% to beyond 5%, depending on the processing conditions. The oxygen transmission rate of composite films was measured under tensile strain. The chemical conversion of both MPMS and VTS with two different photoinitiators was studied by means of photo-calorimetry experiments, with attention paid to the influence of temperature, UV-light intensity and photoinitiator concentration. The conversion data were analyzed using an nth-order kinetic model, including an Arrhenius dependence of the temperature and a power-law dependence of the light intensity on the reaction rate. The improvement in mechanical integrity of the silane/silica barrier coating, with a toughness as high as 80 J/m2 was found to be controlled by the conversion state of the silane.

A new class of synthetic organoclays based on layered double hydroxides (LDH) has been developed that offers improved flame retardancy, gas barrier and mechanical properties. In addition, other advantages are compliance with the European regulations for materials coming in contact with foodstuffs and its higher temperature stability compared to most organoclays. Haimo Tonnaer of AkzoNobel Polymer Chemicals describes recent developments with Perkalite synthetic organoclays.

Thin DLC films coated on polymer surfaces are attracting considerable attention due to their wide applications and their interesting surface properties. When DLC films were coated on polymers, the resulting DLC-polymer composites are highly functionalized materials, some of which presenting dramatically improved gas barrier properties. In this paper, we will introduce several commonly used polymers including polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) for semi-crystalline polymers, and polymethyl methacyrlate (PMMA) for an amorphous polymer. The polymers were coated with thin DLC films and the gas barrier properties of the resulting DLC-polymer composites were investigated. Some of the DLC-polymer composites dramatically improved their gas barrier properties while they presented horizontal crack lines and vertical micro-buckling lines on the DLC surface when stretched to a certain strain. The gas barrier properties of the DLC-polymer composites with fractured DLC surface were also studied. It was found that the gas barrier property of the polymer substrates with lower residual strains was less damaged, when the substrates were mechanically deformed, than that of the polymer substrates with higher residual strains. When the number of the cracks increases, the strain imposed on each crack decreases, since the overall deformation is almost equally distributed to each crack while the crack spacing of each crack becomes shorter. Thus, it was found that the degradation of the gas barrier property after mechanical deformation is dependent on the residual strain of the polymers and the number of cracks on DLC films.

Flying requires enormous energy and some birds have higher mass-specific maximal oxygen consumptions than any mammal. The bird lung is very efficient partly because of an extremely thin blood-gas barrier so that some birds have thinner barriers than any mammals. We show here that in addition to the total barrier being very thin, the interstitium which is responsible for the barrier's strength is extraordinarily thin. This observation is paradoxical because intense exercise raises the pressure in pulmonary capillaries and results in large stresses in the capillary walls thus predisposing them to structural failure. For example, all galloping racehorses break their pulmonary capillaries. We propose that the explanation for how the bird can be so highly energetic yet also have such apparently fragile capillaries is the mechanical support provided by the dense packing of rigid air capillaries around the blood capillaries in the gas exchanging region of the lung. This architecture is very different from that in the mammalian lung.

A Korean beef product seasoned in concentrated soy sauce was vacuum packaged in a gas barrier plastic pouch and pasteurised. Adding vinegar and/or sake to the product was examined as preservation hurdles to improve microbial stability, and sensory quality affected by the additions was evaluated. A combination of vinegar and sake improved the microbial stability of the product at 8 and 20 °C, while added vinegar and/or sake did not improve the sensory quality of the product. The vinegar and sake combination produced significantly inferior initial quality in taste and overall acceptability. The sensory quality of the products with or without single use of vinegar or sake degraded significantly during 10 days of storage at 8 °C, which made the treatment effect less pronounced. Thus, the combined addition of vinegar and sake may be an alternative means of extending shelf life, because sensory quality with this treatment became close to that of the control after extended storage.

The unique properties of diamond like carbon (DLC) film, including its chemical inertness and impermeability, make it possible for new applications in food, beverage and medical market segments. Although these fields involve relatively higher risk for customers, the expected great advantages of DLC films have driven extensive efforts. In this paper, we present our recent results of development in high gas barrier polyethylene terephtalate (PET) bottles for beverage use. We also demonstrate that DLC or fluorinated DLC is a promising candidate coating material for orthopedics implants and blood contacting devices, such as artificial joints, cardiovascular interventional devices, artificial organs and pacemakers. A unique technique of plasma CVD method has been applied to deposit DLC films on the inside surface of PET bottles. The DLC-coated PET bottle exhibits extremely high gas barrier properties against oxygen, carbon dioxide and flavors compared to conventional bottles. For the practical use of PET bottles as a commodity, high speed and low cost coating are essential and lately our newly developed high speed coating machine has been successfully operated for the large production of hot tea drink bottles.

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent SnO 2 thin-film prepared by ion beam-assisted deposition (IBAD) was investigated. After encapsulation process, our organic thin-film transistors (OTFTs) showed somewhat degraded field-effect mobility of 0.5 cm 2 /(V s) that was initially 0.62 cm 2 /(V s), when a buffer layer of thermally evaporated 100 nm SnO 2 film had been deposited prior to IBAD process. However, the mobility was surprisingly sustained up to 1 month and then gradually degraded down to 0.35 cm 2 /(V s) which was still three times higher than that of the OTFT without any encapsulation layer after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over 10 5 to that of the unprotected devices (∼10 4 ) which was reduced from ∼10 6 before aging. Therefore, the enhanced long-term stability of our encapsulated OTFTs should be attributed to well protection of permeation of H 2 O and O 2 into the devices by the IBAD SnO 2 thin-film which could be used as an effective inorganic gas barrier for transparent organic electronic devices.

