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Thermal Breakage and Self-Healing of a Polymer Chain under Tensile Stress
We consider the thermal breakage of a tethered polymer chain of discrete
segments coupled by Morse potentials under constant tensile stress. The chain
dynamics at the onset of fracture is studied analytically by Kramers-Langer
multidimensional theory and by extensive Molecular Dynamics simulations in 1D-
and 3D-space. Comparison with simulation data in one- and three dimensions
demonstrates that the Kramers-Langer theory provides good qualitative
description of the process of bond-scission as caused by a {\em collective}
unstable mode. We derive distributions of the probability for scission over the
successive bonds along the chain which reveal the influence of chain ends on
rupture in good agreement with theory. The breakage time distribution of an
individual bond is found to follow an exponential law as predicted by theory.
Special attention is focused on the recombination (self-healing) of broken
bonds. Theoretically derived expressions for the recombination time and
distance distributions comply with MD observations and indicate that the energy
barrier position crossing is not a good criterion for true rupture. It is shown
that the fraction of self-healing bonds increases with rising temperature and
friction.Comment: 25 pages, 13 picture
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