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Tesi etd-06302016-102913


Thesis type
Tesi di laurea magistrale
Author
CALONACI, NICOLA
URN
etd-06302016-102913
Title
Elasticity and yielding in model polymer glasses
Struttura
FISICA
Corso di studi
FISICA
Commissione
relatore Prof. Leporini, Dino
Parole chiave
  • connectivity
  • polymers
  • glass transition
  • plasticity
  • elasticity
  • molecular dynamics
Data inizio appello
21/07/2016;
Consultabilità
completa
Riassunto analitico
The goal of this thesis is to characterize the mechanical response to deforma-<br>tions of a coarse-grained polymer model in the glassy state. In particular, we want<br>to relate the mechanical behaviour to connectivity. To this aim MD simulations are<br>performed with systematic variation of bond length and chain stiffness, which are<br>the interaction parameters determining the connectivity of the model. Mechanical<br>deformation is simulated via the Athermal Quasi-Static (AQS) procedure at zero<br>temperature. We show that connectivity does not directly affect the elastic shear<br>modulus. However, since the latter depend on the morphology of the solid state, con-<br>nectivity still plays a role as it determines the solidification behaviour of the model.<br>In the plastic regime, we show that the stress at yielding depends on the connectivity-<br>related parameters of the model. Moreover, we find a correlation between the elastic<br>shear modulus and the stress at yielding, compatible with experimental data reported<br>in the literature.
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