The Study of Factors Which Affect the Release Behavior of Poly- ureas and Polyureas-Polyamide Copolymer Microencapsule with the Homemade Analyzing Apparatus
| Autor: | Chang,Chii-Yang, 張啟源 |
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| Rok vydání: | 1993 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 81 Two kind of polymer skins of microencapsules(polyureas and polyureas-polyamide copolymer) are prepared by interfacial condensation polymerization. The core materials of micro- encapsules are organic solvents with pyrene included. At constant temperature the controlled release are observed in different extraction solvents. The apparent swollen behavior of polymer skins caused by ethanol and acetone used as extraction solvents can be observed by polarized optical microscopy.And it will lead to the increasing release rate of core materials. A variety of cross- linking agents with different carbon chain length or amounts or multifunctionality are selected in this experiments. The cross-linking agents are able to change the stiffness and cross-linking density of polymer skins. In other words,the swell effect of extraction solvents to polymer network struction change and then make the release rate different. We also find that the particle size and the thickness of skins of microencapsules are dependent on the viscosity of organic solvents and agitation rate in pre-emulsion process. Another feature of this report is a "release- analysis" apparatus designed by ourselves.It can make the released core materials be carried away immediately by flowing and reflash extraction solvents. The release magnitude can be detected by the optical density of pyrene which has specific UV absorption. It make the studies of released behavior of microencapsules more exactly and reliable. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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