ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The phenomenological analysis of the thermal inversion membrane formation through spinodal decomposition was further developed to include enthalpic and entropic contributions to the Flory-Huggins interaction parameter. We found that material and processing conditions can be lumped into two parameters. One is the Deborah Number, De, which takes into account the thermal quenching relative to the phase separation induction time. The other one, designated as an ε-parameter, takes into account the quenching temperature relative to the spinodal temperature and the ratio of the enthalpic to the entropic contributions to the Flory-Huggins interaction parameter. From the model system, we found that the dimensionless interdomain distance, δ, as a function of 1/De (which is proportional to the cooling rate) falls in a relatively narrow banded region for all practical values of ε. As 1/De approaches infinity, δ is asymptotic up to maximum value of 3.5. This means that membranes made under applicable conditions will have a ratio of pore sizes of no more than 3.5. Other assumptions of the model are: (1) the mobility is temperature-independent; (2) the mutual diffusivity is a linear function of temperature; and (3) the thermal history (Temperature vs. Time), can be represented as two successive linear functions.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760312207
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