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The integration of platelet-shaped montmorillonite particles to improve the oxygen barrier of polyvinyl-alcohol-based barrier layers is state-of-the-art, but research on roll-to-roll coatings of such composite barrier lacquers has not been widely published. In this study, two different coating techniques, slot-die and reverse gravure, were used on a roll-to-roll scale to apply barrier lacquers comprising polyvinyl alcohol and montmorillonite. The lacquers were analyzed regarding viscosity at certain shear rates and surface energy and the dried coating layers regarding oxygen barrier, surface morphology, and particle orientation. Low permeability coefficients delivering a high oxygen barrier of 0.14 and 0.12 cm3(STP)1μmm2dbar were achieved for the coating layers with slot-die and reverse gravure coating, respectively. It turned out that the properties of the barrier lacquer need to be adjusted to the coating technique to achieve high oxygen barrier performance. By tailoring the barrier lacquer formulation, the orientation of the platelet-shaped montmorillonite particles can be achieved using both techniques. A low solid content of down to 3wt% is preferable for the premetered slot-die coating, because it results in low agglomeration quantity in the coating layer. A high solid content of up to 9wt% is preferable for the self-metered reverse gravure coating to assure a homogeneously coated layer.

Polypropylene (PP) has a high recycling potential. However, the properties of mechanically recycled PP (R-PP) have not been fully compared to those of virgin PP (V-PP). Therefore, in this study, properties of R-PP and V-PP were compared using data from recyclers, virgin plastic suppliers, and the literature. The properties of recyclates could not be directly correlated either with the properties of the virgin polymers from which the recyclates were made or the recycling parameters. It was found that the MFR of R-PP was higher; MFR R-PP had a median value (m) of 11 g/10 min while MFR V-PP had a median value of 6.3 g/10 min (at 230 °C and with 2.16 kg). In terms of mechanical properties, in many cases R-PP exhibited stiffer and more brittle behavior, with a slightly higher Young’s modulus (ER-PP = 1400 and EV-PP = 1200 MPa), a reduced elongation at break (ɛbR-PP = 4 l.-% and ɛbV-PP = 83 l.-%), and notched charpy impact strength (NCISR-PP = 4.8 and NCISV-PP = 7.5 kJ/m2). However, the values for every property had a broad distribution. In addition to existing information from the literature, our research sheds fresh light on the variation of the characteristics of recycled polypropylenes presently on the market.

Multilayer films that comprise alternating inorganic barrier and polymer layers deposited on a flexible substrate are often used to protect organic electronic devices from degradation caused by oxygen and water vapor. We tested films consisting of up to 11 inorganic silicon oxide barrier and polymer layers to characterize the water vapor permeability, solubility and diffusivity of each layer based on measurements of water sorption, transient water vapor permeation and lag times. The time-dependency of transient water vapor transmission rates (WVTR) of the structures containing a barrier-polymer-barrier sequence was also estimated using a so-called quasi-steady-state (QSS) approximation. The permeability values and lag times in multilayer structures predicted by QSS approximation agreed with the values determined empirically based on time-dependent WVTR measurements. The steady-state WVTR of the multilayer barrier films was dominated by the permeability of the inorganic barrier layers, whereas the solubility coefficient and thickness of the interleaved polymer layers determined the lag times. The barrier performance and lag time of multilayer structures can be predicted using the parameters obtained from sorption measurements, thus significantly reducing the time required for experiments. The results of this study will allow us to design multilayer barrier films according to the lifetime requirements of flexible organic electronic devices.

Studies on composition optimisation showed that the mixing of nanoclays to whey protein-isolate (WPI)-based coating formulations offers an effective strategy to reduce the oxygen permeability of coated polymer films. The scaling up of the various processing stages of these formulations was undertaken to prove their industrial feasibility. The aim was to investigate the effect of various preparation methods at different production scales (pilot- and semi-industrial scale) on the barrier performance and morphological properties of the applied nanocomposites. A nano-enhanced composition was converted into a so-called &ldquo, ready-to-use&rdquo, formulation by means of a solid-state pre-dispersion process using ball-milling. The process yielded a nearly dust-free, free-flowing powder containing agglomerated particles, which can easily be mixed with water. The preparation of a coating formulation using the ready-to-use granules and its upscaling for roll-to-roll converting at pilot- and semi-industrial scale was also successfully implemented. The effects of both the production at various scales and ultrasound treatment on the morphology and barrier performance of the nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, as well as oxygen permeability measurements. Results have shown that the addition of nanoclays to WPI-based coating formulations ultimately led to significantly reduced oxygen permeabilities to 0.59 cm3, 100 &micro, m&middot, m&minus, 2&middot, d&minus, 1&middot, bar&minus, 1 (barrier improvement factor, BIF of 5.4) and 0.62 cm3, 100 &micro, 1 (BIF of 5.1) in cases of pilot- and semi-industrial-processed coatings, respectively, compared to a reference without nanoclay. In both cases, a similar degree of nanoparticle orientation was achieved. It was concluded that the solid state pre-dispersion of the nanoplatelets during the production of the ready-to-use formulation is the predominant process determining the ultimate degree of nanoparticle orientation and dispersion state.

