MD simulations of supercooled polymeric liquids at the Coarse Grained resolution aim to find connections between the static and morphological properties of the system with its dynamics. The investigation of meaningful correlations between the many space- and time-scales involved in the dynamics of such systems can help us to understand more deeply the physics behind the glass transition. This Thesis work tackles two main areas of current interest, namely the rheology of complex solids and the dynamics of confined liquids, by means of Coarse Grained Molecular Dynamics simulations. It is found that the presence of polymer connectivity raises the elastic modulus G and the shear strength Ty of glassy and semicrystalline solids, but only the introduction of chain stiffness causes deviation from the atomic universal scaling between G and Ty. A universal scaling related to the cage dynamics is also studied in confined liquids, concluding that beta-relaxations have a complex, non-local nature.
Elasticity and scalings in amorphous solids and thin polymer films
2018
Abstract
MD simulations of supercooled polymeric liquids at the Coarse Grained resolution aim to find connections between the static and morphological properties of the system with its dynamics. The investigation of meaningful correlations between the many space- and time-scales involved in the dynamics of such systems can help us to understand more deeply the physics behind the glass transition. This Thesis work tackles two main areas of current interest, namely the rheology of complex solids and the dynamics of confined liquids, by means of Coarse Grained Molecular Dynamics simulations. It is found that the presence of polymer connectivity raises the elastic modulus G and the shear strength Ty of glassy and semicrystalline solids, but only the introduction of chain stiffness causes deviation from the atomic universal scaling between G and Ty. A universal scaling related to the cage dynamics is also studied in confined liquids, concluding that beta-relaxations have a complex, non-local nature.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/129882
URN:NBN:IT:UNIPI-129882