Aligned mica flakes and colloidal zinc oxide can combine to reduce the acid permeability and increase the lag time in polyvinylalcohol (PVA) membranes. The permeability is reduced up to 10 times by the flakes, but is affected much less by the zinc oxide. The lag times are increased by up to 1000 times by a combination of flakes and reaction. The results can be estimated with theories for this transport, including variations with the square of the volume fraction of flakes and the first power of the zinc oxide concentration. These estimates are successful only when the flakes are evenly distributed within the membrane. When they are unevenly distributed, the apparent membrane permeability behaves differently. While the experiments use only polyvinylalcohol as a polymer, the same flakes and reactants will give the same relative permeability reductions with other, less permeable polymers.
Bibliographical noteFunding Information:
E.D. Grassl helped with the microscopy. This work was primarily supported by the US Air Force (AFOSR F49620-01-1-0333). Other support came from the Petroleum Research fund of the American Chemical Society (Grant 36528-AC9). Nancy K. Lape has a National Science Foundation Graduate Research Fellowship.
Copyright 2008 Elsevier B.V., All rights reserved.
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