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The case studies below are derived from discussion threads on the forum. So, they are based on an initial post on diffusion, corrosion or mechanical properties of polymer and polymer based materials in industrial applications, and subsequent comments of forum visitors. Please realize that the case stories are not representative for our commercial reports: there are just a consolidation of an interesting or popular discussion thread. For sample reports we invite you to contact us.
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| Evaluation of Polyimide for
Flexible Thin Film Solar Cell Substrates |
One of the candidate substrate materials for polymer based solar cells and Organic Light Emitting Diodes (OLED's) are transparant polyimides. Because of their combination of mechanical, moisture barrier and corrosion resistance (among which are UV light and exterme high Oxidation resistance) properties - even at high temperatures - they might be suitable. In this case study the water absorption characteristics of a new polyimide in real life circumstances is evaluated. By means of gravimetric, free volume and electrical impedance (EIS) data, it is found that water absorption in this specific polyimide can be rigorously modelled using the dual mode sorption model. According to this model, a part of the water molecules is ‘adsorbed’ on hydrophilic sites in the polymer with a Langmuir isotherm. This part is immobile. Another part ‘dissolves’ in the polymer and can move by normal (Fickian) diffusion. The implications of this significant anomaly on water breakthrough times, on water mass flux into the device, on accelerated weathering tests and on dimensional change are explained thoroughly. Click here to learn more. |
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In new composite equipment, such as in windmill turbines, aerospace parts, body parts for car and trains, electronic packages, medical packaging, membranes for simultaneous carbon dioxide / water vapour removal and other membrane applications, the mechanical retention if the composite is exposed to hygrothermal conditions is one of the main interests. The fact that water diffuses with a considerable rate in polymers, in combination with the anomalous diffusion and uptake behaviour, have lead to a variety of different theories with regard to water behaviour in composites. In this preliminary paper we present our view on water diffusion and mechanical retention in an unreinforced and glass fibre reinforced Derakane 411 Epoxy Vinyl Ester Resin (from Dow Chemicals). We have used IDC-SAC to interpret gravimetric data using two main concepts: [1] localized water adsorption theory, [2] multilayer diffusion simulation. The composite configuration that we tested did not show chemical degradation, but swells to a small extent under the continuous load of water. Click here to learn more. |
| Polyamide Hydrogen barrier Lining on a High Strength Steel Pipeline |
A major concern for future, high capacity hydrogen pipelines is long term durability at an internal gas pressure of 100 bar. It is well known that, already at one third of this pressure, carbon steels are susceptible to hydrogen embrittlement and cracking. In this case we describe integrated mechanical and permeation considerations if we would like to increase the lifetime of such a pipeline. Here, we will specifically focus on lining of an existing natural gas pipeline by glass reinforced polyamide, for future – high pressure - transport of hydrogen.
Interest Areas: lining, liner, coating, coatings for hydrogen (H2) permeation, carbon dioxide (CO2) membrane permeability and selectivity, Carbonic Acid diffusion in coatings and field joints, Liquefied Natural Gas (LNG) permeability, Liquefied Petroleum Gas (LPG) permeation, Hydrogen Sulphide (H2S) diffusion coefficients, Natural Gas transport coating, field joint, Chlorine (Cl2), Chlorine Dioxide permeation in membanes, Moisture, Water Vapour Weld corrosion and chemical resistance, Pipeline Certification, Independent FRP Pipeline Service. Read more. |
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Thermoplastics joints have been developed to solve the corrosion problem of bridges, sluices, dams and other structures. The different steel reinforements are to a greater or lesser extent susceptible to corrosion in the highly alkaline environment of concrete. As a consequence, the thermoplastic joint could provide some basic protection for the less durable materials solutions against diffusion and deterioration. In this paper, the combined aqueous immersion and sustained stress on the service life of a plastic joint is chararacterized. This is done by mechanical testing and simultaneous chemicals exposure. Click here to learn more. |
| Carbon Dioxide Loss from Cola Bottle |
In this case history we see the effect of diffusion of carbon dioxide through Polyethylene Terephthalate (PET) and Polyethylene Naphthalate (PEN) cola bottle walls, cap and capillary mass transfer (between cap and wall). Especially at lower gas pressures, the swelling of the polymer due to gas diffusion is less important than in case of liquid and vapour diffusion. But here, the shelf life of the bottled product is affected.
Please note that modern food and medical packaging materials often consist of more than one material layer, a so called laminate or multilayer material. One can think of combinations like High Density Polyethylene (HDPE), Ethylene Vinyl Alcohol (EVOH), PET, PEN, Polypropylene (PP), Nylon (PA) and Aluminum (AL) Foil. Determination of diffusion and migration rates of gases and liquids through most common multilayer materials can be carried out by the IDC-SAC Simulation Tool, using experimental mass and heat reference data of the individual materials, interfacial data, and experimental baseline data of the different laminate components and combinations of them. Learn more. |
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Usually we fill our tyres with Air. Nowadays there are several discussions in magazines and internet on whether it would be better to fill tyres with 100% Nitrogen or Carbon Dioxide instead of Air. The diffusion resistance layer of tyres are made from a polymer rubber called Polyisobutylene, and a few percent of Isoprene. In this case history it is shown that this polymer has a better diffusion resistance against Nitrogen than Oxygen. Moreover the practical implications of this difference are described.  |
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Here we demonstrate how mass transfer of liquids and saturated vapours is applied in an industrial application. We were commissioned to assess whether it is possible to use a GFRP (Unsaturated Polyester Glass Fibre Reinforced Plastic) pipeline for the transport of methanol. Apart from past effects of alkaline water transport on sustainability of this pipeline, it is shown how the methanol flux changes in the time period evaluated. In this example the counter diffusion of polluting chemicals in ground water was not taken into account. Read more. |
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In a wide range of industries, various composite and lining systems are used with the objective to combine good mechanical and chemical resistance properties. Key to a sustainable and - sometimes even - a multi-purpose service life, is chemical resistance and diffusion analysis in an early development stage.
The case of gasoline in a HDPE lined / coated Epoxy tank gives a clear insight in our approach. We have more information available on similar configurations, like hoses, tubes, adhesives, rubbers and elastomers for gasoline based on PA, PVDF, PPS including different kinds and degrees of reinforcements. Learn more. |
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We want to assess what sort of thermoplastic polymer we can use for containment of toluene at ambient conditions. A special design requirement is prevention of plasticizing of the material by toluene. This requirement is related to diffusion resistance: in many instances plasticizing causes the initial diffusion rate to increase several orders of magnitudes. This can be noticed from the figures in the table for liquid diffusion on the website. If a chemical has a high solubility in the polymer then the weighted average diffusion rate (D|) becomes much larger than the initial rate (D0). Read more...
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In glass fibre reinforced plastics (GFRP) or glass fibre metal laminates (FML's) the combination of the different components do substantially increase the mechanical properties of the material, think for example of high toughness, very long critical crack lengths, etc. At the same time the behaviour of these materials when exposed to chemicals, high pressure and high temperature is becoming more and more complex.
For fully integrated chemical-physical service life time predictions, the situation at the interface should often be the focal point of analysis and simulation. Here, possible voids do appears, temperature or swelling stress beyond the interfacial strength may come into play, cohesive strength, adhesive work, interlaminar shear strength values, pull and peel tests, etc. The attached paper is one of our first works on this subject and was published in the framework of ESAT 2006. Click here to learn more |
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