Concentration and temperature dependence of diffusional deborah number during dodecane transport in crosslinked polystyrene |
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Authors: | Dukjoon Kim Nikolaos A Peppas |
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Affiliation: | (1) Department of Chemical Engineering, Sung Kyun Kwan University, Suwon, Korea;(2) School of Chemical Engineering, Purdue University, 47907 West Lafayette, IN, USA |
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Abstract: | The diffusional Deborah number, De, defined as the ratio of characteristic relaxation time to characteristic diffusion time
was determined as a function of concentration and temperature in the dodecane transport process in polystyrene. The characteristic
relaxation time was obtained from the viscoelastic properties of dodecane/polystyrene systems measured by a dynamic mechanical
analyzer. The characteristic diffusion time was obtained from the concentration and temperature dependence of the diffusion
coefficient measured by NMR PGSE method. Above the room temperature the Deborah number changed significantly during isothermal
transport process; however, the transport mechanism did not deviate from the Fickian transport as the order of De was still
greater than 1. Around the room temperature the transport mechanisms represented by the resulting diffusional Deborah number
changed significantly as the order of magnitude approached 1 with the temperature decreasing from 50°C to the room temperature.
The transport mechanism predicted from the diffusional Deborah number was verified by the diffusional exponent, n, of an exponential
time-dependence of the penetrant uptake. |
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Keywords: | Diffusional Deborah Number Characteristic Relaxation Time Characteristic Diffusion Time Transport Process Viscoelastic Properties |
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