Structure Characterization of Nanocomposites by Synchrotron X-ray Rays
Stony Brook University, US
characterization, ultra-high molecular weight polyethylene, mineralization, synchrotron x-rays, clay
In this talk, we will demonstrate that simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques can contribute significantly to the structural analysis on several length scales in nanocomposites containing a soft matter matrix with embedded nanoscaled fillers (spheres, tubers/rods, plates). Three unique studies will be discussed: (1) Morphological changes in organoclays and nanocomposites were followed in real time during processing, which revealed the complex role of surfactant on the state of filler dispersion (i.e. intercalation and exfoliation) during preparation of polymer clay/nanocomposites. (2) The super-tough performance of nanocomposite films comprising ultra-high molecular weight polyethylene (UHMWPE) and modified carbon nanofiber (MCNF) was investigated. The mobile chains at the UHMWPE/MCNF interface appeared to be the key to overcome the barrier of large chain entanglements in the solid UHMWPE matrix and induce an unexpected large elongation-to-break ratio. (3) The bone mineralization process, i.e. the formation of calcium phosphate nanocrystals within the collagen superstructure, was studied by using fish bone samples with different degrees of mineralization. Detailed analysis revealed the information about the diameter of collagen fibrils, the orientation distribution of fibrils, the coherence length, the mineral crystal dimensions and orientation and the axially projected electron density profiles, etc. Combining with other information, a three-dimensional model was constructed to illustrate the spatial relationship between the collagen molecules and apatite crystals in the mineralized fibril.
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Nanotech 2007 Conference Program Abstract