Diffusion of oxygen into irradiated polypropylene films

Eken, Mahmut; Turhan, Şeref; Kaptan, Yilmaz; Güven, Olgun

doi:10.1016/0969-806x(95)00267-2

Cited by 18 publications

(11 citation statements)

References 3 publications

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“…In our previous works with PMAN, PP, PMMA, and PVAc, we gave the theory of oxygen diffusion in spherical particles, cylinders, and thin sheets and the relationship between the radical concentration at any time t , ( R t ) and D 4–8. Since in the present work the samples used had spherical shapes, brief theoretical information is given below that relates R t with D .…”

Section: Theorymentioning

confidence: 99%

“…The same quantity can also be determined from the slope of the ln ( R t / R 0 ) versus the time graph. Similar equations are also derived and used for other geometries, such as cylinders and thin sheets 7, 8…”

Section: Theorymentioning

confidence: 99%

“…Recently, using poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) as model systems, the oxygen‐diffusion mechanisms and kinetics were studied in considerable detail both theoretically and experimentally in our laboratories. In those studies, we determined the diffusion coefficients of oxygen for PMMA, PVAc, polymethacrylonitrile (PMAN) and polypropylene (PP) by ESR 4–8…”

Section: Introductionmentioning

confidence: 99%

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ESR study on the effect of temperature on the diffusion of oxygen into PMMA and PVAC polymers

Kaptan¹

1999

J. Appl. Polym. Sci.

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ABSTRACT:The free radicals produced by ␥ irradiation in the polymer network are formed with ionizing radiation. The decay rates of radicals in the temperature range were used to estimate the diffusion coefficient of oxygen into polymeric spheres by an electron spin resonance (ESR) technique. The ESR results showed that the activation energy of the diffusion of oxygen into poly(methyl methacrylate) (PMMA) in the temperature range 10 -40°C is 29.6 kJ/mol. There are two activation energies of the diffusion of oxygen into poly(vinyl acetate) (PVAc) in the temperature range 25-50°C. The activation energies below and above 35°C, which is the glass transition temperature of PVAc, were found to be 16.8 and 82.5 kJ/mol, respectively.

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ESR study on the effect of temperature on the diffusion of oxygen into PMMA and PVAC polymers

Kaptan¹

1999

J. Appl. Polym. Sci.

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“…The model was simulated for completely de-aerated PS, polypropylene (PP), and PET microplates. Polypropylene microplates, the second most commonly used microplate type, are similarly permeable toward oxygen as PS microplates due to comparable oxygen solubility and permeability coefficients (Eken et al, 1995;Yasuda and Stannett, 1999). With PET microplates, the gradient at the bottom of the well is much smaller than with PS or PP microplates due to lower solubility and diffusion coefficients of PET, resulting in slower oxygen diffusion through the microplate material into the sample.…”

Section: Heterogeneous Distribution Of Po 2 Within the Microplate Wellmentioning

confidence: 99%

Gas sensing in microplates with optodes: Influence of oxygen exchange between sample, air, and plate material

Arain¹,

Weiss²,

Heinzle³

et al. 2005

Biotech & Bioengineering

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Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2-sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection--that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters.

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“…If a contact lens is irradiated in vacuum and then exposed to air, the radicals trapped in the lens are transformed into peroxide radicals by the addition of molecular oxygen to the free radicals. This effect can be used as a tool to measure the oxygen uptake in irradiated material, and it is a well‐known technique 8–11…”

Section: Introductionmentioning

confidence: 99%

Investigation of oxygen diffusion into contact lenses using electron spin resonance spectroscopy

Aydin

Özgür

Özbey

et al. 2006

J of Applied Polymer Sci

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ABSTRACT:: Oxygen permeability is the most important parameter of contact lenses, as lack of oxygen causes corneal edema and threatens the vision of the patient. This study was unique in that it used an electron spin resonance (ESR) technique to determine the oxygen diffusion coefficient (D) of contact lenses. Although there are many methods and techniques for investigating oxygen diffusion into contact lenses, ESR was used for the first time in this study. The ESR technique is based on the scavenging of radicals produced in lenses by oxygen. As a contact lens is not a paramagnetic substance, it cannot give an ESR spectrum. But it does produce an ESR spectrum after ␥ irradiation. When a vacuumirradiated contact lens is exposed to air, the radicals trapped in the lens are transformed into peroxide radicals by the addition of molecular oxygen to the free radicals, and the ESR spectrum begins to change with time. This effect can be used as a tool to measure oxygen uptake in irradiated contact lenses. The oxygen diffusion coefficient of a contact lens was determined from changes in ESR signal intensity varying with time. The diffusion coefficients of oxygen for a contact lens were determined for rapid decay [(1.5 ϩ 0.4) ϫ 10 Ϫ8 cm 2 /s] and slow decay [(1.3 ϩ 0.3) ϫ 10 Ϫ9 cm 2 /s] in this study. These values are in agreement with the D values given in the literature for polymeric materials used for contact lenses.

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Diffusion of oxygen into irradiated polypropylene films

Cited by 18 publications

References 3 publications

ESR study on the effect of temperature on the diffusion of oxygen into PMMA and PVAC polymers

ESR study on the effect of temperature on the diffusion of oxygen into PMMA and PVAC polymers

Gas sensing in microplates with optodes: Influence of oxygen exchange between sample, air, and plate material

Investigation of oxygen diffusion into contact lenses using electron spin resonance spectroscopy

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