ETD

Archivio digitale delle tesi discusse presso l'Università di Pisa

Tesi etd-11222021-213508


Tipo di tesi
Tesi di laurea magistrale
Autore
VOLPE, SHARON CAROL
URN
etd-11222021-213508
Titolo
Elastic and plastic response of a model porous glassy system
Dipartimento
FISICA
Corso di studi
FISICA
Relatori
relatore Prof. Leporini, Dino
correlatore Dott. Puosi, Francesco
Parole chiave
  • modeling & simulations
  • glass transition
  • phase separation
  • mechanical response
  • porous system
  • Molecular Dynamics
Data inizio appello
13/12/2021
Consultabilità
Non consultabile
Data di rilascio
13/12/2024
Riassunto
Porous materials have become a highly attractive topic in multiple research fields, thanks to the many and various applications which include energy storage and conversion, drugs delivery, tissue engineering. Polymers, in particular, provide several advantages as a constitutive material, since they are lightweight, do not contain heavy metals, and are highly functionalizable. Due to this growing interest and even to extend the applicability range, it is interesting to investigate the mechanical properties of these materials.
The aim of this thesis is to characterise via Molecular Dynamics (MD) simulations the mechanical response of a model porous glassy system, obtained by phase separation of a Coarse-Grained polymer melt.
After equilibration, the system is instantaneously quenched in temperature at constant volume. Negative pressure is created in the system, which leads to viscoelastic phase separation. For target temperatures below the glass transition, the process can be arrested, leading to a bicontinuous sponge-like structure
The mechanical response of the system is studied through the athermal quasi-static deformation protocol, which consists in applying elementary strain steps, followed by energy minimisation.
Young’s and shear modulus are found to be quite low, as one would expect for a porous system.
For large deformations, stress-strain curves show a highly intermittent behaviour, showing avalanches of plastic events.
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