Silica gel is a well-known desiccant. Through dispersion of silica gel in a polymer, films can be made that absorb and desorb water vapor. The water vapor absorption becomes reversible by exposing such films to a water vapor pressure below that of the water vapor pressure during absorption, or by heating the film. The intention of this study was to achieve a better understanding about the water vapor absorption, permeability (H2O, N2, O2, CO2), and mechanical properties of films with dispersed silica gel. Low-density polyethylene (PE-LD) monolayer films with a nominal silica gel concentration of 0.2, 0.4, and 0.6 g dispersed silica gel per 1 g film (PE-LD) were prepared and they absorbed up to 0.08 g water vapor per 1 g of film. The water vapor absorption as a function of time was described by using effective diffusion coefficients. The steady state (effective) water vapor permeation coefficients of the films with dispersed silica gel were a factor of 2 to 14 (8.4 to 60.2&middot, 10&minus, 12 mg&middot, cm&middot, (cm&sup2, &middot, s&middot, Pa)&minus, 1, 23 &deg, C) higher than for pure PE-LD films (4.3&middot, C). On the other hand, the steady state gas permeabilities for N2, O2, and CO2 were reduced to around one-third of the pure PE-LD films. An important result is that (effective) water vapor permeation coefficients calculated from results of sorption and measured by permeation experiments yielded similar values. It has been found that it is possible to describe the sorption and diffusion behavior of water by knowing the permeability coefficient and the sorption capacity of the film (Peff.&asymp, Seff.&middot, Deff.). The tensile stress changed only slightly (values between 10 and 14 N mm&minus, &sup2, ), while the tensile strain at break was reduced with higher nominal silica gel concentration from 318 length-% (pure PE-LD film) to 5 length-% (PE-LD with 0.6 g dispersed silica gel per 1 g film).

Barrier layers are often used to protect sensitive organic devices from the detrimental effects of oxygen and water vapor. We investigated the effect of temperature on the time-dependent behavior of water vapor permeation in multilayer barrier films, focusing on the water vapor solubility, diffusion and permeability coefficients of individual layers and layer sequences. Activation energy measurements helped to explain the permeation mechanisms and showed the possible interactions between water and silicon oxide ( SiO x ). The activation energy for permeation ( E P ) through a two-layer film of polyethylene terephthalate (PET) coated with SiO x was 5.7 kJmol − 1 , about twice the E P value of the uncoated PET substrate. An intermediate ORMOCER® layer, providing a smooth surface for a second SiO x layer in an alternating structure, had only a negligible effect on the E P . Temperature dependent quasi-stationary approximations were derived for permeation through films with at least one inorganic/polymer/inorganic triplet, and were validated according to experimentally determined values. These equations showed the temperature and pressure dependencies of steady-state permeation and lag time in multilayered structures. Accordingly, the temperature dependency of steady-state permeation is determined by the E P of SiO x , whereas the lag time was mainly influenced by the heat of sorption of the intermediate polymeric layer. Furthermore, the increase in water vapor transmission rate was dominated by the partial pressure change with increasing temperature. Using these equations and experimentally determined parameters, we can predict the influence of temperature and humidity on the barrier performance of multilayered barrier structures.

One reason for heat losses in buildings is inadequate insulation. Vacuum Insulation Panels (vips) is emerging as a promising solution, being more energy efficient than conventional insulation materials, thinner and lighter. A VIP is made by placing a core insulation material inside a gas-barrier envelope and evacuating the air from inside the panel. The limitations to wide-scale VIP commercialization lie in lack of low-cost and high-volume processes to turn them into products suitable for use in buildings, and their short in-service lifetimes. These drawbacks were researched in a European funded project "nanoinsulate", and this paper gives an overview of results., European Union Commission Seventh Framework Programme Project “NanoInsulate”

This paper reviews a roll-to-roll technology for manufacturing of functional films as substrates and encapsulation for flexible OLED display and lighting devices. These functional films comprise ultra-high permeation barrier performance and two different types of a transparent electrode. Flexible small molecule OLED devices have been manufactured in roll-to-roll and characterized discussing current challenges for flexible electronic device encapsulation.

