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The simulation of the packing of polymer molecules in crystals is, in a sense, computationally simple. The number of degrees of freedom to be considered is quite limited; they are comprised only of the atom coordinates of the repeat unit and the unit cell parameters. Energy minimization serves to define the structure and often yields very useful results. Computer strategies can be designed to allow...
In this article we review recent computational results on the dynamics of macromolecular crystals. From these studies it has been demonstrated that conformational defects can be created at temperatures as much as 100 K below the melting point of crystalline polyethylene and the concentration of the defects continues to increase (exponentially) with temperature, ultimately leading to a disordered crystal...
This article describes stochastic computer simulations of the local segmental dynamics of synthetic polymers. Particular attention is given to local dynamics in solution. Related work involving experimental methods, analytical theory, and molecular dynamics simulations will also be discussed. An introduction to the concepts involved in stochastic simulations will be presented. Methods of characterizing...
Molecular dynamics simulations have been performed on models of polyethylene (and n-alkane) liquids at their realistic bulk densities. The united atom approximation has been adopted. On stepwise cooling of the system under a constant pressure, the temperature coefficient of specific volume changes abruptly at a temperature mimicking the glass transition phenomenon observed in laboratory. The results...
Analytical and numerical approaches for the treatment of local chain dynamics are reviewed. Two main approaches are considered. First the dynamic rotational isomeric state (DRIS) formalism which has been developed as the dynamic counterpart of the classical rotational isomeric state theory of chain statistics is recapitulated and compared with other analytical treatments of chain conformational dynamics...
The mechanisms operative in diffusion and solubility of light gases in amorphous, dense polymer systems are discussed. Two types of methods used, Molecular Dynamics simulation and an approach based on Transition State Theory, are described. The methods prove to be complementary and to yield identical results in the areas where both can be independently applied.
A continuum mean field approach based on Generalized Flory Theory and the Polymer Reference Interaction Site Model is developed to describe the structural and equation of state properties of normal alkane liquids and linear polyethylene melts. Efficient Monte Carlo simulations based on a new algorithm that employs concerted rotations around up to seven consecutive skeletal bonds along a chain are...
Novel composite algorithms for efficient off-lattice simulations of dense polymer phases are implemented and evaluated in the case of polyethylene in the united and explicit atom approximations. The simulation algorithms are based on combinations of traditional methods with recently developed Monte Carlo moves. The classical Metropolis Monte Carlo (MMC) and Reptation techniques are supplemented with...
The recent development of a microscopic theory of the equilibrium properties of polymer solutions, melts and alloys based on off-lattice Polymer Reference Interaction Site Model (PRISM) integral equation methods is reviewed. Analytical and numerical predictions for the intermolecular structure and collective density scattering patterns of both coarse-grained and atomistic models of polymer melts are...
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