Preparation and Applications of Layered Silicates and Poly(oxyalkylene)amine Hybrids
| Autor: | I-Jein Cheng, 陳宜見 |
|---|---|
| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 In this research, the organic/inorganic hybrids were prepared, in which inorganic part is layered-silicate clay (Na+-montmorillonite or Na+-MMT). Due to highly hydrophilic properties of layer silicates and gallery cations, Na+-MMT is incompatible with polymer or organic solvents. To modify hydrophilic MMT by enlarging the basal-spacing of layered silicates in order to improve the miscibility is the main purpose of this research. In part one, the comb-like copolymers were prepared from the reaction of maleated polypropylene and poly(oxyalkylene)diamine. By the acidification of the end group amine of the copolymers, the quarternary amine salt can exchange with the Na+ in the layer silicate galleries. By using X-ray diffraction analysis, the enlarged basal-spacing was observed. This organic/inorganic hybrids have enhanced surfactancy and can be easily mix with polypropylene (PP) to form PP/clay nanocomposites. In part two, we proved that the basal-spacing of silicate layers were widened by using an increasing molecular weight of intercalating agent which had a backbone of polyoxypropylene (POP). With 2000 Mw POP, the basal spacing reached 58.0 Å (much larger than those reported and commercial organic clay: 30 Å) and able to be dispersible in organic solvents such as toluene and ethanol. The modified organic clay possessed critical micelle concentration (cmc) in toluene/water and effectively lowered the interfacial tension to 1.5 dyne/cm. (The origin interfacial tension between toluene/water is 36.0 dyne/cm) Besides, a thin film was obtained in toluene/water inter-phase. The film has mechanical properties and uniform crystal array clearly observed by SEM. In part three, the epoxy/clay nanocomposites were prepared. With loading the organophilc clay in epoxy polymer matrix, the layer silicates were completely exfoliated in the epoxy polymer matrix. With 10 wt% organoclay loading, the improved tensile strength (2.8 versus 0.3 MPa), flexural modulus (9.5 versus 3.0 Mpa), and elongation (81.2 versus 25.3 %) relative to pristine epoxy were obtained. Due to the silicate dispersion in epoxy matrix, the amount of solvent soaked in polymer was decreased in comparing with pure epoxy. In summary, the highly organophilic and large basal-spacing clay are surfactants. The organophilic clay can be blended with a wide spectrum of polymers to prepare polymer/clay nanocomposites which have better mechanical properties and thermal stability. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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