Abstract
The degradation behavior and residual properties of epoxy/clay nanocomposites were studied after accelerated UV and moisture exposure. The nanocomposite was fabricated by in-situ polymerization after high speed shear mixing and ultrasonication of resin-organoclay mixture. The X-Ray diffraction analysis on cured composites showed the clay intergallery distance being over 4.4 nm, suggesting a mixture of full intercalation and exfoliation of clay. The neat epoxy and nanocomposites after UV exposure at varying durations were characterized to evaluate the changes in chemical element, topography and colour. SEM examination revealed that surface damage leads to microcracking after about 100-300 h of UV exposure. Thicker but shallower cracks were presented in nanocomposites, due to the diffusion barrier properties of organoclay with high aspect ratio. The excellent barrier properties also resulted in less discoloration with increasing clay content. However, the presence of transition metal ions such as Fe2+ or Fe3+ along with low molecular weight organic modifiers applied to the clay accelerated degradation of polymer in nanocomposites, counterbalancing the ameliorating effects brought by the barrier properties of clay. FTIR analysis indicated that photo-degradation generated carbonyl groups (C=O) by chain scission. The photo-degradation rate was slightly higher for the nanocomposites than for the neat epoxy. The residual flexural modulus after moisture absorption was higher for the nanocomposite with 5 wt% clay than the neat epoxy or nanocomposites with lower clay contents.
Original language | British English |
---|---|
Journal | International SAMPE Symposium and Exhibition (Proceedings) |
Volume | 51 |
State | Published - 2006 |
Event | SAMPE '06: Creating New Opportunities For The World Economy - Long Beach, CA, United States Duration: 30 Apr 2006 → 4 May 2006 |
Keywords
- Degradation
- Epoxy/clay nanocomposite
- Microcracking