The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Donald R Paul - One of the best experts on this subject based on the ideXlab platform.
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carbon dioxide sorption and plasticization of thin glassy Polymer Films tracked by optical methods
Macromolecules, 2012Co-Authors: Norman R Horn, Donald R PaulAbstract:Our previous publications have demonstrated that thin glassy Polymer Films respond to highly sorbing penetrants, such as CO2, quite differently than thick Films. These studies focused on CO2 permeation behavior and revealed that, for thin Films, CO2 permeability at constant CO2 pressure goes through a maximum followed by a continual decrease in permeability owing to physical aging. So far, thick and thin glassy Polymer Films have been compared in the context of permeability, but lack of substantial means of obtaining thin film sorption data has prevented adequate comparison of thick and thin Films in the context of gas solubility. In this paper, spectroscopic ellipsometry is used to obtain simultaneously the film thickness and CO2 sorption capacity for thin glassy Polymer Films. This allows a more comprehensive look at CO2 permeability, sorption, and diffusivity as a function of both CO2 pressure and exposure time. The evidence reported here suggests that thin film sorption behavior is substantially diffe...
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physical aging of thin glassy Polymer Films free volume interpretation
Journal of Membrane Science, 2006Co-Authors: Yongjiang Huang, Xiaoyan Wang, Donald R PaulAbstract:Abstract Previous studies have documented the dramatic effects of film thickness, at least compared to the bulk state, and the more modest effects of aging temperature and Polymer structure on physical aging of thin glassy Polymer Films. In this paper, these results are interpreted in terms of the free volume calculated from the refractive index, determined by ellipsometry, using the Lorentz–Lorenz equation. The relative progress of aging towards the final equilibrium state was determined using this approach. The free volume data were fitted to the Struik model for the self-retarding volume contraction on aging to obtain the thickness and temperature dependent parameters. The gas permeability versus aging time is related to the free volume computed from the refractive index. The effect of prior history on the aging of thin glassy Polymer Films was briefly explored.
Norman R Horn - One of the best experts on this subject based on the ideXlab platform.
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carbon dioxide sorption and plasticization of thin glassy Polymer Films tracked by optical methods
Macromolecules, 2012Co-Authors: Norman R Horn, Donald R PaulAbstract:Our previous publications have demonstrated that thin glassy Polymer Films respond to highly sorbing penetrants, such as CO2, quite differently than thick Films. These studies focused on CO2 permeation behavior and revealed that, for thin Films, CO2 permeability at constant CO2 pressure goes through a maximum followed by a continual decrease in permeability owing to physical aging. So far, thick and thin glassy Polymer Films have been compared in the context of permeability, but lack of substantial means of obtaining thin film sorption data has prevented adequate comparison of thick and thin Films in the context of gas solubility. In this paper, spectroscopic ellipsometry is used to obtain simultaneously the film thickness and CO2 sorption capacity for thin glassy Polymer Films. This allows a more comprehensive look at CO2 permeability, sorption, and diffusivity as a function of both CO2 pressure and exposure time. The evidence reported here suggests that thin film sorption behavior is substantially diffe...
Yongjiang Huang - One of the best experts on this subject based on the ideXlab platform.
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physical aging of thin glassy Polymer Films free volume interpretation
Journal of Membrane Science, 2006Co-Authors: Yongjiang Huang, Xiaoyan Wang, Donald R PaulAbstract:Abstract Previous studies have documented the dramatic effects of film thickness, at least compared to the bulk state, and the more modest effects of aging temperature and Polymer structure on physical aging of thin glassy Polymer Films. In this paper, these results are interpreted in terms of the free volume calculated from the refractive index, determined by ellipsometry, using the Lorentz–Lorenz equation. The relative progress of aging towards the final equilibrium state was determined using this approach. The free volume data were fitted to the Struik model for the self-retarding volume contraction on aging to obtain the thickness and temperature dependent parameters. The gas permeability versus aging time is related to the free volume computed from the refractive index. The effect of prior history on the aging of thin glassy Polymer Films was briefly explored.
Easan Sivaniah - One of the best experts on this subject based on the ideXlab platform.
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Structural colour using organized microfibrillation in glassy Polymer Films
Nature, 2019Co-Authors: Masateru M. Ito, Andrew H. Gibbons, Detao Qin, Handong Jiang, Koichiro Tanaka, Daisuke Yamamoto, Daisuke Yamaguchi, Easan SivaniahAbstract:The formation of microscopic cavities and microfibrils at stress hotspots in Polymers is typically undesirable and is a contributor to material failure. This type of stress crazing is accelerated by solvents that are typically weak enough not to dissolve the Polymer substantially, but which permeate and plasticize the Polymer to facilitate the cavity and microfibril formation process^ 1 – 3 . Here we show that microfibril and cavity formation in Polymer Films can be controlled and harnessed using standing-wave optics to design a periodic stress field within the film^ 4 . We can then develop the periodic stress field with a weak solvent to create alternating layers of cavity and microfibril-filled Polymers, in a process that we call organized stress microfibrillation. These multi-layered porous structures show structural colour across the full visible spectrum, and the colour can be tuned by varying the temperature and solvent conditions under which the Films are developed. By further use of standard lithographic and masking tools, the organized stress microfibrillation process becomes an inkless, large-scale colour printing process generating images at resolutions of up to 14,000 dots per inch on a number of flexible and transparent formats^ 5 , 6 .Standing-wave optics can be used to control microfibril and cavity formation in Polymer Films and the resulting porous layered structures can produce tunable structural colour, enabling inkless ‘printing’ of images.
Xiaoyan Wang - One of the best experts on this subject based on the ideXlab platform.
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physical aging of thin glassy Polymer Films free volume interpretation
Journal of Membrane Science, 2006Co-Authors: Yongjiang Huang, Xiaoyan Wang, Donald R PaulAbstract:Abstract Previous studies have documented the dramatic effects of film thickness, at least compared to the bulk state, and the more modest effects of aging temperature and Polymer structure on physical aging of thin glassy Polymer Films. In this paper, these results are interpreted in terms of the free volume calculated from the refractive index, determined by ellipsometry, using the Lorentz–Lorenz equation. The relative progress of aging towards the final equilibrium state was determined using this approach. The free volume data were fitted to the Struik model for the self-retarding volume contraction on aging to obtain the thickness and temperature dependent parameters. The gas permeability versus aging time is related to the free volume computed from the refractive index. The effect of prior history on the aging of thin glassy Polymer Films was briefly explored.