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Molecular statics of polymer configurations

Published online by Cambridge University Press:  31 January 2011

David J. Quesnel
Affiliation:
Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627
Lazhar Mazlout
Affiliation:
Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627
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Abstract

Molecular behaviors of single isolated chains of various lengths are simulated using four energy potentials: the twisting, bending, stretching, and Van der Waals potentials. The origin and analytical form of these potentials is discussed and easy-to-evaluate quantitative expressions are given. A physically based algorithm for energy minimization is developed and used to determine the static configurations of single chains in their lowest energy states. Not surprisingly, the majority of the energy minima found are local minima implying metastability, which is, of course, a central phenomena in noncrystalline material behavior. A progressive distortion approach is then used to suppress conformational variations that depend on initial conditions from developing, thus making possible study of the force displacement characteristics of single chains of various lengths. The single chain force-displacement curve found in this way has a form comparable with the gentle yield point observed in many bulk polymers but with an initial apparent elastic stiffness higher than that of bulk material. Some aspects of the fracture phenomena of single chains are also discussed.

Type
Articles
Copyright
Copyright © Materials Research Society 1988

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References

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