Preparation and Study of Porous Poly(vinyl formal) Foam
| Autor: | Cheng, Weiyu, 鄭偉佑 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 An environment friendly and hydrophilic route towards the synthesis of porous Poly(vinyl formal) foam is presented. Poly(vinyl alcohol) and formaldehyde hybrid materials were synthesized in aqueous medium by using sulfuric acid as catalyst, and compared the method of pore-forming agent with the phase separation phenomenon of porous PVF foam. With the use of the wheat starch and sodium silicate as pore-forming agent within the PVF matrix, in order to obtain an uniform pore size of PVF foam, the effect of the drainage process of PVA solution between two pore-forming cells shall be considered; a capillary suction effect on pressure difference between cell walls and Plateau borders leads to rapid cell walls continuous thinning. A PVF foam with an uniform pore size distribution can be obtained through the well control of the reaction rate, the viscosity and the surface tension of overall solution. A proposed correlation equation is presented in the present article, which can predict the the filter coefficient well under unfavorable deposition conditions. When comparing with available filtration experimental data for both large and small colloidal particles, we found that the present proposed correlation equation can give a good prediction on the filter coefficient of the present made PVF foam. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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