I&EC 14 |
| Electrically conductive bio-nanocomposites with enhanced mechanical properties are particularly attractive for biomedical applications such as bone implants and bone growth stimulation. Nanocomposites obtained from polylactic acid (PLA) and a new nano-sized reinforcing material, expanded graphite nanoplatelets (xGnP), showed increased mechanical properties coupled with a substantial decrease in electrical resistivity. Understanding the nanoscale interactions between the xGnP and the polymer matrix during crystallization is essential for controlling the nanoparticles dispersion and optimizing the nanocomposites processing conditions. We report here on the effects of xGnP on the melting and crystallization behavior of PLA/xGnP nanocomposites under isothermal and nonisothermal crystallization conditions. Hot-stage optical microscopy experiments were designed to characterize the size and distribution of PLA spherulitic structures formed in the presence of varying amounts of xGnP, and under different crystallization conditions. The melting and crystallization were also analyzed using differential scanning calorimetry (DSC), and the results of this classical thermal analysis method were correlated to nano-thermal analysis. While DSC provided quantitative information regarding the dependence of the degree of crystallinity on cooling rates, nanoTA offered the unique advantage of in-situ observation of the polymer's morphology, offering valuable information for practical applications requiring dynamic processing conditions. Atomic force microscopy was used for morphological analysis, as well as for the study of the effect of xGnP on the surface roughness of the resulted nanocomposites. This research is financially supported by EPA-STAR 2002 Award # R830904. |
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High Performance Composites, Sponsored by Advanced Materials and Nanotechnology Sub-Division
8:30 AM-11:50 AM, Sunday, 10 September 2006 Moscone Center -- Room 252/254, Oral
Division of Industrial & Engineering Chemistry |