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Plastic Deformation Mechanisms of Semicrystalline and Amorphous Polymers.

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Deformation mechanisms in the plastic flow regime of
amorphous polymers are rather well understood.
However, the underlying mechanisms of deformation in their
semi-crystalline counterparts are still controversial.

Because of the small length scales involved, it is not possible
to observe experimentally local mechanisms of plastic
deformation and to disentangle the deformations in ordered
and amorphous parts.

The aim of this research was to fill this gap by performing large-scale
molecular dynamics simulations of semicrystalline polymers
and by analyzing the evolution of polymer conformations and
crystalline domains along the stress−strain curve.

It is shown that the strain softening
regime is dominated by (i) deformation of crystallites
via reorientation of chain-folded lamellae toward the tensile
axis, (ii) fragmentation of largest crystalline domains, and (iii) a partial
loss of crystallinity. The strain-hardening regime coincides with
unfolding of chains and recrystallization as a result of strain induced
chain alignment. These results have made the cover of ACS Macro Letters.