We obtain the organical clay (OMMT) by processing the Na–MMT using a kind of interlayer agent which contains –COOH in its structure. The interlayer distance of OMMT is 2.47 nm which is larger than the Na–MMT (1.90 nm). We synthesize the PET/OMMT nanocomposite by in situ interlayer polymerization and then make the composite into film by bi-axis orientation. We find that the barrier property of PET/OMMT film is greatly better than pure PET film.

Polyethylene (PE)/clay nanocomposites were synthesized by melt-intercalation using either PP-g-MA or PE-g-MA as a compatibilizer. The pristine clay was first modified with a swelling agent (octadecylamine) in solution to obtain an organophilic clay before being melt blended with a compatibilizer: PP-g-MA or PE-g-MA. Finally, these compounds were melt intercalated with PE to synthesis the PE/clay nanocomposite. The materials were characterized using X-RD, TEM, SEM, and TGA. The physical properties were observed with DMA and tension tests. Permeability tests of the PE/clay nanocomposites were also performed. The clays in PE/clay nanocomposites with the compatibilizer PP-g-MA were better exfoliated. The mechanical and gas barrier properties improved as the clay content increased.

With the aim of developing a high-performance gas barrier material, a polysilazane film was applied to an indium tin oxide (ITO)-coated organic PET substrate (i.e., the ITO and polysilazane films were formed sequentially on the PET substrate), and its properties were evaluated. The resulting material exhibits favorable gas barrier characteristics (oxygen permeability 0.02 cc/m 2 day, water vapor permeability 0.15 g/m 2 day) and performs well as a gas barrier. By controlling the atmosphere during heat treatment when forming the polysilazane film, it is possible to form a highly transparent film with good gas barrier performance. Since this material also conducts electricity due to the presence of the ITO film, it can be used to implement various advanced functions.

Research on silicon oxide thin films developed as gas-barrier protection for polymer-based components is reviewed, with attention paid to the relations between (i) coating defects, cohesive strength and internal stress state, and (ii) interfacial interactions and related adhesion to the substrate. The deposition process of the oxide from a vapor or a plasma phase leads in both cases to the formation of covalent bonds between the two materials, with high adhesion levels. The oxide coating contains nanoscopic defects and microscopic flaws, and their respective effect on the barrier performance and mechanical resistance of the coating is analyzed. Potential improvements are discussed, including the control of internal stresses in the coating during deposition. Controlled levels of compressive internal stresses in the coating are beneficial to both the barrier performance and the mechanical reliability of the coated polymer. An optimal coating thickness, with low oxygen permeation and high cohesive strength, is determined from experimental and theoretical analyses of the failure mechanisms of the coating under mechanical load. These investigations are found relevant to tailor the interactions and stress state in the interfacial region, in order to improve the reliability of the coating/substrate assembly.

Resorcinol-based polymers are proving to be ideal as gas barrier materials in packaging for highly oxygen-sensitive foods and beverages. Dr. Raj Durairaj discusses the work undertaken to date and opportunities for the future.

Silicon nitride (SiN x ) and silicon oxynitride (SiO x N y ) films have been formed by catalytic chemical vapor deposition (Cat-CVD) method using hexamethyldisilazane (HMDS). Addition of NH 3 gas and increase in gas pressure can prevent carbonization of tungsten (W) catalyzer. These SiO x N y films have high gas barrier ability compare to the case of SiO x N y films using SiH 4 and thus are expected for novel sealing films.

The shelf-life of pasteurized grapefruit segments in syrup packed in trays, two multilayer and one polypropylene, and in tin cans was studied. Retention of ascorbic acid and the development of brown colour (O.D. at 420 nm) were determined as a function of time at four storage temperatures. Degradation of ascorbic acid in all plastic trays followed a first-order reaction. In the multilayer trays containing a gas barrier in their structure, about 6 mg/100 mL ascorbic acid remained after 20 wk storage even at 35°C, while in the PP trays ascorbic acid disintegrated completely after 5 wk at the same temperature. Browning was much slower in the multilayer than in the polypropylene trays. Ascorbic acid degradation and browning were faster in all plastic trays than in tin cans. On the other hand the integrity and texture of the segments were much better in the multilayer plastic trays than in the tin cans due to a shorter heat treatment cycle.

The effects of the gas barrier characteristics of three films (ASI, ASII and ASIII) and storage temperature on the growth of, and aflatoxin production by, Aspergillus flavus in peanuts packaged in air and under a modified gas atmosphere of CO2:N2 (65:35) were investigated. Mold growth was barely visible in air packaged peanuts using high-medium barrier films (ASI and ASII) and stored at 20°C with more extensive growth occurring in air packaged peanuts stored at 25 and 30°C. Extensive mycelial growth and sporulation occurred in all air packaged peanuts in a low barrier film (ASIII), especially at 30°C. Gas packaging inhibited mold growth in peanuts packaged in a high gas barrier film at 20°C. However, mold growth occurred in gas packaged peanuts packaged in film ASII at higher storage temperatures while extensive mycelial growth was observed in all peanuts packaged in film ASIII irrespective of storage temperature. Levels of aflatoxin greater than the regulatory limit of 20 ng/g were detected in all air packaged peanuts with the highest level of aflatoxin (∼76 ng/g) being detected in peanuts packaged in a high gas barrier film ASI. Aflatoxin production was inhibited in gas packaged peanuts using a high barrier film. However, higher levels of aflatoxin were detected in all gas packaged peanuts in medium-low gas barrier films (ASII and ASIII), particularly at higher storage temperatures. This study has shown that MAP using a CO2:N2 (65:35) gas mixture was effective in controlling aflatoxin production by A. flavus in peanuts to levels less than the regulatory limit of 20 ng/g. However, the antimycotic effect of low O2-high CO2 atmospheres is dependent on the gas barrier characteristics of the packaging films, especially at higher storage temperatures.