Effect of ?-irradiation dose for the oxygen diffusion into polymers

Kaptan, H. Yilmaz; Güven, Olgun

doi:10.1002/(sici)1097-4628(19970516)64:7<1291::aid-app7>3.0.co;2-e

Cited by 11 publications

(4 citation statements)

References 2 publications

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“…When vacuum-irradiated polymers are exposed to air, the radicals trapped in the material are transformed into peroxide radicals by the addition of molecular oxygen to the free radicals. Kaptan and Guven [69] have irradiated PMMA with γ radiation in a vacuum and reported a nine-line ESR spectrum. They also showed that the nine-line spectrum changed to a single-peak spectrum when exposed to air, due to the formation of an antisymmetric peroxide radical.…”

Section: Resultsmentioning

confidence: 99%

Fabrication and optical characterization of microstructures in poly(methylmethacrylate) and poly(dimethylsiloxane) using femtosecond pulses for photonic and microfluidic applications

2010

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We fabricated several microstructures, such as buried gratings, surface gratings, surface microcraters, and microchannels, in bulk poly(methylmethacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) using the femtosecond (fs) direct writing technique. A methodical study of the diffraction efficiency (DE) of the achieved gratings was performed as a function of scanning speed, energy, and focal spot size in both PMMA and PDMS. An optimized set of writing parameters has been identified for achieving efficient gratings in both cases. The highest DE recorded in a PDMS grating was ∼10% and ∼34% in a PMMA grating obtained with an 0:65 NA (40X) objective with a single scan. Spectroscopic techniques, including Raman, UV-visible, electron spin resonance (ESR), and physical techniques, such as laser confocal and scanning electron microscopy (SEM), were employed to examine the fs laser-modified regions in an attempt to understand the mechanism responsible for physical changes at the focal volume. Raman spectra collected from the modified regions of PMMA indicated bond softening or stress-related mechanisms responsible for structural changes. We have also observed emission from the fs-modified regions of PMMA and PDMS. An ESR spectrum, recorded a few days after irradiation, from the fs laser-modified regions in PMMA did not reveal any signature of free radicals. However, fs-modified PDMS regions exhibited a single peak in the ESR signal. The probable rationale for the behavior of the ESR spectra in PMMA and PDMS are discussed in the light of free radical formation after fs irradiation. Microchannels within the bulk and surface of PMMA were achieved as well. Microcraters on the surfaces of PMMA and PDMS were also accomplished, and the variation of structure properties with diverse writing conditions has been studied.

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Section: Resultsmentioning

confidence: 99%

Fabrication and optical characterization of microstructures in poly(methylmethacrylate) and poly(dimethylsiloxane) using femtosecond pulses for photonic and microfluidic applications

2010

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“…The maximum temperature where the reliable measurements were carried out was 50°C for PVAc irradiated to a 15-kGy dose. 11 The ln D versus inverse temperature plot is represented by a single line for PMMA. The same plot, however, shows a break at 35°C for PVAc.…”

Section: Resultsmentioning

confidence: 99%

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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“…The initiation of oxidation in the phenolic resins containing metallic oxides is fulfilled by superficial adsorption, when the free radicals may be easily converted due to the initial amounts of gaseous oxygen initially existing in the organic phase [22]. However, the catalytic auto-oxidation process is sustained either by the interaction between the filler and resin, or by the propagation of the oxidation chain [23].…”

Section: Discussionmentioning

confidence: 99%

Insight Into the Oxidative Degradation of Phenolic Resin Destined for the Corrosion Protection of Metallic Surfaces

ZAHARESCU,

BORBATH,

BORBATH

et al. 2023

J. Sci. Arts

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The effects on the stability under accelerated degradation of phenolic resin used for the corrosion inhibition of metallic surfaces in aeronautical and nuclear spare parts are evaluated by nonisothermal chemiluminescence (CL) at four different heating rates: 5, 10, 15, and 20 ⁰C min-1. The simulation of the interface interaction between the metallic bodies and protection layers is achieved by the addition of metallic oxides as corrosion promoters: Gd2O3, CeO2, Pr2O3, MgO, MnO2, Cr2O3, and In2O3. These metallic atoms may be the main alloying elements that are present in the compositions of special application products. The presence of a specific peak in the CL spectra between 160 and 177°C proves the oxidation activity of filler in the connection of electronic interference. The differences between the emission intensities of the studied formulations certify the unlike contributions of alloying components. The heating rate plays also the role of oxidation factor that influences the refreshing surrounding atmosphere. The present results define the thermal technological limits of peculiar operation conditions for any metallic item subjected to a high level of warranty. The initiation of degradation in phenolic resin is done by -irradiation when free fragments are provided for the interaction with metallic structures. The development of oxidation is analyzed by the modification of CL emission intensities from room temperature to 250°C. The diminution of this process parameter over 200°C is found an essential factor for the preservation of surface integrity.

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Effect of ?-irradiation dose for the oxygen diffusion into polymers

Cited by 11 publications

References 2 publications

Fabrication and optical characterization of microstructures in poly(methylmethacrylate) and poly(dimethylsiloxane) using femtosecond pulses for photonic and microfluidic applications

Fabrication and optical characterization of microstructures in poly(methylmethacrylate) and poly(dimethylsiloxane) using femtosecond pulses for photonic and microfluidic applications

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

Insight Into the Oxidative Degradation of Phenolic Resin Destined for the Corrosion Protection of Metallic Surfaces

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