What makes cellulose auxetic?

IRG/WP 16-40767

A Asamoah, S Eichhorn, K Evans

The 1D bundles of cellulose microfibrils (lignified flax fibre) and 2D networks of cellulose mi-crofibrils form tunicate, bacterial and microfibrillated celluloses were strained in tension, and their molecular deformation followed by Raman spectroscopy in order to fully understand the origins and magnitudes of in-plane auxetics for the information of innovation. Cellulose is found to exhibit three distinct yielding. Both crystalline and amorphous cellulose are found to be auxe-tic so long as intermolecular hydrogen bonding remain intact. Auxetics of crystalline cellulose is found to be around unity (-1) while that of cellulose amorphous is found to be around twice (-2) that of crystalline cellulose with the possibility of 1D bundles of cellulose microfibrils registering auxetics higher than -7 in the absence of lignin. Though 2D networks of cellulose microfibrils enhance strain to failure, they also significantly limit auxetics of single 1D cellulose microfibrils in networks. Differences in auxetics between crystals and amorphous must predominantly arise from differences in intermolecular geometry. Similarity of in-plane auxetics of cellulose to the off-axis auxetics of zeolites (especially thomsonite zeolites) indicates the possibility of combining both semi-crystalline materials to produce functionalized composites with photo-electromechanical properties.


Keywords: axial, lateral, expansion, poisons, ratio and unusual

Conference: 16-05-15/19 Lisbon, Portugal


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