Synthesis and Characterization of Thermo-sensitive Hydrogel Membranes with Interpenetrating Networks Structure of Poly(N-isopropylacrylamide) and Poly(ethylene-co-vinyl alcohol)
| Autor: | Jiang-Yuan, Hu, 胡智遠 |
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| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 The gel membranes of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene-co-vinyl-alcohol) (PEVAL) with fully-interpenetrating polymer networks structure were prepared and characterized. The chemical structure of the gels could be confirmed by the infrared spectroscopy and element analysis. The morphology of the membranes became less porous when more PEVAL was added as the samples were freeze-dried and then observed by SEM. The differential scanning calorimetric, DSC, analysis showed there was only one glass transition temperature, Tg, in all of the xerogel membranes. It indicated that the amorphous portion of the gels was homogeneously blended by PNIPAAm and PEVAL. In addition, the more PEVAL was added, the lower glass transition temperature was obtained. There was also a crystalline region of PEVAL in the IPN gels. Thermal gravimetric analysis showed that the thermal decomposition temperature was shifted to 250 oC from the original thermal decomposition temperature of pure PNIPAAm, 360 oC, by adding PEVAL. As expected, the mechanical properties were significantly improved when PEVAL was added. The tensile strength, elongation and Young’s modulus of the N60E hydrogel membrane were better than N70E hydrogel membrane because the crystalline region of PEVAL could enhance the mechanical properties of hydrogels. The more PEVAL was added, the less swelling ratio of the membranes was. The swelling ratio of pure PNIPAAm membranes was 10 but it dropped to 1 if PEVAL content was more than 40%. When PEVAL was added, the LCST of the gels didn’t have much change but the extent of the thermal-responsive properties were reduced. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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