Flexible organic electronic devices are often protected from degradation by encapsulation in multilayered films with very high barrier properties against moisture and oxygen. However, metrology must be improved to detect such low quantities of permeants. We therefore developed a modified ultra-low permeation measurement device based on a constant-flow carrier-gas system to measure both the transient and stationary water vapor permeation through high-performance barrier films. The accumulation of permeated water vapor before its transport to the detector allows the measurement of very low water vapor transmission rates (WVTRs) down to 2 × 10−5 g m−2 d−1. The measurement cells are stored in a temperature-controlled chamber, allowing WVTR measurements within the temperature range 23–80 °C. Differences in relative humidity can be controlled within the range 15%–90%. The WVTR values determined using the novel measurement device agree with those measured using a commercially available carrier-gas device from MO...

Novel cost efficient high barrier envelopes are developed for vacuum insulation panels. In order to fulfil the required maximum oxygen permeability (at 23 °C and 50% relative humidity (RH)) of 1 × 10 −14 m 3 (STP) m −2 day −1 Pa −1 and water vapour transmission rate (at 23 °C and 85% → 0% RH) of 1 × 10 −6 kg m −2 day −1 , hybrid polymeric (ORMOCER ® ) and aluminium barrier layers are combined. Using roll-to-roll processes, these materials are deposited from the liquid or gas phase on top of a poly(ethylene terephthalate) substrate film. The low adhesion strength observed between aluminium and ORMOCER ® layers is significantly increased by the deposition of an additional aluminium oxide layer between the two materials. The lamination of a polyethylene or polypropylene sealing film does not weaken the adhesion strength. The resulting barrier structure has reached an oxygen permeability of lower than 5 × 10 −14 m 3 (STP) m −2 day −1 Pa −1 (at 37 °C and 30% RH). Electrochemical impedance spectroscopy gives evidence for a possible penetration of the ORMOCER ® lacquer into the aluminium oxide layer (synergistic effect), which explains the improved adhesion and barrier performance due to the aluminium oxide layer.

The requirement for evaluating high performance barrier layers with water vapor transmission rates (WVTR) far below 10−3 g/m2 d has been sparked by the growing application of flexible and organic electronics. While several highly sensitive WVTR-measurement techniques are described in the literature, their accuracy and comparability has not yet been tested. There is an absence of direct comparison of these methods. With a growing body of literature referring to different coating and barrier technologies (often under different testing conditions), it is extremely difficult to gather a coherent picture both of the performance of the materials studied and the permeation measurement methods used. In order to clarify these points we report on independent WVTR measurements of the same batch of a high performance barrier film under two sets of conditions in several laboratories with different state-of the-art methods. These methods also include several calcium test set-ups. The results showed that, while some differences are present, there is a remarkable level of agreement between the measurement methods even prior to harmonization.

Flexible packaging films for highly sensitive products that are to be protected against moisture and oxygen need high barrier materials. In the food and pharmaceutical packaging industries, barrier films, which contain a single inorganic layer on top of a polymeric substrate, provide sufficient barrier. For the protection of more sensitive products, such as vacuum insulation panels, organic photovoltaic cells, or organic light emitting diodes, the barrier films are, however, not sufficient and multilayered structures of alternating inorganic and polymeric layers are required as encapsulation material to ensure sufficient product lifetime. One approach for the production of multilayered structures is the face-to-face lamination of two barrier films via lamination adhesives. Such multilayered structures are usually referred to as multilayered high-barrier laminates. Solvent-free, UV-curable, epoxy-based adhesives are promising candidates for multilayered high-barrier laminates. The adhesives best suited for multilayered high-barrier laminates are those that provide both high laminate bond strength as well as barrier performance. In this paper three different types of such adhesives are discussed in terms of their water vapor barrier and adhesion performance. The effects of the structural differences in the adhesives - chain mobility, crosslink density and surface energy - on the laminate bond strength and barrier performance are investigated. Laminate bond strength tests were performed and failure types and failure locations in the laminates were examined. The results suggest that the intrinsic barrier performance of the adhesive significantly affects the barrier performance of the laminate. On the other hand, the adhesive having the best barrier performance shows a weak adhesion performance. An appropriate adhesive was designed by adjusting the type of the flexibilizer and photoinitiator used in its formulation. This adhesive in combination with a barrier film having an enhanced surface energy shows at the same time a promising laminate bond strength as well as barrier performance.

