Abstract
Physical chemistry and microstructure of polyimide / clay nanocomposites were investigated in this study. Diffusion of diamine monomers into the clay gallery prior to polymerization was carefully controlled in order to demonstrate the physical constraint during the formation of the nanocomposites. In addition, diamines with different chemical reactivity were employed to show the effect of chemical reaction on the resultant composites. The microstructure and morphology were identified with X-ray diffraction (XRD) and transmission electron microscopy (TEM), while thermal gravimetric analysis (TGA) was performed to demonstrate the thermal stability of the composites.
XRD and TEM results indicate that the final properties and microstructure of the PI / clay nanocomposites were profoundly affected by both the diffusion and chemical reactivity of the monomers prior to the formation of polyamic acid and the subsequent thermal imidization had almost no effect. It should be emphasized that diffusion and chemical reactivity of the monomers are highly competitive. An exfoliated or intercalated nanocomposites can be formed only with a low-reactivity diamine and long enough diffusion time; this ensures polymerization was taken place within the clay gallery. On the other hand, a PI / clay blend is formed with insufficient diffusion time and high diamine reactivity. Under this circumstance, nearly all monomers were captured outside the clay gallery and a homo-polyimide was formed independent of clay. These results were consistent with observations from TGA. The maximum degradation temperature (Td) of the nanocomposite increased with increasing diffusion time; Td of the nanocomposites with low-reactivity 1,3-phenylenediamine was 30oC greater than the nanocomposites with high-reactivity 4,4¡¦-oxydianiline.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0808101-141256 |
| Date | 08 August 2001 |
| Creators | Yu, Chun-Lin |
| Contributors | Jeh-Jeng Wang, Wun-Gue Lee, Tzu-Chien J. Hsu |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0808101-141256 |
| Rights | off_campus_withheld, Copyright information available at source archive |
Page generated in 0.0021 seconds