55 research outputs found
Predictors of cavitation in glassy polymers under tensile strain: a coarse grained molecular dynamics investigation
The nucleation of cavities in a homogenous polymer under tensile strain is
investigated in a coarse-grained molecular dynamics simulation. In order to
establish a causal relation between local microstructure and the onset of
cavitation, a detailed analysis of some local properties is presented. In
contrast to common assumptions, the nucleation of a cavity is neither
correlated to a local loss of density nor, to the stress at the atomic scale
and nor to the chain ends density in the undeformed state. Instead, a cavity in
glassy polymers nucleates in regions that display a low bulk elastic modulus.
This criterion allows one to predict the cavity position before the cavitation
occurs. Even if the localization of a cavity is not directly predictable from
the initial configuration, the elastically weak zones identified in the initial
state emerge as favorite spots for cavity formation
Molecular dynamics simulations of glassy polymers
We review recent results from computer simulation studies of polymer glasses,
from chain dynamics around the glass transition temperature Tg to the
mechanical behaviour below Tg. These results clearly show that modern computer
simulations are able to address and give clear answers to some important issues
in the field, in spite of the obvious limitations in terms of length and time
scales. In the present review we discuss the cooling rate effects, and dynamic
slowing down of different relaxation processes when approaching Tg for both
model and chemistry-specific polymer glasses. The impact of geometric
confinement on the glass transition is discussed in detail. We also show that
computer simulations are very useful tools to study structure and mechanical
response of glassy polymers. The influence of large deformations on mechanical
behaviour of polymer glasses in general, and strain hardening effect in
particular are reviewed. Finally, we suggest some directions for future
research, which we believe will be soon within the capabilities of state of the
art computer simulations, and correspond to problems of fundamental interest.Comment: To apear in "Soft Matter
Confinement-Induced Stiffening of Thin Elastomer Films: Linear and Nonlinear Mechanics vs Local Dynamics
Reaction selectivity in a porous catalyst pellet: Analysis of a kinetic model of two parallel, first order, irreversible reactions with a second order inhibition kinetic term in one of them
Statistical calculation of elastic moduli for atomistic models
info:eu-repo/semantics/publishe
Stochastic Reassembly Strategy for Managing Information Complexity in Heterogeneous Materials Analysis and Design
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