This talk discusses the characterization of cellulose nanocrystals via atomic force microscopy. Cellulose nanocrystals are crystaline fibers of cellulose that are 2 to 20 nm wide and 100 to 5000 nm long. They have potential applications in nanocomposites and thin films. Specifically, this talk addresses issues that arise when attempting to measure mechanical properties of nanostructres with force-displacement atomic force microscopy. An uncertainty analysis is performed for the measurement of transverse elastic modulus of an isolated cellulose nanocrystal. The transverse elastic modulus for this isolated crystal has a mean value of 8.8 GPa. It is shown that if one accounts for calibration, model, and measurement uncertainty the resulting uncertainty in transverse elastic modulus is large. The 95 % confidence interval for the transverse elastic modulus of the measured crystal is 2.8 to 22.0 GPa. The uncertainty is dominated by the nondimensional photodiode sensitivity.
Dr. Robert Moon is a Materials Research Engineer with the US Forest Service- Forest Products Laboratory (FPL) and an Adjunct Assistant Professor in the School of Materials Engineering at Purdue University. Dr. Moon received his B.S. degree in Metallurgy from the University of Wisconsin (1994), and his M.S. degree (1996) and PhD (2000) in Materials Engineering from Purdue University. His postdoctoral research (2000-2005) was completed within the School of Materials Science and Engineering at the University of New South Wales, Australia. His specialty is in processing-structure-property relationships of layered, gradient, and hierarchical structured materials and composites.
In 2005, Dr. Moon joined the FPL and has focused his expertise in the processing-structure-property relationships of cellulose nanoparticles and their composites. Critical to this, is developing the fundamental understanding as to the role of hierarchical structures and interfaces on the various mechanisms that dictate the properties at the nano, meso and macro length scales. In 2007, Dr. Moon was selected by FPL to lead a collaborative research program between Purdue University and FPL that advances nanoscale science and engineering of forestry based materials, primary focus of this effort is in cellulose nanoparticles and their composites.
Ryan Wagner is a graduate student at Purdue University in the school of mechanical engineering. He is co advised by Professors Arvind Raman and Robert Moon. His research interests include atomic force microscopy meteorology, cellulose nanocrystals, and uncertainty analysis techniques.
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Digital Learning Center, Purdue University, West Lafayette, IN