Nitrile rubber (NBR, 39:61 wt% of acrylonitrile:butadiene) and styrene butadiene rubber (SBR, 50:50 wt% of styrene:butadiene) matrices have been equilibrated by molecular dynamics (MD) simulations. Transition-state approach is used to calculate the diffusion and solubility coefficients of small penetrants in these matrices, indicating quite low values in NBR and reasonable agreement with experimental results. MD simulations have been performed to analyze water diffusion in these matrices. Aggregation of water molecules is observed in the hydrophobic matrix SBR. MD simulations with fictitious nonpolar water molecules inhibit aggregation and lead to enhanced diffusion in SBR. In NBR there is a slight increase in diffusion for fictitious water molecules. The lower diffusion constants in NBR result from slower local relaxation of the matrix due to tighter intermolecular packing and higher cohesive energy density. The free volume distribution that affects solubility coefficients is not a major determining factor for the diffusion coefficients in these matrices.

We performed molecular dynamics simulations on oxygen transport in dry and hydrated (with 3 and 13 wt% water content) amorphous ethylene-vinyl alcohol (EVOH) copolymers. As the water content increases, the intermolecular hydrogen bonding in the matrix decreases and the cavity sizes increase, which result in increased diffusion coefficients. The local chain mobility increases significantly only at 13% water content. The predicted glass transition temperatures fall into reported experimental ranges. The solubility coefficients of oxygen slightly decrease with increasing water content, which indicates that the excessive increase in permeability mainly results from increased diffusion rates.

The objective of this study is to investigate the relationship between gas permeability and the chemical structure and conformational properties for copolymers of styrene and its homopolymer. The diffusion and the solubility coefficients of small gas molecules (He, H 2 , Ne, O 2 , N 2 , CH 4 , Ar, CO 2 ) in amorphous structures of poly (styrene- alt -maleic anhydride) copolymer (SMA), poly (styrene- stat -butadiene) rubber (SBR), and atactic polystyrene (PS) are investigated by the transition state approach. Simulation results are found to be in good agreement with the experimentally measured values. The transport behavior of H 2 O molecules is also studied in the same bulk structures by fully atomistic molecular dynamics simulations. In general, the diffusion coefficients of the gases in these matrices decrease in the following order: SBR>PS>SMA, whereas the solubility coefficients follow the reverse order. The differences in the mobility of the matrices seem to be the dominant determining factor for diffusion. And the solubility coefficients depend on the free volume distribution of the matrices.

Metallized films consisting of thin, vacuum-deposited inorganic layers are used for a wide range of packaging applications for foods, pharmaceuticals and other technical purposes. They are made as laminates and consist of a polymeric film (substrate), an inorganic layer, mostly aluminum (Al), and a top layer, laminated to the inorganic layer using a suitable adhesive. One major quality indicator in such flexible packaging materials is the adhesion strength between the inorganic layer and the substrate. In order to measure the adhesion strength of thin Al layers deposited on a substrate, the following procedure is often used: Ethylene acrylic acid (EAA)-films are thermally sealed to the Al layers. In a subsequent peel test, the EAA-film is peeled-off at 180 degrees peel angle, delaminating the Al layer from the substrate. This method shows weaknesses in cases of high bond strength: The sealed EAA-film is elongated or even torn during the measurements, whereby it is difficult to obtain reproducible and repeatable results. In this study two alternative approaches have been tested to overcome the weaknesses of EAA-peel test. One of them is to use thermally sealable polymeric films, such as amorphous poly(ethylene terephthalate) and amorphous polyamide (both having a high mechanical strength), instead of the EAA film. Although the adhesion forces might have been weakened during the heat lamination of these selected films onto the Al surface, a quantitative comparison between the three different types of metallized films (with low, medium and high adhesion strength) is found to be promising by this approach. The other approach is to perform the peel tests with the laminates of the metallized films. The laminates are produced by laminating a low density polyethylene film (PE-LD) on top of the metallized film using an adhesive via a bench lamination process. The laminated PE-LD film in this case replaces the EAA-film. In this approach, the laminate structure is similar to the final product in the end-use. The metal adhesion strength is found to be in good agreement with the strength measured for similar structures produced at pilot scale.